Sub-cytotoxic mitochondrial stress in cardiomyocytes and whole-organism toxicity in c. elegans induced by molnupiravir

Abstract

Many antiviral agents are known to induce off-target mitochondrial toxicity due to the prokaryotic origin of mitochondria. Mitochondrial dysfunction is frequently linked to cardiotoxicity. We aimed to elucidate the mitochondrial toxicity profile of molnupiravir via focusing on mitochondrial dynamics, biogenesis, and oxidative stress in cardiac cells. Mitochondrial function was evaluated by luminometric measurement of ATP (adenosine triphosphate) content, and flow cytometric analysis of mitochondrial membrane potential, and mitochondrial mass. The expression levels of genes involved in mitochondrial fusion-fission were assessed by RT-PCR. In addition, molecular docking analysis was performed to evaluate the interaction between molnupiravir and the dynamin related-protein DRP1. Protein carbonylation was determined as an oxidative stress parameter. Toxicity evaluation was further investigated in Caenorhabditis elegans to support the in vitro findings at the organismal level. Molnupiravir exposure led to a significant dose-dependent reduction in intracellular ATP level and mitochondrial mass, accompanied by increased protein carbonylation. Mitochondrial membrane potential remained slightly increased. Alterations in the expression of genes regulating mitochondrial dynamics suggested an imbalance between fusion and fission processes, while mitochondrial biogenesis-related signaling was progressively suppressed. C. elegans exposed to higher concentrations of the drug (20-500 µM) exhibited significant lifespan reduction at all doses. Molecular docking analysis demonstrated a moderate binding affinity of molnupiravir to DRP1, supporting a potential direct interaction with mitochondrial fission machinery. In conclusion, our results demonstrate that molnupiravir induces mitochondrial stress through oxidative damage, impaired biogenesis, and altered dynamics, emphasizing the need for careful evaluation of mitochondrial safety of molnupiravir in cardiac tissue.