Background: Benjakul [BEN], a Thai Traditional medicine preparation, is composed of five plants: Piper chaba fruit [PC], Piper sarmentosum root [PS], Piper interruptum stem [PI], Plumbago indica root [PL] and Zingiber officinale rhizome [ZO]. From selective interviews of folk doctors in Southern Thailand, it was found that Benjakul has been used for cancer patients.
Objective: To investigate cytotoxicity activity of Benjakul preparation [BEN] and its ingredients against three human cancer cell lines, large lung carcinoma cell line (COR-L23), cervical cancer cell line (Hela) liver cancer cell line (HepG2) as compared with normal lung fibroblast cell (MRC-5) by using SRB assay.
Material and Method: The extraction as imitated the method used by folk doctors was done by maceration in ethanol and boiling in water. Bioassay guided isolation was used isolated cytotoxic compound.
Results: The ethanolic extracts of PL, ZO, PC, PS, BEN and PS showed specific activity against lung cancer cell (IC50= 3.4, 7.9, 15.8, 18.4, 19.8 and 32.91 μg/ml) but all the water extracts had no cytotoxic activity. Three active ingredients [6 gingerol, plumbagin and piperine as 0.54, 4.18 and 7.48% w/w yield of crude extract respectively] were isolated from the ethanolic extract of BEN and they also showed cytotoxic activity with plumbagin showing the highest cytotoxic activity against COR-L23, HepG2, Hela and MRC-5 (IC50 = 2.55, 2.61, 4.16 and 11.54 μM respectively).
Conclusion: These data results may support the Thai traditional doctors who are using Benjakul to treat cancer patients and three of its constituents (6-gingerol, plumbagin and piperine) are suggested to be used as biomarkers for standardization of this preparation.

Keywords: Cytotoxicity test, SRB assay, Thai medicinal plants, Benjakul preparation, Lung cancer, Liver cancer, Cervical cancer