A Small‐Molecule Drug for the Self‐Checking of Mitophagy

Mitophagy that disrupt mitochondrial membrane potential (MMP), represents a critical focus in pharmacology. However, the discovery and evaluation of MMP‐disrupting drugs are often hampered using commercially available marker molecules that target similar or identical zones. These markers can significantly interfere with, obscure, or amplify the functional effects of MMP‐targeting drugs, frequently leading to clinical failures. In response to this challenge, we propose a “one‐two punch” drug design strategy that integrates both target‐zone drug functionality and non‐target zone biological reporting within a single small‐molecule drug. We have developed a novel mitophagy self‐check drug (MitoSC) that exhibits dual‐color and dual‐localization properties. The functional component of this system is a variable MitoSC that disrupts MMP homeostasis, thereby inducing mitophagy. Upon activation, this component transforms into a blue‐fluorescent monomer (MitoSC‐fun) specifically within the mitochondrial target zone. The biological reporting component is represented by a red‐fluorescent monomer (MitoSC‐rep) that localizes to lysosomes, the non‐target zone. As mitophagy progresses, the fluorescent signals from MitoSC‐rep (lysosomes) and MitoSC‐fun (mitochondria) converge, enabling real‐time monitoring of the mitophagy process. Our findings underscore the potential of a single‐molecule drug to exert target‐zone specific actions while simultaneously providing non‐target zone self‐checking, offering a new perspective for drug design.