Influence of 15 retinoic acid amides on urinary bladder carcinogenesis in the mouse.

A series of experiments was conducted to determine the efficacy of 15 synthetic retinoic acid amides (retinamides) as inhibitors of chemical carcinogenesis of the urinary bladder in C57BL/6 x DBA/2F1 mice. Eight of the retinamides tested had significant protective activity when administered at nontoxic levels in the diet. Minor structural alterations, such as the addition of a methyl or hydroxyl group to the terminal amide moiety had a major influence on the anticarcinogenic activity of the retinamides. Although 13-cis retinamides generally were less toxic on a molar basis than were their all-trans isomers, no consistent pattern of differential anticarcinogenic activity was noted among the six pairs of all-trans and 13-cis isomers tested. All-trans-4-hydroxyphenyl retinamide was among the most active and least toxic of the retinoids tested, and appears to be the compound of choice for further study.