Selective inhibition of cholesterol side-chain cleavage by potential pro-drug forms of aminoglutethimide

Potential pro-drugs for aminoglutethimide (1) an agent used for the treatment of hormone-dependent breast cancer have been synthesized, namely the azo-(2), azoxy-(3) and hydrazo-(4) derivatives. These compounds have been tested for inhibitory action towards the two main target enzymes for 1, aromatase and the cholesterol side-chain cleavage enzyme complex, P-450scc. None inhibited aromatase but 3 and 4 inhibited P-450scc, the respective IC50 values being about twice and one-half that for 1. Compounds 1 and 3 were also tested as inhibitors of the 17 alpha-hydroxylase-C17,20 lyase complex in comparison with ketoconazole which acts against prostatic cancer by this mechanism. The azoxy-derivative 3 was a weak inhibitor but 1 was inactive.