Suppressive effects of Adenophora triphylla extracts on in vitro tumor cell growth and in vivo gastric epithelial proliferation.

Adenophora triphylla (AT), an oriental medicinal plant, was extracted using water and several organic solvents and each fraction was assayed for its tumoricidal effects on human Jurkat T cells with 3-(4,5-dimethylthiazolyl)-2,5-diphenyltetrazolium bromide (MTT). The influence on induction of apoptosis and G1 arrest was also examined. The ethyl acetate fraction showed the most pronounced inhibitory effects on proliferation of Jurkat T cells. Apoptosis was induced in line with up-regulation of FasL, tyrosine phosphorylation and c-fos mRNA levels. Arrest in G1 of the cell cycle was observed in A2780 cells with a wild type p53 gene but not HT-29 cells with a mutant p53 gene. Modifying effects of AT on cell turnover and glutathione(GSH) levels in vivo were also investigated in the stomach of rats given 150 mg/kg of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) by gavage and then fed a diet supplemented with 5% or 1% pulverized AT and 0.5% or 0.2% ethylacetate-extracted AT for 42 hours. The 5% AT and both of the ethylacetate fractions caused significant reduction in proliferating cell nuclear antigen (PCNA)-labeling in the glandular stomach epithelium as compared with the value for the MNNG alone group. In addition, the treatments significantly increased the gastric GSH levels. These results suggest that AT could be a chemopreventive agent against gastric cancer.