Leaf extracts of Cassia alata L (akapulko), traditionally used for treatment of a variety of diseases, wereevaluated for their potential antitumor properties in vitro. MTT assays were used to examine the cytotoxiceffects of crude extracts on five human cancer cell lines, namely MCF-7, derived from a breast carcinoma,SK-BR-3, another breast carcinoma, T24 a bladder carcinoma, Col 2, a colorectal carcinoma, and A549, a nonsmallcell lung adenocarcinoma. Hexane extracts showed remarkable cytotoxicity against MCF-7, T24, andCol 2 in a dose-dependent manner. This observation was confirmed by morphological investigation using lightmicroscopy. Further bioassay-directed fractionation of the cytotoxic extract led to the isolation of a TLC-pureisolate labeled as f6l. Isolate f6l was further evaluated using MTT assay and morphological and biochemicalinvestigations, which likewise showed selectivity to MCF-7, T24, and Col 2 cells with IC50 values of 16, 17, and17 μg/ml, respectively. Isolate f6l, however, showed no cytotoxicity towards the non-cancer Chinese hamsterovarian cell line (CHO-AA8). Cytochemical investigation using DAPI staining and biochemical investigationusing terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)-a method used to detectDNA fragmentation-together with caspase assay, demonstrated apoptotic cell death. Spectral characterizationof isolate f6l revealed that it contained polyunsaturated fatty acid esters. Considering the cytotoxicity profileand its mode of action, f6l might represent a new promising compound with potential for development as ananticancer drug with low or no toxicity to non-cancer cells used in this study.
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