Inhibitors of poly(adenosine diphosphate ribose) polymerase induce sister chromatid exchanges

Benzamide and m-aminobenzamide, which are the most potent inhibitors of poly(adenosine diphosphate ribose) polymerase known, induced many sister chromatid exchanges (SCEs) in Chinese hamster ovary cells CHO-K1. Nicotinamide, o-aminobenzamide, p-aminobenzamide and 3-acetylpyridine, which are moderate inhibitors of the enzyme, induced SCEs significantly. 1-Methylnicotinamide +, N′-methylnicotinamide, nicotinic acid and benzoic acid, which are very weak inhibitors of the enzyme, induced no appreciable SCEs. There was a positive correlation between the inhibitory effects of these compounds on the enzyme and their effects in inducing SCEs.