ascorbic-acid and myricetin

In recent years, the acreage used for organic agriculture and the demand for organic fruit and vegetables have increased considerably. Given this scenario, landraces, such as Capsicum landraces, can provide valuable germplasm. Capsicum peppers are very interesting because of their high phenolic content, and particularly their flavonoid content, which provides a high added value. Moreover, the broad genetic diversity in local varieties expands the opportunities for adaptation to organic production and for exploiting genotype × environment interactions to select peppers with the highest phenolic content.. In this work, the main flavonoids of peppers were exhaustively evaluated over 2 years in a wide collection of heirlooms, both unripe and fully ripe, under organic and conventional cultivation. The genotype and ripening stage contributed to a high degree to the variation in flavonoids. The growing system influenced this variation to a lesser extent. Luteolin and quercetin showed the highest contributions to total phenolic content (70% and > 20%, respectively) at both ripening stages, while myricetin, apigenin, and kaempferol showed lower contributrions. The average flavonoid content was higher in ripe fruits, and organic management significantly increased the accumulation of total flavonoids and luteolin. Positive correlations between flavonoids were found at both ripening stages, especially between main flavonoids luteolin and quercetin and between kaempferol and quercetin (ρ > 0.7).. Genotype × environment interaction enabled the identification of accessions with high flavonoid content grown under organic conditions at both ripening stages, particularly total flavonoids and luteolin at the fully ripe stage. Our results reinforce the importance of a wide genetic variation and of considering different ripening stages and growing conditions for breeding high-quality peppers. © 2020 Society of Chemical Industry.

Topics: Antioxidants; Ascorbic Acid; Capsicum; Crops, Agricultural; Flavonoids; Food Analysis; Fruit; Kaempferols; Luteolin; Organic Agriculture; Phenols; Plant Development; Quercetin

Topics: Ascorbic Acid; Azetidinecarboxylic Acid; Biological Availability; Caco-2 Cells; Catechin; Flavonoids; Humans; Intestinal Mucosa; Iron; Iron Chelating Agents

Bioassay-guided fractionation of the methanol extract of the shoots of Myrsine africana led to the isolation of the new compound myricetin 3-O-(2″,4″-di-O-acetyl)-α-l-rhamnopyranoside (9) and 11 known compounds. The known compounds quercetin 3-O-(3″,4″-di-O-acetyl)-α-l-rhamnopyranoside (8), rutin (10), quercetin 3-O-α-l-rhamnopyranoside (11), and myricetin 3-O-α-l-rhamnopyranoside (12) are reported for the first time from the methanol extract of the shoots of M. africana. Compounds 10 and 12 showed significant inhibition of tyrosinase with 50% inhibition (IC

Topics: Agaricales; Antioxidants; Flavonoids; Glycosides; Molecular Docking Simulation; Myrsine; Plant Extracts; Quercetin

There are large differences between flavonoids to protect against apoptosis, a process in which cytochrome c (Cyt c) plays a key role. In this work, we show that 7 of 13 flavonoids studied have a capacity to reduce Cyt c similar or higher than ascorbate, the flavonols quercetin, kaempferol and myricetin, flavanol epigallocatechin-gallate, anthocyanidins cyanidin and malvidin, and the flavone luteolin. In contrast, the kaempferol 3(O)- and 3,4'(O)-methylated forms, the flavanone naringenin, and also apigenin and chrysin, had a negligible reducing capacity. Equilibrium dialysis and quenching of 1,6-diphenyl-1,3,5-hexatriene fluorescence experiments showed that flavonoids did not interfere with Cyt c binding to cardiolipin (CL)/phosphatidylcholine (PC) vesicles. However, the CL-induced loss of Cyt c Soret band intensity was largely attenuated by flavonoids, pointing out a stabilizing action against Cyt c unfolding in the complex. Moreover, flavonoids that behave as Cyt c reductants also inhibited the pro-apoptotic CL-induced peroxidase activity of Cyt c, indicating that modulation of Cyt c signaling are probable mechanisms behind the protective biological activities of flavonoids. © 2016 BioFactors, 43(3):451-468, 2017.

Topics: Animals; Anthocyanins; Ascorbic Acid; Cardiolipins; Catechin; Cytochromes c; Diphenylhexatriene; Flavonoids; Fluorescent Dyes; Horses; Kaempferols; Luteolin; Oxidation-Reduction; Peroxidases; Phosphatidylcholines; Protein Binding; Protein Conformation; Quercetin; Reducing Agents; Spectrometry, Fluorescence; Static Electricity; Unilamellar Liposomes

Chinese cabbage (Brassica rapa L. ssp. Pekinensis) is a green leafy vegetable used mainly in kimchi, salted and fermented dishes. Consumer preference for the leaf portion differs according to the type of dishes. In this study, Chinese cabbage was divided into three parts, and their antioxidant activities were investigated through in vitro assays. The total phenolic contents (TPC), total flavonoid contents (TFC), and vitamin C contents were also determined as indicators of antioxidant contents. The phenolic acids and flavonoids were separated and identified using high performance liquid chromatography (HPLC) and liquid chromatography/mass spectrometry (LC/MS). The outer leaf had the strongest antioxidant activity with the maximum antioxidant contents, followed by the mid- and inner leaves. Principal component analysis (PCA) revealed that outer leaf is positively related to caffeic acid, p-coumaric acid, ferulic acid, and myricetin contents, whereas the mid- and inner leaves are negatively related to sinapic acid contents.

Topics: Antioxidants; Ascorbic Acid; Brassica; Chromatography, High Pressure Liquid; Coumaric Acids; Flavonoids; Phenols; Plant Leaves; Propionates

In this study, phenolic compounds were analyzed in developing berries of four Canadian grown sea buckthorn (Hippophae rhamnoides L.) cultivars ('RC-4', 'E6590', 'Chuyskaya' and 'Golden Rain') and in leaves of two of these cultivars. Among phenolic acids, p-coumaric acid was the highest in berries, while gallic acid was predominant in leaves. In the flavonoid class of compounds, myricetin/rutin, kaempferol, quercetin and isorhamnetin were detected in berries and leaves. Berries of the 'RC-4' cultivar had approximately ⩾ 2-fold higher levels of myricetin and quercetin at 17.5mg and 17.2 mg/100 g FW, respectively, than the other cultivars. The flavonoid content in leaves was considerably more than in berries with rutin and quercetin levels up to 135 mg and 105 mg/100 g FW, respectively. Orthologs of 15 flavonoid biosynthesis pathway genes were identified within the transcriptome of sea buckthorn mature seeds. Semi-quantitative RT-PCR analysis of these genes in developing berries indicated relatively higher expression of genes such as CHS, F3'H, DFR and LDOX in the 'RC-4' cultivar than in the 'Chuyskaya' cultivar. Vitamin C levels in ripened berries of the Canadian cultivars were on the high end of the concentration range reported for most other sea buckthorn cultivars. Orthologs of genes involved in vitamins C and E biosynthesis were also identified, expanding the genomic resources for this nutritionally important plant.

Topics: Antioxidants; Ascorbic Acid; Chromatography, High Pressure Liquid; Coumaric Acids; Flavonoids; Fruit; Hippophae; Nuclear Magnetic Resonance, Biomolecular; Phenols; Plant Leaves; Polymerase Chain Reaction; Propionates; Quercetin; Tocopherols

Flavonoids are ubiquitous phenolic plant metabolites. Many of them are well known for their pro- and antioxidant properties. Myricetin has been reported to be either a potent antioxidant or a pro-oxidant depending on the conditions. The reaction conditions for the pro- and antioxidant activities were therefore investigated using variations of the deoxyribose degradation assay systems.. The deoxyribose degradation assay systems were conducted as follows; H(2)O(2)/Fe(III)/ascorbic acid, H(2)O(2)/Fe(III), Fe(III)/ascorbic acid, and Fe(III). Each system was carried out in two variants, FeCl(3) (iron ions added as FeCl(3)) and FeEDTA (iron added in complex with ethylenediaminetetraacetic acid).. When ascorbic acid was present, myricetin showed antioxidant properties, especially when it occurred in complex with iron. In ascorbic acid-free systems, pro-oxidant activities prevailed, which where enhanced if iron was in complex with EDTA.. Myricetin's antioxidant activity depends on both the reactive oxygen species (ROS) scavenging and iron ions chelation properties. The pro-oxidative properties are caused by reduction of molecular oxygen to ROS and iron(III) to iron(II). Myricetin is able to substitute for ascorbic acid albeit less efficiently.

Topics: Antioxidants; Ascorbic Acid; Chlorides; Deoxyribose; Dose-Response Relationship, Drug; Edetic Acid; Ferric Compounds; Ferrous Compounds; Flavonoids; Hydrogen Peroxide; Molecular Structure; Oxidation-Reduction; Reactive Oxygen Species

The increased interest in sea buckthorn (Hippophae rhamnoides L.) made it possible to investigate the antioxidant content in it. To address this issue, the presence of following antioxidant compounds were analyzed: trans-resveratrol, catechin, myricetin, quercetin, p-coumaric acid, caffeic acid, L-ascorbic acid (AA), and gallic acid (linear range of 50-150 micromol/L) in six different varieties of sea buckthorn berries extracts (sea buckthorn varieties: "Trofimovskaja (TR)," "Podarok Sadu (PS)," and "Avgustinka (AV),") received from two local Estonian companies. Trans-Resveratrol, catechin, AA, myricetin, and quercetin were found in extracts of sea buckthorn. Moreover, AA, myricetin, and quercetin contents were quantified. The biggest average AA content was found in TR (740 mg/100 g of dried berries, respectively). Furthermore, the same varieties gave the biggest quercetin content 116 mg/100 g of dried berries, respectively. For analysis, CZE was used and the results were partly validated by HPLC. Statistically no big differences in levels of antioxidants were consistently found in different varieties of sea buckthorn extracts investigated in this work.

Topics: Antioxidants; Ascorbic Acid; Catechin; Chromatography, High Pressure Liquid; Electrophoresis, Capillary; Estonia; Flavonoids; Fruit; Hippophae; Quercetin; Resveratrol; Stilbenes

Reduction of extracellular ferricyanide [Fe(CN)(6)](-3) to ferrocyanide by intact cells reflects the activity of a trans-plasma membrane oxidoreductase that, in human red blood cells, utilizes ascorbic acid as an electron donor. We herein report that the flavonoids quercetin and myricetin, while inhibiting dehydroascorbic acid uptake-and thus the erythrocyte ascorbic acid content-effectively stimulate the extracellular reduction of ferricyanide. Other flavonoids such as rutin, acacetin, apigenin, and genistein do not show the same effect. The notion that quercetin or myricetin may serve as an intracellular donor for a trans-plasma membrane oxidoreductase is supported by the following lines of evidence: (i) they afford direct reduction of ferricyanide; (ii) extracellular reduction of ferricyanide was not mediated by direct effects of the flavonoids released by the cells and was abolished by the sulphydryl reagent parachloromercuribenzenesulfonic acid (pCMBS); (iii) the intracellular concentrations of quercetin or myricetin well correlate with increases in ferricyanide reduction; (iv) the intracellular concentration of the flavonoids dramatically declines after ferricyanide exposure. Taken together, the results presented in this study demonstrate that myricetin and quercetin, which accumulate in large amounts in red blood cells, act as intracellular substrates of a pCMBS-sensitive trans-plasma membrane oxidoreductase. This may represent a novel mechanism whereby these flavonoids exert beneficial effects under oxidative stress conditions.

Topics: 4-Chloromercuribenzenesulfonate; Ascorbic Acid; Dehydroascorbic Acid; Electron Transport; Erythrocyte Membrane; Erythrocytes; Ferricyanides; Flavonoids; Humans; NADH, NADPH Oxidoreductases; Oxidation-Reduction; Quercetin

In HL-60, U937 and Jurkat cells, the intracellular accumulation of ascorbic acid occurred via uptakes of both dehydroascorbic acid (an oxidized metabolite of ascorbic acid) and ascorbic acid (vitamin C). Dehydroascorbic acid and ascorbic acid were transported into cells by sodium-independent glucose transporters (GLUT 1 and GLUT 3) and sodium-dependent ascorbic acid transporters, respectively. Flavonoids inhibited the intracellular accumulation of ascorbic acid by blocking dehydroascorbic acid and ascorbic acid uptakes in the transformed cells. At flavonoid concentrations of 10-70 micromol/L, approximately 50% of dehydroascorbic acid uptake was inhibited in the cells. In Jurkat cells, two potent flavonoids (myricetin and quercetin) competitively inhibited dehydroascorbic acid uptake, and K(i) values were approximately 14 and 15 micromol/L, respectively. Because GLUT 1 and GLUT 3 transport dehydroascorbic acid, the inhibition of dehydroascorbic acid uptake by flavonoids was investigated by using Chinese hamster ovary cells overexpressing rat GLUT 1 or human GLUT 3. Myricetin at concentrations of 22 and 18 micromol/L, respectively, inhibited half of dehydroascorbic acid uptake in the cells overexpressing GLUT 1 and GLUT 3. Myricetin also inhibited ascorbic acid uptake; inhibition was noncompetitive with K(i) = 14 micromol/L in Jurkat cells. These data indicate that flavonoids inhibit both ascorbic acid and dehydroascorbic acid uptake but do so by different mechanisms. These data may contribute to new understanding of the biological effect of flavonoids on the intracellular accumulation of ascorbic acid in human cells.

Topics: Animals; Ascorbic Acid; CHO Cells; Cricetinae; Dehydroascorbic Acid; Dose-Response Relationship, Drug; Drug Interactions; Flavonoids; Glucose Transporter Type 1; Glucose Transporter Type 3; HL-60 Cells; Humans; Jurkat Cells; Monosaccharide Transport Proteins; Nerve Tissue Proteins; Quercetin; Rats; U937 Cells

We investigated the ability of various plant flavonoids (a) to inhibit 5-lipoxygenase and cyclooxygenase activities in rat peritoneal leukocytes, (b) to inhibit lipid peroxidation in rat liver microsomes, and (c) to stimulate DNA degradation caused by the antibiotic bleomycin in the presence of ferric ions. These compounds were compared with a range of synthetic phenolic substances including carnosol, vanillin, vitamin E and its analogue trolox c. The flavonoids were potent inhibitors of non-enzymatic peroxidation in membranes but this was not significantly correlated with their ability to inhibit either pathway of eicosanoid synthesis, suggesting that their mode of inhibition of 5-lipoxygenase/cyclooxygenase is not simply due to interception of peroxyl radicals generated at the active site of the enzymes. Many of the flavonoids and other compounds (including carnosol, vitamin E and trolox c) stimulated Fe3+/bleomycin-dependent DNA degradation. Those flavonoids which stimulated DNA degradation at low concentrations but which inhibited it at higher concentrations ("biphasic" effect, possibly caused by changing relative contributions of ability to reduce ferric-bleomycin or to chelate iron ions from the bleomycin) were selective inhibitors of 5-lipoxygenase compared to cyclo-oxygenase. In contrast, those flavonoids that did not stimulate DNA degradation at all proved to be cyclo-oxygenase selective inhibitors. Compounds that increased Fe3+/bleomycin-dependent DNA damage up to a maintained plateau were non-selective inhibitors of both 5-lipoxygenase and cyclo-oxygenase. Thus, a combination of iron-chelating and iron ion-reducing properties appears to be required for selective 5-lipoxygenase inhibition by phenolic compounds. Carnosol, vitamin E and trolox c were also found to be 5-lipoxygenase inhibitors of varying potency, and all were less active as cyclo-oxygenase inhibitors.

Topics: Abietanes; Animals; Antioxidants; Ascorbic Acid; Chromans; Cytochrome c Group; Diet; DNA Damage; Female; Ferric Compounds; Flavonoids; Flavonols; Leukocytes; Lipid Peroxidation; Lipoxygenase Inhibitors; Microsomes, Liver; Oxidation-Reduction; Oxygenases; Phenanthrenes; Phenols; Plant Extracts; Quercetin; Rats; Rats, Inbred Strains; Vitamin E