M. Chopra et al., Nonalcoholic red wine extract and quercetin inhibit LDL oxidation without affecting plasma antioxidant vitamin and carotenoid concentrations, CLIN CHEM, 46(8), 2000, pp. 1162-1170
Background: Antioxidant enrichment of LDL can increase its resistance to ox
idation and hence reduce its atherogenicity. The objective of the present s
tudy was to investigate whether in vivo supplementation with nonalcoholic r
ed wine extract and quercetin can increase the oxidative resistance of LDL,
and also whether the supplementation has any effect on other antioxidative
micronutrients present in the blood.
Methods: Twenty-one male subjects were supplemented with a placebo drink fo
r 2 weeks and randomized into two groups. One group (n = 11) received the r
ed wine extract (1 g/day, equivalent to 375 mL, of red wine) and the other
group (n = 10) quercetin (30 mg/day) for 2 weeks, followed by a 5-week wash
out period.
Results: In the red wine extract-supplemented group, ex vivo copper-initiat
ed oxidation of LDL (lag phase, mean +/- SD) was 40 +/- 11 min at the basel
ine, and increased significantly to 47 +/- 6 min [P <0.05 compared with pla
cebo (38 +/- 4 min) and the washout values (40 +/- 5 min)]. In the querceti
n-supplemented group, the lag phase was 44 +/- 11 and 40 +/- 5 min for the
baseline and placebo, respectively, and increased significantly to 51 +/- 7
min [P <0.05 compared with placebo and washout (41 +/- 9 min)] after suppl
ementation. Plasma lipids (triglycerides, total cholesterol, LDL- and HDL-c
holesterol) did not change during the study period. Supplementation with re
d wine extract or quercetin had no effect on plasma vitamin C and E, retino
l, and carotenoid concentrations.
Conclusions: Alcohol-free red wine extract and one of its components, querc
etin, can inhibit LDL oxidation after in vivo supplementation; such "inhibi
tion" is unrelated to changes in antioxidant vitamin and carotenoid concent
rations. (C) 2000 American Association for Clinical Chemistry.