Plant sterols have been widely used as chemotherapeutic agents for colorectal cancer for years together. In this study, a novel phytosterol was isolated and characterized from the leaf extract of a medicinal plant, Datura inoxia and was coined as RinoxiaB (RB). This phytosterol was observed to have antiproliferative activity against human colon adenocarcinoma cells, HCT 15. The cell viability assay revealed the IC50 value of the RB as 4 µM. Moreover, RB treated cells showed prominent morphological changes dose dependently and progressively increased the number of dead cells. Additionally, results of the comet, flow cytometry, and cell cycle analysis revealed that the majority of cells were arrested in their S and G2/M phase by blocking the mitotic spindle formation. The western blot analysis (Bcl-2, BAX, Cytochrome C, Caspases 9 & 3) clearly indicated that RB has the ability to induce apoptosis by significantly upregulating (P < 0.05) Bcl-2 and causing mitochondrial damage leading to Cytochrome C release and activation of caspases, which subsequently results in downregulation of BAX expression in the cytosol. Furthermore, the expression of tumor suppressors (p53 and p21) and cell cycle regulatory proteins (Cyclins D1 & B1) suggested that RB inhibit cell proliferation. Thus, the present finding concludes that RB can offer possible apoptotic effects by targeting BAX/Bcl2 pathway in HCT 15 cells, thus alleviating colon cancer.
Keywords: BAX; Bcl-2; Datura inoxia; HCT 15; Phytosterol; RinoxiaB.
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