Cocoa powder enhances the level of antioxidative activity in rat plasma

The aims of the present study were to determine the level of (-)-epicatechi n (EC) and its metabolites in rat plasma after oral administration of cocoa powder and to evaluate the protective effect of cocoa powder in terms of s uppressing the oxidation of plasma components. Rats were orally administere d 1 g cocoa powder/kg body weight, containing 7.80 mg EC, and their blood w as collected before administration and at designated time intervals thereaf ter. The EC and its metabolites in plasma were treated with beta -glucuroni dase and/or sulfatase, then analysed by HPLC and by liquid chromatography-M S. Several EC-related compounds were detected in plasma such as free EC, an d glucuronide, sulfate, and glucuronide-sulfate conjugates of non-methylate d or methylated EC. All EC metabolites showed a maximum concentration in pl asma at 30-60 min post-administration. Glucuronide conjugates of both non-m ethylated and methylated EC were found in high concentration in plasma. Mor eover, administration of cocoa powder significantly reduced the accumulatio n of lipid peroxides in plasma and significantly reduced the consumption of alpha -tocopherol in plasma oxidized by treatment with 2,2 ' -azobis-(2-am idinopropane) dihydrochloride (AAPH (25 mmol/l)) or CuSO4 (100 mu mol/l) co mpared with that in the case of plasma obtained before administration. The total EC concentration in plasma was negatively correlated with the level o f accumulation of lipid peroxides in plasma oxidized by treatment with AAPH (25 mmol/l) and was positively correlated with the level of residual alpha -tocopherol in plasma oxidized by treatment with CuSO4 (100 mu mol/l). The se results indicate that EC in cocoa powder was absorbed from the digestive tract, that various conjugated forms of EC were generated in the digestive tract and distributed to the plasma, and that these enhanced the antioxida tive activity of plasma.