quercetin-3--o-beta-d-glucopyranoside and hyperoside

Walnut (Juglans regia L.) is an abundant source of polyphenols. Although phenolic species in the walnut kernel have been studied comprehensively, their compositional profile in the internal fruit septum, a traditional nutraceutical material in China, has been rarely explored. In the current study, the methanolic extract of the walnut septum was analysed by Ultra-performance liquid chromatography coupled with Orbitrap mass spectrometry. Totally seventy-five phenolics belonging to flavonoids, tannins and phenolic acids were identified based on mass spectra, references and literatures. Among them, quercetin-3-O-galactoside, quercetin-rhamnose-pentoside, quercetin-3-O-glucoside, quercetin-rhamnose-hexoside, kaempferol-rhamnoside, and two isomers of quercetin-rhamnoside were reported for the first time in walnut. The total polyphenol content was found to be 122.78 ± 2.55 mg GAE/g dry weight in septum. This study is the first to comprehensively investigate and identify phenolic compounds in the fruit septum of walnut and indicates that the septum to be a rich resource of polyphenols.

Topics: China; Chromatography, Liquid; Dietary Supplements; Flavonoids; Fruit; Glucosides; Juglans; Mass Spectrometry; Nuts; Phenols; Polyphenols; Quercetin

The effect of the postharvest treatment of methyl jasmonate enantiomers in conjunction with ethanol on bioformation of resveratrol and quercetin glycosides in grapes was evaluated. The antioxidant activity of treated grape extracts as compared with untreated extracts was also assayed. Exogenous (-)-methyl jasmonate in combination with ethanol induced a significant increase in the levels of resveratrol (from 27 to 39 μg g(-1)), quercetin-3-O-glucoside (from 59 to 136 μg g(-1)), quercetin-3-O-galactoside (from 398 to 807 μg g(-1)) and quercetin-3-O-rutinoside (from 23 to 43 μg g(-1)). (+)-Methyl jasmonate with ethanol also resulted in increase of quercetin-3-O-glucoside and quercetin-3-O-rutinoside. However, no (+)-methyl jasmonate effect was observed for resveratrol and quercetin-3-O-galactoside. Both (-)- and (+)-methyl jasmonate treatments provided with extracts with higher antioxidant activity. From the results found in the present work postharvest treatment with (-)-methyl jasmonate in conjunction with ethanol is proposed as a mean to obtain polyphenol-enriched grape extracts with improved antioxidant properties. The procedure here developed is proposed as a mean to obtain functional grapes. Extracts obtained from grapes treated with (-)-methyl jasmonate with ethanol can be particularly useful for industry due to their high antioxidant capacity.

Topics: Acetates; Antioxidants; Cyclopentanes; Ethanol; Flavonoids; Food Handling; Fruit; Glucosides; Oxylipins; Polyphenols; Quercetin; Resveratrol; Rutin; Stilbenes; Vitis

Quercetin is a plant-derived flavonoid and its cytotoxic properties have been widely reported. However, in nature, quercetin predominantly occurs as various glycosides. Thus far the cytotoxic activity of these glycosides has not been investigated to the same extent as quercetin, especially in animal models. In this study, the cytotoxic properties of quercetin (1), hyperoside (quercetin 3-O-galactoside, 2), isoquercitrin (quercetin 3-O-glucoside, 3), quercitrin (quercetin 3-O-rhamnoside, 4), and spiraeoside (quercetin 4'-O-glucoside, 5) were directly compared in vitro using assays of cancer cell viability. To further characterize the influence of glycosylation in vivo, a novel zebrafish-based assay was developed that allows the rapid and experimentally convenient visualization of glycoside cleavage in the digestive tract. This assay was correlated with a novel human tumor xenograft assay in the same animal model. The results showed that 3 is as effective as 1 at inhibiting cancer cell proliferation in vivo. Moreover, it was observed that 3 can be effectively deglycosylated in the digestive tract. Collectively, these results indicate that 3 is a very promising drug candidate for cancer therapy, because glycosylation confers advantageous pharmacological changes compared with the aglycone, 1. Importantly, the development of a novel and convenient fluorescence-based assay for monitoring deglycosylation in living vertebrates provides a valuable platform for determining the metabolic fate of naturally occurring glycosides.

Topics: Animals; Flavonoids; Glucosides; Glycosides; Glycosylation; HCT116 Cells; Humans; Molecular Structure; Quercetin; Structure-Activity Relationship; Vertebrates; Zebrafish

To explore the mechanism of the absorption of flavonoids from Abelmoschus manihot flowers, in situ intestinal recirculation was performed to study the effect of the absorption at different concentrations and different intestinal regions. To evaluate the conditions of the absorption of six flavonoids from Abelmoschus manihot flowers, the concentrations of Abelmoschus manihot in the perfusion solution were determined by HPLC at predesigned time. And we have investigated the inhibitory effect of six flavonoids from Abelmoschus manihot flowers on P-glycoprotein (P-gp) drug efflux pump. The results demonstrated that the absorption rates of flavonoids from Abelmoschus manihot flowers are not significantly different (P > 0.05) at various drug concentrations, the absorption of flavonoids from Abelmoschus manihot flowers is a first-order process with the passive diffusion mechanism. The absorption rates of each of flavonoids are significantly different. The absorption rate of flavonoid glycoside was lower than that of aglycone; the flavonoids from Abelmoschus manihot flowers could be absorbed in all of the intestinal segments. The best parts of intestine to absorb hyperoside and myricetin are jejunum and duodenum, separately. Verapamil could enhance the absorption of isoquercitrin, hyperoside, myricetin and quercetin-3'-O-glucoside by inhibiting P-glycoprotein (P-gp) drug efflux pump.

Topics: Abelmoschus; Animals; ATP Binding Cassette Transporter, Subfamily B; Flavonoids; Flowers; Glucosides; Intestinal Absorption; Male; Perfusion; Plant Extracts; Plants, Medicinal; Quercetin; Rats; Rats, Sprague-Dawley; Verapamil