Structure-activity relationships of synthetic antibiotic analogues of anisomycin.

A general synthetic sequence was used to synthesize a series of analogues of anisomycin, and the biological activities of the new synthetic analogues as antiprotozoals, antifungals, and antibacterials were evaluated. The synthetic antibiotics included 3 beta-acetoxy-4 alpha-hydroxy-2 beta-(p-methylbenzyl)pyrrolidine (1b), 3 beta-acetoxy-2 beta-benzyl-4 alpha-hydroxypyrrolidine (1c), 3 beta-acetoxy-4 alpha-hydroxy-2 beta-(m-methoxybenzyl)pyrrolidine (1d), 3 beta-acetoxy-4 alpha-hydroxy-2 beta-(o-methoxybenzyl)pyrrolidine (1e), 3 beta-acetoxy-4 alpha-hydroxy-2 beta-(alpha-methyl-p-methoxybenzyl)pyrrolidine (1f), and 3 beta-acetoxy-4 alpha-hydroxy-2 beta-(alpha-phenyl-p-methoxybenzyl)pyrrolidine (1g). The anisomycin analogues showed activity against protozoa and fungi, but this activity was restricted primarily to the p-methylbenzyl and benzyl analogues 1b and 1c. The activities dropped dramatically as the methoxy substituent was moved to the meta or ortho positions of the benzyl group (1d and 1e) or a methyl or phenyl group was attached at the alpha-benzyl carbon (1f and 1g).