Design, synthesis and in vitro evaluation of fangchinoline derivatives as potential anticancer agents

The isolation and modification of natural products play an important role in the synthesis of anti-tumor drugs for the treatment of cancer. The present study was designed to evaluate the effects of fangchinoline derivatives against cancer cells. In vitro cytotoxicity of all derivatives against five cancer cell lines (A549, Hela, HepG-2, MCF-7 and MDA-MB-231 cell lines) and HL-7702 normal cells was assessed using the CCK-8 assay, and the results showed that most of the synthesized compounds displayed better cytotoxic effects on all the tested cells compared to that of the parent fangchinoline. In particular, compound 3i had the strongest inhibitory effect on cell proliferation, with an IC₅₀ value of 0.61 µM against A549 cells. Compared with fangchinoline and HCPT (hydroxycamptothecine), the anti-proliferative activity of compound 3i was significantly increased. More interestingly, compound 3i had slight toxic side effects on normal cells, with an IC₅₀ value of 27.53 µM. Moreover, the cell viability and cell cycle assays revealed that compound 3i inhibited A549 cell proliferation and arrested A549 cells at the G2/M-phase. The apoptosis-inducing effects of compound 3i and the associated molecular mechanisms were assessed using flow cytometry, cell staining, reactive oxygen species assays, RT-qPCR and Western blot analysis. These results suggested that compound 3i induces apoptosis through a mitochondria-mediated intrinsic pathway. This study revealed that compound 3i is a promising candidate for future development as an anti-tumor drug.