Anticancer activity of 28-Oxoallobetulin on HT-29 human colon cancer cells

Many successful therapeutic drug, including several anticancer agents, have been isolated for natural products. In a recent screen of methanolic extracts from several natural products, we isolated an active compound, from the methanolic extract of persimmon calyx, which promoted cytotoxicity and apoptosis in HT-29 human colon cancer cells. This compound was identified as 28-oxoallobetulin, a prototypical compound, by UV-MS analysis and various NMR spectroscopic methods. The highly cytotoxic effects of 28-oxoallobetulin on HT-29 cells were demonstrated using MTT reduction, LDH release, and colony formation assays. Furthermore, we were able to detect apoptotic bodies in HT-29 cells by Hoechst staining as well as flow cytometric analysis for the presence of sub-G1 DNA peaks, indicative of apoptotic cells. Finally apoptosis in HT-29 cells following 28-oxoallobetulin treatment was also confirmed by the presence of activated caspase-3 and specific proteolytic cleavage of poly (ADP-ribose) polymerase.