Abstract: The effects of the crude ethanol extract of Phyllostachys praecox. C.d. Chu et C.S. Chao leaves grown in Beijing and its major active components, flavoneglycosides and phenolic acids, on the proliferation, apoptosis and Akt signaling pathway of Chinese hamster ovary (CHO) cells were compared to investigate whether the crude ethanol extract has the potential to produce active components harmful to normal cells. The proliferation, apoptosis and Akt signaling pathway activation of CHO cells were measured by MTT assay, Annexin V-FITC/PI double-staining flow cytometry and In cell Analyzer 1000, respectively. The results showed that: 1) the crude ethanol extract and its components had no obvious effect on the viability of CHO cells at doses ranging from 50 to 400μg/mL. the proliferation rate significantly decreased at doses ≥ 800μg/mL (P＜ 0.05) and distinct cytotoxicity was observed and the phenolic acid fraction revealed the strongest cytotoxicity; 2) all the tested samples significantly decreased apoptosis in CHO cells at doses between 200 and 800μg/mL (P＜ 0.05). However, the crude ethanol extract and its flavoneglycoside fraction exhibited apoptosis-inducing effect at the dose of 1600μg/mL with a significant difference (P ＜ 0.05) and the latter resulted in higher apoptosis rate, 14.21%; 3) the flavoneglycosides had little effect on Akt signaling pathway activation at doses ranging from 100 to 800μg/mL compared with the control, but Akt signaling pathway activation increased significantly in the presence of the crude extract at the doses of 400μg/mL and 800μg/mL (P ＜ 0.01). Akt signaling pathway activation increased in a significant dose-effect fashion along with the increasing dose of the phenolic acids (P＜ 0.01). From these results, it can be concluded that the crude ethanol extract and its two fractions have different effects on CHO cells and that the phenolic acid fraction may consist of major toxic components.

Key words: bamboo leaf extract, flavoneglycosides, phenolic acids, cell proliferation, apoptosis, Akt signaling pathway, CHO cells