Elucidation of basic mechanisms of flavokawin B inhibitory effects on the growth of selected cancer and transformed normal cell lines

Flavokawin B (FNB) is a hydroxychalcone isolated from a local plant species,Alpinia zerumbet of the Zingiberaceae family. It has been shown to have antioxidant and pro-immune properties. The aim of the present study was to assess the basic growth inhibitory mechanisms of FNB, on 21 cell lines, comprising tumour and transformed cell lines. The cells were treated with FNB at 0.1, 1, 3, 10, 30 and 100 μM. Over 3 to 4 days exposure, FNB selectively inhibited the growth of all the cell lines. Tumour cells were more sensitive to FNB than normal cells. MTT cytotoxicity assay was then conducted in order to assess the cytotoxic-indices of FNB. Caco-2, CEM-SS, MCF-7, T-47D and U87MG were found to be the five most sensitive cell lines, with IC50 values of 6.53 ± 0.81, 2.00 ± 0.41, 7.67 ± 0.71, 8.67 ± 1.40 and 14.00 ± 3.00 μM respectively. Tamoxifen (TMX) was used as a positive control for the 5 cell lines, with all the IC50 values found to be comparable to that of FNB. Cell survival analysis confirmed very significant patterns of FNB efficacy (P0.05, at 45 μM) and a significant FNB anti-clastogenicity (P