Relationship of electrochemical oxidation of catechins on their antioxidant activity in microsomal lipid peroxidation.
The oxidation potentials of catechins were measured by employing flow-through column electrolysis. The oxidation potentials of catechins were shown to depend on their structures. At the same time, the antioxidant activity of catechins on NADPH-dependent lipid peroxidation in rat liver microsomes was evaluated. Catechins showed a 50% inhibition of lipid peroxidation in the concentration range of 10-51 microM. Among those studied, galloylated catechins exhibited stronger antioxidant activities than those of nongalloylated catechins. A quantitative relationship has been obtained to describe the antioxidant activity of catechins: log IC50 (microM)= 1.56+2.49E1/2 (V)-0.29 logP (r=0.907), where IC50 represents the concentration for 50% inhibition of lipid peroxidation, E1/2 represents the half-wave potential of the first oxidation wave, and P represents the octanol/water partition coefficient. This relationship suggested two important characteristics determining catechin antioxidant activity, namely the ease of oxidation and the lipophilicity.
Yang
B
B
Institute of Chinese Materia Medica, China Academy of Traditional Chinese Medicine, Beijing.
Kotani
A
A
Arai
K
K
Kusu
F
F
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D002392:Catechin / Q000737:chemistry* / Q000494:pharmacology*; D004563:Electrochemistry; D015227:Lipid Peroxidation; D008862:Microsomes, Liver / Q000378:metabolism*; D010084:Oxidation-Reduction; D051381:Rats
D000975:Antioxidants; D002392:Catechin