Evaluation of the Anticancer Activity of Conessine against Human Melanoma (SK-MEL-28) Cells via Mitochondrial-Mediated Apoptotic Pathway

Background: Conessine is a steroidal alkaloid with diverse pharmacological activities, but its anticancer potential against melanoma and the mode of action remain poorly understood. Objectives: The present study evaluated the anticancer activity of conessine against human melanoma SK-MEL-28 cells and investigated its involvement in mitochondrial-mediated apoptosis. Materials and Methods: The cytotoxic effect of conessine was assessed using the MTT assay. Mitochondrial superoxide generation, membrane potential, induction of apoptosis, caspase-3 activity, and expression of apoptosis-related genes were examined using MitoSOX™ Red staining, flow cytometry, indirect ELISA, and real-time PCR, respectively. Results: Conessine significantly reduced SK-MEL-28 cell proliferation in a concentration-dependent manner (IC₅₀=76.78 µg/mL), whereas lower toxicity was observed in Human Dermal Fibroblast (HDF) cells (IC₅₀=143.33 µg/mL). Treatment with conessine enhanced the production of mitochondrial superoxide (76.78 µg/mL) and induced mitochondrial membrane depolarisation (54.50%). Conessine increased caspase-3 activity (1.7-fold increase), upregulated BAX expression, downregulated BCL2 expression, and enhanced the apoptotic cell populations (≥ 60%). Conclusion: These findings demonstrated that conessine exerts selective anticancer activity against SK-MEL-28 melanoma cells by inducing mitochondrial dysfunction and triggering the intrinsic apoptotic pathway. The study highlights conessine as a promising natural molecule for further development as a potential therapeutic agent against melanoma.