Stability of Phenyl-Modified Triphenylphosphonium Conjugates and Interactions with DTPA.

Triphenylphosphonium (TPP) conjugates are effective in targeting drugs and probes to the mitochondria due to their lipophilic character that allows them to readily cross membranes and their large cationic radius that enables mitochondrial uptake because of the mitochondria's negative membrane potential. TPP conjugates, while effectively sequestered by the mitochondria, are also known to uncouple oxidative phosphorylation (OXPHOS) and depolarize the mitochondrial membrane. xTPP conjugates with para-substitutions of functional groups on the phenyl rings of the TPP moiety display different levels of dose-mediated cytotoxicity due to differing potencies of uncoupling.