Design, synthesis, and mechanistic study of novel isoflavone derivatives as mitochondrial complex I inhibitors for non-small cell lung cancer treatment

Non-small cell lung Cancer (NSCLC) remains the most prevalent and lethal form of lung Cancer, highlighting an urgent need for novel therapeutic agents. Given its status as a critical hub for tumor bioenergetics, mitochondrial complex I has emerged as a promising therapeutic target. In this study, to optimize the efficacy of our previously identified mitochondrial complex I inhibitor DBI-2, we designed and synthesized 27 novel isoflavone derivatives. Among them, compound IV-16 exhibited the most potent antiproliferative activity against human NSCLC A549 cells (IC₅₀ = 0.43 μM), demonstrating a 2.7-fold increase in potency compared to the lead compound DBI-2, while maintaining low cytotoxicity against normal cells. Mechanistically, compound IV-16 suppressed the cellular oxygen consumption rate, which could be reversed by the complex II substrate succinate, confirming its specific inhibition of mitochondrial complex I. This binding mode was further elucidated by molecular dynamics simulations, highlighting dominant interactions with key residues GLU204 and PHE86. Furthermore, compound IV-16 significantly inhibited cell migration and induced Apoptosis in vitro. Notably, compound IV-16 triggered Autophagy by activating the AMPK signaling pathway and subsequently inhibiting the downstream mTOR/S6 axis. In silico ADMET prediction further indicated that compound IV-16 possesses favorable pharmacokinetic profiles and low toxicity risks. Collectively, this study elucidates the structure-activity relationships of these novel isoflavone derivatives and identifies compound IV-16 as a promising mitochondrial complex I inhibitor with therapeutic potential for the treatment of NSCLC.

Isoflavone; Mitochondrial complex I; Molecular dynamics simulation; Non-small cell lung cancer.