Estragole Induces Apoptosis in A549 Lung Cancer Cells via ROS-mediated Oxidative Stress and Modulation of Caspase Activation and Bax/Bcl-2 Pathway

Background Lung cancer remains a major cause of death globally, responsible for a significant portion of all cancer-related deaths despite advancements in therapeutic modalities. Consequently, there is a great demand for new treatment strategies that can improve anti-cancer efficiency while minimizing toxicity in vivo . Purpose The present work was dedicated to understanding the anti-cancer activity and possible underlying mechanisms of estragole against lung cancer cells. Materials and Methods The antioxidant capacity of estragole was studied using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging assay. The cytotoxic effect of estragole (5–100 µM) on A549 cells was tested by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Intracellular reactive oxygen species (ROS) generation was quantified via specific fluorescence staining techniques. Furthermore, the levels of oxidative stress biomarkers were determined using specialized assay kits. To understand the molecular mechanisms involved, the protein levels of apoptotic and cell-cycle regulatory proteins, including Bax, B-cell lymphoma 2 (Bcl-2), cyclin D1, and caspase-3/9, were quantified using appropriate biochemical assay kits. Results Estragole administration showed a dose-dependent diminution in DPPH radical levels, which evidences its antioxidant effects. Treatment with estragole showed a significant decrease in the viability of A549 lung cancer cells. Additionally, estragole treatment showed marked elevation in intracellular ROS generation in A549 cells. Biochemical analysis revealed that estragole exposure exacerbated oxidative stress, evidenced by increased thiobarbituric acid reactive substances (TBARS) levels and a concomitant depletion of the antioxidant system. Furthermore, estragole treatment shifted the apoptotic balance by upregulating Bax protein levels and caspase activation while significantly downregulating cyclin D1 levels. Conclusion The present study demonstrates that estragole effectively inhibits cellular viability, triggers oxidative stress, and promotes apoptosis in A549 cells by regulating Bax/Bcl-2 signaling, caspase activation, and downregulation of cyclin D1. Hence, it was clear that estragole holds significant promise as a novel anti-cancer lead for the treatment of lung cancer.