ANTIOXIDANT ACTIVITY OF TETRANDRINE AND ITS INHIBITION OF QUARTZ-INDUCED LIPID-PEROXIDATION

Tetrandrine is a benzylisoquinoline alkaloid that has been used in Chi na as an antifibrotic drug to treat the lesions of silicosis. Its mech anism in the treatment of silicosis is unclear. Electron spin resonanc e (ESR) spin trapping was employed to investigate the antioxidant prop erties of tetrandrine. The spin trap used was 5,5-dimethyl-1-pyrroline N-oxide (DMPO). Tetrandrine efficiently reacted with hydroxyl ((OH)-O -.) radicals with a reaction rate of approximately 1.4 x 10(10) M(-1) s(-1). The (OH)-O-. radicals were generated by the Fenton reaction [Fe (II) + H2O2) as well as by reaction of chromium(V) with H2O2. Similar results were obtained using (OH)-O-. radicals generated by reaction of freshly fractured quartz particles with aqueous medium. Tetrandrine a lso scavenged superoxide (O-2(-)) radicals produced from xanthine/xant hine oxidase. The effect or tetrandrine on lipid peroxidation induced by freshly fractured quartz particles was evaluated using linoleic aci d as a model lipid. The results showed that tetrandrine caused a signi ficant inhibition on freshly fractured quartz-induced lipid peroxidati on.