INHIBITORY EFFECTS OF CATECHOL DERIVATIVES ON OXIDATION OF SOYBEAN PHOSPHATIDYLCHOLINE LIPOSOMES INDUCED BY HYDROPHILIC AND HYDROPHOBIC FREE-RADICAL INITIATORS

Effects of pyrocatechol and six of its monosubstituents on oxidation o f soybean phosphatidylcholine liposome induced by hydophilic free radi cal initiator, 2,2'-azobis(2-amidinopropane)dihydrochloride (AAPH), an d hydrophobic free radical initiator, 2,2'-azobis(2,4-dimethylvaleroni trile) (AMVN), were determined and relationships with their redox pote ntials and hydrophobic parameters were studied for their inhibitory ef fects by regression analysis, Inhibitory potencies of the catechol com pounds on hydrophilic AAPH-induced oxidation clearly correlated with t heir redox potentials, whereas no significant effects of the hydrophob icities of the compounds were found, These results indicated that scav enging activities of these compounds on AAPH-initiated radical chain r eactions were controlled by their electron donor activities. Inhibitor y potencies of these compounds on hydrophobic AMVN-induced oxidation o f liposome, in contrast, were significantly correlated with their hydr ophobicity, although regression analysis revealed that their electron donor activities were also important,