3-methylquercetin and myricetin

To determine whether dietary intake of flavonols is associated with Alzheimer dementia.. The study was conducted among 921 participants of the Rush Memory and Aging Project (MAP), an ongoing community-based, prospective cohort. Participants completed annual neurologic evaluations and dietary assessments using a validated food frequency questionnaire.. Among 921 MAP participants who initially had no dementia in the analyzed sample, 220 developed Alzheimer dementia. The mean age of the sample was 81.2 years (SD 7.2), with the majority (n = 691, 75%) being female. Participants with the highest intake of total flavonols had higher levels of education and more participation in physical and cognitive activities. In Cox proportional hazards models, dietary intakes of flavonols were inversely associated with incident Alzheimer dementia in models adjusted for age, sex, education,. Higher dietary intakes of flavonols may be associated with reduced risk of developing Alzheimer dementia.

Topics: Aged; Aged, 80 and over; Alzheimer Disease; Cohort Studies; Diet; Female; Flavonoids; Flavonols; Humans; Incidence; Kaempferols; Male; Proportional Hazards Models; Prospective Studies; Protective Factors; Quercetin

Chickpea (Cicer arietinum L.) genotypes, nine kabuli from Mexico and 9 desi from other countries, were investigated for their phenolic profiles and antioxidant activity (AA). Phenolics in methanol extracts (ME) were analyzed by ultra-performance liquid chromatography coupled to diode array detection and mass spectrometry (UPLC-DAD-MS), whereas the AA was measured as Trolox equivalents (TE) by ABTS, DPPH and FRAP methods. Twenty phenolic compounds were identified in the ME and their levels showed a great variability among the chickpea genotypes. Phenolic acids and flavonoids were the most abundant compounds in kabuli and desi genotypes, respectively. The AA values (μmol TE/ 100 g dw) by ABTS (278-2417), DPPH (52-1650), and FRAP (41-1181) were mainly associated with the content of sinapic acid hexoside, gallic acid, myricetin, quercetin, catechin, and isorhamnetin, suggesting they are the main compounds responsible for the AA. The sum of the AA obtained for standards of these compounds evaluated at the concentration found in the extracts accounted for 34.3, 69.8, and 47.0% of the AA in the extract by ABTS, DPPH, and FRAP, respectively. In the AA by DPPH, most of the mixtures of these compounds resulted in synergistic interactions. Three desi genotypes with black seeds (ICC 4418, ICC 6306, and ICC 3761) showed the highest AA and flavonoids content, whereas the most promising kabuli genotypes were Surutato 77, Bco. Sin. 92, and Blanoro that showed the highest values of phenolic acids. These genotypes represent good sources of antioxidants for the improvement of nutraceutical properties in chickpea.

Topics: Antioxidants; Catechin; Chromans; Chromatography, Liquid; Cicer; Flavonoids; Gallic Acid; Genotype; Hydroxybenzoates; Mass Spectrometry; Quercetin; Seeds

This is the first in vitro study to investigate gender-related differences in the regulation of human cytochrome P450 by the flavonoids. Activities of CYP2E1 and CYP3A were measured in the presence of quercetin, myricetin, or isorhamnetin in hepatic microsomal pools from male and female donors. Hydroxylation of p-nitrophenol (PNPH) was measured to determine CYP2E1 activity, and O-dealkylation of 7-benzyloxy-4-trifluoromethylcoumarin (BFC) was measured to determine CYP3A activity. Quercetin, but not myricetin or isorhamnetin, competitively inhibited PNPH activity in human recombinant cDNA-expressed CYP2E1 with the Ki=52.1±6.31μM. In the human microsomes, slight inhibition of PNPH activity by quercetin was not considered as physiologically relevant. Quercetin inhibited BFC activity in human recombinant cDNA-expressed CYP3A4 competitively with the Ki=15.4±1.52μM, and myricetin - noncompetitively with the Ki=74.6±7.99μM. The degree of inhibition by quercetin was similar between genders. Myricetin showed somewhat stronger inhibition in female pools, but the Ki values were higher than physiologically relevant concentrations. Isorhamnetin did not affect either PNPH or BFC activity. We concluded that observed inhibition of CYP2E1 and CYP3A by some flavonols were not gender-dependent.

Topics: Coumarins; Cytochrome P-450 CYP2E1; Cytochrome P-450 CYP2E1 Inhibitors; Cytochrome P-450 CYP3A; Enzyme Inhibitors; Female; Flavonoids; Humans; Hydroxylation; Male; Microsomes, Liver; Nitrophenols; Quercetin; Sex Factors

We investigated the chemical constituents of the leaves of Psidum littorale, which include 16 flavonoids, including seven flavonols, six flavonoid glycosides and three flavonones. The compounds were isolated by silica gel column chromatography. Their structures were elucidated on the basis of spectral analysis and by comparison with published data. Seven flavonols were kaempferol (1), isorhamnetin (2), myricetin- 3,7,3’-trimethyl ether(3), laricitrin (4), quercetin (5), myricetin (6) and quercein-3,4’-dimethyl ether (7), six flavonoid glycosides were guaijaverin (8), hyperoside (9), 5,4’-dyhydroxy-3,7,5’-methoxyflavone-3’-O-β-D- glucoside (10), laricitrin-3-O-xyloside (11), myricetin-3-O-α-L-rhamnopyranoside (12) and myricetin-3-O-β-D- xyloside (13). Three flavonones were 4’-O-methyldihydroquercetin (14), dihydroapigenin (15) and ampelopsin 4’-O-β-D-glucopyranoside (16). Compound 10 is a new chemical, compounds 2-4, 7, 10-16 were first isolated from this plant. (1)H NMR and (13)C NMR data of compound 11 were not reported in literature.

Topics: Flavonoids; Flavonols; Glycosides; Kaempferols; Plant Leaves; Psidium; Quercetin

In this study, carbamate-embedded triacontyl-modified silica (Sil-CBM-C30) is successfully prepared and used as an efficient sorbent for solid-phase extraction. The extraction performance of the resultant sorbent is evaluated with five flavonoids including myricetin, quercetin, luteolin, kaempferol and isorhamnetin. Main parameters, which affect extraction efficiencies, are carefully investigated and optimized. Comparative experiments between Sil-CBM-C30 and commercial C18 sorbents indicate that the extraction efficiencies of the former one surpass the latter one. The modification of carbamate-embedded triacontyl group on surface of silica causes analytes extracted by hydrophobic, hydrogen bonding and π-π interactions. Under optimal conditions, good linearities and satisfied LODs and LOQs are achieved. The SPE-HPLC-DAD method is successfully developed and applied for the honey sample analysis.

Topics: Carbamates; Chromatography, High Pressure Liquid; Flavonoids; Food Analysis; Honey; Kaempferols; Limit of Detection; Luteolin; Quercetin; Silicon Dioxide; Solid Phase Extraction

It has been reported that quercetin is an activator of rat vitamin D receptor (rVDR). However, the conclusion was based on experiments performed without all the appropriate control groups, raising the possibility of a false-positive finding. Furthermore, distinct differences exist in the chemical structures of quercetin and 1α,25-dihydroxyvitamin D3, which is a prototypic agonist of VDR. Therefore, we investigated systematically whether quercetin and other flavonols are agonists of rVDR, mouse VDR (mVDR), or human VDR (hVDR). Quercetin, 3-hydroxyflavone, galangin, datiscetin, kaempferol, morin, isorhamnetin, tamarixetin, myricetin, and syringetin did not activate rVDR, mVDR, or hVDR in HEK-293 and HepG2 cells transfected with the corresponding receptor expression plasmid and either the secreted phosphoprotein 1 (Spp1) or cytochrome P450 24A1 (CYP24A1) reporter plasmid, when compared to the respective empty vector control group transfected with one or the other reporter plasmid and treated with one of the flavonols. Control analysis indicated that lithocholic acid and 1α,25-dihydroxyvitamin D3, but not rifampicin, activated rVDR, mVDR, and hVDR. As shown in transfected HEK293 and HepG2 cells, the flavonols did not influence hVDR ligand binding domain transactivation, steroid receptor coactivator-1 recruitment, or hVDR target gene expression (transient receptor potential cation channel 6 and CYP24A1) in hVDR-expressing Caco-2 or LS180 cells. The cumulative data from the cell-based experiments were corroborated by results obtained from molecular docking analysis. In conclusion, quercetin, 3-hydroxyflavone, galangin, datiscetin, kaempferol, morin, isorhamnetin, tamarixetin, myricetin, and syringetin are not agonists of rVDR, mVDR, or hVDR, as judged by cell-based and in silico evidence.

Topics: Animals; Caco-2 Cells; Calcitriol; Disaccharides; Flavonoids; Gene Expression Regulation; HEK293 Cells; Hep G2 Cells; Humans; Kaempferols; Mice; Molecular Docking Simulation; Osteopontin; Quercetin; Receptors, Calcitriol; Structure-Activity Relationship; Transgenes; Vitamin D3 24-Hydroxylase

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, a broad category of nonnutrient food components, are potential protective dietary factors in the etiology of some cancers. However, previous epidemiological studies showing associations between flavonoid intake and cancer risk have used unvalidated intake assessment methods. A 62-item food frequency questionnaire (FFQ) based on usual intake of a representative Australian adult population sample was validated against a 3-day diet diary method in 60 young adults. Spearman's rank correlations showed 17 of 25 individual flavonoids, 3 of 5 flavonoid subgroups, and total flavonoids having strong/moderate correlation coefficients (0.40-0.70), and 8 of 25 individual flavonoids and 2 of 5 flavonoid subgroups having weak/insignificant correlations (0.01-0.39) between the 2 methods. Bland-Altman plots showed most subjects within ±1.96 SD for intakes of flavonoid subgroups and total flavonoids. The FFQ classified 73-90% of participants for all flavonoids except isorhamnetin, cyanidin, delphinidin, peonidin, and pelargonidin; 73.3-85.0% for all flavonoid subgroups except Anthocyanidins; and 86.7% for total flavonoid intake in the same/adjacent quartile determined by the 3-day diary. Weighted kappa values ranged from 0.00 (Isorhamnetin, Pelargonidin) to 0.60 (Myricetin) and were statistically significant for 18 of 25 individual flavonoids, 3 of 5 subgroups, and total flavonoids. This FFQ provides a simple and inexpensive means to estimate total flavonoid and flavonoid subgroup intake.

Topics: Adolescent; Adult; Anthocyanins; Diet; Diet Records; Feeding Behavior; Flavonoids; Humans; Middle Aged; Quercetin; Reproducibility of Results; Surveys and Questionnaires; Young Adult

Polygonum aviculare L. (Common Knotrgrass) (Polygonaceae Juss.) is an annual from which pharmacopoeial (Ph. Eur.) plant material Polygoni avicularis herba is obtained. Although its main active constituents are flavonoids and its standardization is based on their total content, no profound qualitative analysis has been performed, yet. The use of hyphenated analytical methods: UHPLC-DAD coupled with ion trap or time of flight mass detectors together with acidic hydrolysis products analysis allowed for a comprehensive determination of flavonoid composition. Among dominating compounds, myricetin, kaempferol, isorhamnetin and kaempferide glucuronides, which were not previously reported in P. avicularis herba, were discovered. The developed method can be used as a suitable tool for a more insightful, metabolome-based standardization of flavonoid rich pharmacopoeial plant material -P. avicularis herba.

Topics: Chromatography, High Pressure Liquid; Flavonoids; Glucuronides; Kaempferols; Mass Spectrometry; Plant Extracts; Polygonum; Quercetin

A rapid and reliable analytical method for quantification of flavonoids in onions was developed and validated. Five extraction methods were tested on freeze-dried onions and subsequently high performance liquid chromatography (HPLC) with UV detection was used for quantification of seven flavonoids. The extraction efficiencies were lowest for the conventional water bath extraction compared to pressurized liquid extraction (PLE), ultrasonication, ultrasonic liquid processor, and microwave extraction, which yielded similar efficiencies. The reproducibility was in the same range (RSD: 1-11%) for all tested extraction methods. However, PLE was the preferred extraction method because the method can be highly automated, use only small amounts of solvents, provide the cleanest extracts, and allow the extraction of light and oxygen-sensitive flavonoids to be carried out in an inert atmosphere protected from light. The method parameters: extraction temperature, sample weight, flush volume and solvent type were optimised, and a clean-up step was integrated in the PLE procedure by in-cell addition of C18-material to the extraction cells, which slightly improved the recovery and reproducibility of the method. The one-step PLE method showed good selectivity, precision (RSDs=3.1-11%) and recovery of the extractable flavonoids (98-99%). The method also appeared to be a multi-method, i.e. generally applicable to, e.g. phenolic acids in potatoes and carrots.

Topics: Chemistry Techniques, Analytical; Chromatography, High Pressure Liquid; Flavonoids; Flavonols; Kaempferols; Mass Spectrometry; Microwaves; Molecular Structure; Onions; Plant Extracts; Quercetin; Reproducibility of Results; Sonication; Spectrophotometry, Ultraviolet

Topics: Chromatography, High Pressure Liquid; Expectorants; Flavonoids; Flavonols; Kaempferols; Luteolin; Plants; Quercetin; Rutin