Cytotoxic, apoptotic and genotoxic effects of thymoquinone‑oxime derivative on gastric cancer cells: An in vitro study

Gastric cancer (GC) remains a notable global health concern, emphasizing the need for novel and effective therapeutic agents. The present study investigated the cytotoxic, genotoxic and apoptotic effects of thymoquinone‑oxime (TQ‑ox) on human gastric adenocarcinoma AGS cells and assessed its potential to induce DNA damage. Cytotoxicity was evaluated in AGS and normal human gastric epithelial cells (HGEpiCs) using a luminometric ATP assay. Intracellular reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) were measured fluorometrically, whereas intracellular glutathione (GSH) content was determined via a luminometric GSH assay kit. DNA damage was quantified by a comet assay, and apoptosis was assessed by fluorescence microscopy with acridine orange/ethidium bromide (AO/EB) double staining. TQ‑ox exhibited dose‑dependent cytotoxicity in gastric cells, with AGS cells having a slightly higher sensitivity to TQ‑ox treatment than HGEpiCs [half‑maximal inhibitory concentration (IC₅₀): 40.29 vs. 46.42 µM]. Treatment with TQ‑ox significantly increased intracellular ROS levels and DNA damage, while also inducing a significant depletion of intracellular GSH and a reduction of MMP, indicating an increase in oxidative stress (OS) and mitochondrial dysfunction. AO/EB staining supported a dose‑dependent increase in apoptosis of gastric cells at sub‑IC₅₀ concentrations of TQ‑ox. Similarly, comet assay results revealed greater genotoxic effects in AGS cells compared with HGEpiCs, particularly at higher doses of TQ‑ox. These findings demonstrated that TQ‑ox exerted cytotoxic, pro‑apoptotic and genotoxic effects on GC cells, likely mediated by OS, mitochondrial impairment and DNA damage. Taken together, these results provide additional evidence supporting the mechanistic effects of TQ‑ox on GC cells and highlighted its potential as a candidate molecule for further preclinical evaluation.