Dissertations / Theses on the topic 'Phlorizin'

This thesis describes an investigation of the effects of vitamin A deficiency on gut function, The central hypothesis to be tested was that acute vitamin A deficiency affects glucose uptake from the small intestine- The hypothesis was tested using a system involving perfusion of isolated segments of the small intestine in the anaesthetized rat. The system was used to study effects on glucose uptake under steady-state conditions. In the initial part of the study, experiments were diverted towards setting up the system for measuring steady-state uptake, and determining the relative contributions of active uptake and diffusion. Phenol red was found to be a reliable non-absorbable marker for determining net water movement. Phlorizin, generally at 1 mmol/L, was used as a competitive (reversible) inhibitor of active uptake. It is difficult however to confirm complete inhibition of active uptake by phlorizin because of the limited solubility of the inhibitor. The kinetics of glucose uptake f ram intra-luminal maltose were found to be, in general, not significantly different from those applying to the uptake of glucose from an equivalent glucose solution. Maltase activity in the perfused gut segment was found to be sufficient to hydrolyse most of the maltose (80 per cent or more) in the solution being perfused, a much greater proportion than was absorbed. Glucose absorptive capacity, measured on an intestinal dry weight basis, was greatest in the duodenum and progressively less in the jejunum and ileum. The rate of water uptake f ran the gut was increased by the presence of glucose in the lumen, and was linked to glucose uptake as shown by the inhibition of water uptake by phlorizin. Uptake of glucose by solvent drag was demonstrated by showing an increased rate of glucose uptake when the rate of water uptake was increased by perfusing a solution of reduced osmotic pressure. In the experiment a low intra-luminal glucose concentration was used to preclude net uptake by diffusion and active uptake was blocked with phlorizin. This process was further investigated using streptozotocin-diabetic rats in which the diabetes establishes a hyperosomotic blood with hyperglycaemia. Uptake by solvent drag was more obvious in diabetic animals. A back-diffusion (exsorption) of glucose from the tissues to the lumen was also shown; the rate being proportional to plasma glucose concentration. Vitamin A deficiency was established in weanling rats after 6-7 weeks feeding on a diet based on wheat starch, coconut oil, and casein washed with hot ethanol, together with vitamins and minerals. The vitamin A deficiency led to classic eye signs and was reversed by the addition to the diet of retinoic acid (5 g/g diet). Vitamin A deficiency decreased intestinal mucus production (dry weight) but had no detectable effect on the histology of the villous epithelium as shown under the light microscope. Using perfusion experiments it was shown that vitamin A deficiency had no significant effect on the rate of active uptake of glucose, but that deficiency increased the rate of passive uptake.

Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第21802号
農博第2315号
新制||農||1065(附属図書館)
学位論文||H31||N5174(農学部図書室)
京都大学大学院農学研究科応用生物科学専攻
(主査)教授 久米 新一, 教授 松井 徹, 教授 廣岡 博之
学位規則第4条第1項該当

Kyoto University (京都大学)
0048
新制・論文博士
博士(農学)
乙第12973号
論農博第2823号
新制||農||1037(附属図書館)
学位論文||H28||N4955(農学部図書室)
32411
新制||農||1037
(主査)教授 久米 新一, 教授 今井 裕, 教授 松井 徹
学位規則第4条第2項該当

Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Ciências Farmacêuticas
A Diabetes Mellitus é uma patologia crónica considerada uma epidemia global. Atinge ambos os sexos, surge cada vez mais precocemente, e a sua prevalência está aumentada na obesidade e nos indivíduos com uma alimentação desequilibrada. A morbilidade e mortalidade associadas a esta doença, assim como o consequente impacto negativo quer nos doentes, quer na sociedade e na economia, fazem com que o controlo da Diabetes Mellitus seja apontado como um enorme desafio para a Saúde Pública Mundial. A terapêutica não farmacológica (que inclui programas de exercício físico e implementação de uma dieta saudável e equilibrada) é a base do tratamento da Diabetes Mellitus. No entanto, a maioria dos pacientes não atinge os objetivos terapêuticos apenas com estas medidas, havendo necessidade de recorrer adicionalmente à terapêutica farmacológica (agentes antidiabéticos orais e/ou insulinoterapia). Apesar de as terapêuticas farmacológicas existentes serem eficazes no controlo das glicemias, estas apresentam diversas limitações (risco de hipoglicemia, aumento de peso, efeitos gastrointestinais adversos e/ou retenção de fluídos) que condicionam a sua utilização. Por esse motivo, são necessários novos agentes terapêuticos com melhores perfis de risco-benefício, que possibilitem um melhor controlo glicémico e uma maior redução das complicações associadas à Diabetes Mellitus. Os inibidores do co-transportador sódio-glicose 2 (SGLT2) apresentam-se assim como uma alternativa terapêutica baseada num mecanismo de ação inovador, que pode ultrapassar algumas limitações da terapêutica já existente e contribuir para um melhor controlo desta epidemia. Com o presente trabalho, pode constatar-se que os inibidores do co-transportador de sódio-glicose 2 parecem ser uma solução terapêutica promissora, com um mecanismo de ação independente da insulina, com as vantagens da diminuição da hemoglobina glicada, diminuição da glicose em jejum e pós prandial, diminuição do peso, melhoria da hiperuricemia (se presente), redução da pressão sanguínea e prevenção de complicações micro e macrovasculares melhorando, deste modo, a qualidade de vida do doente e dos seus familiares. No entanto, apesar das expectativas depositadas nesta classe de fármacos, com o evoluir dos estudos constatou-se que estes também apresentam diversos efeitos adversos, tais como o aumento de infeções urinárias e genitais, aumento do colesterol total e LDL, desidratação, aumento da frequência e volume urinário e hipotensão postural. Diabetes Mellitus is a chronic pathology considered a global epidemy. This disease affects both men and women, now appears at earlier ages, and its prevalence is increased in obesity and in individuals with an unbalanced diet. Morbidity and mortality associated with this disease, as well as the consequent negative impact on patients, society and economy, make the control of Diabetes Mellitus a major challenge for the World Healthcare. Non-pharmacological treatment (which includes physical exercising programmes and implementation of a healthy and balanced diet) is the basis of Diabetes Mellitus' treatment. However, most patients do not reach the therapeutic goals using only these measures and need to resort to pharmacological therapies (oral antidiabetic agents and/or insulin). Although the existing drug therapies are effective in controlling blood glucose levels, they present several limitations (risk of hypoglycemia, weight gain, gastrointestinal side effects and/or fluid retention) that limit its use. Therefore, new therapeutic agents with improved risk-benefit profiles that enable a better glycemic control and reduce the complications associated with Diabetes Mellitus are needed. Sodium-glucose co-transporter 2 (SGLT2) inhibitors appear as an alternative therapeutic approach based on a different mechanism of action that may overcome some of the limitations of the existing therapeutic agents and contribute to a better control of this epidemy. In this work, the inhibitors of the sodium-glucose co-transporter 2 appear as a promising therapeutic solution, with a mechanism of action that is independent of insulin, with the advantages of decreasing the glycated haemoglobin, the fasting and postprandial blood glucose levels and weight, improving hyperuricemia (if present), decreasing blood pressure and preventing micro and macrovascular complications, therefore improving the life quality of the patient and his family. However, despite the expectations placed on this class of drugs, with the progress of the studies, it was found that these agents also have several adverse effects, such as the increase of urinary and genital infections, increase of total and LDL cholesterol, dehydration, increase of the frequency and urinary volume and postural hypotension.

Fibroblast growth factors (FGFs) are a family of growth factors which includes twenty three proteins. FGFs work as modulators for various cellular activities like mitosis, differentiation and survival. Among the FGF family, human fibroblast growth factor-1 (hFGF-1), which is also known as acidic fibroblast growth factor, is a potent angiogenic agent, involved in the formation of new blood vessels in various tissues. hFGF-1 is regarded as a prototype of the FGF family. It serves as one of the potential targets in tumor inhibition and obesity due to its involvement in new blood vessel formation in cancerous regions and adipose tissues. In general, FGFs exert their action by binding to heparin, forming FGF-heparin complex, which can then bind to fibroblast growth factor receptors (FGFRs). Inhibition of FGF dependent signal transduction by heparin mimicking compounds has shown promising results in control and treatment of tumor growth. Naturally occurring glycoside called phloridzin found to have anticancer property. Phloridzin (2-glucoside of phloretin) has structural resemblance to heparin; it is a natural antioxidant, widely known for its antidiabetic activity, besides controlling tumor growth. Phloridzin can mimic heparin and compete with it for FGF binding. This binding can be agonistic or antagonistic in nature on FGF signal transduction. In the present study, we investigated the molecular level interaction between phloridzin and hFGF-1 using various biophysical techniques like steady state fluorescence, limited trypsin digestion and protein-NMR spectroscopy. hFGF-1 needed for the study was expressed in recombinant Escherichia coli cells. The expressed protein was then purified using heparin sepharose affinity chromatography. Both expression and purification were monitored using SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis). Conformational stability of purified hFGF-1 was assessed through steady state fluorescence. Purified hFGF-1 is in, its native, properly folded conformation. Interaction studies, such as thermal unfolding and limited trypsin digestion were performed to assess the thermal stability and solvent accessibility of hFGF-1 in the presence of phloridzin respectively. It was found from interaction studies that hFGF-1 in the presence of phloridzin shown increased thermal stability and increased resistance against trypsin digestion. In order to locate the sites of interaction on hFGF-1 surface, a protein-NMR study was performed. Exact sites of interaction of phloridzin on hFGF-1 surface were found. In future, isothermal titration calorimetry will be performed to determine kinetics of the enthalpy change and dissociation constant of phloridzin-hFGF-1 interaction. In vivo studies will also be performed after completion of in vitro studies, which will give an insight about possibility of phloridzin and hFGF-1 interaction under physiological condition

Phloridzin, an antidiabetic and antineoplastic agent usually found in fruit trees, is a dihydrochalcone constituent that has a clinical/pharmaceutical significance as a sodiumglucose linked transport 2 (SGLT2) inhibitor. Phloridzin never experienced widespread clinical usage in the pharmaceutical market due to its side effects and poor bioavailability when compared to other antidiabetic therapeutics. The poor bioavailability is primarily attributed to the degradation of the glycosidic bond of the phloridzin, resulting in the formation of phloretin, the aglycone of phloridzin and glucose. While phloretin displays a reduced capacity of SGLT2 inhibition, this nutraceutical shows enhanced antineoplastic activity in comparison to phloridzin. Gold nanoparticles (AuNPs) have been explored in improving the bioavailability of many drugs and therefore we opt for gold nanoparticle mediated delivery of phloridzin and phloretin and exploration of their anticancer mechanism. In this study, we have synthesized phloridzin and phloretin conjugated gold nanoparticles (Phl-AuNP and Pht-AuNP) in a single-step, rapid, biofriendly processes. The synthesized AuNPs morphology and elemental composition was characterized via transmission electron microscopy, UV-Vis spectroscopy, scanning electron microscopyenergy dispersive x-ray spectroscopy, and thermogravimetric analysis. Assessment of the antineoplastic potency of the dihydrochalcone-conjugated AuNPs against cancerous cell lines was accomplished through monitoring via flow cytometry. We posit that the functionalization of these chalcones onto the gold nanoparticles’ surface has improved the pharmacokinetic profile of phloridzin and phloretin.

e algumas vias de sinalização envolvidas com a reabsorção de HCO3-, além do efeito do tratamento com florizina e com streptozotocina. Para isso, utilizamos o método de microperfusão estacionária in vivo. Perfusões tubulares com solução de glicose 5mM aumentaram a reabsorção de bicarbonato em comparação com soluções contendo florizina sem glicose. Porém, perfusão de soluções de glicose 20mM ocasionaram efeito intermediário sobre esta reabsorção. A perfusão de solução contendo glicose 5mM com os inibidores PD169316 e LY294002 aboliu o efeito estimulatório promovido pela glicose 5mM. O tratamento com streptozotocina aboliu o efeito inibitório da perfusão de solução de glicose 20mM. Já o tratamento com florizina, não apresentou nenhum efeito adicional à inibição ocasionada pela perfusão de glicose 20mM mas inibiu o efeito estimulatório produzido pela perfusão de glicose 5 mM.
We studied the modulation of bicarbonate reabsorption by the apical Na+/H+ exchanger of renal proximal tubule by luminal glucose, and the signaling path of this relationship. Treatment with phloridzin and streptozotocin diabetes on HCO3- reabsorption was also studied. We used stationary microperfusion in vivo for this purpose. Tubule perfusions with 5 mM glucose increased bicarbonate reabsorption compared to solutions without glucose plus phloridzin. Perfusion with 20 mM glucose caused an intermediate effect on JHCO3- compared to 0/phloridzin and 5 mM glucose. The inhibitors PD169316 and LY294002 with 5 mM glucose blocked the stimulatory effect of the latter, but H89 had no such effect. Streptozotocin diabetes abolished the inhibitory effect of 20 mM glucose perfusion. Chronic phloridzin did not produce any additional effect on JHCO3- during 20 mM glucose perfusion in normal rats., but blocked JHCO3- during perfusion with 5 mM glucose.

Ruminants possess a unique digestive system. Using the high metabolic potential of the symbiotic microflora of the rumen, ruminants are capable of digesting plant material and obtaining nutrients and energy from this process. Because of the ruminal fermentation, the most bioactives are not stable in the harsh ruminal environment. Therefore there is a need to improve the bioavailability of a bioactive by protecting it from the ruminal digestion. The formulation of protected bioactive can be delivered in the rumen in a controlled manner and over a long period of time. In this project the degree of rumen protection was estimated using model substrates (sugar pellets and granules). These materials were coated with the pH-sensitive polymer Eudragit E. The model bioactive (phloridizin) was coated using the coating methodology adopted from exploratory studies with model substrates. The bioavailability of protected (coated) phloridizin was assessed by administering directly into the abomasum of fistulated cows. Formulation of protected phloridizin was used to demonstrate the feasibility of bioactive controlled delivery based on ART ( Active Rumen Technology ). This technology uses an elevated gas pressure created by a hydrogen-producing cell to drive a plunger which extrudes bioactive formulation from an intraruminal controlled-release device. Four groups of devices filled with formulation containing different amounts of protected phloridizin were tested. The bioactive was released in a controlled manner over several days. The formulation release profiles were reproducible suggesting that in principle the technology can be further developed to use in a commercial sense or for research purposes. The limitations of the technology, including formulation issues and gas diffusion through barrel walls, were identified.

碩士
國立中興大學
生物化學研究所
89
In the present study, we attempt to generate low-lactose milk in vivo by expressing a human lactase-phlorizin hydrolase in the mice mammary gland during lactation. To achieve this, we amplified a fragment of hLPH probe from Human Small Intestine Marathon-Ready cDNA and screened in Human Small Intestine 5’-STRETCH cDNA Library. After three-rounds screening, we identified a novel hLPH cDNA clone (hLPH-1), which containing a coding region homologous to published hLPH cDNA 1716 nt to 5122 nt, but which exon12, exon15, exon16, and exon17 were complete deletion, and a novel 3’-UTR sequence followed with exon14. The 3’-UTR sequence is different from published hLPH cDNA. We proposed that hLPH-1 is a product through hLPH gene alternative splicing. It maybe is a member of the LPH gene family. By deducing the novel 3’-UTR secondary structure, we could find which have stable secondary structure. So we proposed the novel 3’-UTR can protect hLPH-1 mRNA when translation. In order to understand what function hLPH-1 have, we constructed the novel hLPH-1 gene under the control of the promoter of the milk protein, α-lactalbumin, and then micro-injected into the pronuclei of mouse one-cell embryos to understand if hLPH-1 has lactase activity as LPH and to produce low-lactose milk of transgenic mice. Unfortunately, the hLPH-1 transgenic mice was not produced until now, so we still not know hLPH-1 gene has what biological function.

At the last time, we can see increased interest of lactose-free dairy products. The aim of the thesis was to evaluate offer of such products at selected retail chains in the South Bohemian region, then to conclude a sensory assessment of selected products and to verify of public awareness about lactose intolerance with a questionnaire survey. The widest offer of lactose-free dairy products has been found in Globus and Tesco, in the opposite the lowest offer has been found in Billa. Location of these products within the store was most the transparent in Globus (compared other stores). Three samples of white lactose free yoghurts and two samples of milk (with lactose and lactose-free) were evaluated by a sensory assessment. The sample of yoghurt from the company Madeta, line Nature was rated the best. On the contrary sample of yoghurt from the company Tatranská mliekáreň, line Nature´s Promise was rated the worst. The preference between two milk samples among the evaluators was balanced, despite large to moderate differences of intensity were described between them. Most respondents (79 %) knew what the term lactose intolerance means, but substantial part (22 %) of respondents badly indicated this the issue as allergy to milk casein. Because of high number of lactose-intolerant people in population this issue is still very actual, and it needs to be addressed.

碩士
國立中興大學
生命科學系
93
Human intestinal lactase-phlorizin hydrolase (hLPH), a major lactose digestive enzyme in small intestine of newborn, is synthesized as a high-molecular-mass precursor comprising four tandemly repeated domain. During the maturation, the precursor protein was glycosylation, proteolytic cleavage and dimerization on the membrane. In the previously study, a novel hLPH gene with C-terminal truncated membrane anchorless form had been identified from Small Intestine cDNA library in Human Small Intestine cDNA library, so we defined the novel hLPH as hLPH1. The hLPH1 cDNA and a normal intact hLPH were transfected into CHO cell, individually, to compare their cellular location and lactase activity in vitro. The result showed that the C-terminal truncated hLPH1 exhibiting lactase activity in extracellular space using X-Fuc staining. To further validate the hLPH1 activity in vivo , the hLPH1 gene was constructed under α-lactalbumin promoter control to generate a mammary-specific expression transgenic mice model. Since lactose is the major sugar present in milk and is an important osmotic regulator of milk secretion. This transgenic mice model provided us a good hLPH1 functional assay system. Data showed that the hLPH1 protein has been detected secretion in mammary aloveli and tubules by IHC assay and LPH activity in X-Fuc staining. Therefore, the hLPH1 can be redefined as extracellular hLPH (EC-LPH). A part of lactose has been hydrolyzed to galactose and glucose in vivo in the transgenic milk by TLC analysis. The growth performance of transgenic mice compared with wild type ICR mice had significant difference in body weight (p<0.001) during lactation stage. Key words: lactase-phlorizin hydrolase, hypolactasia, transgenic mice, X-Fuc

DIPLOMA THESIS Purification of phlorizin from Malus domestica Borkh.by solid-phase extraction and semi-preparative high-performance liquid chromatography Eva Prachařová Charles University, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Botany The aim of this diploma thesis was to find the best conditions for purification of a flavonoid extract from leaves of Malus domestica Borkh., and obtaining the purest fraction of phlorizin. Phlorizin may be used in the treatment of diabetes mellitus type 2 in the future, it has the ability to reduce glycemia by reducing the absorption of glucose in the small intestine and by increasing urinary glucose excretion. The first step was to find an SPE cartridge with a suitable sorbent and a suitable eluent for solid phase extraction. The DPA-6S cartridge and 100% methanol as an eluentwerefound to be the most suitable for SPE. The next step was to find the best possible conditions for semi-preparative HPLC using an ACE 5 C18 column (5 μm, C18, 150 x 10 mm i.d., 150 mm length). The mobile phase consisted of 1% (v/v) acetic acid in water (solvent A) and ethanol 100% (v/v) (solvent B), and a linear gradient elution was used (10-100% B), 0-60 min, the flow: 1mL/min. This method resulted in the 91.05% purity of phlorizin. Keywords: phlorizin, SPE,...

Le myo-inositol (MI) est un soluté organique impliqué dans diverses fonctions physiologiques de la cellule dont la signalisation cellulaire. Il est également un osmolyte compatible reconnu. Trois co-transporteurs de type actif secondaire responsables de son absorption ont été identifiés. Deux d’entre eux sont couplés au transport du sodium (SMIT1 et SMIT2) et le troisième est couplé au transport de protons (HMIT). L’objectif de cette étude a été la caractérisation du transport du MI par SMIT2 dans des membranes en bordure en brosse (BBMv) issues du rein de lapin et de l’intestin de rat ainsi qu’après expression dans les ovocytes de Xenopus laevis. La quantification de l’ARNm de SMIT1 et de SMIT2 dans le rein nous a appris que SMIT1 est majoritairement présent dans la médullaire alors que SMIT2 est principalement localisé dans le cortex. Ces résultats ont été confirmés par immunobuvardage en utilisant un anticorps dirigé contre SMIT2. Grâce à l’inhibition sélective de SMIT1 par le L-Fucose et de SMIT2 par le D-chiro-inositol (DCI), nous avons démontré que SMIT2 semble le seul responsable du transport luminal de MI dans le tubule contourné proximal avec un Km de 57 ± 14 µM. Pour ce qui est de l’intestin, des études de transport de MI radioactif ont démontré une absence de transport de MI chez le lapin alors que l’intestin de rat présente un transport de MI très actif. Une quantification par qRT-PCR nous a permis de constater que l’intestin de lapin ne semble pas posséder les transporteurs de MI nécessaires. Comme pour le rein, SMIT2 semble le seul transporteur de MI présent au niveau du pôle apical des entérocytes intestinaux chez le rat. Il est chargé du prélèvement du MI de l'alimentation avec un Km de 150 ± 40 µM. Les analyses fonctionnelles exécutées sur SMIT2 de rat en électrophysiologie après expression dans les ovocytes de Xenopus laevis donnent sensiblement les mêmes résultats que pour les BBMv de rein de lapin et d’intestin de rat. Dans les ovocytes, SMIT2 présente une grande affinité pour le MI (270 ± 19 µM) et le DCI (310 ± 60 µM) et aucune affinité pour le L-fucose. Il est ii également très sensible à la phlorizine (16 ± 7 µM). Une seule exception persiste : la constante d’affinité pour le glucose dans les BBMv d’intestin de rat est 40 fois plus petite que celle observée sur les ovocytes de Xenopus laevis. Nous avons également testé la capacité de certains transporteurs de sucre présents à la surface des membranes apicales des entérocytes à prélever le MI. Vu que l'inhibition de ces transporteurs (SGLT1 et GLUT5) ne changeait rien au taux de MI radioactif transporté, nous en avons conclu qu'ils ne sont pas impliqués dans son transport. Finalement, l’efflux de MI à partir du pôle basolatéral des entérocytes n’est pas effectué par GLUT2 puisque ce dernier lorsqu'il est exprimé dans des ovocytes, est incapable de transporter le MI.
Myo-inositol (MI) is an organic solute involved in various aspects of cell physiology, including cell signaling. It is also known as a compatible osmolyte. Three secondary active MI cotransporters have been identified; two are Na+- coupled (SMIT1 and SMIT2) and one is H+-coupled (HMIT). The main aim of this study was to characterize MI uptake throught SMIT2 as expressed in epithelial cells and in Xenopus laevis oocytes. In order to achieve the characterization of this transport system, we used purified brush border membrane vesicles (BBMv) isolated from rabbit kidney and rat intestine. We first performed a quantification of mRNA levels in rabbit kidney using real time PCR for both SMIT1 and SMIT2. We found that SMIT1 is mainly expressed in the renal medulla while SMIT2 is mainly localized in the renal cortex. This result was confirmed on Western blots using an antibody raised against SMIT2. Through inhibition studies using selective substrates for SMIT1 (inhibited by L-fucose) and SMIT2 (inhibited by D-chiroinositol), we showed that SMIT2 seems to be responsible for all the apical transport of MI into the proximal convoluted tubule with a Km of 57 ± 14 µM. By transport studies we established that rabbit intestine seems to lack apical transport of MI while rat intestine has a very active uptake of this molecule. qRT-PCR quantification confirmed the absence of MI transporters in rabbit intestine. As for kidney, SMIT2 seems to be the only transporter responsible for apical MI uptake in enterocytes with a Km of 150 ± 40 µM. Functional analysis of rat SMIT2 activity, via electrophysiological studies in Xenopus oocytes, demonstrated similarities to the activities of SMIT2 from rat intestine and rabbit kidney. SMIT2 displays high affinities for MI (270 ± 19 µM), DCI (310 ± 60 µM) and no affinity for L-fucose. SMIT2 is very sensitive to phlorizin (Pz; 16 ± 7 µM). Although these functional characteristics essentially confirmed those found in rat intestine, a iv discrepancy exists between the two systems studied. Indeed, the affinity constant for glucose was approximately 40-fold lower in vesicles than in oocytes. We also tested the ability of SGLT1 and GLUT5, other sugar transport systems present in enterocytes apical membranes, to perform MI uptake. Because the inhibition of these transporters did not alter radiolabeled MI uptake, we concluded that they had no significant contribution to MI transport in rat intestine. Finally, the basolateral efflux of MI was not mediated by GLUT2 because when expressed in oocytes, this transporter was not able to transport MI.