Deciphering the Genotoxic Mechanisms of Plumbagin: A Natural Product Lead for Translational Targeting of DNA Damage Pathways in Lung Cancer

Abstract

Natural products continue to play a pivotal role in anticancer drug discovery. In this study, we investigated the mechanistic and translational potential of plumbagin, a bioactive naphthoquinone isolated from Plumbago zeylanica, in non-small cell lung cancer (NSCLC). The objective was to delineate whether plumbagin induces DNA damage through direct DNA interaction or via alternative molecular mechanisms, and to evaluate its potential as a genotoxic lead compound. Cytotoxicity assays demonstrated dose-dependent growth inhibition in NSCLC cells. DAPI staining, AO/EtBr dual staining, γ-H2AX immunofluorescence, and DNA laddering confirmed significant DNA damage and apoptotic induction. Notably, DNA damage persisted even after ROS inhibition using N-acetylcysteine (NAC), indicating the involvement of ROS-independent mechanisms. Gene expression analysis revealed modulation of key DNA damage response (DDR) regulators. To assess direct DNA interaction, UV–Vis spectroscopy, circular dichroism (CD), and isothermal titration calorimetry (ITC) were performed, revealing weak and non-disruptive DNA binding. Molecular dynamics simulations further demonstrated structural stability of the plumbagin–DNA complex without major conformational distortion. To identify potential alternative targets, in silico molecular docking was extended to key DDR associated proteins, revealing energetically favorable interactions with regulatory domains involved in genome integrity signaling. ADMET and drug-likeness predictions indicated favorable physicochemical properties and compliance with Lipinski’s criteria, supporting drug development feasibility. Importantly, these findings suggest that plumbagin-mediated genotoxicity is unlikely to arise from classical DNA intercalation, but rather from modulation of cellular DNA damage pathways. This integrated mechanistic and computational framework highlights plumbagin as a promising natural product lead with translational potential for targeted therapeutic development in lung cancer.