Intracellular Targeting and Pharmacological Activity of the Superoxide Dismutase Mimics MnTE-2-PyP⁵⁺ and MnTnHex-2-PyP⁵⁺ Regulated by Their Porphyrin Ring Substituents

Abstract

Manganese porphyrin-based drugs are potent mimics of the enzyme superoxide dismutase. They exert remarkable efficacy in disease models and are entering clinical trials. Two lead compounds, MnTE-2-PyP⁵⁺ and MnTnHex-2-PyP⁵⁺, have similar catalytic rates, but differ in their alkyl chain substituents (ethyl vs <i>n</i>-hexyl). Herein we demonstrate that these changes in ring substitution impact upon drug intracellular distribution and pharmacological mechanism, with MnTnHex-2-PyP⁵⁺ superior in augmenting menadione toxicity. These findings establish that both catalytic activity and intracellular distribution determine drug action