Inhibition in vitro linoleic acid peroxidation and haemolysis by caffeoyltryptophan.
Antioxidant activities of caffeoyltryptophan were investigated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging system, the superoxide anion generation system and the superoxide anion-mediated linoleic acid peroxidation system. At 10 microM, caffeoyltryptophan showed greater scavenging activity on DPPH than dl-alpha-tocopherol or ascorbic acid. DPPH radical scavenging activity of caffeoyltryptophan increased dose-dependently at concentrations ranging from 1 to 50 microM; 1 mol of caffeoyltryptophan reacted with ca 4 mol of radical. Caffeoyltryptophan caused 80% inhibition of superoxide anion generation at 50 microM. The inhibitory activity of caffeoyltryptophan was as strong as that of 5-caffeoylquinic acid. Caffeoyltryptophan inhibited the formation of conjugated diene from linoleic acid. The inhibitory activity increased in the order caffeic acid < 5-caffeoylquinic acid < caffeoyltryptophan < dl-alpha-tocopherol. Effects on the in vitro haemolysis and peroxidation of mouse erythrocytes induced by H2O2 were also examined. Caffeoyltryptophan exhibited strong inhibitory activities; Tryptophan was ineffective in these systems. These data suggest that caffeoyltryptophan may be a natural antioxidant in the human diet and, as such, may intervene in toxicological processes that are mediated by radical mechanisms.
Ohnishi
M
M
Department of Pharmaceutical Science, Kansai Shinkyu Medical College, Osaka, Japan.
Morishita
H
H
Toda
S
S
Yase
Y
Y
Kido
R
R
D000818:Animals; D000975:Antioxidants / Q000737:chemistry / Q000494:pharmacology*; D002109:Caffeic Acids / Q000737:chemistry / Q000494:pharmacology*; D016166:Free Radical Scavengers / Q000737:chemistry / Q000494:pharmacology; D006461:Hemolysis / Q000187:drug effects*; D019787:Linoleic Acid / Q000378:metabolism*; D015227:Lipid Peroxidation / Q000187:drug effects*; D008297:Male; D051379:Mice; D014364:Tryptophan / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology
D000975:Antioxidants; D002109:Caffeic Acids; D016166:Free Radical Scavengers; C112672:caffeoyltryptophan; D014364:Tryptophan; D019787:Linoleic Acid