quercetin-3--o-beta-d-glucopyranoside and petunidin-3-glucoside

In this study, intermolecular copigmentation between five primary wine monoglucosidic anthocyanins (cyanidin-3-O-glucoside, peonidin-3-O-glucoside, delphinidin-3-O-glucoside, petunidin-3-O-glucoside, and malvidin-3-O-glucoside) and three common wine phenolics (gallic acid, (-)-epicatechin, and quercetin-3-O-glucoside) were investigated through experimental and theoretical methods, and the influence of substituent pattern of anthocyanin B ring was studied emphatically. Chromatic and thermodynamic analysis showed there were great differences among these different pigment-copigment systems. Spatial conformations of the 15 copigmentation complexes were obtained through theoretical calculation, and diverse π-π stacking modes were observed. These results indicated that the substituent pattern of anthocyanin B ring had significant impact on its affinity to copigments, and more, the structures of pigments and copigments determined the color expression and stability of copigmentation together.

Topics: Anthocyanins; Color; Glucosides; Molecular Structure; Phenols; Quercetin; Wine

Flavonoids present in skin extracts of red seedless table grape varieties Summer Royal, Autumn Royal, and Crimson, and white seedless varieties Carati and Thompson were analyzed by HPLC-DAD-MS, in 3 y of study (2006 to 2008). The anthocyanins, delphinidin-3-O-glucoside, cyanidin-3-O-glucoside, petunidin-3-O-glucoside (with their corresponding p-coumaroyl derivatives), peonidin-3-O-glucoside, and malvidin-3-O-glucoside (with their corresponding acetyl, caffeoyl, and p-coumaroyl derivatives) were found. In addition the flavonols quercetin-3-O-glucuronide, quercetin-3-O-rutinoside, quercetin-3-O-glucoside, kaempferol-3-O-glucoside, kaempferol-3-O-galactoside, and the flavan-3-ols procyanidin B1, procyanidin B2, and catechin were also detected. Anthocyanins were the main flavonoids in red grapes ranging from 24 (Crimson) to 500 (Summer Royal) mg/kg fresh weight of grapes; consistent levels of flavonols and flavan-3-ols were also quantified in all varieties. To determine the effective climatic influence on flavonoids content in field conditions, viticultural practices have been developed, that could exclude the effects of direct solar radiation from confounding the assessment of those related to thermal conditions alone. A strong positive correlation was determined between flavonoids and temperature data that seem to be responsible for the difference of these metabolites along the years; furthermore, it has been possible to define a linear relationship (R(2) = 0.6871, P = 0.0057) between thermal amplitude and total flavonoids values in the red grapes.. Grapes are economically the most important fruit species in the world and approximately 30% of its production is used as fresh fruit. Because of the very important role of flavonoids in food quality as well as their health-promoting properties, and considering that our experiments were performed along 3 consecutive years, gathered results in this research are quite promising to give a useful information on the flavonoid contents and their evolution in 5 seedless table grapes that are widespread in Mediterranean regions but also in California and South America, and are grown in a viticultural climate (Apulia, South Italy) very close to some regions of Spain, Turkey, Tunisia, and Israel.

Topics: Anthocyanins; Biflavonoids; Catechin; Chromatography, High Pressure Liquid; Flavonoids; Galactosides; Glucosides; Italy; Kaempferols; Linear Models; Monosaccharides; Proanthocyanidins; Quercetin; Vitis