Quercetin Glycosides (quercetin + glycoside)

Distribution by Scientific Domains

Selected Abstracts

Flavonol glycosides and antioxidant capacity of various blackberry and blueberry genotypes determined by high-performance liquid chromatography/mass spectrometry

Mi Jin Cho
Abstract Flavonol glycoside composition and content in blueberry and blackberry extracts were determined using a high-performance liquid chromatographic (HPLC) separation method coupled with photodiode array (PDA) and mass spectrometric (MS) detection. The hydrophilic antioxidant capacities of crude and fractionated flavonol extracts were also determined by the oxygen radical-absorbing capacity (ORACFL) and photochemiluminescence (PCL) assays. Eight flavonols of quercetin and quercetin,sugar conjugates were identified in Kiowa blackberry, namely rutinoside, galactoside, methoxyhexoside, glucoside, pentoside, [6,-(3-hydroxy-3-methylglutaroyl)]-,-galactoside, glucosylpentoside and oxalylpentoside. Thirteen flavonols were detected in Ozarkblue blueberry. Of these, myricetin 3-hexoside and 12 quercetin,sugar conjugates, namely rutinoside, galactoside, methoxyhexoside, glucoside, pentoside, glucosylpentoside, caffeoylglucoside, oxalylpentoside, rhamnoside, dimethoxyrhamnoside, acetylgalactoside and acetylglucoside, were identified. In Bluecrop blueberry, two additional quercetin,sugar conjugates were identified, namely glucuronide and caffeoylgalactoside. Quercetin glycosides accounted for 75% of total flavonols in the blueberry genotypes. Total flavonol contents ranged from 99 to 150 mg kg,1 for blackberries and from 192 to 320 mg kg,1 for blueberries. Quenching of peroxyl and superoxide anion radicals by the flavonol fractions ranged from 1.5 to 2.3 mmol Trolox equivalents (TE) kg,1 and from 0.5 to 0.7 mmol TE kg,1 respectively for blackberries and from 2.9 to 5.2 mmol TE kg,1 and from 0.8 to 1.4 mmol TE kg,1 respectively for blueberries. The HPLC method allowed for complete separation and identification of flavonols commonly found in blackberries, and blueberries. Our results showed that blueberry and blackberry genotypes varied significantly in flavonol content and antioxidant capacity. Even though total flavonol content did not correlate well with antioxidant capacity, their ability to scavenge peroxyl and superoxide anion radicals was apparent. Copyright 2005 Society of Chemical Industry [source]

A Novel Process for the Recovery of Polyphenols from Grape (Vitis vinifera L.) Pomace

Dietmar Kammerer
ABSTRACT: A novel process for enzyme-assisted extraction of polyphenols from winery by-products was established on a pilot-plant scale. Optimization of enzymatic hydrolysis of grape skins, that is, selection of pectinolytic and cellulolytic enzymes, enzyme-substrate ratio, and time-temperature regime of enzymatic treatment, was conducted on a laboratory scale. Enzyme activities were monitored by viscosity measurement of resuspended grape pomace and by quantification of oligomeric pectin and cellulose degradation products released from cell wall material. Optimal conditions were obtained with 5000 ppm (based on dry matter) of a pectinolytic and 2500 ppm of a cellulolytic enzyme preparation, respectively, at 50C, which were also applied in pilot-plant scale experiments. Concomitant determination of individual polyphenolics demonstrated a significantly improved yield for most compounds when compared with experiments without enzyme addition. Recovery rates were comparable to those obtained when grape pomace was extracted using sulfite. Pre-extraction of the pomace with hot water followed by treatment with cell wall degrading enzymes even increased yields of phenolic compounds. Only some quercetin glycosides and malvidin coumaroylglucoside were partly hydrolyzed due to enzyme side activities. This new process may provide a valuable alternative to the application of sulfite, which is considered crucial in food processing. [source]

Identification and quantification of galloyl derivatives, flavonoid glycosides and anthocyanins in leaves of Pistacia lentiscus L.

A. Romani
Abstract Separation, identification and quantification of polyphenols was carried out on leaves of Pistacia lentiscus L., an evergreen member of the family Anacardiaceae, using semi-preparative HPLC, HPLC-photodiode array detection and HPLC-MS analysis, together with 1H- and 13C NMR. Three major classes of secondary metabolites were detected: (i) gallic acid and galloyl derivatives of both glucose and quinic acid; (ii) flavonol glycosides, i.e. myricetin and quercetin glycosides; and (iii) anthocyanins, namely delphinidin 3- O -glucoside and cyanidin 3- O -glucoside. Low amounts of catechin were also detected. The concentration of galloyl derivatives was extremely high, representing 5.3% of the leaf dry weight, and appreciable amounts of myricetin derivatives were also detected (1.5% on a dry weight basis). These findings may be useful in establishing a relationship between the chemical composition of the leaf extract and the previously reported biological activity of P. lentiscus, and may also assign a new potential role of P. lentiscus tissue extracts in human health care. Copyright 2002 John Wiley & Sons, Ltd. [source]

Effect of lectins on the transport of food ingredients in Caco-2 cell cultures

BIOFACTORS, Issue 1-4 2004
Y. Ohno
Abstract We investigated the effect of several lectins, such as soy bean lectin (SBA), concanavalin A (Con A), and wheat germ agglutinin (WGA), on the transport of some food ingredients (isoflavones, quercetin glycosides, carnosine/anserine) across Caco-2 cell monolayers. After incubation of food ingredients (0.03,2 mmol/L) in the presence or absence of lectins (1,180 ,/ml) on the apical side, aliquots were taken from the apical and basolateral solution, and were subjected to HPLC analysis. We also examined the effect of lectins on the permeability of the tight junction by measuring the transepithelial electrical resistance (TER) value of the Caco-2 cell monolayer. Isoflavones, which was not transported to the basolateral solution without lectins, could be transported in the presence of lectins, whereas their aglycones were detected at the same levels with or without the lectin treatment. The transport of quercetin glycosides also increased in the presence of lectins, however, that of peptides was not affected by the lectins. Con A and WGA, but SBA, decreased the TER value, indicating that Con A and WGA increased the transport via paracellular pathway, whereas SBA did via a different pathway. [source]