Growth inhibitory activity of ethanol extracts of Chinese and Brazilian propolis in four human colon carcinoma cell lines.

More than 300 bio-active compounds have been identified from bee propolis in various regions of the world. The objective of this study was to examine whether the ethanol extracts of Chinese and Brazilian propolis may exert anticancer activities in four human colon carcinoma cell lines, namely CaCo2, HCT116, HT29 and SW480. Propolis samples were extracted with ethanol, and the crude extracts were dissolved in dimethylsulfoxide and used for the experiments. In HCT116, HT29 and SW480 cell lines, the extracts of both Chinese and Brazilian propolis caused a marked dose-dependent growth inhibition, with IC50 values in the range of 4-41 microg/ml. In HCT116 cell line, Chinese propolis extract induced apoptosis in the cells after 72 h of treatment. In addition, Chinese propolis extract caused a dose-dependent increase in the cellular mRNA levels of p21CIP1 and p53 in the HCT116 cell line. These findings indicate that the ethanol extracts of propolis contain components that may have anticancer activity. Thus, propolis and related products may provide a novel approach to the chemoprevention and treatment of human colon carcinoma.