Apoptosis-Inducing Activity of HPLC Fraction from Voacanga globosa (Blanco) Merr. on the Human Colon Carcinoma Cell

Voacanga globosa (Blanco), a plant endemic to the Philippines, is traditionally used especially by indigenouspeople of Bataan in the treatment of ulcers, wounds and tumorous growths. This study aimed to providescientific evidence to therapeutic properties by determining cytotoxic and pro-apoptotic activity of HPLCfractions from leaves on HCT116 human colon carcinoma and A549 human lung carcinoma cell lines. Ethanolicextraction was performed on V globosa leaves followed by hexane and ethyl acetate partitioning. Silica gelcolumn chromatography and high performance liquid chromatography (HPLC) produced MP1, MP2 andMP3 fractions. Cytotoxic activity of the fractions was determined through MTT assay against the cancer celllines HCT116 and A549 and the non-cancer AA8 Chinese hamster ovarian cell line. Pro-apoptotic activities ofthe most active fractions were further assessed through DAPI staining, TUNEL assay and JC-1 mitochondrialmembrane potential assay with HCT116 cells. While the MP1 fraction exerted no significant activity against allcell lines tested, MP2 and MP3 fractions demonstrated high toxicity against HCT116 and A549 cells. The MP3fraction induced formation of apoptotic bodies, condensed DNA and other morphological changes consistentwith apoptosis of HCT116 cells and TUNEL assay showed significant increase in DNA fragmentation overtime. In these cells, the MP3 fraction also induced mitochondrial membrane destabilization, which is generallyassociated with the beginning of apoptosis. Phytochemical analysis demonstrated the presence only of saponinsand terpenoids in the MP3 fraction. The results indicate that the MP3 fraction exerts cytotoxic activity onHCT116 cells via induction of apoptosis triggered by loss of mitochondrial membrane potential crucial for cellsurvival.