title: A study of the potential anticancer activity ofMangifera zeylanicabark: Evaluation of cytotoxic and apoptotic effects of the hexane extract and bioassay-guided fractionation to identify phytochemical constituents.
abstract: The present study investigated the potential anticancer activity of the bark of Mangifera zeylanica, an endemic plant in Sri Lanka that has been traditionally used for cancer therapy. Cytotoxic and apoptotic effects were investigatedin vitrousing sulphorodamine assay, acridine orange and ethidium bromide staining, caspase-3 and -7 activity, DNA fragmentation and reverse transcription-quantitative polymerase chain reaction in estrogen receptor positive MCF-7 and triple-negative MDA-MB-231 breast cancer cell lines, SKOV-3 ovarian cancer cell line and MCF-10A normal mammary epithelial cells. Hexane extract demonstrated increased levels of cytotoxicity in cancer cells (IC50, 86.6-116.5 µg/ml) compared with normal cells (IC50, 217.2 µg/ml). Chloroform extract demonstrated increased cytotoxicity to normal cells (IC50, 92.9 µg/ml) compared with cancer cells (IC50, 280.1-506.5 µg/ml). Exposure to the hexane extract led to morphological changes characteristic of apoptosis and DNA fragmentation in the three cancer cell lines. Caspase-3 and -7 were significantly activated in MDA-MB-231 and SKOV-3 cells, indicating the occurrence of caspase-dependent apoptosis in these cells, and caspase-independent apoptosis in MCF-7 cells. Furthermore, upregulation of proapoptotic Bcl-2-associated X protein occurred in the three cancer cell lines, and antiapoptotic survivin was downregulated in MCF-7 and SKOV-3 cells; by contrast, tumor protein p53 was upregulated only in MCF-7 cells, suggesting p53-mediated apoptosis in MCF-7 cells and p53-independent apoptosis in the remaining cancerous cell lines. In addition, fraction M1obtained from bioactivity-guided fractionation of the hexane extract demonstrated increased cytotoxicity in cancer cells (IC50, 15.4-38.7 µg/ml) compared with normal cells (IC50, 114.6 µg/ml), with the highest cytotoxicity observed in MDA-MB-231 triple-negative breast cancer cells. The hexane extract of M. zeylanica bark contained polyphenols and flavonoids, and caused free radical scavenging activity. Its gas chromatography-mass spectrometry profile revealed the presence of long-chain hydrocarbons, including β-sitosterol and β-amyrin. Fraction M1contained seven unknown compounds and a small number of known non-cytotoxic compounds. Collectively, results obtained in the present study indicate that the hexane extract of M. zeylanica bark mediates cytotoxic activities through induction of apoptosis in three cancer cell lines; thus, the hexane extract may be used to isolate novel anti-cancer compounds.
authors.affiliation: Institute of Biochemistry, Molecular Biology and Biotechnology, University of Colombo, Colombo 00300, Sri Lanka.
authors.forename: Meran Keshawa
authors.initials: MK
authors.lastname: Ediriweera
authors.affiliation: Institute of Biochemistry, Molecular Biology and Biotechnology, University of Colombo, Colombo 00300, Sri Lanka.
authors.forename: Kamani Hemamala
authors.initials: KH
authors.lastname: Tennekoon
authors.affiliation: Institute of Biochemistry, Molecular Biology and Biotechnology, University of Colombo, Colombo 00300, Sri Lanka.
authors.forename: Sameera Ranganath
authors.initials: SR
authors.lastname: Samarakoon
authors.affiliation: Institute of Biochemistry, Molecular Biology and Biotechnology, University of Colombo, Colombo 00300, Sri Lanka.
authors.forename: Ira
authors.initials: I
authors.lastname: Thabrew
authors.affiliation: Department of Chemistry, Faculty of Science, University of Colombo, Colombo 00300, Sri Lanka.
authors.forename: Egodage
authors.initials: E
authors.lastname: Dilip DE Silva
keywords: Mangifera zeylanica; anticancer activity; apoptosis; breast cancer; cytotoxicity; ovarian cancer; phytochemical constituents