IN-VITRO AND EX-VIVO FREE-RADICAL SCAVENGING ACTIVITIES OF CARAZOSTATIN, CARBAZOMYCIN B AND THEIR DERIVATIVES

Free radical scavenging activities of various carbazole compounds, car azostatin, carbazomycin B and their chemically modified derivatives we re studied in vitro and ex vivo. Among these compounds, carazostatin, which was isolated as a free radical scavenger from the culture of Str eptomyces chromofuscus, showed the most potent inhibitory activity aga inst lipid peroxidation of rat brain homogenate in vitro. Carbazomycin B, a known antimicrobial antibiotic, also exhibited strong activity i n this system. Although O-modified derivatives of carazostatin and car bazomycin B retained considerable activity, N,O-dimethyl derivatives d id not suppress the peroxidation. On the other hand, the results from the ex vivo evaluation of these carbazoles in the lipid peroxidation s ystem of mouse blood plasma showed that the original compounds as well as their O-modified derivatives had a strong inhibitory activity upon oral administration to mice. These findings suggest that these natura l carbazoles and their effective derivatives can protect tissues from the peroxidative damage due to generation of free radicals.