Induction of hepatic antioxidant enzymes by phenolic acids in rats is accompanied by increased levels of multidrug resistance-associated protein 3 mRNA expression

A diet rich in dietary fiber from cocoa improves lipid profile and reduces malondialdehyde in hypercholesterolemic rats

OBJECTIVE

The potential hypolipidemic effect of a new cocoa product rich in dietary fiber (DF) naturally containing antioxidant polyphenols (cocoa fiber [CF]) was studied in a rat model of dietary-induced hypercholesterolemia.

METHODS

For 3 wk animals were fed normal, cholesterol-free diets or diets supplemented with cholesterol to evoke hypercholesterolemia. Control diets contained 10% cellulose as DF, and test diets were supplemented with 165 g of CF per kilogram (providing 10% DF). Lipid profile, total antioxidant capacity, and malondialdehyde were measured in serum in addition to the activity of the antioxidant enzymes catalase, glutathione reductase, glutathione peroxidase, and superoxide dismutase and concentrations of glutathione and malondialdehyde in the liver.

RESULTS

Hypercholesterolemia and hypertriglyceridemia were established as a consequence of the cholesterol-rich diets. CF showed an important hypolipidemic action, returning triacylglycerol levels in hypercholesterolemic animals to normal values. The hypocholesterolemic effect was also patent, reducing total and low-density lipoprotein cholesterol, yet basal values were not attained. Decreased lipid peroxidation in serum and liver as a consequence of CF intake was patent not only in hypercholesterolemic but also in normocholesterolemic animals. No apparent effects on serum total antioxidant capacity or on the activity of antioxidant enzymes and hepatic levels of glutathione were observed. These effects might be attributed to the high DF content of CF and to the natural presence of antioxidant polyphenols.

CONCLUSION

The consumption of CF with a hypercholesterolemic diet improved the lipidemic profile and reduced lipid peroxidation, suggesting that CF might contribute to a reduction of cardiovascular risk.

Anthocyanin-rich purple potato flake extract has antioxidant capacity and improves antioxidant potential in rats

Anthocyanins from various vegetables and fruits have antioxidant activities, however, the bioactivities of coloured potato anthocyanins are not well studied. We examined the antioxidant capacities of pigmented fractions from purple potato flakes in vitro, and the antioxidant potentials of purple potato flakes in vivo. 1,1-Diphenyl-2-picrylhydrazyl radical scavenging activity of the pigmented fraction from Hokkai no. 92 (H92) potato flakes was higher than that from Kitamurasaki (KM) potato flakes. Extracts equivalent to 600 μg pigmented fractions from KM and H92 potato flakes inhibited linoleic acid oxidation in the order trolox>H92 ≥ KM>control. Rats were fed 25 % KM or H92 potato flake diets for 4 weeks. The major anthocyanin was identified as petanin. Control rats were fed a diet with cornstarch instead of potato flakes for 4 weeks. The serum antioxidant potential level in the H92 group was significantly higher than that in the control group. The degree of hepatic lipid peroxidation in the H92 group was significantly lower than that in the control group. Hepatic Cu/Zn-superoxide dismutase (SOD), Mn-SOD and glutathione peroxidase (GSH-Px) mRNA levels in the H92 group were significantly higher than those in the control group. Similar significant differences in Cu/Zn-SOD and Mn-SOD mRNA levels between the KM and control groups were found. The present results suggest that purple potato flakes have antioxidant functions with regard to radical scavenging activity and inhibition of linoleic acid oxidation, and that they improve the antioxidant potentials in rats by enhancing hepatic Mn-SOD, Cu/Zn-SOD and GSH-Px mRNA expression.