CGN extract treatment reduces human cancer cell viability. (A) HeLa (B) HepG2 and (C) ZR751 cells were treated with doses range from 5 – 160 μg/ml for up to 24 h prior to analysis of cell viability by MTT assay. Cell survival was determined as the percentage of the control from three independent experiments. Accordingly, IC50 were also determined. Each bar represents the mean ± SD (n = 3). Means marked with different letters, within each row, are significantly different (P < 0.05) analysed by one-way ANOVA supplemented with Tukey’s HSD test.