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Academic literature on the topic 'Phenols'

Author: Grafiati

Published: 4 June 2021

Last updated: 29 July 2024

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Journal articles on the topic "Phenols"

Shi, Zhen Jing, Meng Xiang Fang, Chun Guang Zhou, Shu Rong Wang, and Zhong Yang Luo. "Studies on the Extraction of Phenols from Coal Tar Produced in Multi-Generation System." Advanced Materials Research 347-353 (October 2011): 673–77. http://dx.doi.org/10.4028/www.scientific.net/amr.347-353.673.

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Isolation of phenols from the middle oil fraction(170-230°C) of tar produced in the multi-cogeneration system has been investigated for the purpose of recovering valuable pure phenols, such as phenol, cresols, xylenol and ethyl-phenol. Phenolic compounds were separated from the middle oil by liquid-liquid extraction using alkali and sulfuric acid. The yield of phenolic fraction from the middle oil (170-230°C) is up to 37%, which is much higher compared with those of metallurgical coke plants. Chromatography-mass spectrometry was used to analyse phenolic compounds. The result shows that the phenol content is less than 2%, and main compounds are cresol(14%), xylenol(20%) . Phenols of the middle oil fraction(230-280°C) was also analysed, which main contain methyl naphthol(20%).

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Malenica, Mladenka, Magdalena Biesaga, Sandra Pedisić, and Lara Saftić Martinović. "Stability of Propolis Phenolics during Ultrasound-Assisted Extraction Procedures." Foods 13, no. 13 (June 26, 2024): 2020. http://dx.doi.org/10.3390/foods13132020.

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Propolis has gained popularity in recent years as a potential preventive and therapeutic agent due to its numerous health benefits, which include immune system boosting, blood pressure lowering, allergy treatment, and skin disease treatment. The pharmacological activity of propolis is primarily attributed to phenolics and their interactions with other compounds. Given that phenols account for most of propolis’s biological activity, various extraction methods are being developed. The resin–wax composition of the propolis matrix necessitates the development of an extraction procedure capable of breaking matrix–phenol bonds while maintaining phenol stability. Therefore, the aim of this study was to assess the stability of two major groups of phenolic compounds, flavonoids and phenolic acids, in propolis methanol/water 50/50 (v/v) extracts obtained after ultrasound-assisted extraction (USE) under different extraction parameters (extraction time and pH) and heat reflux extraction (HRE). The methodology involved varying the USE parameters, including extraction time (5, 10, and 15 min) and pH (2 and 7), followed by analysis using liquid chromatography–tandem mass spectrometry (LC-MS/MS) to quantify phenolic recoveries. Results revealed that benzoic acid and chlorogenic acid derivatives demonstrated excellent stability across all ultrasound extraction procedures. The recoveries of flavonoids were highly diverse, with luteolin, quercitrin, and hesperetin being the most stable. Overall, neutral pH improved flavonoid recovery, whereas phenolic acids remained more stable at pH = 2. The most important optimization parameter was USE time, and it was discovered that 15 min of ultrasound resulted in the best recoveries for most of the phenols tested, implying that phenols bind strongly to the propolis matrix and require ultrasound to break the bond. However, the high variability in phenol extraction and recovery after spiking the propolis sample shows that no single extraction method can produce the highest yield of all phenols tested. As a result, when working with a complex matrix like propolis, the extraction techniques and procedures for each phenol need to be optimized.

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Helal, Ahmed, Stephane Desobry, Sylvie Banon, and Sherif M. Shamsia. "Antioxidant activity and bioaccessibility of phenols-enriched edible casein/caseinate coatings during in vitro digestion." Journal of Dairy Research 82, no. 1 (October 20, 2014): 56–63. http://dx.doi.org/10.1017/s0022029914000557.

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Active films were developed for food coating applications. Entrapped phenol susceptibility to digestion was studied. Sodium caseinate (Na-CN) coatings were formulated with 0, 10, 20% Casein (CN) incorporating selected phenols as model antioxidants. This study investigated phenol/CN/Na-CN interactions, in vitro bioaccessibility of phenols and CN role in phenols retention during in vitro gastric and pancreatic digestion. The antioxidant activity of catechin (CAT), rutin (RUT), chlorogenic acid (CHL), gallic acid (GAL), and tannic acid (TA) in coatings varied with the phenolic compound type and CN concentration and was related to phenol hydrophobic binding to CN. ABTS method gave activities ranged from 412 down to 213, and DPPH method gave values from 291·7 to 190·9. An inverse relationship was found with CN content due to CN/phenol interaction. During digestion, a part of phenols was degraded by alkaline pH of pancreatic fluid. Simultaneously, CN proteolysis led to release of phenols and the bioaccessibility index remained above 80% for all phenols. The results suggested the possibility of protecting phenols against oxidation and digestive alteration by entrapment in CN and Na-CN coating films. These positive results showed the ability to produce antioxidant-enriched edible coatings to increase food protection and phenol nutritional intake.

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Brezani, Viliam, Karel Smejkal, Jan Hosek, and Veronika Tomasova. "Anti-inflammatory Natural Prenylated Phenolic Compounds - Potential Lead Substances." Current Medicinal Chemistry 25, no. 10 (April 9, 2018): 1094–159. http://dx.doi.org/10.2174/0929867324666170810161157.

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Background: Natural phenolics are secondary plant metabolites, which can be divided into several categories with the common structural feature of phenolic hydroxyl. The biological activity of phenolics is often modified and enhanced by prenylation by prenyl and geranyl; higher terpenoid chains are rare. The type of prenyl connection and modification affects their biological activity. Objective: This review summarizes information about prenylated phenols and some of their potential sources, and provides an overview of their anti-inflammatory potential in vitro and in vivo. Method: The literature search was performed using SciFinder and keywords prenyl, phenol, and inflammation. For individual compounds, an additional search was performed to find information about further activities and mechanisms of effects. Result: We summarized the effects of prenylated phenolics in vitro in cellular or biochemical systems on the production and release of inflammation-related cytokines; their effects on inhibition of cyclooxygenases and lipoxygenases; the effects on production of nitric oxide, antiradical and antioxidant activity; and the effect on the inhibition of the release of enzymes and mediators from neutrophils, mast cells and macrophages. The information about the antiphlogistic potential of prenylated phenolics is further supported by a review of their action in animal models. Conclusion: Almost 400 prenylated phenols were reviewed to overview their antiinflammatory effect. The bioactivity of several prenylated phenols was confirmed also using in vivo assays. A pool of natural prenylated phenols represents a source of inspiration for synthesis, and prenylated phenols as components of various medicinal plants used to combat inflammation could be their active principles.

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B.M, Dr Khalid, and Afreen Banu. "SPECTROPHOTOMETRIC DETERMINATION OF TOTAL PHENOLIC CONTENT IN AMALAKI, ASHWAGANDHA, LAKSHMAN PHAL." Avishkara 01, no. 04 (2022): 17–20. http://dx.doi.org/10.56804/avishkara.2022.1404.

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Introduction: Amalaki, Ashwaghandha and Lakshmanphal are the three common rejuvenating drugs which has been used treatment, due to its high phenols and antioxidant activity hence study conducted the analysis total phenols content in above samples. Materials & Methods: Aims & Objectives: Estimation of total phenolic content, Study setting: ACRL Laboratory SJGAMC&H Koppal. Total phenolic content using UV Visible spectrophotometer the amounts of phenols were determined by Folin Ciocalteau reagent method, Gallic acid is used as standard and total phenols were expressed as mg/g equivalent to Gallic acid. Results & Discussion: The value obtained for Amalaki is 275.57 mg of GA/g equivalent, Ashwagandha is 210.89 mg of GA/g equivalent, Lakshmanphal 73.05 mg of GA/g equivalent Conclusion: Amalaki shown high total phenol content in all three samples, Ashwagandha, Lakshmanphal also rich source of phenols and justifies their use for health benefits.

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Ezerskis, Z., and Z. Jusys. "Oxidation of chlorophenols on Pt electrode in alkaline solution studied by cyclic voltammetry, galvanostatic electrolysis, and gas chromatographymass spectrometry." Pure and Applied Chemistry 73, no. 12 (January 1, 2001): 1929–40. http://dx.doi.org/10.1351/pac200173121929.

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Potentiodynamic investigations on a platinum electrode show that oxidation of phenol, monochlorophenols, dichlorophenols, 2,3,6-, 2,4,5-, 2,4,6-trichlorophenols, and pentachlorophenol in 1 M NaOH solution, containing 1 mM of phenols, proceeds in the potential region of Pt oxide formation. The oxidation rate of phenols decreases with the increase in the number of chlorine atoms in the benzene ring in the row: phenol > monochlorophenols > dichlorophenols > trichlorophenols > pentachlorophenol. The electrochemical stability of phenols, as studied using a cyclic voltammetry, depends on their chlorination degree and isomerism. Galvanostatic oxidation of 1 M NaOH solutions containing 1 mM of phenol, monochlorophenols, dichlorophenols, 2,3,6-, 2,4,5-, 2,4,6-trichlorophenols, and pentachlorophenol were carried out on a platinum electrode using 30 mA cm2 current density. The electrolysis of the solutions was performed in the course of 10 h, and concentration of phenols in the anolytes was monitored during oxidation. The concentration of phenolic compounds diminishes from 1 mM to 1050 mM during 45 h of electrooxidation and does not change during further galvanostatic oxidation. A decrease in concentration of phenols during galvanostatic electrolysis weakly depends on the isomerism and a chlorination degree of the compounds. A rapid decrease in concentration of studied phenols during the first 45 h of electrolysis and a nonselective oxidation of different chlorophenols suggest that the oxidation proceeds via electrochemically generated oxidants. Further decrease in concentration of phenols is rather small due to deactivation of the electrode as a result of polymerization of corresponding phenols and diffusion limitations.

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Muráriková, A., K. Kaffková, S. Raab, and J. Neugebauerová. "Evaluation of content of phenolics in Salvia species cultivated in South Moravian Region / Hodnotenie obsahu fenolov vo vybraných druhoch rodu Salvia L. pestovaných v Juhomoravskom kraji." Acta Facultatis Pharmaceuticae Universitatis Comenianae 62, s9 (June 1, 2015): 18–22. http://dx.doi.org/10.1515/afpuc-2015-0007.

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Abstract In this study, total phenolic content (TPC) and rosmarinic acid (RA) of 37 samples sage (Salvia L.) of extracts were determined using spectrophotometric methods. The amount of total phenols was analysed with Folin-Ciocalteu reagents. Gallic acid was used as a standard compound and the total phenols were expressed as mg.g−1 gallic acid equivalents of dried plant material. The values of the extracts displayed substantial differences. All of the investigated species except Salvia jurisicii (990.79 mg GAE. g−1 d.w.) exhibited higher content of phenolics. Among the studies, species demonstrated the highest content of phenol, followed in sequence by Salvia tomentosa, Salvia fruticosa, Salvia triloba, Salvia officinalis ‘Extrakta’, Salvia officinalis. TPC varied from 990.79 to 4459.88 mg GAE. g−1 d.w. in the extracts. The total amount of RA was between 0.88 and 8.04% among species. Salvia tomentosa, Salvia verticillata and Salvia officinalis ‘Extrakta’ had the highest content of RA. The high content of phenolic compounds indicated that these compounds contribute to the antioxidant activity.

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Zhu, Lei, Chuan Zhan, Xinchu Yu, Xixi Hu, Sibo Gao, Yanqing Zang, Di Yao, Changyuan Wang, and Jingyu Xu. "Extractions, Contents, Antioxidant Activities and Compositions of Free and Bound Phenols from Kidney Bean Seeds Represented by ‘Yikeshu’ Cultivar in Cold Region." Foods 13, no. 11 (May 29, 2024): 1704. http://dx.doi.org/10.3390/foods13111704.

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To thoroughly understand the profile of phenolic phytochemicals in kidney bean seeds cultivated in a cold region, the extractions, contents, antioxidant activities, compositions of free and bound phenols in the seed coat and cotyledon, and also relevant color attributes, were investigated. The results indicated that ultrasound-assisted extraction was an efficient method for free phenols. The bound phenols in seed coat and cotyledon were released more efficiently by alkali-acid and acid-alkali sequential hydrolysis, respectively. Under the optimized extractions, total phenols (TPC), flavonoids (TFC), and anthocyanins (TAC) ranged in 7.81–32.89 mg GAE/g dw, 3.23–15.65 mg RE/g dw, and 0–0.21 mg CE/g dw in the whole seeds of the five common kidney beans. There was a big difference in phenolic distribution between red and white seeds. From whole seed, the phenols in the four red cultivars mainly existed in free state (78.84%) and seed coat (71.56%), while the phenols in the white ‘Sark’ divided equally between free (51.18%) and bound (48.82%) states and consisted chiefly in cotyledon (81.58%). The correlation analyses showed that the antioxidant activities were significantly and positively correlated with TPC and TFC. The phenolic attributes were closely associated with the color of the seed coat. Red seeds had higher total contents of phenols than white seeds. TAC had a positively significant correlation with redness. Brightness and yellowness showed a negatively significant correlation with TPC, TFC, and antioxidant capacities, which were necessarily linked with redness degree and spot in red seeds. The spotted red ‘Yikeshu’ with the most outstanding performance on phenolic attributes was selected to analyze phenolic compounds with UHPLC-QE-MS. Among the 85 identified phenolics, 2 phenolic acids and 10 flavonoids were dominant. The characteristic phenolics in free and bound states were screened in both seed coat and cotyledon, respectively. The available information on the phenolic profile may expand the utilization of kidney beans as a nutritional ingredient in the food industry.

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Abraham Sisein Eboh, Faith Owabhel Robert, and Wodu Ebizimor. "Phenolics and phytochemicals in methanolic extract of Peperomia pellucidia quantified by HPLC." Open Access Research Journal of Life Sciences 3, no. 2 (June 30, 2022): 059–62. http://dx.doi.org/10.53022/oarjls.2022.3.2.0045.

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Phenolics are compounds that contributed greatly to the healing potentials of many herbs, spices and plants of which Peperomia pellucidia is inclusive. This research aimed at determining the various phenolics present in the methanolic extract of Peperomia pellucidia extract. High performance liquid chromatography was used to analyse the phenolic content in Peperomia pellucidia extract. The result showed the presence of phenols and flavonoid quantified as total phenol 12.78 ± 2.70 mg GAE/g dry extract and total flavonoid as 10.97 ± 0.00 mg QE/g dry extract. HPLC result reveals the following phenols p-coumaric acid 32.76 mg/100g, gallic acid with a concentration of 138.07 mg/100 g. caffeic acid and naringenin were also detected in larger concentration as showed in the table. Ferulic acid, syringic acid and quercetin each has a retention time of 17.09, 17.47 and 22.60 min, a percentage area of 136.77, 96.93 and 91.06 while the concentrations where 16.129 mg/100g, 17.688 and 75.56 mg/100g respectively. Other phenolics with much higher quantity are rosmarinic acid and chlorogenic acid with retention time 23.97 and 25.06, a percentage area of 94.44 and 24.48, while the amounts quantified in Peperomia pellucidia extract was 19.133 mg/100g and 28.865 mg/100g. In conclusion methanolic extract of Peperomia pellucidia showed a lot of phenols that are very useful in the alleviation of stress that is linked with many diseases.

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Rodríguez-Romero, Manuela, Alejandro Gallardo, and Fernando Pulido. "Geographical and within-population variation of constitutive chemical defences in a Mediterranean oak (Quercus ilex)." Forest Systems 29, no. 2 (August 10, 2020): e011. http://dx.doi.org/10.5424/fs/2020292-16943.

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Aim of study: to assess whether constitutive levels of total phenols and condensed tannins acting as chemical defences in Quercus ilex vary across regions, populations and genotypes.Area of study: acorns from six Spanish regions with natural presence of Q. ilex were collected for later sowing in the greenhouse of the University of Extremadura at Plasencia, western Spain.Materials and methods: 1176 acorns from 12 populations (2 per region) were sown according to a nested design (6 regions x 2 populations/region x 7 genotypes/population). After five months, 588 emerged seedlings were harvested for phenol extraction from their leaves. Quantification of total phenols through the Folin-Ciocalteu method and condensed tannins by Porter's reagent method was carried out.Main results: total phenolics and condensed tannins correlated positively. Significant differences were found for the concentration of total phenolics and condensed tannins among regions and among genotypes, but not among populations within regions. The lowest levels of constitutive defences were found in the northern Iberian Peninsula. Also, the defensive phenolic content was significantly higher in regions with acidic soils. Heritability values (total phenols 0.37±0.08 and condensed tannins 0.48±0.36) were lower than those obtained of total tannins in a previous study.Research highlights: constitutive levels of heritable chemical defences in holm oak significantly depend on their geographical origin and genotype.Keywords: condensed tannins, genetic and latitudinal variability, heritability, total phenolics.

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Dissertations / Theses on the topic "Phenols"

Rubió, Piqué Laura. "Phenol-enriched olive oil with its own phenolic compounds and complemented with phenols from thyme: a functional food development model." Doctoral thesis, Universitat de Lleida, 2014. http://hdl.handle.net/10803/146133.

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L'enriquiment de l’oli d'oliva amb els seus propis fenols esdevé una estratègia interessant per augmentar i normalitzar la ingesta diària d’hidroxitirosol sense augmentar el consum calòric. No obstant això, olis amb alt contingut fenòlic proporcionen un gust amarg que podria provocar rebuig entre els consumidors. A més, altes dosis d'hidroxitirosol podria tenir una acció pro-oxidant. En aquesta tesi es va plantejar l'estratègia d'enriquiment d’un oli d'oliva no només amb els seus propis fenols, sinó amb fenols complementaris d'herbes aromàtiques, concretament de farigola, amb la hipòtesi de que apart de proporcionar millores en l'estabilitat de l'oli i l'acceptació dels consumidors, també podria aportar beneficis addicionals per a la salut. Un cop desenvolupat l'oli d'oliva enriquit en fenols, es va avaluar la biodisponibilitat dels fenols mitjançant mètodes in vitro i in vivo, avaluant possibles interaccions o sinergies entre ambdues fonts fenòliques.
El enriquecimiento de aceite de oliva con sus propios fenoles se convierte en una estrategia interesante para aumentar y normalizar la ingesta diaria de hidroxitirosol sin aumentar el consumo calórico. Sin embargo, aceites con alto contenido fenólico tienen un sabor amargo que podría provocar rechazo entre los consumidores, y además sus altas dosis de hidroxitirosol podría tener una acción pro-oxidante. En esta tesis se planteó la estrategia de enriquecimiento de aceite de oliva no sólo con sus propios fenoles, sino con fenoles complementarios de hierbas aromáticas, concretamente tomillo, con la hipótesis de que no sólo podría proporcionar mejoras en la estabilidad del aceite y la aceptación de los consumidores, sino que podría aportar beneficios adicionales para la salud. Una vez desarrollado el aceite de oliva enriquecido se evaluó la biodisponibilidad de los fenoles mediante métodos in vitro e in vivo, evaluando posibles interacciones o sinergias entre ambas fuentes fenólicas.
The enrichment of olive oil with its own phenolic compounds becomes an interesting strategy to increase and standardize the daily intake of hydroxytyrosol without increasing the caloric intake. Concerning olive oils with high phenolic content, however, they have a bitter taste, which could promote a refusal among consumers, and contain high doses of hydroxytyrosol that could have a pro-oxidant action. In this context, the strategy of enriching olive oil not only with its own phenolics but also with complementary phenols from aromatic herbs was outlined in this thesis with the hypothesis that it could not only improve olive oil stability and consumers’ acceptation but also provide additional health benefits. In this thesis a phenol-enriched olive oil was developed using the aromatic herb of thyme, and the bioavailability of the phenolic compounds was assessed, evaluating possible interactions or synergies between both sources through in vitro and in vivo approaches.

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Lucach, Sandra Ortega. "Phenols in petroleum systems." Thesis, University of Newcastle Upon Tyne, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273711.

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Goss, Ben. "Novel phenolic composites." Thesis, Queensland University of Technology, 1997. https://eprints.qut.edu.au/36933/1/36933_Goss_1997.pdf.

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Composites were prepared from a phenolic resin formulation reinforced with ultra high modulus polyethylene (UHMPE) fibre. Two commercially prepared samples of UHMPE were used: Spectra® prepared by Allied Signal in the USA and Dyneema® prepared by DSM in Holland. To these fibres a number of surface treatments were applied, predominantly oxygen and water plasma, in order to improve composite properties. The effect of treatment was monitored usmg X-ray Photoelectron Spectroscopy (XPS), and treatment time was optimised by this technique. The influence of treatment time on fibre tensile strength was also determined. The change in adhesion was determined using the fibre pullout test and other composite properties were determined by interlaminar shear strength (ILSS) and flexural tests. An improvement in adhesion was observed. The effect of fibre volume fraction on ILSS and shear modulus was also determined. It was found that the oxygen / carbon ratio reached a threshold after 60 seconds whereas adhesion was maximised after only 20 to 30 seconds. SEM examination showed that this was due to the occurrence of a second failure mechanism, shear failure of the fibre, that occurred when interfacial adhesion exceeded fibre shear strength. This was also observed in the ILSS tests. The measurement of ILSS was used to optimize both the surface treatment and volume fraction of fibre in the composite. It is the onset of fibre shear failure that is the limiting factor in UHMPE composite materials.

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Fimbres, Michael. "Competitive sulfonimidate alkylations of phenols." Thesis, California State University, Long Beach, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1526904.

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Ethyl N-tert-butyl-4-nitrobenzenesulfonimidate and isopropyl N-(1-adamantyl)-4-nitrobenzenesulfonimidate have been shown to alkylate a variety of different phenols, along with thiophenol and selenophenol. It was shown that ethylation and isopropylation can be successfully carried out using these sulfonimidates with the help of an acid catalyst, tetrafluoroboric acid dimethyl ether complex. Their ability to alkylate selectively on functionally similar groups resulted in the formation of ethers, sulfides, and selenides. Competitive reactions with sterically hindered phenols formed the less sterically hindered ethers in greater amounts. Electronic substituent effects in para-substituted phenols favored alkylation on the more electron rich phenols. Hammett sigma para-substituent constants correlated with relative rates of phenol alkylations to give negative reaction constant (p) values for each alkyl sulfonimidate reagent. Thus, the major goal of this project was accomplished in finding general trends in functional groups, steric hindrance, and substituent effects to make reasonable predictions for sulfonimidate reactions in the future.

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Johns, Stephen Christopher. "De Novo Synthesis of Phenols." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/4646.

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This thesis is divided into three chapters. In the first, the methods currently available for the synthesis ofphenols from acyclic precursors are reviewed. The review concentrates on methods that have been usedto form a range of phenols and is divided up according to the type of chemistry employed. The secondchapter describes the development of a novel route to phenols. Initial optimisation results are describedfirst, followed by the synthesis of a library of phenols. The majority of these have not been reportedpreviously. The attempted extension of this work to the formation of anilines, nitrobenzenes and morehighly oxygenated aromatics is also presented. Finally, work towards the synthesis of the aglycone ofpseudopterosin A is described, following a route that would utilise the phenol-forming chemistry in amore complex natural product environment. The final section details the experimental procedures usedto form the compounds described in section two, along with associated spectroscopic data.

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Balasainath, Ravindra Kotha. "Regiospecific Synthesis of Ortho Substituted Phenols." TopSCHOLAR®, 2011. http://digitalcommons.wku.edu/theses/1084.

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Phenol is highly reactive toward electrophilic aromatic substitution. By this general approach, many groups can be appended to the ring, via halogenation, acylation, sulfonation, and other processes. Phenol contains the hydroxyl group (–OH), which is a strongly activating ortho/para directing group in aromatic electrophilic substitution (AES). AES gives a mixture of ortho-and para isomers, which must be separated. The strong directing ability of phenol can also result in multiple substitutions on the aromatic ring which could be a major concern in the regiospecific synthesis of phenols. AES and Directed ortho--Metalation (DoM) are the only ways to directly substitute a proton on an aromatic ring and to synthesize regiospecifically substituted phenols. Phenol is a versatile precursor to a large collection of drugs, most notably aspirin, but also many herbicides and pharmaceuticals. AES reactions are useful in regiospecific synthesis as a way of introducing many reactive groups on the benzene ring and also help us to design a suitable method for synthesizing compounds in an efficient manner. Dimethylbenzylamine products are obtained as a result of the reaction of phenols with Eschenmoser’s salt (N,N-Dimethylmethyleneiminium iodide). This approach enables us to prepare regiospecifically ortho substituted phenols by using the AES protocol. We have discovered that Eschenmoser’s salt has the ability in basic medium containing triethylamine (TEA) to remove the proton and bond to the aromatic ring exclusively in ortho position to the –OH substituent. Our research work focused on efforts to render isolated products with minimum impurities, greener and more atom economical by use of limiting reagent in the reactions. For the purpose of evaluation of the obtained compounds and intermediates we use Gas Chromatography (GC), Gas Chromatography coupled with Mass Spectrometry (GC-MS) and Nuclear Magnetic Resonance (NMR). Our future work is to synthesize novel benzoheterocyclic compounds from the ortho-derivatised phenols as well as multi-substituted aromatic compounds. The dimethylamino methyl group can act as a directing group in the ortho-lithiation process; subsequent ortho--metalation and treatment with electrophiles generates 1,2,3- trisubstituted phenolic derivatives. Thus, phenolic precursors can be transformed into numerous derivatives which can be used in the chemical, agricultural and pharmaceutical industries.

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Izimas, M. "Selective control of chlorination of phenols." Thesis, Swansea University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637380.

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The chlorination of meta-cresol by sulfuryl chloride in the presence of different sulfur containing catalysts was studied. In homogeneous conditions, the chlorination of meta-cresol was catalysed by dialkyl sulfides and dithia-alkenes. The influence of various reaction parameters was investigated. The dithia-alkanes were not commercially available and needed to be synthesised prior to their use. A new method for the synthesis of unsymmetrical dithia-alkanes was developed. The chlorination of meta-cresol using di-iso-propyl sulfide and di-n-butyl sulfide was scaled up and the reaction mixture separated by fractional distillation. The catalyst was recovered and reused. 5,18-Dithiadocosane, a successful catalyst for the chlorination of meta-cresol, was also tested as catalyst for the chlorination of phenol, anisole, meta-xylenol, toluene and naphthalene. In heterogeneous conditions, the chlorination of meta-cresol was catalysed by polymers containing thia-alkyl groups. The synthesis of the polymers by modification of bromopolystyrene and Merrifield resin was studied and a new method was developed to avoid crosslinking. A polythia-alkane was also synthesised from 1,6-hexanedithiol and 1,8-dibromo-octane.

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Amiri, Fariba. "Influence of pH and NOM on Sorption of Phenols onto Aquifer Material." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1112166354807-33548.

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Geosorption processes play an important role as retardation mechanism in subsurface transport of organic water constituents. Geosorption behaviour of Ionisable Hydrophobic Organic compounds (IHOCs) especially influence of dissolved natural organic materials on their sorption coefficients is poorly investigated. In this study influence of pH and NOM on the sorption of three different phenols (2-methyl-4,6-dinitrophenol, 2,4,6-trichlorophenol and pentachlorophenol) on a natural sandy aquifer material collected from a bank filtration site was studied in flow through column experiments. In first step the sorption coefficients of investigated phenols from NOM-free solutions with different pH values were determined. Single as well as multi (mixed) solutes experiments confirmed that there was no competition effect among the phenols investigated. An increasing sorption/retardation was observed with decreasing pH. A linear model was used to resolve the apparent sorption coefficient into an ionised species and neutral species component. This model allows a prediction of apparent sorption coefficients for any pH value. Analysis of data also revealed that the anion of 2-M-4,6-DNP show no significant sorption and a simple model based on the neutral form sorption coefficient was useful in predicting the apparent sorption coefficient over the entire pH range investigated. For 2,4,6-TCP and PCP, the anion sorption is much lower than that of the neutral species but cannot be neglected completely. For PCP, the anion sorption is even as high as the sorption of neutral 2,4,6-TCP. Thus for such hydrophobic phenols prediction of sorption based only on the partitioning of non-dissociated species may lead to an error, especially at high pH values (> pKa), where ionised form is present predominantly. On the other hand prediction of sorption based on the partitioning of non-dissociated species is useful at pH < pKa or in cases where the anion sorption can be neglected. The advantage of this prediction is that it allows predicting the pH-dependent sorption only on the basis of LFER correlations. It was shown that the organic carbon normalized sorption coefficients of the neutral forms of the phenols can be predicted better by solubility based regression correlations than by n-octanol-water partition coefficient based correlations. In second step the apparent sorption coefficients of investigated phenols from NOM-containing solutions (mixed solution of phenols dissolved in natural river water) with different pH values were determined; the sorption coefficients obtained from this step were compared with the results of the first step examinations. Analysis of data revealed that binding of 2-M-4,6-DNP by dissolved humic substances (DHS) reduces the sorption coefficient significantly. In contrast to it, the sorption of the more hydrophobic chlorinated phenols was not affected by DHS. A strong reduction of sorption onto aquifer material caused by complex formation with DHS was also observed for a second nitrophenol (2,4-DNP) and seems to be typically for nitrophenols. A combined sorption and complex formation model was proposed which could be used successfully to describe the effect of pH and NOM concentration on sorption reduction and to estimate binding constants. The binding constant found for 2-M-4,6-DNP is much higher than those reported by Ohlenbusch and Frimmel, 2001, for chlorophenols associated with Aldrich humic acid. This can be interpreted as a result of specific interactions between the nitrophenol and DHS. This phenomenon may cause an increase of the amount of nitrophenols, which can be transported with the groundwater flow and has to be considered in transport modelling, especially in cases where pH is lower than pKa. The models developed here are a useful tool to describe the influence of pH and NOM on geosorption processes and to estimate the Kd values which have to be used in transport models.

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Bassey, E. N. "The extraction of phenols from ammoniacal liquors." Thesis, University of Bradford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372179.

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Messenger, Beatrice. "Salivary gland peptide hormones and dietary phenols." Thesis, University of Surrey, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326511.

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Books on the topic "Phenols"

A, Muscolo, and Sidari M, eds. Soil phenols. Hauppauge, N.Y: Nova Science Publishers, 2009.

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Muscolo, A. Soil phenols. Hauppauge, N.Y: Nova Science Publishers, 2009.

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A, Muscolo, and Sidari M, eds. Soil phenols. Hauppauge, N.Y: Nova Science Publishers, 2009.

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Juha, Kallas, and Lappeenrannan teknillinen korkeakoulu, eds. Treatment technology of wastewater containing phenols and phenolic compounds. Lappeenranta: Lappeenranta University of Technology, 1992.

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International Program on Chemical Safety., World Health Organization, United Nations Environment Programme, and International Labour Organisation, eds. Phenol health and safety guide. Geneva: World Health Organization, 1994.

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Rappoport, Zvi, ed. The Chemistry of Phenols. Chichester, UK: John Wiley & Sons, Ltd, 2003. http://dx.doi.org/10.1002/0470857277.

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Tyman, J. H. P. Synthetic and natural phenols. Amsterdam [The Netherlands]: Elsevier, 1996.

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Miller, W. Lash. Toxicity and chemical potential. [Toronto]: University library ; pub. by the Librarian, 1995.

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Burlakova, E. B., and N. V. Zagoskina. Fenolʹnye soedinenii︠a︡: Fundamentalʹnye i prikladnye aspekty. Moskva: Nauchnyĭ mir, 2010.

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Gutsche, C. David. Calixarenes. Cambridge: Royal Society of Chemistry, 1992.

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Book chapters on the topic "Phenols"

Weber, Manfred, and Markus Weber. "Phenols." In Phenolic Resins: A Century of Progress, 9–23. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-04714-5_2.

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Patnaik, Pradyot. "Phenols." In Handbook of Environmental Analysis, 277–80. Third edition. | Boca Raton : Taylor & Francis, CRC Press, 2017.: CRC Press, 2017. http://dx.doi.org/10.1201/9781315151946-49.

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Pengelly, Andrew. "Phenols." In The constituents of medicinal plants, 18–40. 3rd ed. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789243079.0002.

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Abstract This chapter focuses on phenols and their pharmacological properties. Phenols are one of the largest groups of secondary plant constituents. They are aromatic alcohols since the hydroxyl group is always attached to a benzene ring. Like all alcohols, the names of phenols almost always end in the letters 'ol'. In addition, the ring system may bear other substitutes, such as methyl groups and carboxylic acid.

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Smith, Robert M., and Arthur E. Martell. "Phenols." In Critical Stability Constants, 366–99. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4615-6764-6_14.

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Singleton, V. L. "Wine Phenols." In Wine Analysis, 173–218. Berlin, Heidelberg: Springer Berlin Heidelberg, 1988. http://dx.doi.org/10.1007/978-3-642-83340-3_7.

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Pospíšil, Jan. "Antioxidants: hindered phenols." In Plastics Additives, 73–79. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-5862-6_9.

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Smith, Robert M., and Arthur E. Martell. "Erratum to: Phenols." In Critical Stability Constants, 647. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4615-6764-6_36.

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Cohen, G. B. "The Analysis of Coffee Phenols and Phenolic Acids." In ACS Symposium Series, 356–63. Washington, DC: American Chemical Society, 2000. http://dx.doi.org/10.1021/bk-2000-0754.ch036.

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Thurman, E. M. "Carboxylic Acids and Phenols." In Organic Geochemistry of Natural Waters, 113–50. Dordrecht: Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-009-5095-5_6.

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Simándi, László I. "Catalytic Oxidation of Phenols." In Catalysis by Metal Complexes, 196–248. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-2850-6_5.

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Conference papers on the topic "Phenols"

Tschanner, Julius, Jinchang Ren, Frances Jack, Stephen Marshall, and Huimin Zhao. "Employing NIR-SWIR hyperspectral imaging to predict the smokiness of scotch whisky." In OCM 2017 - 3rd International Conference on Optical Characterization of Materials. KIT Scientific Publishing, 2017. http://dx.doi.org/10.58895/ksp/1000063696-1.

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Scotch Whisky makes a significant contribution to the UK’s food and drinks export. The flavour of this high quality spirit is derived naturally from the whisky making process, with smoky aromas being a key character of certain Scotch whiskies. The level of smokiness is determined by the amount of phenolic compounds in the spirit. Phenols are introduced by exposing the barley malt to peat smoke during the kilning process. The current techniques to determine the levels of phenols, such as High Performance Liquid Chromatography (HPLC), are time consuming as they require distillation of the malt prior to analysis. To speed up this process and enable real-time detection before processing, the possibilities of Near-infrared to Short-wave-infrared (NIR-SWIR) Hyperspectral Imaging (HSI) to detect these phenols directly on malted barley are explored. It can be shown that via regression analysis, various levels of phenol concentration used as working levels for whisky production could be estimated to a satisfying degree. To further optimise industrial application, a hyperspectral band selection algorithm is applied that yields good results and reduces computational cost and may open possibilities to employ multispectral rather than hyperspectral cameras in future applications.

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Djelić, Gorica, Vesna Veličković, and Milica Pavlović. "SESELI RIGIDUM WALDST. & KIT: SECONDARY METABOLITES AND ANTIOXIDANT ACTIVITY OF METHANOL, ETHYL ACETATE AND ACETONE EXTRACTS." In 2nd International Symposium on Biotechnology. University of Kragujevac, Faculty of Agronomy, 2024. http://dx.doi.org/10.46793/sbt29.34gdj.

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Representatives of the Seseli genus are recognized for their biological activities. The objective of this study was to analyze the phenolic and flavonoid content, along with the antioxidant effects, of methanol, ethyl acetate, and acetone extracts obtained from the roots, leaves, stems, and fruits of S. rigidum. Through spectrophotometric measurements of phenols and flavonoids, the results revealed that the polar (methanol) solvent extract from the leaves exhibited the highest concentrations of phenols (98.66 ± 2.64 mg GA/g) and flavonoids (20.74 ± 0.55 mg RU/g), surpassing those obtained from the stem. Specifically, the methanol extract from the leaves demonstrated the highest antioxidant activity at 25.87 ± 0.05 μg/mL, while the fruit extract exhibited the lowest antioxidant activity at 638.5 ± 0.01 μg/mL. Notably, the total phenol content displayed a strong positive correlation with the antioxidant activity of the extracts, unlike the total flavonoid content.

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Todorović, Jovana D., Aleksandra D. Vesić, Nevena N. Petrović, and Marijana M. Kosanić. "Edible mushrooms as promising antioxidants." In 2nd International Conference on Chemo and Bioinformatics. Institute for Information Technologies, University of Kragujevac, 2023. http://dx.doi.org/10.46793/iccbi23.300t.

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Antioxidant activity of the acetone extracts of the mushrooms Macrolepiota procera and Chlorophyllum rhacodes has been screened in vitro by using different methods (DPPH radical scavenging and reducing power assay), and also it has been determined the total phenolic compounds as total flavonoid content. The research findings indicate that the acetone extract of M. procera demonstrated superior antioxidant activities when compared to C. rhacodes. Similarly, the mushroom M. procera displayed a more pronounced effect on reducing power. In addition, the total content of phenol and flavonoid in extracts were determined as pyrocatechol equivalent, and as rutin equivalent, respectively. A higher content of total phenols and flavonoids was detected in the extract of M. procera. The strong relationships between total phenolic and flavonoid contents and the antioxidative activities of tested extracts imply that these compounds have a significant impact on antioxidant activity. The present study highlights that the tested mushroom species exhibit potent antioxidant properties and can be regarded as valuable sources of natural antioxidants.

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Pavlović, M., Z. Simić, and Gorica Đelić. "DETERMINATION OF HEAVY METALS AND SECONDARY METABOLITES OF „PEUCEDANUM OREOSELINUM“ (APIACEAE)." In 1st INTERNATIONAL Conference on Chemo and BioInformatics. Institute for Information Technologies, University of Kragujevac, 2021. http://dx.doi.org/10.46793/iccbi21.206p.

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The total quantity of metals (Mg, Ca, Ni, Fe, Mn, Zn, Cu) in soil samples and in sixteen different extracts from plant parts of Peucedanum oreoselinum (L.) Moench as well as the content of total phenols and flavonoids in plant extracts was determined. The contents of metals were determined by the atomic absorption spectrometer. Based on the average values of the metal concentration in the soil, they could be arranged in the following sequence: Fe > Ca > Mg > Mn > Zn > Cu > Ni. Soil concentrations of all tested metals were lower than the maximum allowed concentration. The results demonstrated that the analyzed plant extracts contained higher quantities of Ni and Ca. Although the studied species accumulate analyzed metals in different quantities, they are not hyperaccumulators of these metals. Total phenols were determined using Folin-Ciocalteu reagent and their amounts ranged from 1.94 to P. oreoselinum, hyperaccumulation, phenols, flavonoids32.38 mg GA/g. The amounts of flavonoids in plant extracts were in range from 0.69 to 25.83 mg RU/g. We examined the correlation of metals and the phenolic compounds content in the extracts. According to our results the use P. oreoselinum for tea preparation is safe to a great extent for people, because in spite of the determined metal absorption by plant organs, the tea does not contain dangerous quantity of heavy metals. Also, it is suitable for the preparation of teas and herbal extracts due to minimal content of toxic metal (Ni), phenols and flavonoids.

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Šaćirović, Sabina, Andrija Ćirić, Mališa Antić, and Zoran Marković. "HPLC ANALYSIS OF PHENOLS OF SLOVENIAN RED WINES: CABERNET SAUVIGNON AND MERLOT." In 1st INTERNATIONAL Conference on Chemo and BioInformatics. Institute for Information Technologies, University of Kragujevac, 2021. http://dx.doi.org/10.46793/iccbi21.165s.

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In this study, HPLC-DAD rapid analysis of phenols in wine samples was performed. The recording was performed at different wavelengths: phenolic acid (254nm), flavan-3-ols and stilbene (280nm), flavonoids (340nm) and anthocyanins (520nm). In selected wines, the concentrations of the following compounds were determined and expressed in mg/l of wine. The isolated derivatives were: hydroxybenzoic acids, derivatives of caffeic, ferulic, syringic, and vanillic acids, catechin (flavanol), rutin, myricetin and quercetin (flavonols), and the stilbene derivative-resveratrol. The properties and quantities of phenolic compounds in organic wines were investigated. The results show the content of phenolic compounds in organic wines do not differ qualitatively and quantitatively from those in conventional wines. Wine samples have shown good antioxidative activity according to both DPPH and FRAP analysis, which indicates the good antioxidative potential and high antioxidant concentration in tested wines. Cabernet Sauvignon wines have shown better radical scavenging activity than Merlot, especially when the DPPH test was considered.

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Stoilova, I., A. Krastanov, H. Yemendzhiev, and Z. Alexieva. "Degradation of phenols by Fusarium moniliforme." In Proceedings of the II International Conference on Environmental, Industrial and Applied Microbiology (BioMicroWorld2007). WORLD SCIENTIFIC, 2009. http://dx.doi.org/10.1142/9789812837554_0042.

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Antonac, Irena, Pavle Trošelj, Davor Margetić, Zoran Glasovac, and Mirjana Eckert-Maksić. "Microwave assisted carboxymethylation of anilines and phenols." In The 10th International Electronic Conference on Synthetic Organic Chemistry. Basel, Switzerland: MDPI, 2006. http://dx.doi.org/10.3390/ecsoc-10-01439.

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Kolb, Vera M., and Patrick J. Liesch. "Astrobiological relevance of phenols and their silicates." In Optical Engineering + Applications, edited by Richard B. Hoover, Gilbert V. Levin, Alexei Y. Rozanov, and Paul C. Davies. SPIE, 2008. http://dx.doi.org/10.1117/12.792665.

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Đelić, Gorica, Milica Pavlović, and Vesna Velicković. "Qualitative content of selected phenolic compounds in different extracts of plant species Iris pumila L." In 2nd International Conference on Chemo and Bioinformatics. Institute for Information Technologies, University of Kragujevac, 2023. http://dx.doi.org/10.46793/iccbi23.555dj.

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The aim of this paper is to determine the content of selected phenolic compounds and to find the appropriate optimal extraction agent for the extraction of phenolic compounds from the plant species Iris pumila L. The content of total phenols and flavonoids in the rhizome and aboveground parts of the plant was determined by the application of the spectrophotometric method in the examined extracts obtained by the maceration method. By comparatively analyzing the application of two solvents for extraction, we concluded that the application of methanol in the conventional maceration technique contributes to a higher yield of phenolic compounds. Using methanol as a solvent, it was found that the content of selected phenolic compounds in the rhizome (28.57 mg/g extract total phenolic and for total flavonoids 24.21 mg/g extract) compared to ethyl acetate as solvent. Tested extracts of parts of Iris pumila L. plant contain high levels of phenolic compounds and are suitable for use as a source of compounds with pronounced antioxidant activity.

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Tong, Xin, Wenhao Shen, and Xiaoquan Chen. "Quantitative Studies of Ambient Gases in Pulp and Paper Mills and Their Degradation with Photo-catalytic Oxidation Technology." In Advances in Pulp and Paper Research, Oxford 2017. Fundamental Research Committee (FRC), Manchester, 2017. http://dx.doi.org/10.15376/frc.2017.1.409.

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In order to reduce gaseous pollution emissions and achieve the goal of cleaner production in paper industry, in this study, (I) First, the concentrations of four potential compositions of gaseous pollutants, TVOC, HCHO, H2S and CxHy, in the ambient air on 30 sampling sites in 5 pulp and paper mills were analysed. The analysed results were discussed in the following aspects: (a) the levels of four gaseous pollutants on all the sampling sites in five mills; (b) gaseous pollution differences due to different production processes; (c) gaseous pollution comparisons on the common sites. (II) Secondly, the compositions of VOCs in a secondary fiber paper mill were determined with GC-MS method. The main identified substances in the four sites were as follows: (a) waste paper sorting room: alkanes, phenols and esters; (b) paper machine hall: benzene homologues, alkanes, ethers and phenols; (c) vacuum pulp outlet: benzene homologues and phenols; (d) office area: benzene homologues and phenols. (III) Third and last, aiming a the detected formaldehyde and benzene pollutants, a photo-catalytic reactor was developed and its performance with respect to degradation was studied. The performance tests of reactor showed that both formaldehyde and benzene could be completely degraded, but the degradation time for benzene was much longer than that for formaldehyde.

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Reports on the topic "Phenols"

Jayaweera, Ananda. Kinetics of proton transport in lipid membranes induced by some chlorinated phenols. Portland State University Library, January 2000. http://dx.doi.org/10.15760/etd.215.

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Katzenellenbogen, John A., and Dong Zhou. Expedited Synthesis of Fluorine-18 Labeled Phenols. A Missing Link in PET Radiochemistry. Office of Scientific and Technical Information (OSTI), March 2015. http://dx.doi.org/10.2172/1176765.

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Nicholson, Ralph, Reuven Reuveni, and Moshe Shimoni. Biochemical Markers for Disease Resistance in Corn. United States Department of Agriculture, May 1996. http://dx.doi.org/10.32747/1996.7613037.bard.

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The objective was to screen maize lines for their ability to express resistance based on biochemical traits. Cultivars were screened for retention of the hydroxamic acid DIMBOA and the synthesis of phenols (based on anthocyanin production) as markers for resistance. Lines were selected and inoculated with fungal pathogens (Exserohilum turcicum, Puccinia sorghi, Cochliobolus heterostraphus, Colletotricum graminicola.), and the Maize Dwarf Mosaic and Johnson Grass Mosaic viruses. Lines were screened in the field and greenhouse. Results showed that lines selected for augmented phenol synthesis do exhibit heightened levels of resistance to fungal pathogens. Isolation of mRNA followed by northern analyses for expression of A1 (dihydroflavanol reductase) and peroxidase confirmed that genes for these enzymes were turned on in response to inoculation of lines predicted to exhibit resistance. Peroxidase and b-1,3-glucanase were assayed in breeding lines having or lacking the se gene. A specific ionically-bound peroxidase isozyme and a b-1,3-glucanase isozyme were revealed in lines having the se gene. Data suggest that peroxidase and b-1,3-glucanase isozymes, may be considered as markers to identify resistance to E. turcicum in maize genotypes with the se gene.

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Savage, P. E. Oxidation of substituted phenols in supercritical water. Final technical report, September 1992--August 1996. Office of Scientific and Technical Information (OSTI), November 1996. http://dx.doi.org/10.2172/469173.

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Word, Robert. Distribution of Ionized and Neutral Halogenated Phenols in an Octanol-water Membrane Model System. Portland State University Library, January 2000. http://dx.doi.org/10.15760/etd.7083.

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Kim, Yun-mi, Samuel Farrah, and Ronald H. Baney. Structure--Antimicrobial Activity Relationship Comparing a New Class of Antimicrobials, Silanols, to Alcohols and Phenols. Fort Belvoir, VA: Defense Technical Information Center, April 2006. http://dx.doi.org/10.21236/ada447843.

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Hensler, Sven. Distribution Coefficients of Ionized and Un-ionized Halogenated Phenols in an Octanol-water System and their Relationship to Molecular Structure. Portland State University Library, January 2000. http://dx.doi.org/10.15760/etd.7045.

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Maskarinec, M. P., D. L. Manning, and R. W. Harvey. Application of XAD-4 solid sorbent and HPLC (high performance liquid chromatography) with electrochemical detection to the analysis of phenols in water: Final report, November 1983-November 1985. Office of Scientific and Technical Information (OSTI), June 1987. http://dx.doi.org/10.2172/6478788.

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Steffens, John, Eithan Harel, and Alfred Mayer. Coding, Expression, Targeting, Import and Processing of Distinct Polyphenoloxidases in Tissues of Higher Plants. United States Department of Agriculture, November 1994. http://dx.doi.org/10.32747/1994.7613008.bard.

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Polyphenol oxidase (PPO) catalyzes the oxidation of phenols to quinones at the expense of O2. PPOs are ubiquitous in higer plants, and their role in oxidative browning of plant tissues causes large annual losses to food production. Despite the importance of PPOs to agriculture, the function(s) of PPOs in higher plants are not understood. Among other roles, PPOs have been proposed to participate in aspects of chloroplast metabolism, based on their occurrence in plastids and high Km for O2. Due to the ability of PPO to catalyze formation of highly reactive quinones, PPOs have also been proposed to be involved in a wide array of defensive interactions with insect, bacterial, and fungal pests. Physiological and biochemical studies of PPO have provided few answers to the major problems of PPO function, subcellular localization, and biochemical properties. This proposal achieved the following major objectives: cloning of PPO cDNAs in potato and tomato; characterization of the tomato PPO gene family; antisense downregulation of the tomato PPO gene family; and reduction in post-harvest enzymic browning of potato through expression of antisense PPO genes under the control of tuber-specific promoters. In addition, we established the lumenal localization of PPO, characterized and clarified the means by which PPOs are imported and processed by chloroplasts, and provided insight into the factors which control localization of PPOs. This proposal has thereby provided fundamental advances in the understanding of this enzyme and the control of its expression.

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Kanner, Joseph, Edwin Frankel, Stella Harel, and Bruce German. Grapes, Wines and By-products as Potential Sources of Antioxidants. United States Department of Agriculture, January 1995. http://dx.doi.org/10.32747/1995.7568767.bard.

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Several grape varieties and red wines were found to contain large concentration of phenolic compounds which work as antioxidant in-vitro and in-vivo. Wastes from wine production contain antioxidants in large amounts, between 2-6% on dry material basis. Red wines but also white wines were found to prevent lipid peroxidation of turkey muscle tissues stored at 5oC. The antioxidant reaction of flavonoids found in red wines against lipid peroxidation were found to depend on the structure of the molecule. Red wine flavonoids containing an orthodihydroxy structure around the B ring were found highly active against LDL and membrane lipid peroxidation. The antioxidant activity of red wine polyphenols were also found to be dependent on the catalyzer used. In the presence of H2O2-activated myoglobin, the inhibition efficiency was malvidin 3-glucoside>catechin>malvidin>resveratol. However, in the presence of an iron redox cycle catalyzer, the order of effectiveness was resveratol>malvidin 3-glucoside = malvidin>catechin. Differences in protein binding were found to affect antioxidant activity in inhibiting LDL oxidation. A model protein such as BSA, was investigated on the antioxidant activity of phenolic compounds, grape extracts, and red wines in a lecithin-liposome model system. Ferulic acid followed by malvidin and rutin were the most efficient in inhibiting both lipid and protein oxidation. Catechin, a flavonal found in red-wines in relatively high concentration was found to inhibit myoglobin catalyzed linoleate membrane lipid peroxidation at a relatively very low concentration. This effect was studied by the determination of the by-products generated from linoleate during oxidation. The study showed that hydroperoxides are catalytically broken down, not to an alcohol but most probably to a non-radical adduct. The ability of wine-phenolics to reduce iron and from complexes with metals were also demonstrated. Low concentration of wine phenolics were found to inhibit lipoxygenase type II activity. An attempt to understand the bioavailability in humans of antocyanins from red wine showed that two antocyanins from red wine were found unchanged in human urine. Other antocyanins seems to undergo molecular modification. In hypercholesterolemic hamsters, aortic lipid deposition was significantly less in animals fed diets supplemented with either catechin or vitamin E. The rate of LDL accumulation in the carotid arteries was also significantly lower in the catechin and vitamin E animal groups. These results suggested a novel mechanism by which wine phenolics are associated with decreased risk of coronary heart diseases. This study proves in part our hypothesis that the "French Paradox" could be explained by the action of the antioxidant effects of phenolic compounds found at high concentration in red wines. The results of this study argue that it is in the interest of public health to increase the consumption of dietary plant falvonoids. Our results and these from others, show that the consumption of red wine or plant derived polyphenolics can change the antioxidant tone of animal and human plasma and its isolated components towards oxidative reactions. However, we need more research to better understand bioavailability and the mechanism of how polyphenolics affect health and disease.

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