Effect of grape antioxidant dietary fiber on the total antioxidant capacity and the activity of liver antioxidant enzymes in rats

The present study was aimed at evaluating the in vivo effects in rats of a diet rich in antioxidant dietary fiber (AODF) from grapes on antioxidant (glutathione) concentration, antioxidant enzymes (catalase, glutathione reductase, glutathione peroxidase and superoxide dismutase) activity in liver homogenates, and the plasma and liver antioxidant capacity (measured by the ferric reducing antioxidant power and the ABTS-2,2'-azinobis-3-ethylbenzothioline-6-sulphonic acid- assays). Additionally, the potential protective effect against oxidative stress of grape AODF was tested in rats submitted to acute oxidative stress induced by acetaminophen. Feeding rats with an AODF-rich diet for 3 weeks did not modify the plasma antioxidant capacity. It did evoke an increase of the steady-state activity of glutathione peroxidase but did not affect the activity of the other enzymes nor the glutathione concentration in the liver. No protective effect of polyphenol-rich grape ACDF was seen, since it did not change the response of the hepatic antioxidant system against an acetaminophen-induced oxidative stress. (C) 2003 Elsevier Inc. All rights reserved.