Chiral Separation of Catechins in Buckwheat Groats and the Effects of Phenolic Compounds in Mice Subjected to Restraint Stress

Abstract

This paper investigates the stereochemistry of catechin and epicatechin compounds in buckwheat ( Fagopyrum esculentum Moench) groats and then examines the effects of an orally administered mixture of the phenolic compounds isolated from the groats in restrained mice. Phenolic compounds separated by Sephadex LH-20 chromatography contained catechin and epicatechin compounds with a sugar moiety or esterified with phenolic acid derivatives along with rutin. Other unidentified major compounds in the HPLC chromatogram were also deduced on the basis of the spectrometric data with LC-MS/MS analysis to be catechin or epicatechin compounds. A chiral HPLC separation technique under normal-phase conditions showed that catechin and its derivative compounds in buckwheat groats were (+)-isomers, whereas epicatechin and its derivative compounds were (-)-isomers. Propylene glycol (PPG) or buckwheat groats phenolic compounds (BGP) in PPG (10 or 100 mg/kg of body weight) were administered intragastrically once per day for 3 days to mice, which were then restrained for 24 h. Unrestrained mice were given PPG solution with or without free access to feed and water. Restraint stress induced an elevation in plasma arteriosclerotic index, hepatic total cholesterol, and the amount of thiobarbituric acid-reactive substances (TBARS) in plasma and liver tissues. In contrast, these variables were suppressed in the restrained mice that were given BGP. These results suggest that BGP has in vivo antistress effects against the reactions induced by immobilization in mice.