Chemical modification and anticancer effect of prenylated flavanones from Taiwanese propolis.

Our previous studies demonstrated that eight prenylated flavanones (1-8), isolated from Taiwanese propolis, were capable of a broad spectrum of biological activities. Among them, nymphaeol A (3), nymphaeol B (4) and nymphaeol C (7), abundant in Taiwanese propolis, exhibited cytotoxicity against cancer cell lines. It therefore seemed interesting to improve their activity via a semi-synthetic strategy. In this study, 12 novel prenylated flavanones were synthesised in our laboratory and their activities were assessed for two human prostate cancer cell lines, PC-3 and DU-145, and a human hepatoma cell line, Hep-3B. Of these compounds, 10c, 11 and 12 showed more potent cytotoxicity against the PC-3 cell line than 5-Fu. Using cytometric analysis followed by double staining with annexin V-FITC and propidium iodide, it was observed that these compounds induced apoptosis as well. This suggests that prenylated flavanones 10c, 11 and 12 may have anticancer potential for further development.