Abstract Natural products from medicinal plants and traditional medicine have been a fertile source for identification of novel molecules with human health-protective effects. Triphala is an Ayurvedic medicine used as a dietary supplement to prevent and cure ailments of the gastro-intestinal tract in India from ancient times. It is a formulation made from dry powder of three fruits, Terminalia chebula, Emblica officinalis and Terminalia bellerica and has been used to treat microbial infections and ulcers of stomach and colon. In order to identify bioactive principles and their molecular targets, colon cancer cells HCT-116 (5×103 cells) were seeded in 96 well plates and treated with the methanolic extract of triphala at varying concentrations for 24, 48 and 72 hours. Cell proliferation assay demonstrated a dose-dependent inhibition of cell growth and the IC50 was determined to be ∼100 μg/ml. RNA isolated from colon cancer cells treated for 6 hours with the methanolic extract at 100 and 200 μg/ml concentrations revealed a dose-dependent down-regulation of MUC1 gene expression as detected by qRT-PCR. Also, MUC1 antibody immunohistochemistry showed down-regulation of MUC1 protein expression, when cells grown in chamber slides were treated with the methanolic extract. In addition, qRT-PCR revealed down-regulation of expression of the inflammatory molecules IL-6, IFNγ, COX-2, NF-κB and the cell cycle-regulatory molecule, cyclin D1. These results suggest that triphala extract exerts its anti-tumorigenic effects by influencing the expression of mucins via modulation of inflammatory molecules that are up-stream of mucin expression, in colon cancer cells. FTICR-MS (Fourier-transform Ion Cyclotron Resonance MS) analysis of the methanolic extract of triphala readily confirmed the presence of previously reported compounds such as gallic acid, ellagic acid, several mucic acid gallates, chebulic acid, ascorbic acid, citric acid, and several tannins. Sub-fractionation of the methanolic extract with ethyl acetate, when tested on colon cancer cells, showed higher efficacy (IC50 = 50 µg/ml) suggesting enrichment of select bioactive principles. FTICR-MS analysis of the ethyl acetate extract revealed enrichment of gallic acid, ellagic acid, and several other tannins, while mucic acid and their gallates were not. HPLC fingerprinting of the methanolic and ethyl acetate extracts confirmed the enrichment of phenolics into ethyl acetate fraction. The fractionation results suggest that enrichment of distinct set of active principles of triphala into different fractions is a viable strategy to help identify their specific molecular targets. More extensive fractionation of the methanolic extract of triphala is currently underway (Supported from Agnes Brown Duggan Endowment). Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5696.