Cytotoxic and Apoptotic Properties of the Flavonoid-rich Ethyl Acetate Fraction of the Crude Methanol Leaf Extract of Syzygium samarangense (Blume) Merr. (Myrtaceae) against MCF-7 Breast Cancer Cells.

Abstract

Breast cancer is the most common cancer among women in the Philippines and about 3 in every 100 Filipina will be diagnosed with breast cancer in their lifetime. There is a need to discover safe, yet inexpensive herbal extracts with potential cytotoxic properties as potential treatment modalities to treat breast cancer. This study seeks to explore the cytotoxic and apoptotic properties of the ethyl acetate fraction of the defatted crude methanol leaf extract of Syzygium samarangense in MCF-7 breast cancer cell lines. Screening for flavonoids of the extracts was performed using TLC, total flavonoids, total phenols, FTIR and LC-MS spectroscopy. The hydrogen peroxide and ferric reducing anti-oxidant power were used as substrates to assess in vitro anti-oxidative properties of the extracts. The MTT dye viability assay was used to assess the cytotoxic properties of the extracts against MCF-7 cells. Apoptotic properties of the extracts in MCF-7 cells were determined by caspase-3 activation assay, DNA fragmentation patterns and fluorescence microscopy after annexin-V and propidium iodide staining. The abundance of flavonoids in the ethyl acetate fraction of the crude methanol leaf extract was established by TLC, FTIR, LC-MS/MS, total flavonoid and total phenol analyses. The in vitro anti-oxidative properties of this extract was comparable to ascorbic acid. The median inhibitory concentration (IC50) of this extract in MCF-7 breast cancer cell lines was 7.2 mcg/mL while doxorubicin registered an IC50 of 1.2 mcg/mL. At this concentration, the extract was not cytotoxic to normally-dividing breast epithelial cells. Cytotoxicity of the extract was mediated via apoptosis as demonstrated by DNA fragmentation, caspase-3 activation and fluorescence microscopic analyses. The study shows that the flavonoid-rich ethyl acetate fraction of the crude methanol leaf extract of S. samarangense possesses potent apoptotic and cytotoxic properties against MCF-7 breast cancer cell lines at low concentrations.