ANTIOXIDANT ACTIVITIES OF NATURAL AND SYNTHETIC CARBAZOLES

The antioxidant activities of various natural and synthetic carbazoles were studied in the oxidations of methyl linoleate in homogeneous sol ution and soybean phosphatidylcholine (PC) liposomes in aqueous disper sion induced by free radicals. Carazostatin, 1-heptyl-3-hydroxy-2-meth yl carbazole, which was isolated from a culture of Streptomyces chromo fuscus, was found to be a strong antioxidant in both oxidation systems . Carbazomycin B, 4-hydroxy-3-methoxy-1,2-dimethylcarbazole, showed a moderate antioxidant activity. Other derivatives from these carbazoles without a free hydroxy group did not suppress the oxidation appreciab ly. The antioxidant activity of carazostatin in the oxidation of soybe an PC liposome was stronger than that of alpha-tocopherol, although th e latter exhibited stronger antioxidant activity than carazostatin in the oxidation in homogeneous solution. Vitamin C acted as a synergist in combination with carazostatin in the oxidation of soybean PC liposo mes.