Commercial Grape Juices Inhibit the in Vitro Oxidation of Human Low-Density Lipoproteins

Abstract

This study was aimed at determining the antioxidant activity of commercial grape juices in inhibiting the copper-catalyzed oxidation of human low-density lipoproteins (LDL) in vitro and at relating this activity to the phenolic composition of the juices. This work also evaluated the effect of vitamin C on this antioxidant activity. When standardized to a total phenolic concentration of 10 μM gallic acid equivalents (GAE), samples of grape juices inhibited LDL oxidation from 62 to 75%. White grape juices inhibited LDL oxidation on the average by 72%, Concord purple grape juice by 67%, and grape juice blends (mixture of white and Concord grape juice) by 63%. Vitamin C had no significant effect on the antioxidant activity of the grape juices tested. The antioxidant activity of Concord juice samples was related to their anthocyanin levels, while that of the white grape juices was related to their levels of flavan-3-ols and hydroxycinnamates, as determined by HPLC. On the basis of the same total phenolic concentration, the antioxidant activity of grape juices toward LDL oxidation was comparable to that of several California red wine. However, based on their undiluted total phenolic concentration, the Concord and blends of grape juices had comparable activity to that of the red wines, while the white grape juices were less active. Keywords: LDL oxidation; phenolic compounds; antioxidants; grape juice; flavonoids; hexanal; HPLC

Total polyphenol content and antioxidant activity of commercial Noni (Morinda citrifolia L.) juice and its components

“…Frankel et al (1998) and Vinson et al (1999) reported that in grape juice, the antioxidant activity was similar to that found in red wines. Grape juice contains a higher content of glycosylated phenolic compounds than red wine which, according to Hollman et al (1995), are more easily absorbed than the respective aglicons.…”

Use of HPLC for characterization of sugar and phenolic compounds in Vitis labrusca juice

“…However, compared with other studies of 100% Concord grape juice the means were generally lower than those reported elsewhere: e.g. Frankel et al (1998) in Westfield, NY (318.2 and 443.7 mg/L); and Borges et al (2013) in Southern Brazil (548.8 mg/L). Many of the differences between this study and others are likely due to sample processing methods.…”

Phenolic Compounds and Antioxidant Activity in Grape Juices: A Chemical and Sensory View

“…Pastrana-Bonilla et al [25] found a total concentration of phenolic compounds of about 2178.8, 374.6 and 23.8 mg/g GAE (gallic acid equivalent) in skin, seed and pulp, respectively. Grape skins are the main source of grape phenolic compounds changing their content with grape variety, soil composition, climate, geographic origin, cultivation practices or exposure to diseases, such as fungal infections and reactions occurring during storage [1,[26][27][28]. The total phenolic compounds content in grapes juices (400 to 3000 mg/L) depends on the grape variety, grape maturity, geographical origin and soil type, sunlight exposure, and many other factors [29], besides the grape juice processing technology, such as grape juice extraction, contact time between juice and the grape solid parts (skins and seeds), pressing, thermal and enzymatic treatments.…”