Differential cytotoxicity of ethyl acetate extract of Malaysian marine endophytic fungus (MBL) against human breast cancer cell lines

The global cancer burden is increasing. Breast cancer, in particular, accounts for more than 500,000 deaths worldwide. Current anticancer therapy, unfortunately, is often compromised by side effects and development of drug resistance. This has led to active drug discovery from natural sources like endophytes. Capitalising on the abundance of Malaysian marine endophytic fungi, the present study aimed to assess cytotoxic profiles of ethyl acetate extract of endophytic fungus MBL that originated from Avicennia sp. against two breast cancer cell lines, MDA468 and MCF7. The fungal culture MBL was first examined using gross observation and environmental scanning electron microscope (ESEM). The cultures were then extracted with ethyl acetate and concentrated using rotary evaporator. The resultant extract (0.01 - 100 µg/mL) was screened for its cytotoxicity against MDA468 and MCF7. SRB assay was then performed after 72 h treatment. Data generated was used to determine the IC50 so ( concentration required to inhibit 50 % cell population). The present findings found MBL to produce modest cytotoxic activity against MDA468 and MCF7 with IC50 at 33.5 µg/mL and 40.8 µg/mL, respectively. Its IC50 values were beyond the NCI cut off concentration (IC50 < 20 µg/mL) for a crude extract to be considered as cytotoxic. Besides, it was found to be at least 5.5-fold less potent than paclitaxel and tamoxifen, the positive controls. The present findings warrant further investigation in other types of cancer cell lines in the future.