Enhancement of antioxidative ability of rat plasma by oral administration of (-)-epicatechin.
To check whether ingestion of (-)-epicatechin (EC) affects the antioxidative defense in blood plasma, we studied the oxidizability of plasma from Wistar rats after intragastrical EC administration at 10 or 50 mg/rat. The plasma pool obtained from control or EC-administered rats was oxidized with copper sulfate or 2,2'-azobis(2-amidinopropane)dihydrochloride (AAPH). EC metabolites in plasma 1 h after EC administration contained glucuronide and glucuronide-sulfate conjugates in both the free and O-methylated form. After 6 h, the plasma concentration of total EC metabolites decreased and the remaining conjugates were mostly present as the O-methylated form. Compared to the control group, the plasma obtained from rats 1 and 6 h after EC administration was more resistant against copper sulfate-induced oxidation on the basis of cholesteryl ester hydroperoxide (CE-OOH) accumulation. Also, the consumption of alpha-tocopherol during oxidation was suppressed in the plasma obtained from EC-treated rats. The content of CE-OOH and consumption of alpha-tocopherol in the plasma from EC-administered animals was much lower than those expected from the amount of nonmetabolized EC present in the plasma. Similar results were obtained from AAPH-induced oxidation of rat plasma after EC administration, except for the fact that CE-OOH accumulation was less suppressed in the plasma 6 h following administration. The O-methylated form was found to be more stable than the free form when EC-administered rat plasma was auto-oxidized at 37 degrees. These results suggest that EC metabolites, particularly conjugates in the free form, possess an effective antioxidative activity in blood plasma.
Da Silva
E L
EL
National Food Research Institute, Ministry of Agriculture, Forestry and Fisheries, Tsukuba, Japan.
Piskula
M
M
Terao
J
J
D000284:Administration, Oral; D000578:Amidines / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage* / Q000378:metabolism*; D002392:Catechin / Q000008:administration & dosage* / Q000097:blood* / Q000378:metabolism; D002788:Cholesterol Esters / Q000097:blood; D019327:Copper Sulfate / Q000494:pharmacology; D005609:Free Radicals / Q000378:metabolism; D066298:In Vitro Techniques; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D008745:Methylation; D016877:Oxidants / Q000494:pharmacology; D010949:Plasma / Q000187:drug effects* / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D014810:Vitamin E / Q000097:blood
D000578:Amidines; D000975:Antioxidants; D002788:Cholesterol Esters; D005609:Free Radicals; D016877:Oxidants; D014810:Vitamin E; C046728:2,2'-azobis(2-amidinopropane); D002392:Catechin; D019327:Copper Sulfate