Cytotoxicity of the extracts and fractions from Allanblackia gabonensis (Clusiaceae) towards a panel of cancer cell lines

Cancer stands as one of the most common causes of death worldwide. Allanblackia gabonensis, a widely distributed plant in the Democratic Republic of Congo and Cameroon, is traditionally used as medicinal plant to cure dysenteries, toothaches, cold and to improve virility in men. The present study aims at evaluating the cytotoxicity of the extracts of five parts of A. gabonensis as well as that of the fractions of the most active part against cancer cell lines. The cytotoxicity was assessed by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay. The fruit's extract (AgFr) was the most active against tested cancer cell lines. It reduced the viability of cervical (HeLa), pancreatic (MIAPaCa-2) and breast (MCF-7) cancer cell lines, even below 30 μg/mL (IC50) compared to glioblastoma and lung cancer cells without affecting the normal cell line (up to 50 μg/mL). Its hexane (AgFr-H) and dichloromethane (AgFr-D) fractions displayed better growth inhibition against 4/7 and 5/7 tested cancer cell lines compared to normal cells. The lowest IC50 values were obtained with AgFr-H (15.43 μg/mL) and AgFr-D (16.38 μg/mL) against HeLa cells. AgFr-D induced apoptosis in HeLa cells with the alteration of the mitochondrial membrane potential as detected by flow cytometry. Decreased expression of pro-caspase 3 and 7 by western blot analysis further confirmed the AgFr-D-induced apoptosis. It also stopped cell cycle in G0/G1 phase and inhibited HeLa cells' migration along with MMP-9 down-regulation. This investigation provided supportive data for the possible use of A. gabonensis fruits' extract and particularly its hexane and dichloromethane fractions as chemotherapeutic in cancer.