Thesis (M.Sc.)--Chulalongkorn University, 2012

The antiproliferative activity of the 24 plant ethanolic crude extracts of Thai rejuvenating herbal plants present in the traditional Thai medicinal recipe against the human estrogen receptor negative breast cancer cells (MDA-MB-231) at the concentration of 0.1, 1, 10, 100 and 1,000 µg/ml with the aid of MTT assay was done. The results revealed that the breast cancer cell survival rates were decreased significantly following the treatment with the increasing doses of the certain plant crude extracts as determined by the IC₅₀ values. The top three of the most potent plant ethanolic crude extracts according to their IC₅₀ values were Stephania venosa, Piper nigrum (seed) and Stephania erecta. (IC₅₀; 24.85, 31.34 and 32.42 µg/ml, respectively) The same set of plant samples were evaluated for apoptosis assay with the aid of flow cytometry. The plant ethanolic extract treatments exhibited typical apoptotic features. The apoptosis was confirmed with Western blot and the results showed activation of caspase-3 and cleavage of PARP by caspase-3, decrease expression of Bcl-2, in the 3 plant samples. However, caspase-8 and BID were not inactivated by 3 plant samples. The result indicated that the plant ethanolic extract can induces apoptosis via intrinsic pathway. The study confirms the potential of the three Thai rejuvenating herbal plants against the estrogen receptor negative breast cancer cells.