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1
McNulty, Helene, and Kristina Pentieva. "Folate bioavailability." Proceedings of the Nutrition Society 63, no. 4 (November 2004): 529–36. http://dx.doi.org/10.1079/pns2004383.
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The achievement of optimal folate status to prevent neural-tube defects, and possibly other diseases, is hindered by the well-recognised incomplete bioavailability of the natural folates found in foods compared with the synthetic vitamin, folic acid. Folate bioavailability from different foods is considered to be dependent on a number of factors, including the food matrix, the intestinal deconjugation of polyglutamyl folates, the instability of certain labile folates during digestion and the presence of certain dietary constituents that may enhance folate stability during digestion. There is conflicting evidence as to whether the extent of conjugation of polyglutamyl folate (in the absence of specific inhibitors of deconjugation in certain foods) is a limiting factor in folate bioavailability. Estimates of the extent of lower bioavailability of food folates compared with folic acid (relative bioavailability) show great variation, ranging anywhere between 10 and 98%, depending on the methodological approach used. The lack of accurate data on folate bioavailability from natural food sources is of particular concern in those countries in which there is no mandatory folic acid fortification, and therefore a greater reliance on natural food folates as a means to optimise status. Apart from the incomplete bioavailability of food folates, the poor stability of folates in foods (particularly green vegetables) under typical conditions of cooking can substantially reduce the amount of vitamin ingested and thereby be an additional factor limiting the ability of food folates to enhance folate status. A recent workshop convened by the Food Standards Agency concluded that gaining a better understanding of folate bioavailability in representative human diets is a high priority for future research.
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Cossins, Edwin A. "Canadian Society of Plant Physiologists Gold Medal Review / Synthèse médaillée d'or de la Société canadienne physiologie végétaleThe fascinating world of folate and one-carbon metabolism." Canadian Journal of Botany 78, no. 6 (June 1, 2000): 691–708. http://dx.doi.org/10.1139/b00-061.
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Folate was first isolated from spinach leaves in 1941 and characterized as pteroylglutamic acid. Although plants, fungi, and bacteria synthesize folate de novo, animal cells lack key enzymes of the folate biosynthetic pathway and a dietary source of folate is required for normal growth and development. Folates have importance in human nutrition, health, and disease, and antifolate drugs are commonly used in cancer chemotherapy. In the majority of living cells folates occur as one-carbon substituted tetrahydropteroylpolyglutamate derivatives. These folates donate one-carbon groups during the synthesis of purines, formylmethionyl-tRNA, thymidylate, serine, and methionine. In the last 30 years, research on the folate biochemistry of plant species has intensified and been aided by the development of improved methods for folate isolation and characterization. These studies have resulted in basic information on the nature of plant folylpolyglutamates, folate biosynthesis, the enzymology of several folate-dependent reactions, and the roles of chloroplasts, mitochondria, and the cytosol in the pathways of one-carbon metabolism.Key words: plants, folates, folate biosynthesis, folate-dependent enzymes, one-carbon metabolism.
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Shulpekova, Yulia, Vladimir Nechaev, Svetlana Kardasheva, Alla Sedova, Anastasia Kurbatova, Elena Bueverova, Arthur Kopylov, Kristina Malsagova, Jabulani Clement Dlamini, and Vladimir Ivashkin. "The Concept of Folic Acid in Health and Disease." Molecules 26, no. 12 (June 18, 2021): 3731. http://dx.doi.org/10.3390/molecules26123731.
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Folates have a pterine core structure and high metabolic activity due to their ability to accept electrons and react with O-, S-, N-, C-bounds. Folates play a role as cofactors in essential one-carbon pathways donating methyl-groups to choline phospholipids, creatine, epinephrine, DNA. Compounds similar to folates are ubiquitous and have been found in different animals, plants, and microorganisms. Folates enter the body from the diet and are also synthesized by intestinal bacteria with consequent adsorption from the colon. Three types of folate and antifolate cellular transporters have been found, differing in tissue localization, substrate affinity, type of transferring, and optimal pH for function. Laboratory criteria of folate deficiency are accepted by WHO. Severe folate deficiencies, manifesting in early life, are seen in hereditary folate malabsorption and cerebral folate deficiency. Acquired folate deficiency is quite common and is associated with poor diet and malabsorption, alcohol consumption, obesity, and kidney failure. Given the observational data that folates have a protective effect against neural tube defects, ischemic events, and cancer, food folic acid fortification was introduced in many countries. However, high physiological folate concentrations and folate overload may increase the risk of impaired brain development in embryogenesis and possess a growth advantage for precancerous altered cells.
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Bagley, Pamela J., and Jacob Selhub. "Analysis of Folate Form Distribution by Affinity Followed by Reversed-Phase Chromatography with Electrochemical Detection." Clinical Chemistry 46, no. 3 (March 1, 2000): 404–11. http://dx.doi.org/10.1093/clinchem/46.3.404.
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Abstract Background: Naturally occurring folates exist in multiple forms, differing in pteridine ring structure and number of glutamate residues. The ability to measure these folate coenzymes in tissues and cells gives important information about in vivo folate metabolism. Methods: Folates were heat-extracted from biological samples. A two-column HPLC system with four-channel coulometric electrochemical detection was used for analysis. An affinity column was used first to purify folates from the extract. Purified folates were eluted from the affinity column onto a phenyl analytical column, utilizing a switching valve, and folate forms were separated using an acetonitrile gradient. Results: Folate forms differing in pteridine ring structure and number of glutamate chain residues were identified by retention time and characteristic response across the channels of the detector. Folates were quantified by comparison to an external calibration mixture. Limits of detection for pentaglutamyl folates ranged from 0.21 pmol for tetrahydrofolate to 0.41 pmol for 5-methyltetrahydrofolate. CVs (n = 5) for peaks containing 9–67 pmol of folate were 0.6–6.4% (within day) and 5.2–8.4% (between days). CVs (n = 5) for peaks containing 0.9–3.5 pmol folate were 5.7–16% (within day) and 8.4–13% (between days). Conclusions: This automated HPLC system allows the simultaneous determination of polyglutamyl forms of folates from biological samples, including tetrahydrofolate, 5-methyltetrahydrofolate, formylated folates, and pteroylglutamate. The low detection limits allow analysis of folate form distribution in human samples such as erythrocytes and lymphocytes.
5
Chan, Sherwin Y., and Edwin A. Cossins. "The Intracellular Distribution of Folate Derivatives in Pea Leaves." Pteridines 14, no. 1 (February 2003): 17–26. http://dx.doi.org/10.1515/pteridines.2003.14.1.17.
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Abstract After hydrolysis of polyglutamate derivatives, leaf extracts of pea (Pisum sativum L.) seedlings were examined for individual folates using high Performance liquid chromatography and microbiological assays employing Lactobacillus rhamnosus and Pediococcus acidilactici. 14-day seedlings contained 0.17±0.01 nmol folate mg-1 protein that was predominantly methylated and associated with the cytosolic fraction. Percoll gradient-purified mitochondria and chloroplasts contained 11.0±2.3% and 8.4±0.6% of cellular folate, respectively. Mitochondrial folates (0.47±0.11 nmol folate mg-1 protein) were predominately (90%) formylated and unsubstituted. In contrast, chloroplasts contained a less concentrated (0.02±0.001 nmol folate mg-1 protein) folate pool consisting of approximately 30% methylated folate. The total folate content of pea leaves increased by 40% when dark-grown (etiolated) 9-day seedlings were exposed to light for 48 hours. During this light treatment, the mitochondrial folate pool, on a per mg protein basis, increased 10-fold. This light treatment also changed the composition of the mitochondrial folate pool with a shift occurring from methylated to formylated and unsubstituted derivatives. These changes in the folates of greening tissues are discussed in relation to the metabolism of glycine and serine that accompanies photorespiration in leaf tissues.
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WIGERTZ, KARIN, ULLA K. SVENSSON, and MARGARETHA JÄGERSTAD. "Folate and folate-binding protein content in dairy products." Journal of Dairy Research 64, no. 2 (May 1997): 239–52. http://dx.doi.org/10.1017/s002202999700215x.
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Recent findings suggest a protective role for folates in the reduction of neural tube defects and possibly also coronary heart disease and cancer. Consequently, an increase in the daily intake of folates is warranted, which emphasizes the need for quantitative as well as qualitative measurements of dietary folates. Milk plays an important part in the food chain in many Western countries today. Several studies suggest that folate-binding proteins might have an impact on folate absorption and therefore their concentrations are also important. The mean concentration of the predominant form of folate, 5-methyltetrahydrofolate (5-CH3THF), was determined using HPLC in thirteen selected dairy products; skim milk powder, two pasteurized milks, UHT milk, two fermented milks, three whey products and four different cheeses. All results were corrected for recovery by spiking the samples with 5-CH3THF. Effects of storage of dairy products on 5-CH3THF concentrations were also investigated; generally small and insignificant fluctuations were found, except for hard cheese, in which 5-CH3THF decreased significantly. There was a significant seasonal variation in the folate concentration of pasteurized milk which peaked in the summer months. The concentrations of folate-binding protein in skim milk powder and pasteurized milk analysed using an enzyme-linked immunosorbent assay were similar. UHT milk and fermented milk, both of which are processed at temperatures >90°C, contained significantly lower concentrations of folate-binding protein.
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Chan, Sherwin Y., and Edwin A. Cossins. "The Intracellular Distribution of Folate Derivatives in Pea Leaves." Pteridines 14, no. 3 (August 2003): 17–26. http://dx.doi.org/10.1515/pteridines.2003.14.3.17.
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Abstract After hydrolysis of polyglutamate derivatives, leaf extracts of pea (Pisum sativum L.) seedlings were examined for individual folates using high performance liquid chromatography and microbiological assays employing Lactobacillus rhamnosus and Pediococcus acidilactici. 14-day seedlings contained 0.17+0.01 nmol folate mg'1 protein that was predominantly methylated and associated with the cytosolic fraction. Percoli gradient-purified mitochondria and chloroplasls contained 11,0±2.3% and 8.4±0.6% of cellular folate, respectively. Mitochondrial folates (0.47+0.11 nmol folate mg"' protein) were predominately (90%) formylatcd and unsubstituted. In contrast, chloroplasts contained a less concentrated (0.02±0.001 nmol folate mg"' protein) folate pool consisting of approximately 30% methylated folate.The total folate content of pea leaves increased by 40% when dark-grown (etiolated) 9-day seedlings were exposed to light for 48 hours. During this light treatment, the mitochondrial folate pool, on a per mg protein basis, increased 10-fold. This light treatment also changed the composition of the mitochondrial folate pool with a shift occurring from methylated to formylated and unsubstituted derivatives. These changes in the folates of greening tissues are discussed in relation to the metabolism of glycine and serine that accompanies photorespiration in leaf itssues.
8
Shohag, M. J. I., Yanyan Wei, Jie Zhang, Ying Feng, Michael Rychlik, Zhenli He, and Xiaoe Yang. "Genetic and physiological regulation of folate in pak choi (Brassica rapa subsp. Chinensis) germplasm." Journal of Experimental Botany 71, no. 16 (July 8, 2020): 4914–29. http://dx.doi.org/10.1093/jxb/eraa218.
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Abstract Folates are one of the essential micronutrients for all living organisms. Due to inadequate dietary intake, folate deficiency remains prevalent in humans. Genetically diverse germplasms can potentially be used as parents in breeding programs and also for understanding the folate regulatory network. Therefore, we investigated the natural genetic diversity of folates and their physiological regulation in pak choi (Brassica rapa subsp. Chinensis) germplasm. The total folate concentration ranged from 52.7 μg 100 gFW–1 to 166.9 μg 100 gFW–1, with 3.2-fold variation. The main folate vitamer was represented by 5-CH3-H4folate, with 4.5-fold variation. The activities of GTP cyclohydrolase I and aminodeoxy chorismate synthase, the first step of folate synthesis, were high in high folate accessions and low in low folate accessions. Analysis of the transcription levels of 11 genes associated with folate metabolism demonstrated that the difference in folate concentrations may be primarily controlled at the post-transcriptional level. A general correlation between total folate and their precursors was observed. Folate diversity and chlorophyll content were tightly regulated through the methyl cycle. The diverse genetic variation in pak choi germplasm indicated the great genetic potential to integrate breeding programs for folate biofortification and unravel the physiological basis of folate homeostasis in planta.
9
Khanal, S., J. Xue, R. Khanal, W. Xie, J. Shi, K. P. Pauls, and A. Navabi. "Quantitative Trait Loci Analysis of Folate Content in Dry Beans,Phaseolus vulgarisL." International Journal of Agronomy 2013 (2013): 1–9. http://dx.doi.org/10.1155/2013/983641.
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Dry beans (Phaseolus vulgarisL.) contain high levels of folates, yet the level of folate may vary among different genotypes. Folates are essential vitamins and folate deficiencies may lead to a number of health problems. Among the different forms of folates, 5-methyltetrahydrofolate (5MTHF) comprises more than 80% of the total folate in dry beans. The objectives of this paper were to compare selected genotypes of dry beans for the folate content of the dry seeds and to identify quantitative trait loci (QTL) associated with the folate content in a population derived from an inter-gene-pool cross of dry beans. The folate content was examined in three large-seeded (AC Elk, Redhawk, and Taylor) and one medium-seeded (Othello) dry bean genotypes, their six F1(i.e., one-way diallel crosses), and the F2of Othello/Redhawk that were evaluated in the field in 2009. Total folate and 5MTHF contents were measured twice with one-hour time interval. The significant variation (P<0.05) in the folate content was observed among the parental genotypes, their F1progeny, and members of the F2population, ranging from 147 to 345 μg/100 g. There was a reduction in the 5MTHF and total folate contents in the second compared to the first measurement. Dark red kidney variety Redhawk consistently had the highest and pinto Othello had the lowest total folate and 5MTHF contents in both measurements. A single marker QTL analysis identified three QTL for total folate and 5MTHF contents in the first measurement and one marker for the total folate in the second measurement in the F2. These QTL had significant dominance effects and individually accounted for 7.7% to 10.5% of the total phenotypic variance. The total phenotypic variance explained by the four QTL was 18% for 5MTHF and 19% for total folate in the first measurement, but only 8% for total folate in the second measurement.
10
Wright, Anthony J. A., Maria J. King, Caroline A. Wolfe, Hilary J. Powers, and Paul M. Finglas. "Comparison of (6S)-5-methyltetrahydrofolic acidv.folic acid as the reference folate in longer-term human dietary intervention studies assessing the relative bioavailability of natural food folates: comparative changes in folate status following a 16-week placebo-controlled study in healthy adults." British Journal of Nutrition 103, no. 5 (October 26, 2009): 724–29. http://dx.doi.org/10.1017/s0007114509992339.
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Folic acid (pteroylmonoglutamic acid) has historically been used as the reference folate in human intervention studies assessing the relative bioavailability of dietary folate. Recent studies using labelled folates indicated different plasma response kinetics to folic acid than to natural (food) folates, thus obviously precluding its use in single-dose experiments. Since differences in tissue distribution and site of biotransformation were hypothesised, the question is whether folic acid remains suitable as a reference folate for longer-term intervention studies, where the relative bioavailability of natural (food) folate is assessed based on changes in folate status. Healthy adults aged 18–65 years (n163) completed a 16-week placebo-controlled intervention study in which the relative bioavailability of increased folate intake (453 nmol/d) from folate-rich foods was assessed by comparing changes in plasma and erythrocyte folate concentration with changes induced by an equal reference dose of supplemental (6S)-5-methyltetrahydrofolic acid or folic acid. The relative increase in plasma folate concentration in the food group was 31 % when compared with that induced by folic acid, but 39 % when compared with (6S)-5-methyltetrahydrofolic acid. The relative increase in erythrocyte folate concentration in the food group when compared with that induced by folic acid was 43 %, and 40 % when compared with (6S)-5-methyltetrahydrofolic acid. When recent published observations were additionally taken into account it was concluded that, in principle, folic acid should not be used as the reference folate when attempting to estimate relative natural (food) folate bioavailability in longer-term human intervention studies. Using (6S)-5-methyltetrahydrofolic acid as the reference folate would avoid future results' validity being questioned.
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Sybesma, Wilbert, Marjo Starrenburg, Michiel Kleerebezem, Igor Mierau, Willem M. de Vos, and Jeroen Hugenholtz. "Increased Production of Folate by Metabolic Engineering of Lactococcus lactis." Applied and Environmental Microbiology 69, no. 6 (June 2003): 3069–76. http://dx.doi.org/10.1128/aem.69.6.3069-3076.2003.
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ABSTRACT The dairy starter bacterium Lactococcus lactis is able to synthesize folate and accumulates large amounts of folate, predominantly in the polyglutamyl form. Only small amounts of the produced folate are released in the extracellular medium. Five genes involved in folate biosynthesis were identified in a folate gene cluster in L. lactis MG1363: folA, folB, folKE, folP, and folC. The gene folKE encodes the biprotein 2-amino-4-hydroxy-6-hydroxymethyldihydropteridine pyrophosphokinase and GTP cyclohydrolase I. The overexpression of folKE in L. lactis was found to increase the extracellular folate production almost 10-fold, while the total folate production increased almost 3-fold. The controlled combined overexpression of folKE and folC, encoding polyglutamyl folate synthetase, increased the retention of folate in the cell. The cloning and overexpression of folA, encoding dihydrofolate reductase, decreased the folate production twofold, suggesting a feedback inhibition of reduced folates on folate biosynthesis.
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Hoey, Leane, Helene McNulty, Elizabeth M. E. McCann, Kelvin J. McCracken, John M. Scott, Barbara Blaznik Marc, Anne M. Molloy, Ciaren Graham, and Kristina Pentieva. "Laying hens can convert high doses of folic acid added to the feed into natural folates in eggs providing a novel source of food folate." British Journal of Nutrition 101, no. 2 (June 23, 2008): 206–12. http://dx.doi.org/10.1017/s0007114508995647.
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There are few good sources of natural food folates apart from green leafy vegetables and these may have a limited potential to increase folate status because of substantial losses that can occur during cooking. Fortified foods can overcome this but are controversial because of safety concerns regarding chronic exposure to high-dose folic acid (FA; the synthetic form). The aim of the present study was to develop eggs with an enriched natural folate content and minimal unmetabolised FA. Forty-eight, 30-week-old laying hens were randomised to receive the basal feed (formulated to provide 1 mg folate/kg feed) to which had been added one of the following FA levels (0, 2, 4, 8, 16, 32 mg/kg feed). Total folate was measured in eggs collected throughout the 12-week study period and the FA content estimated at 12 weeks. Results showed that the maximal egg folate content was achieved by adding 16 mg FA/kg feed. At this optimal dose, the total folate content per egg was 75 μg (compared with 32 μg in a regular egg) of which FA represented at most 10 %, a level which would probably be converted into natural folates by humans after ingestion. The results demonstrate that it is possible to use synthetic FA at high doses to produce novel animal foods enriched with natural folates in a cost-efficient process. Such foods may be particularly relevant to European populations without access to FA fortification and therefore dependent on natural food folate sources for the primary prevention of folate-related disease.
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Mizuno, Y., E. Kokue, N. Ohnishi, and Y. Toride. "Effect of oral administration of folate sources on plasma folate levels in pigs: Comparison between reduced and oxidized forms of folate." Canadian Journal of Animal Science 77, no. 3 (September 1, 1997): 497–502. http://dx.doi.org/10.4141/a96-088.
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Two experiments were conducted to evaluate the response of plasma folate levels after oral administration of oxidized or reduced forms of folates, using seven Göttingen minipigs. Plasma folate levels, tetrahydrofolate (THF) and 5-methyltetrahydrofolate (5CH3-THF), were determined by high-performance liquid chromatography with electrochemical detection. In exp. 1, the absorption of the oxidized form of folate [(synthetic folic acid(FA)] and the reduced forms of folate (5-formyltetrahydrofolate (5HCO-THF), liver powder and digested bacterial cell powder (DBCP) were evaluated by measuring changes in plasma folate levels after a single oral administration. Liver powder and DBCP contained much reduced forms of folate. The administration of the reduced form of folates increased plasma THF levels while the levels of plasma THF and 5CH3-THF decreased after FA administration. In exp. 2, plasma folate levels were measured after long-term oral administration of FA for 30 d. Immediately after the beginning of the administration, the levels of both THF and 5CH3-THF decreased significantly and remained at a low level during the 30-d administration. Supplementation of sow feed with FA has been recommended in many countries improving reproductive performance. The present study, however, suggests that the oral administration of an oxidized form of folate, FA, may not be as effective as previously thought, and the reduced forms of folate might be preferable for the supplementation of pig feeds. Key words: Folate (reduced), folic acid, pig, oral administration, bacterial cell wall, absorption
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Konings, Erik J. M., Freddy J. Troost, Jacqueline J. M. Castenmiller, Harry H. S. Roomans, Piet A. van den Brandt, and Wim H. M. Saris. "Intestinal absorption of different types of folate in healthy subjects with an ileostomy." British Journal of Nutrition 88, no. 3 (September 2002): 235–42. http://dx.doi.org/10.1079/bjn2002613.
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Our knowledge on the absorption of folate is incomplete. The deconjugation process as a possible limiting factor in the absorption of folates was investigated. The study also attempted to validate the use of the area under the serum response curve (AUC) from food compared with folic acid as a proxy variable for food folate bioavailability. Folate absorption was determined in healthy ileostomy volunteers (n11) using a single-dose short-term protocol. In a randomised crossover design, volunteers received spinach meals and a supplement. Based on analysis of test meals and ileostomy effluents, there was no difference in folate absorption between spinach with a mono-:polyglutamate ratio 40:60 and the same spinach with a 100:0 ratio. The absolute absorption of spinach folate (79 %) calculated from the difference between folate intake and folate content of ileostomy effluents was approximately equal to the relative absorption (81 %) calculated from the AUC after consumption of spinach meals in relation to the AUC after consumption of the folic acid supplement. We conclude that the deconjugation process is not a limiting factor in the absorption of spinach folates. Comparison of AUC of food folatev.folic acid in a short-term protocol may be suitable for assessing food folate bioavailability.
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Kulkarni, Medha V., C. P. Parameswaran Nair, and Gomathy Viswanathan. "Varying Folate Pattern in Different Strains of Mice Fed Coconut Oil and Sesame Seed Oil Diet." Pteridines 7, no. 4 (November 1996): 143–47. http://dx.doi.org/10.1515/pteridines.1996.7.4.143.
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Summary The effect of coconut oil feeding with and without cholesterol on folate metabolism in the two strains of mice, C57BL/6 and AKR have been studied. Liver total folate levels are higher in AKR mice. Coconut oil feeding markedly decreased the ratio of nonmethyl/methyl folates in C57BL/6 strain but not in AKR. Cholesterol supplementation to the coconut oil diet increased the percentage of monoglutamyl folates at the expense of polyglutamyl folates in both strains. Only C57BL/6 strain showed growth retardation on coconut oil feeding. The differences in hepatic folate metabolism between the two strains could possibly have an important role in determining their differences in susceptibility to diet induced atherosclerosis.
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Pfeiffer, Christine M., Maya R. Sternberg, Zia Fazili, David A. Lacher, Mindy Zhang, Clifford L. Johnson, Heather C. Hamner, et al. "Folate status and concentrations of serum folate forms in the US population: National Health and Nutrition Examination Survey 2011–2." British Journal of Nutrition 113, no. 12 (April 28, 2015): 1965–77. http://dx.doi.org/10.1017/s0007114515001142.
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Serum and erythrocyte (RBC) total folate are indicators of folate status. No nationally representative population data exist for folate forms. We measured the serum folate forms (5-methyltetrahydrofolate (5-methylTHF), unmetabolised folic acid (UMFA), non-methyl folate (sum of tetrahydrofolate (THF), 5-formyltetrahydrofolate (5-formylTHF), 5,10-methenyltetrahydrofolate (5,10-methenylTHF)) and MeFox (5-methylTHF oxidation product)) by HPLC–MS/MS and RBC total folate by microbiologic assay in US population ≥ 1 year (n approximately 7500) participating in the National Health and Nutrition Examination Survey 2011–2. Data analysis for serum total folate was conducted including and excluding MeFox. Concentrations (geometric mean; detection rate) of 5-methylTHF (37·5 nmol/l; 100 %), UMFA (1·21 nmol/l; 99·9 %), MeFox (1·53 nmol/l; 98·8 %), and THF (1·01 nmol/l; 85·2 %) were mostly detectable. 5-FormylTHF (3·6 %) and 5,10-methenylTHF (4·4 %) were rarely detected. The biggest contributor to serum total folate was 5-methylTHF (86·7 %); UMFA (4·0 %), non-methyl folate (4·7 %) and MeFox (4·5 %) contributed smaller amounts. Age was positively related to MeFox, but showed a U-shaped pattern for other folates. We generally noted sex and race/ethnic biomarker differences and weak (Spearman's r< 0·4) but significant (P< 0·05) correlations with physiological and lifestyle variables. Fasting, kidney function, smoking and alcohol intake showed negative associations. BMI and body surface area showed positive associations with MeFox but negative associations with other folates. All biomarkers showed significantly higher concentrations with recent folic acid-containing dietary supplement use. These first-time population data for serum folate forms generally show similar associations with demographic, physiological and lifestyle variables as serum total folate. Patterns observed for MeFox may suggest altered folate metabolism dependent on biological characteristics.
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Szpylka, John, Jon De Vries, Andrea Cheney, and Steve House. "Determination of Total Folates in Infant Formula and Adult Nutritionals by Trienzyme Extraction and UPLC-MS/MS Quantitation: First Action 2011.06." Journal of AOAC INTERNATIONAL 95, no. 6 (November 1, 2012): 1547–54. http://dx.doi.org/10.5740/jaoacint.cs2011_06.
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Abstract The method for “Determination of Total Folates in Infant Formula and Adult Nutritionals by Trienzyme Extraction and UPLC-MS/MS Quantitation” was submitted to the Folate Working Group for consideration for adoption as Official First Action by AOAC INTERNATIONAL. This method uses ultra performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) to determine the total folates in infant formulas and adult nutritionals after trienzyme digestion. Deconjugation of the various folate polyglutamates to folate monoglutamates is achieved by using rat plasma conjugase after the sample digestion with protease and α-amylase during the trienzyme digestion process. This method shows linearity of folate concentrations in the range of 10–19 100 μg/100 g. Extension of the range to cover folate concentrations of 5–2 000 000 μg/100 g can be achieved with appropriate adjustment of the sample weight and SPE cleanup loading volume. The recoveries ranged from 94.10 to 101.34%.
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Laiño, Jonathan Emiliano, Jean Guy LeBlanc, and Graciela Savoy de Giori. "Production of natural folates by lactic acid bacteria starter cultures isolated from artisanal Argentinean yogurts." Canadian Journal of Microbiology 58, no. 5 (May 2012): 581–88. http://dx.doi.org/10.1139/w2012-026.
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Folate is a B-group vitamin that cannot be synthesized by humans and must be obtained exogenously. Although some species of lactic acid bacteria (LAB) can produce folates, little is known about the production of this vitamin by yogurt starter cultures. Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus strains were isolated from artisanal Argentinean yogurts and were grown in folate-free culture medium (FACM) and nonfat milk after which intracellular and extracellular folate production were evaluated. From the initial 92 isolated LAB strains, 4 L. delbrueckii subsp. bulgaricus and 32 S. thermophilus were able to grow in the absence of folate. Lactobacillus delbrueckii subsp. bulgaricus CRL 863 and S. thermophilus CRL 415 and CRL 803 produced the highest extracellular folate levels (from 22.3 to 135 µg/L) in FACM. In nonfat milk, these strains were able to increase the initial folate concentrations by almost 190%. This is the first report where native strains of L. delbrueckii subsp. bulgaricus were shown to produce natural folate. The LAB strains identified in this study could be used in developing novel fermented products bio-enriched in natural folates that could in turn be used as an alternative to fortification with the controversial synthetic chemical folic acid.
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Sanderson, Peter, Helene McNulty, Pierpaolo Mastroiacovo, Ian F. W. McDowell, Alida Melse-Boonstra, Paul M. Finglas, and Jess F. Gregory. "Folate bioavailability: UK Food Standards Agency workshop report." British Journal of Nutrition 90, no. 2 (August 2003): 473–79. http://dx.doi.org/10.1079/bjn2003889.
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The UK Food Standards Agency convened a group of expert scientists to review current research investigating folate bioavailability. The workshop aimed to overview current research and establish priorities for future research. Discrepancies were observed in the evidence base for folate bioavailability, especially with regard to the relative bioavailability of natural folates compared with folic acid. A substantial body of evidence shows folic acid to have superior bioavailability relative to food folates; however, the exact relative bioavailability still needs to be determined, and in particular with regard to mixed diets. The bioavailability of folate in a mixed diet is probably not a weighted average of that in the various foods consumed; thus the workshop considered that assessment of folate bioavailability of whole diets should be a high priority for future research.
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Shaw, S., E. Jayatilleke, V. Herbert, and N. Colman. "Cleavage of folates during ethanol metabolism. Role of acetaldehyde/xanthine oxidase-generated superoxide." Biochemical Journal 257, no. 1 (January 1, 1989): 277–80. http://dx.doi.org/10.1042/bj2570277.
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Although folate deficiency and increased requirements for folate are observed in most alcoholics, the possibility that acetaldehyde generated from ethanol metabolism may increase folate catabolism has not been previously demonstrated. Folate cleavage was studied in vitro during the metabolism of acetaldehyde by xanthine oxidase, measured as the production of p-aminobenzoylglutamate from folate using h.p.l.c. Acetaldehyde/xanthine oxidase generated superoxide, which cleaved folates (5-methyltetrahydrofolate greater than folinic acid greater than folate) and was inhibited by superoxide dismutase. Cleavage was increased by addition of ferritin and inhibited by desferrioxamine (a tight chelator of iron), suggesting the importance of catalytic iron. Superoxide generated from the metabolism of ethanol to acetaldehyde in the presence of xanthine oxidase in vivo may contribute to the severity of folate deficiency in the alcoholic.
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Kesavan, V., N. Singh, M. S. Pote, and G. Viswanathan. "Synthesis and Regulation of Folate Coenzymes During early Germination in Vigna radiata." Pteridines 12, no. 4 (November 2001): 172–76. http://dx.doi.org/10.1515/pteridines.2001.12.4.172.
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Abstract Folate profiles and DNA synthesis were studied during the early germinating period in Vigna radiata. Total folate andmethyl folate forms were increased from 4 to 32 hours during germination period studied. Formyl folates, involved in purine synthesis, were raised 30-fold after 26 hours of incubation followed by DNA synthesis, indicatmg that folate synthesis precedes nucleotide synthesis channelising the one-carbon moieties into nucleotide precursors. This is also supported by the observation of folate mediated one-carbon pool incorporation of 2-'4C-Histidine into nucleic acid during this period. The two folate enzymes, folylpolyglutamate hydrolase which was greatly lowered and folylpolyglutamate synthetase which was significantly elevated, might playa crucial role regulating a balanced supply of the required folate precursors during the early germination period of Vigna radiata.
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Peters, Godefridus J., Ietje Kathmann, Clara Lemos, Jan Hendrik Hooijberg, Nienke Losekoot, and Gerrit Jansen. "Folate homeostasis of cancer cells affects sensitivity to not only antifolates but also other non-folate drugs: effect of MRP expression." Pteridines 24, no. 1 (June 1, 2013): 81–86. http://dx.doi.org/10.1515/pterid-2013-0019.
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AbstractSensitivity to antifolates can be decreased by endogenous or exogenous folates. Leucovorin protects cancer patients against toxicity of the dihydrofolate reductase inhibitor methotrexate (MTX), while folic acid is used to protect rheumatoid arthritis patients against MTX. Folates and antifolates can be effluxed from the cell by ABC transporters multidrug resistance protein 1 (MRP1), 2 and 3. We previously demonstrated in 2008 ovarian cancer cells that MRP overexpression reduced cellular folate content by 40%, while folate depletion increased expression of MRP1. As MRPs mediate resistance to several unrelated drugs, we investigated whether folate status would affect sensitivity to doxorubicin, daunorubicin, etoposide and vincristine. Ovarian cancer 2008 cells and its MRP1 transfected variant (2008/MRP1) were adapted from normal folate medium [2.3 μM; high folate (HF) cells] to short-term folate depletion (up to 7 days) (low folate cells); drugs were added after 2 days and sensitivity was tested by the MTT test after 3 additional days. The effect on folate homeostasis was evaluated by measurement of intracellular homocysteine using high-performance liquid chromatography and glutathione using a kit. MRP expression of wild-type (WT) 2008 cells did not increase homocysteine pools in 2008/MRP1 cells. Three day folate depletion increased homocysteine pools 23-fold in 2008 cells and 8.6-fold in the MRP variant. Folate depletion increased glutathione 20%–40% in 2008/WT and 2008/MRP1. In 2008 HF cells MRP1 expression did not affect sensitivity to MTX, but induced 4- to 10-fold resistance to doxorubicin, daunorubicin, etoposide and vincristine. Folate depletion decreased 50% growth inhibition (IC50) for MTX in both 2008 variants 25- to 4-fold, but that to doxorubicin and daunorubicin approximately 2-fold. Sensitivity to etoposide and vincristine was not affected. In conclusion, folate depletion markedly increased homocysteine, but moderately increased glutathione. Folate depletion increased MTX sensitivity, but effects on other drugs were most pronounced in WT cells, probably because MRP expression is already high in transfected variants.
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Gmelch, Lena, Daniela Wirtz, Michael Witting, Nadine Weber, Lisa Striegel, Philippe Schmitt-Kopplin, and Michael Rychlik. "Comprehensive Vitamer Profiling of Folate Mono- and Polyglutamates in Baker’s Yeast (Saccharomyces cerevisiae) as a Function of Different Sample Preparation Procedures." Metabolites 10, no. 8 (July 23, 2020): 301. http://dx.doi.org/10.3390/metabo10080301.
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Folates are a group of B9 vitamins playing an important role in many metabolic processes such as methylation reactions, nucleotide synthesis or oxidation and reduction processes. However, humans are not able to synthesize folates de novo and thus rely on external sources thereof. Baker’s yeast (Saccharomyces cerevisiae) has been shown to produce high amounts of this vitamin but extensive identification of its folate metabolism is still lacking. Therefore, we optimized and compared different sample preparation and purification procedures applying solid phase extraction (SPE). Strong anion exchange (SAX), C18 and hydrophilic–lipophilic-balanced (HLB) materials were tested for their applicability in future metabolomics studies. SAX turned out to be the preferred material for the quantitative purification of folates. Qualification of several folate vitamers was achieved by ultra-high pressure liquid chromatography quadrupole time of flight mass spectrometry (UHPLC-Q-ToF-MS) measurements and quantification was performed by liquid chromatography tandem mass spectrometry (LC-MS/MS) applying stable isotope dilution assays (SIDAs). The oxidation product s-pyrazino-triazine (MeFox) was included into the SIDA method for total folate determination and validation. Applying the best protocol (SAX) in regard to folate recovery, we analyzed 32 different vitamers in different polyglutamate states up to nonaglutamates, of which we could further identify 26 vitamers based on tandem-MS (MS2) spectra. Total folate quantification revealed differences in formyl folate contents depending on the cartridge chemistry used for purification. These are supposedly a result of interconversion reactions occurring during sample preparation due to variation in pH adjustments for the different purification protocols. The occurrence of interconversion and oxidation reactions should be taken into consideration in sample preparation procedures for metabolomics analyses with a focus on folates.
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Robinson, Bruce R., Carolina Garcia Salinas, Perla Ramos Parra, John Bamberg, Rocio I. Diaz de la Garza, and Aymeric Goyer. "Expression Levels of the γ-Glutamyl Hydrolase I Gene Predict Vitamin B9 Content in Potato Tubers." Agronomy 9, no. 11 (November 9, 2019): 734. http://dx.doi.org/10.3390/agronomy9110734.
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Biofortification of folates in staple crops is an important strategy to help eradicate human folate deficiencies. Folate biofortification using genetic engineering has shown great success in rice grain, tomato fruit, lettuce, and potato tuber. However, consumers’ skepticism, juridical hurdles, and lack of economic model have prevented the widespread adoption of nutritionally-enhanced genetically-engineered (GE) food crops. Meanwhile, little effort has been made to biofortify food crops with folate by breeding. Previously we reported >10-fold variation in folate content in potato genotypes. To facilitate breeding for enhanced folate content, we attempted to identify genes that control folate content in potato tuber. For this, we analyzed the expression of folate biosynthesis and salvage genes in low- and high-folate potato genotypes. First, RNA-Seq analysis showed that, amongst all folate biosynthesis and salvage genes analyzed, only one gene, which encodes γ-glutamyl hydrolase 1 (GGH1), was consistently expressed at higher levels in high- compared to low-folate segregants of a Solanum boliviense Dunal accession. Second, quantitative PCR showed that GGH1 transcript levels were higher in high- compared to low-folate segregants for seven out of eight pairs of folate segregants analyzed. These results suggest that GGH1 gene expression is an indicator of folate content in potato tubers.
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Selhub, J., D. Emmanouel, T. Stavropoulos, and R. Arnold. "Renal folate absorption and the kidney folate binding protein. I. Urinary clearance studies." American Journal of Physiology-Renal Physiology 252, no. 4 (April 1, 1987): F750—F756. http://dx.doi.org/10.1152/ajprenal.1987.252.4.f750.
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The kidney possesses a high concentration of a folate binding protein (FBP) that resides primarily in the brush-border membrane (BBM) of the proximal tubular cells. To assess the possible involvement of this protein in renal conservation of folate we determined the urinary clearance, in rats, of three forms of folates with sharply different affinities for FBP. After single intravenous injections of 0.1 to 1.0-nmol doses of radioactive folates the urinary clearance based on radioisotope determination was in the sequence: folic acid less than 5-methyltetrahydrofolate (5-CH3 THF) much less than methotrexate. At higher doses the urinary folate clearance was increased and the differences between the three injected forms were narrowed and were no longer noticeable at 100-nmol doses. Under conditions of continuous infusion to attain plasma folate levels of 2.3-5.7 pmol/ml, the urinary clearance based on chromatographic analyses of plasma and urine after correction for plasma folate binding was 0.20 ml/min for folic acid, 0.37 ml/min for 5-CH3 THF, and 1.76 ml/min for methotrexate. These chromatographic analyses have also shown the presence in both plasma and urine of metabolites formed from infused folates. Metabolites found after infusion of folic acid include 5-CH3 THF with a urinary clearance of 0.3 ml/min and an unknown with a urinary clearance of 0.8 ml/min. The latter metabolite appears also to occur in plasma and urine after infusion of 5-CH3 THF. Infusion of methotrexate was associated with the appearance of a metabolite with a urinary clearance of 2.5 ml/min. This sequence of urinary clearance is in inverse order to the affinities of these three forms of folate for the kidney BBM FBP.(ABSTRACT TRUNCATED AT 250 WORDS)
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Büttner, Barbara E., Veronica E. Öhrvik, Peter Köhler, Cornelia M. Witthöft, and Michael Rychlik. "Quantification of Isotope-Labeled and Unlabeled Folates and Folate Catabolites in Urine Samples by Stable Isotope Dilution Assay." International Journal for Vitamin and Nutrition Research 83, no. 2 (April 1, 2013): 112–21. http://dx.doi.org/10.1024/0300-9831/a000152.
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Dual-label stable isotope dilution assays for the simultaneous quantification of isotopologic folates in clinical samples offer the perspective for differentiating between unlabeled folates from endogenous body pools and administered [13C5]-labeled folates from a test dose when performing bioavailability trials. In contrast to intact folates, this methodology could hitherto not be applied to the quantification of the folate catabolites, p-aminobenzoyl glutamate and p-acetamidobenzoyl glutamate. In this study, [2H4]-p-aminobenzoyl glutamate, [2H4]-p-acetamidobenzoyl glutamate, and unlabeled p-acetamidobenzoyl glutamate were synthesized. The synthesis of the [2H4]-labeled compounds started at unlabeled p-aminobenzoic acid. For the formation of p-acetamidobenzoyl glutamate, p-aminobenzoyl glutamate was acetylated. The new substances were applied successfully in stable isotope dilution assays for the simultaneous quantification of the [13C5]-labeled and unlabeled folate catabolites, p-aminobenzoyl glutamate and p-acetamidobenzoyl glutamate, along with the predominant folate vitamers in urine. The assays were based on clean-up by strong anion exchange followed by liquid chromatography-tandem mass spectrometry detection. Assay sensitivity was sufficient to detect the folate catabolites in physiologic concentrations. The limit of detection was below 0.4 and 0.3 nmol/100 g for p-aminobenzoyl glutamate isotopologues and p-acetamidobenzoyl glutamate isotopologues in urine, respectively. The successful synthesis of [2H4]-p-aminobenzoyl glutamate, [2H4]-p-acetamidobenzoyl glutamate, and unlabeled p-acetamidobenzoyl glutamate and the implementation of these substances in stable isotope dilution assays allows dual-label designs that provide a more detailed insight into human folate metabolism.
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Qiu, Andong, Sang Hee Min, Michaela Jansen, Usha Malhotra, Eugenia Tsai, Diane C. Cabelof, Larry H. Matherly, Rongbao Zhao, Myles H. Akabas, and I. David Goldman. "Rodent intestinal folate transporters (SLC46A1): secondary structure, functional properties, and response to dietary folate restriction." American Journal of Physiology-Cell Physiology 293, no. 5 (November 2007): C1669—C1678. http://dx.doi.org/10.1152/ajpcell.00202.2007.
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This laboratory recently identified a human gene that encodes a novel folate transporter [ Homo sapiens proton-coupled folate transporter ( HsPCFT); SLC46A1] required for intestinal folate absorption. This study focused on mouse ( Mus musculus) PCFT ( MmPCFT) and rat ( Rattus norvegicus) PCFT ( RnPCFT) and addresses their secondary structure, specificity, tissue expression, and regulation by dietary folates. Both rodent PCFT proteins traffic to the cell membrane with the NH2- and COOH-termini accessible to antibodies targeted to these domains only in permeabilized HeLa cells. This, together with computer-based topological analyses, is consistent with a model in which rodent PCFT proteins likely contain 12 transmembrane domains. Transport of [3H]folates was optimal at pH 5.5 and decreased with increasing pH due to an increase in Km and a decrease in Vmax. At pH 7.0, folic acid and methotrexate influx was negligible, but there was residual (6 S)5-methyltetrahydrofolate transport. Uptake of folates in PCFT-injected Xenopus oocytes was electrogenic and pH dependent. Folic acid influx Km values of MmPCFT and RnPCFT, assessed electrophysiologically, were 0.7 and 0.3 μM at pH 5.5 and 1.1 and 0.8 μM at pH 6.5, respectively. Rodent PCFTs were highly specific for monoglutamyl but not polyglutamyl methotrexate. MmPCFT mRNA was highly expressed in the duodenum, proximal jejunum, liver, and kidney with lesser expression in the brain and other tissues. MmPCFT protein was localized to the apical brush-border membrane of the duodenum and proximal jejunum. MmPCFT mRNA levels increased ∼13-fold in the proximal small intestine in mice fed a folate-deficient vesus folate-replete diet, consistent with the critical role that PCFT plays in intestinal folate absorption.
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Mikhailyukova, V. A. "An Ideal Folate: Myth or Reality?" Doctor.Ru 19, no. 8 (2020): 55–60. http://dx.doi.org/10.31550/1727-2378-2020-19-8-55-60.
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Objective of the Review: To assess the benefits and risks of using various doses and forms of folic acid as part of pre-conception care and during pregnancy. Key Points: Folic acid (vitamin B9) is known to be an essential microelement, required for DNA replication and several enzyme reactions in amino acid synthesis and metabolism of vitamins. During pregnancy folate requirements rise. According to Order No. 572n of the Russian Federation Ministry of Health, dated November 1, 2012, women should receive folic acid starting in the pre-conception period at doses not exceeding 400 μg/day. A pregnant woman’s folate status is critical for the prevention of folate-associated birth defects and for the baby’s postnatal development. There is still some controversy about the advantages of different forms of folates, the safety of low and high folate doses, the duration of treatment, and the benefits of folates compared with multivitamins. Conclusion: Currently, there is no doubt that women should receive vitamin-mineral products containing folic acid as part of their preconception care and during pregnancy. There is a need, however, for a formal federal protocol for pre-conception care that will guide the use of vitamin-mineral products containing various forms of folates and describe a personalized approach to micronutrient support for various categories of women, including its composition, doses, and duration. Keywords: folates, folic acid, 5-methyltetrahydrofolate, pregnant women, newborns, disorders of pregnancy, Femibion Natalcare.
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Samodelov, Sophia L., Zhibo Gai, Gerd A. Kullak-Ublick, and Michele Visentin. "Renal Reabsorption of Folates: Pharmacological and Toxicological Snapshots." Nutrients 11, no. 10 (October 2, 2019): 2353. http://dx.doi.org/10.3390/nu11102353.
Full textAbstract:
Folates are water-soluble B9 vitamins that serve as one-carbon donors in the de novo synthesis of thymidylate and purines, and in the conversion of homocysteine to methionine. Due to their key roles in nucleic acid synthesis and in DNA methylation, inhibiting the folate pathway is still one of the most efficient approaches for the treatment of several tumors. Methotrexate and pemetrexed are the most prescribed antifolates and are mainly used in the treatment of acute myeloid leukemia, osteosarcoma, and lung cancers. Normal levels of folates in the blood are maintained not only by proper dietary intake and intestinal absorption, but also by an efficient renal reabsorption that seems to be primarily mediated by the glycosylphosphatidylinositol- (GPI) anchored protein folate receptor α (FRα), which is highly expressed at the brush-border membrane of proximal tubule cells. Folate deficiency due to malnutrition, impaired intestinal absorption or increased urinary elimination is associated with severe hematological and neurological deficits. This review describes the role of the kidneys in folate homeostasis, the molecular basis of folate handling by the kidneys, and the use of high dose folic acid as a model of acute kidney injury. Finally, we provide an overview on the development of folate-based compounds and their possible therapeutic potential and toxicological ramifications.
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Natsuhori, M., M. Shimoda, and E. Kokue. "Alteration of plasma folates in gestating sows and newborn piglets." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 270, no. 1 (January 1, 1996): R99—R104. http://dx.doi.org/10.1152/ajpregu.1996.270.1.r99.
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Plasma folates tetrahydrofolate (THF) and N5-methyltetrahydrofolate (5MF) were determined in nongestating, gestating, and lactating sows (2 to 4 yr old, 2-6 parities, n = 88) and in newborn, growing, and finishing pigs (0 to 158 days old, n = 191) with the use of high-performance liquid chromatography with an electrochemical detector. Plasma folates after folic acid injection (1 mg/kg iv) were also monitored in 2-day-, 2-wk-, and 2-mo-old pigs. In sows, plasma folates decreased significantly as pregnancy advanced. This was mainly due to the decrease of THF, which must be caused by the folate supply from the maternal body to the fetuses. In newborn piglets, levels of “total” plasma folates were much higher than those in adults (nongestating sows), and 5MF was the major folate content. This result may be related to the observation that, after folic acid injection, newborn piglets showed much higher metabolic activity of folic acid to 5MF than adults. Rapid and drastic decrease of plasma folate was observed during nursing in piglets, which is considered to be associated with the decrease of the metabolic activity of folic acid and rapid expansion of body volume together with negative folate intake during the nursing period.
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Ruggeri, Stefania, Elisa De Arcangelis, Altero Aguzzi, Maria Cristina Messia, and Emanuele Marconi. "Design of Cereal Products Naturally Enriched in Folate from Barley Pearling By-Products." Nutrients 14, no. 18 (September 10, 2022): 3729. http://dx.doi.org/10.3390/nu14183729.
Full textAbstract:
Folate is a fundamental vitamin for human health in prevention of many diseases; however, unfortunately its deficiency is widespread, so a greater availability of folate rich foods is desirable. The aim of this study was to design new cereal products naturally enriched in folate using barley flour from pearling as ingredient. Folate content of unfortified and fortified commercial grain-based products was considered to identify the best ingredients for new formulation and for folate content comparisons. Nineteen Italian barley cultivars were evaluated for their folate content and Natura was chosen for its highest folate levels = 69.3 μg/100 g f.w. Application of pearling gave a by-product flour with a high folate level: 221.7 ± 7.0 μg/100 g; this flour was employed to design pasta and biscuits naturally enriched in folate: 87.1 μg/100 g and 70.1 ± 3.7 μg/100 g f.w., respectively. Folate content of new products is higher than commercial samples: 39.2 μg/100 g in refined pasta, 60.4 μg/100 g in wholemeal pasta, 62.1 μg/100 g in fortified biscuits and 10.4 μg/100 g in unfortified ones. Enriched pasta had higher folate retention (68.5%) after cooking compared to the fortified one (27.8%). This research shows promising results concerning the pearling technique to design new cereal products naturally enriched in folates.
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Sybesma, Wilbert, Erwin van den Born, Marjo Starrenburg, Igor Mierau, Michiel Kleerebezem, Willem M. de Vos, and Jeroen Hugenholtz. "Controlled Modulation of Folate Polyglutamyl Tail Length by Metabolic Engineering of Lactococcus lactis." Applied and Environmental Microbiology 69, no. 12 (December 2003): 7101–7. http://dx.doi.org/10.1128/aem.69.12.7101-7107.2003.
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ABSTRACT The dairy starter bacterium Lactococcus lactis is able to synthesize folate and accumulates >90% of the produced folate intracellularly, predominantly in the polyglutamyl form. Approximately 10% of the produced folate is released into the environment. Overexpression of folC in L. lactis led to an increase in the length of the polyglutamyl tail from the predominant 4, 5, and 6 glutamate residues in wild-type cells to a maximum of 12 glutamate residues in the folate synthetase overproducer and resulted in a complete retention of folate in the cells. Overexpression of folKE, encoding the bifunctional protein 2-amino-4-hydroxy-6-hydroxymethyldihydropteridine pyrophosphokinase and GTP-cyclohydrolase I, resulted in reduction of the average polyglutamyl tail length, leading to enhanced excretion of folate. By simultaneous overexpression of folKE and folC, encoding the enzyme folate synthetase or polyglutamyl folate synthetase, the average polyglutamyl tail length was increased, again resulting in normal wild-type distribution of folate. The production of bioavailable monoglutamyl folate and almost complete release of folate from the bacterium was achieved by expressing the gene for γ-glutamyl hydrolase from human or rat origin. These engineering studies clearly establish the role of the polyglutamyl tail length in intracellular retention of the folate produced. Also, the potential application of engineered food microbes producing folates with different tail lengths is discussed.
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Hunter, Tracy S. "L-methylfolate in the Therapeutic Management of Major Depressive Disorder." Journal of Pharmacy Practice 21, no. 4 (July 22, 2008): 278–86. http://dx.doi.org/10.1177/0897190008318132.
Full textAbstract:
Optimal levels of the bioactive folate are necessary for maintaining proper brain and body functioning. Folate deprivation and impaired folate metabolism are clinically associated with defects in the developing nervous system. Numerous studies implicate a deficiency of bioactive folate with an increased risk of major depressive disorder and other neuropsychiatric disorders. Bioactive forms of folate, particularly L-methylfolate, have been found to augment the therapeutic efficacy of antidepressants in patients with major depressive disorder, who fail to adequately respond to standard therapies. The antidepressant action of L-methylfolate appears to improve treatment outcomes most effectively when administered as an adjuvant to traditional antidepressants. This new understanding of the role of folates in major depressive disorder and other mood disorders offers opportunities to improve treatment outcomes.
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Sid, Victoria, Yaw L. Siow, and Karmin O. "Role of folate in nonalcoholic fatty liver disease." Canadian Journal of Physiology and Pharmacology 95, no. 10 (October 2017): 1141–48. http://dx.doi.org/10.1139/cjpp-2016-0681.
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Nonalcoholic fatty liver disease (NAFLD) is a spectrum of chronic liver conditions that are characterized by steatosis, inflammation, fibrosis, and liver injury. The global prevalence of NAFLD is rapidly increasing in proportion to the rising incidence of obesity and type 2 diabetes. Because NAFLD is a multifaceted disorder with many underlying metabolic abnormalities, currently, there is no pharmacological agent that is therapeutically approved for the treatment of this disease. Folate is a water-soluble B vitamin that plays an essential role in one-carbon transfer reactions involved in nucleic acid biosynthesis, methylation reactions, and sulfur-containing amino acid metabolism. The liver is the primary organ responsible for storage and metabolism of folates. Low serum folate levels have been observed in patients with obesity and diabetes. It has been reported that a low level of endogenous folates in rodents perturbs folate-dependent one-carbon metabolism, and may be associated with development of metabolic diseases such as NAFLD. This review highlights the biological role of folate in the progression of NAFLD and its associated metabolic complications including obesity and type 2 diabetes. Understanding the role of folate in metabolic disease may position this vitamin as a potential therapeutic for NAFLD.
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Alam, Camille, Susanne Aufreiter, Constantine J. Georgiou, Md Tozammel Hoque, Richard H. Finnell, Deborah L. O’Connor, I. David Goldman, and Reina Bendayan. "Upregulation of reduced folate carrier by vitamin D enhances brain folate uptake in mice lacking folate receptor alpha." Proceedings of the National Academy of Sciences 116, no. 35 (August 12, 2019): 17531–40. http://dx.doi.org/10.1073/pnas.1907077116.
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Folates are critical for central nervous system function. Folate transport is mediated by 3 major pathways, reduced folate carrier (RFC), proton-coupled folate transporter (PCFT), and folate receptor alpha (FRα/Folr1), known to be regulated by ligand-activated nuclear receptors. Cerebral folate delivery primarily occurs at the choroid plexus through FRα and PCFT; inactivation of these transport systems can result in very low folate levels in the cerebrospinal fluid causing childhood neurodegenerative disorders. These disorders have devastating effects in young children, and current therapeutic approaches are not sufficiently effective. Our group has previously reported in vitro that functional expression of RFC at the blood–brain barrier (BBB) and its upregulation by the vitamin D nuclear receptor (VDR) could provide an alternative route for brain folate uptake. In this study, we further demonstrated in vivo, using Folr1 knockout (KO) mice, that loss of FRα led to a substantial decrease of folate delivery to the brain and that pretreatment of Folr1 KO mice with the VDR activating ligand, calcitriol (1,25-dihydroxyvitamin D3), resulted in over a 6-fold increase in [13C5]-5-formyltetrahydrofolate ([13C5]-5-formylTHF) concentration in brain tissues, with levels comparable to wild-type animals. Brain-to-plasma concentration ratio of [13C5]-5-formylTHF was also significantly higher in calcitriol-treated Folr1 KO mice (15-fold), indicating a remarkable enhancement in brain folate delivery. These findings demonstrate that augmenting RFC functional expression at the BBB could effectively compensate for the loss of Folr1-mediated folate uptake at the choroid plexus, providing a therapeutic approach for neurometabolic disorders caused by defective brain folate transport.
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Holm, Jan, and Steen Ingemann Hansen. "Binding of Radiolabeled Folate and 5-Methyltetrahydrofolate to Cow's Milk Folate Binding Protein at pH 7.4 and 5.0. Relationship to Concentration and Polymerization Equilibrium of the Purified Protein." Bioscience Reports 21, no. 6 (December 1, 2001): 733–43. http://dx.doi.org/10.1023/a:1015576522416.
Full textAbstract:
Binding of folate (pteroylglutamate) and 5-methyltetrahydrofolate, the major endogenous form of folate, to folate binding protein purified from cow's milk was studied at 7°C to avoid degradation of 5-methyltetrahydrofolate. Both folates dissociate rapidly from the protein at pH 3.5, but extremely slowly at pH 7.4, most likely due to drastic changes in protein conformation occurring after folate binding. Dissociation of 5-methyltetrahydrofolate showed no increase at 37°C suggesting that protein-bound-5-methyltetrahydrofolate is protected against degradation. Binding displayed two characteristics, positive cooperativity and a binding affinity that increased with decreasing concentrations of the protein. The binding affinity of folate was somewhat greater than that of 5-methyl tetrahydrofolate, in particular at pH 5.0. Ligand-bound protein exhibited concentration-dependent polymerization (8-mers formed at 13 μM) at pH 7.4. At pH 5.0, only folate-bound forms showed noticeable polymerization. The fact that folate at pH 5.0 surpasses 5-methyltetrahydrofolate both with regard to binding affinity and ability to induce polymerization suggests that ligand binding is associated with conformational changes of the protein which favor polymerization.
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Shehata, Z. "The role of folate and one-carbon metabolism in brain development and hydrocephalus: a literature review." Manchester Medical Journal 2, no. 1 (October 2, 2017): 1. http://dx.doi.org/10.7227/mmj.0018.
Full textAbstract:
Folate metabolism has been known to influence the development of the nervous system, as found in the case of neural tube defects. Folates are a group of compounds involved in one-carbon metabolism, which is necessary for the formation of purine and thymidine nucleotides, as well as methionine and methyl donors. In addition to the well-documented role of folates within the pathogenesis of neural tube defects, current literature provides evidence that folate imbalances may play a significant role in the development and effects of hydrocephalus. This review considers the possibility that folate imbalances in hydrocephalic cerebrospinal fluid may be responsible for the neurological deficit seen in patients with this condition. Understanding the details of this potential imbalance may provide further insight into novel treatment options for hydrocephalus in the future.
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Inoue, Katsuhisa, Yasuhiro Nakai, Sayaka Ueda, Shunsuke Kamigaso, Kin-ya Ohta, Mai Hatakeyama, Yayoi Hayashi, Masaki Otagiri, and Hiroaki Yuasa. "Functional characterization of PCFT/HCP1 as the molecular entity of the carrier-mediated intestinal folate transport system in the rat model." American Journal of Physiology-Gastrointestinal and Liver Physiology 294, no. 3 (March 2008): G660—G668. http://dx.doi.org/10.1152/ajpgi.00309.2007.
Full textAbstract:
Proton-coupled folate transporter/heme carrier protein 1 (PCFT/HCP1) has recently been identified as a transporter that mediates the translocation of folates across the cellular membrane by a proton-coupled mechanism and suggested to be the possible molecular entity of the carrier-mediated intestinal folate transport system. To further clarify its role in intestinal folate transport, we examined the functional characteristics of rat PCFT/HCP1 (rPCFT/HCP1) expressed in Xenopus laevis oocytes and compared with those of the carrier-mediated folate transport system in the rat small intestine evaluated by using the everted tissue sacs. rPCFT/HCP1 was demonstrated to transport folate and methotrexate more efficiently at lower acidic pH and, as evaluated at pH 5.5, with smaller Michaelis constant ( Km) for the former (2.4 μM) than for the latter (5.7 μM), indicating its characteristic as a proton-coupled folate transporter that favors folate than methotrexate as substrate. rPCFT/HCP1-mediated folate transport was found to be inhibited by several but limited anionic compounds, such as sulfobromophthalein and sulfasalazine. All these characteristics of rPCFT/HCP1 were in agreement with those of carrier-mediated intestinal folate transport system, of which the Km values were 1.2 and 5.8 μM for folate and methotrexate, respectively, in the rat small intestine. Furthermore, the distribution profile of the folate transport system activity along the intestinal tract was in agreement with that of rPCFT/HCP1 mRNA. This study is the first to clone rPCFT/HCP1, and we successfully provided several lines of evidence that indicate its role as the molecular entity of the intestinal folate transport system.
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Xie, Chong, Pei Wang, Jianwei Chang, Qiaoe Wang, Yongbin Han, and Runqiang Yang. "Effect of Amino Acids on Folates Accumulation in Wheat Seedlings during Germination under Red Light Radiation." Molecules 27, no. 20 (October 13, 2022): 6868. http://dx.doi.org/10.3390/molecules27206868.
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Deficiency of folates can cause various health problems, and germination is a potential way to enrich folates in grain-based food materials. In the present study, the effects of six amino acids (phenylalanine, tyrosine, tryptophan, glutamate, γ-aminobutyric acid, and p-aminobenzoic acid) on folate accumulation during wheat germination under red light radiation were investigated, and an optimized combination of amino acids for promoting folate enrichment was established. The results showed that applying phenylalanine, tyrosine, tryptophan, glutamate, or p-aminobenzoic acid to wheat seedlings during germination can significantly increase the content of total folates through activating the synthesis of the precursors for folate synthesis (pterin and p-aminobenzoic acid) or condensation of these two moieties. Meanwhile, up-regulation of corresponding genes was observed by measuring their expressions to investigate the mechanism for promoting the accumulation of folates. The highest content of folates (ca. 417 µg/100 g DW) was observed when the germinated wheat was cultured with a mixture of 1.5 mM phenylalanine, 0.5 mM tyrosine, 0.5 mM tryptophan, 0.75 mM p-aminobenzoic acid, and 0.5 mM glutamic acid, which was 50% higher than the control seedlings. This study established a promising and practical approach to enhance the accumulation of folates in wheat seedlings.
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Fardous, Ali M., Safa Beydoun, Andrew A. James, Hongzhi Ma, Diane C. Cabelof, Archana Unnikrishnan, and Ahmad R. Heydari. "The Timing and Duration of Folate Restriction Differentially Impacts Colon Carcinogenesis." Nutrients 14, no. 1 (December 21, 2021): 16. http://dx.doi.org/10.3390/nu14010016.
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Diet plays a crucial role in the development of colorectal cancer (CRC). Of particular importance, folate, present in foods and supplements, is a crucial modulator of CRC risk. The role of folate, and, specifically, the synthetic variant, folic acid, in the primary prevention of CRC has not been fully elucidated. Animal studies varied considerably in the timing, duration, and supplementation of folates, leading to equivocal results. Our work attempts to isolate these variables to ascertain the role of folic acid in CRC initiation, as we previously demonstrated that folate restriction conferred protection against CRC initiation in a β-pol haploinsufficient mouse model. Here we demonstrated that prior adaptation to folate restriction altered the response to carcinogen exposure in wild-type C57BL/6 mice. Mice adapted to folate restriction for 8 weeks were protected from CRC initiation compared to mice placed on folate restriction for 1 week, irrespective of antibiotic supplementation. Through analyses of mTOR signaling, DNA methyltransferase, and DNA repair, we have identified factors that may play a critical role in the differential responses to folate restriction. Furthermore, the timing and duration of folate restriction altered these pathways differently in the absence of carcinogenic insult. These results represent novel findings, as we were able to show that, in the same model and under controlled conditions, folate restriction produced contrasting results depending on the timing and duration of the intervention.
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Vickers, Tim J., and Stephen M. Beverley. "Folate metabolic pathways in Leishmania." Essays in Biochemistry 51 (October 24, 2011): 63–80. http://dx.doi.org/10.1042/bse0510063.
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Trypanosomatid parasitic protozoans of the genus Leishmania are autotrophic for both folate and unconjugated pteridines. Leishmania salvage these metabolites from their mammalian hosts and insect vectors through multiple transporters. Within the parasite, folates are reduced by a bifunctional DHFR (dihydrofolate reductase)-TS (thymidylate synthase) and by a novel PTR1 (pteridine reductase 1), which reduces both folates and unconjugated pteridines. PTR1 can act as a metabolic bypass of DHFR inhibition, reducing the effectiveness of existing antifolate drugs. Leishmania possess a reduced set of folate-dependent metabolic reactions and can salvage many of the key products of folate metabolism from their hosts. For example, they lack purine synthesis, which normally requires 10-formyltetrahydrofolate, and instead rely on a network of purine salvage enzymes. Leishmania elaborate at least three pathways for the synthesis of the key metabolite 5,10-methylene-tetrahydrofolate, required for the synthesis of thymidylate, and for 10-formyltetrahydrofolate, whose presumptive function is for methionyl-tRNAMet formylation required for mitochondrial protein synthesis. Genetic studies have shown that the synthesis of methionine using 5-methyltetrahydrofolate is dispensable, as is the activity of the glycine cleavage complex, probably due to redundancy with serine hydroxymethyltransferase. Although not always essential, the loss of several folate metabolic enzymes results in attenuation or loss of virulence in animal models, and a null DHFR-TS mutant has been used to induce protective immunity. The folate metabolic pathway provides numerous opportunities for targeted chemotherapy, with strong potential for ‘repurposing' of compounds developed originally for treatment of human cancers or other infectious agents.
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Netzel, Dumler, Weber, Striegel, Rychlik, Hong, and O’Hare. "The Inside and out of Folate in Strawberries and Avocados." Proceedings 36, no. 1 (February 2, 2020): 86. http://dx.doi.org/10.3390/proceedings2019036086.
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Folate, an important B-group vitamin, is considered a critical vitamin in many countries, with folate deficiency being associated with neural tube defects in newborns. Strawberries and avocados are considered a healthy, tasty snack by many consumers, and may potentially be an important dietary source of natural folates, depending on variety and growing environment. A selection of Australian-grown strawberry varieties and breeding lines, as well as commercial avocado cultivars, were screened for their folate content and vitamer profile by stable isotope dilution assay. Total folate content ranged from 69–170 μg/100 g fresh weight (fw) for strawberries and 76–196 μg/100 g fw for avocados, which was well above the values in the Australian Food Composition Database (39 μg/100 g fw for strawberries and 90 μg/100 g fw for avocados, respectively). Furthermore, folate concentration in the outer strawberry tissue was found to be 1.7-fold higher than the inner tissue of the fruit, whereas the inner avocado tissue had 1.4-fold higher folate than the outer green edible tissue. 5-Methyltetrahydrofolate, the biologically active form in humans, was the principal vitamer present. With these high folate concentrations, a punnet (250 g) of Australian-grown strawberries or 200 g of Australian-grown avocados would deliver the FSANZ recommended dietary intake (RDI) for folate (400 μg dietary folate equivalents/day/adult). Furthermore, the differences between outer and inner tissue could indicate that flatter, longer strawberries may have greater potential to accumulate folate than fruit with a more spherical shape, whereas more folate could be accumulated in a rounder-shaped avocado.
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Spark, M. J., D. A. Winkler, and P. R. Andrews. "Conformational analysis of folates and folate analogues." International Journal of Quantum Chemistry 22, S9 (June 19, 2009): 321–33. http://dx.doi.org/10.1002/qua.560220730.
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Czarnowska-Kujawska, Marta, Anna Draszanowska, Elżbieta Gujska, Joanna Klepacka, and Marta Kasińska. "Folate Content and Yolk Color of Hen Eggs from Different Farming Systems." Molecules 26, no. 4 (February 16, 2021): 1034. http://dx.doi.org/10.3390/molecules26041034.
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This study aimed to compare folate contents in hen eggs from four different farming systems, namely organic, free range, barn, and cage one. Folate retention during egg boiling was studied as well. The contents of individual folate vitamers were determined using the high-performance liquid chromatography method (HPLC), following trienzyme treatment. Folate content in eggs differed significantly (p < 0.05) due to the rearing system, with the highest mean content determined in the eggs from organic farming (113.8 µg/100 g). According to this study, one egg (60 g) may provide 40–86 µg of folates, which corresponds to 10–22% of the recommended daily intake for adults, 400 µg according to the Nutrition Standards for the Polish Population. The predominant folate form found in egg was 5-methyltetrahydrofolate, which showed considerably greater stability under boiling compared to 10-formylfolic acid present in a lower amount. In most eggs tested, the losses in total folate content did not exceed 15%. The color of yolk of the most folate-abundant organic eggs, had the highest value of lightness (L*) and the lowest value of redness (a*). This, however, does not correspond to consumer preferences of intense golden yolk color.
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Owusu, Matilda, Jane Thomas, Edwin Wiredu, and Maria Pufulete. "Folate status of Ghanaian populations in London and Accra." British Journal of Nutrition 103, no. 3 (October 14, 2009): 437–44. http://dx.doi.org/10.1017/s0007114509991838.
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Migration to the UK is associated with higher incidence of stroke in African populations. A low folate status has been associated with increased risk of stroke, likely to be mediated through raised plasma homocysteine concentrations. We conducted a cross-sectional study to compare blood folate and homocysteine concentrations in eighty healthy Ghanaian migrants living in London matched by sex, age and occupation to 160 individuals from an urban population in Accra, Ghana. Folate intake was determined using three 24 h recalls. Fasting blood samples were collected for the determination of serum and erythrocyte folate and plasma homocysteine concentrations and the methylenetetrahydrofolate reductase (MTHFR) 677C → T polymorphism. Reported mean folate intake was 20 % lower in London compared with Accra (P < 0·001). However, serum folate was 44 % higher, erythrocyte folate 30 % higher and plasma homocysteine was 26 % lower in subjects from London compared with those from Accra (P < 0·001). These differences persisted after adjusting for confounders including the MTHFR 677C → T mutation, which was rare in both populations. Although there were no associations between dietary folate intake and blood folates (P>0·05), folic acid supplement use, which was more prevalent in London than Accra (25 and 10 %, respectively,P = 0·004) was associated with erythrocyte folate in both populations (P < 0·01). The main predictors of plasma homocysteine concentrations were erythrocyte folate and male sex (P < 0·001). Findings from the present study suggest that migration from Ghana to the UK results in improvement of biomarkers of folate status despite the fact that reported dietary intake of folate was apparently lower in subjects from London.
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Oisaki, Kounosuke, Motomu Kanai, Katsuya Maruyama, Katarzyna Joanna Malawska, and Natsuki Konoue. "Synthesis of Tryptophan–Folate Conjugates." Synlett 31, no. 08 (February 26, 2020): 784–87. http://dx.doi.org/10.1055/s-0039-1691735.
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A mild protocol for the synthesis of folate–peptide/protein conjugates targeting tryptophan residues is described. This synthetic protocol is advantageous for homogeneous conjugation of chemically sensitive folates to biomolecules, with potential applications in cancer therapy and diagnostics.
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Herter-Aeberli, Isabelle, Nina Wehrli, Kurt Bärlocher, Maria Andersson, and Janice Sych. "Inadequate Status and Low Awareness of Folate in Switzerland—A Call to Strengthen Public Health Measures to Ensure Sufficient Intakes." Nutrients 12, no. 12 (December 3, 2020): 3729. http://dx.doi.org/10.3390/nu12123729.
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Background: Folate plays an essential role in the prevention of neural tube defects, yet little is known about the folate status of women of reproductive age or to what degree the general population is aware of the importance of folate in early-life development. We aimed to determine folate status in women of reproductive age and pregnant women in Switzerland, and to assess folate awareness in the Swiss population. Methods: In a convenience sample of 171 women of reproductive age and 177 pregnant women throughout Switzerland, we measured red blood cell (RBC) folate concentration. In a second convenience sample (n = 784, men and women) we assessed folate knowledge with an online survey. Results: RBC folate concentration (median interquartile range) was 442 (366, 564) nmol/L in women of reproductive age and 873 (677, 1177) nmol/L in pregnant women. Folate deficiency (RBC folate <340 nmol/L) was found in 19.9% of women of reproductive age and 2.8% of pregnant women, while 91.8% of women of reproductive age and 52.0% of pregnant women showed folate concentrations indicating an elevated risk of neural tube defects (RBC folate <906 nmol/L). The online survey showed that a high proportion (≥88%) of participants were aware of folate’s role in neural tube defect (NTD) prevention and fetal development, yet knowledge about dietary sources and national recommendations of folate supplementation when planning pregnancy were limited. Conclusion: The high prevalence of folate inadequacy in Swiss women suggests an elevated risk of neural tube defects and calls for urgent measures to increase folate intakes.
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Sangha, Vishal, Md Tozammel Hoque, Jeffrey Henderson, and Reina Bendayan. "Localization of the Folate Transport Systems in the Murine Central Nervous System." Current Developments in Nutrition 5, Supplement_2 (June 2021): 922. http://dx.doi.org/10.1093/cdn/nzab049_035.
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Abstract Objectives Folates are critical for normal neurodevelopment, and folate transport in the brain is primarily mediated by folate receptor alpha (FRα) at the blood-cerebrospinal fluid barrier (BCSFB). However, studies have reported folate transporter/receptor expression in other brain compartments, which may significantly contribute to overall brain folate uptake. The objective of this study is to characterize the localization of the folate transport systems i.e., reduced folate carrier (RFC), proton-coupled folate transporter (PCFT), and FRα in the mouse central nervous system, which will provide insight on novel routes of brain folate transport. In particular, folate transporter/receptor localization is examined at brain barriers [blood-brain barrier (BBB), BCSFB, arachnoid barrier (AB)] and in brain parenchyma (astrocytes, microglia, neurons). Methods The localization of RFC, PCFT and FRα was observed in the brains of C57BL6/N wildtype mice by applying immunohistochemistry (IHC). Mouse brains were isolated, and IHC was performed on frozen coronal sections. Transporter/receptor localization was examined at brain barriers (BBB, BCSFB, AB) and in brain parenchyma (astrocytes, neurons, microglia) using specific antibodies. Standard IHC markers were utilized to identify various brain compartments, with confocal microscopy used for imaging. Results At the mouse BBB and BCSFB, localization of RFC, PCFT and FRα was observed, which is consistent with previous reported data and our own work. At the AB, in astrocytes and neurons localization of RFC and PCFT (but not FRα) was observed. In microglia, no expression of the folate transporters or receptor was detected. Conclusions RFC and PCFT localization at the AB may represent a novel route of folate transport into the CSF, with transporter expression in neurons and astrocytes facilitating folate uptake into brain parenchyma cellular targets. Modulating folate transport at these brain compartments may provide a novel strategy in increasing brain folate uptake in disorders associated with defective FRα and impaired brain folate transport at the BCSFB. Funding Sources This work is supported by the Natural Sciences and Engineering Research Council of Canada (RB). VS is a recipient of several graduate scholarships.
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Khaitovich, M. V. "Folates: Modern Pregnant Health Support." HEALTH OF WOMAN, no. 4(150) (May 30, 2020): 37–42. http://dx.doi.org/10.15574/hw.2020.150.37.
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Folates (folic acid-based chemical compounds) got their name from the Latin “folio” - “leaf”, since they were first synthesized from spinach leaves, in which vitamin B9 is found in maximum quantities. As an important cofactor in carbon metabolism, folates are involved in the most important metabolic processes in the body, in particular, they play a key role in the synthesis of nucleotides and DNA replication. The article provides information on the physiological role of folates, their metabolism and its genetic aspects. The clinical significance of folate deficiency is examined, their sources and doses are described, and the interaction of folic acid and drugs is highlighted. Keywords: folate, metabolism, folic acid deficiency, pregnancy.
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Konings, Erik J. M. "A Validated Liquid Chromatographic Method for Determining Folates in Vegetables, Milk Powder, Liver, and Flour." Journal of AOAC INTERNATIONAL 82, no. 1 (January 1, 1999): 119–27. http://dx.doi.org/10.1093/jaoac/82.1.119.
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Abstract A liquid chronoat (LG) method was elaborated for determining folates in foods. Folates were extracted by homogenizing in buffer and heat treatment. A portion was incubated with an enzyme preparation containing conjugase, amylase, and protease. After purification by affinity chromatography, folate monoglutamates were determined by reversed-phase LG with fluorescence and diede array detection. Gradient elution with phosphate buffer and acetonitrile was used to separate vitamers. The most abundant folate forms naturally present in foods were detected, including tetrahy-drofolic acid, 5-methyltetrahydrofolic acid, and 5-formyltetrahydrofolic acid. 10-Formylffolic acid could be detected by applying a second fluorescence detector. Folic acid, used for fortification, might also be quantitated with this system. The difference between folate concentrations in sample extracts, with and without treatment of conjugase, is a measure of the quantity Of polyglutamates in the food matrixes. An additional treatment with conjugase, amylase, and protease reflects the arnount of matrix-bound folates. The LC system gave a linear response over the range 0–100 ng/mL. Detection limit for these compounds were 7 pg/mL for tetrahydrofolic acid and 5-methyltetrahydrofolic acid and folic acid were 1ng/ml. Repetability relative standard deviation values for separate folates in 3 candidate Certified Reference Materials (CRMs)—mixed vegetables (CRM 485), pig liver (CRM 487), and whole-meal flour (CRM 121)—and a Certified Reference Material milk powder (CRM 421) varied from 3.3 to 21.0% for the concentration range 1.8–1440 μg/100 g. Recoveries ranged from 73 to 109%. Use of amylase and protease was advantageous. Use of a comercially available folate-binding protein for cleanup saved time and money and was effective. Results for 5-methyltetrahydrofolioc acid were in good agreement with results obtained with other LC methods. Results for total folates were lower than results obtained with microbiological methods.