EFFECT OF PEROXISOMICINE AND RELATED ANTHRACENONES ON CATALASE ACTIVITY

Dimeric anthracenones were isolated from toxic plants of the genus Karwinskia (Rhamnaceae). T 514 or peroxisomicine A(1) is one of these toxic compounds which produces an irreversible and selective damage on the peroxisomes of yeast cells in vivo. In this paper we now report the inhibitory effect in vitro of peroxisomicine Al and other structurally related anthracenones on liver catalase activity. The peroxisomicine A(1) produces a non-competitive inhibition with respect to H2O2 on bovine, dog, and mouse liver catalases. In the three cases V-max was decreased whereas K-m was unaffected. Other dimeric anthracenones of natural origin were also found to be inhibitors of bovine liver catalase. There is a relationship between structure and degree of inhibition of all anthracenonic compounds tested. Peroxisomicine A(1) and peroxisomicine A(2) caused the highest degree of inhibition (IC50 = 3.34 and 3.64 mu M, respectively).