Molecular mechanisms of antiproliferative and pro-apoptotic effects of essential oil active constituents in MCF7 and T24 cancer cell lines: in vitro insights and in silico modelling of proapoptotic gene product-compound interactions.

This study aims to investigate the in vitro antiproliferative and pro-apoptotic/apoptotic potential of active constituents of essential oils on two cancer cell lines; namely, breast adenocarcinoma (MCF-7) and urinary bladder cancer (T24). Essential oils active constituents (EO-ACs) entail a spectrum of phytochemicals with widely demonstrated anticancer potential. We assessed the effects of eight essential oils active constituents on T24 and MCF-7 cell lines in both dose- (16-1024 µg/mL) and time-dependent manners. Among these, five EO-ACs (citral, carvacrol, eugenol, geraniol, and thymol) exhibited IC values, ranging from 24 µg/mL to 34 µg/mL, as determined by the MTT assay over 72 h. It was observed that the mitochondrial membrane potential decreased while ROS generation increased substantially in treated cells compared to the control. The underlying apoptotic pathway with regard to pro-apoptotic/apoptotic genes was explored through qRT-PCR and western blotting, which showed significant (p < 0.05) upregulation of Bax, Bak, caspase 7, caspase 9, and downregulation of Bcl-2, pERK, and pAkt. The in-silico study showed strong interaction of thymol and carvacrol with Caspase 9, with complex binding energies of -6.1 Kcal/mol and - 6.3 Kcal/mol, respectively. In conclusion, EO-ACs, particularly thymol and carvacrol, effectively reduced cell viability, and triggered caspase-dependent apoptosis in both MCF-7 and T-24 cell lines. These findings categorically underscore EO-ACs as promising active compounds for anticancer therapy, warranting further in-depth exploration through in vivo studies.