Acute effects of alkylating agents on canine renal function: specifically designed synthetic maleimides

Maleimidohippurates and maleimidobenzoates were synthesized that possess a carboxy group for active uptake into renal proximal tubular cells and a reactive maleimide moiety to covalently bond with proximal tubular components. The reactivity of the maleimide moiety in each series was progressively reduced by substitution of methyl groups in place of the vinyl hydrogens. In contrast to N-ethylmaleimide (NEM), the resulting maleimidohippurates and maleimidobenzoates did not possess significant diuretic activity in the dog following renal arterial administration. However, as predicted, the nephrotoxicity of the maleimidohippurates paralleled their in vitro alkylating ability and was quite specifically located in the proximal portion of the canine renal tubule.