Cytotoxic and antimicrobial effects induced by ethyl acetate extracts of Malaysian endophytic fungi (MBS 3.2, MOBS 1.1 and MBL 1.2) / Nur Syazwani Abdul Rashid

It is known that plants host endophytic microorganisms which are rich sources of bioactive metabolites. Endophytic bioactive compounds are progressively becoming significant in discoveries of novel drugs given the diversity of their biological activities which include antimicrobial and anticancer effects. Capitalising on the abundance of unexplored Malaysian endophytes that reside within marine plants, this study was undertaken to assess the cytotoxic and antimicrobial profiles of ethyl acetate extracts of endophytic fungi (MBS 3.2, MDBS 1.1 and MBL 1.2) originated from Sonneratia sp. ("Berembang"), Thespesia sp. ("Daun Baru") and Avicennia sp. ("Bakau"). Another two marine fungi (SM 1.4 PLATE 1 and SW 4.1) originated from sea mud and sea water were also included for comparison purposes. For cytotoxic assay, H CT 116 (human colorectal carcinoma cell line) were treated with the ethyl acetate fungal extracts (0.01 - 100 µg/mL) for 72 h. SRB assay was performed to generate data from which the IC50 (the concentration required to achieve half maximal inhibition.) was determined. The antimicrobial assay was carried out using the Minimum Inhibitory Concentration (MIC) Method. Both Gram-positive (Staphylococcus aureus) and negative (Escherichia coli, Salmonella typhimurium and Pseudomonas aeruginosa) bacteria were exposed to ethyl acetate fungal extracts (0.01 - lOOµg/mL) for 24 h after which MIC was determined. The present findings found MBS 3 .2 to be the most potent extract with IC50 observed at O. l 6µg/mL Interestingly, its IC50 is approximately 3-fold more potent than that of 5-FU, the positive control. MBS 3.2 also demonstrated potential antimicrobial activity against S. aureus, P aeruginosa and S. typhimurium (MIC = O.lmg/mL, 0.7mg/mL and lmg/mL, respectively). Its MIC against S. typhimurium, in particular, was comparable to that of gentamicin, the positive control. MBS 3.2 has emerged as the lead ethyl acetate extract and the promising results warrant in-depth cytotoxic and antimicrobial studies using its pure compounds.