Design, Synthesis, and Anticancer Activity of Natural Product Hybrids With Paclitaxel Side Chain Inducing Apoptosis in Human Colon Cancer Cells

Based on the strong activity dependence of paclitaxel (PTX; Taxol) or docetaxel (Taxotere) on the C-13 side chain, a small library of dehydroepiandrosterone, cholesterol, vitamin D2, and alkaloids talatisamine and songorine-PTX hybrids have been synthesized and evaluated for in vitro anticancer activity by MTT assay against human breast (MCF-7), colon (HCT116), lung carcinoma (A549), and renal adenocarcinoma (786-0) cancer cell lines. Most hybrids (11b, 12b, 13b, 15b, and 18b) reduced the growth of MCF-7 and 786-0 cells with low PTX sensitivity in vitro. Among the synthesized compounds, hybrid 11b was better in inhibiting the growth of the 4 cells than PTX. A relatively low IC50 value of compound 11b (8.16 +/- 0.04 mu M) was also examined after exposure for 48 hours. Hybrid 11b showed a proapoptotic effect in HCT116 cells evaluated by Annexin V/propidium iodide binding assay. The level of hybrid 11b leading to protective cell death in HCT116 cells was detected using western blot and not easily observed in our basic examinations.