The cytotoxic and apoptotic activity of Costus speciosus (Koenig) Smith (Costaceae) leaves against MCF-7 and HeLa cells

Introduction: Costus cuspidatus and Costus subsessilis have shown cytotoxic effects in HL60, Jurkat, and THP-1 cells. This study aimed to evaluate the cytotoxicity and apoptotic activity of the ethanol extract and fractions of C. speciosus leaves against MCF-7 and HeLa cells and to study the binding affinity of known phytoconstituents in C. speciosus toward caspase-3. Methods: The leaves were extracted with 96% ethanol for 72 hours. The extract was further subjected to a liquid-liquid fractionation by employing water, n-hexane, and ethyl acetate solvents. The cytotoxicity of the ethanol extract (CSEE), as well as water (CSWF), n-hexane (CSHF), and ethyl acetate (CSEF) fractions on MCF-7 and HeLa cells was carried out using the CCK-8/WST-8 reagent, followed by flow cytometry analysis to obtain the apoptotic activity on both cells. Results: On MCF-7 cells, the best cytotoxicity was exhibited by CSEF (IC50 of 58.71 µg/mL), followed respectively by CSHF, CSWF, and CSEE. On HeLa cells, the extract and fractions weakly inhibited the survival growth rate, with the best cytotoxicity respectively shown by CSEF (IC50 of 233.881 µg/mL), CSEE, and CSHF. Furthermore, the exposure of CSEF to MCF7 cells resulted in an average of 22.9% undergoing early-stage apoptosis, to HeLa cells resulted in an average of 40.85% undergoing necrosis. Molecular docking simulation revealed that diosgenin and beta-sitosterol interacted with caspase-3 residues with considerable affinity. Conclusion: The CSEF of C. speciosus leaves induces cytotoxicity, whose mechanism seems to be either at the early apoptosis stage on MCF-7 cells or by necrosis on HeLa cells.