Antimicrobial activity, cytotoxicity and chemical constituents of the freshwater microalga Oscillatoria princeps

Abstract

The microalgae Oscillatoria sp. are promising sources of bioactive metabolites used in both pharmaceutical and nutraceutical applications. The main objective of present study is to determine the antimicrobial activity, cytotoxicity, and chemical profile of Oscillatoria princeps r extracts and its fractions. O. princeps extracts were prepared by successive extraction method, and chemical constituents were identified using GC-MS. Diethyl ether extract (DEE) had antimicrobial activity against all tested microorganisms and the highest inhibition zones 20.7 and 20.2 mm was observed against P. aeruginosa and A. flavus, respectively. Also, DEE showed an anticancer activity with IC50 values of 35.18, 46.6, and 79.18 µg ml-1 against breast cancer (MCF7), colon cancer (HCT116), and hepatocellular carcinoma (HePG2) cell lines, respectively. By DEE fractionation, fraction F7 showed the highest antimicrobial activity followed by fraction F4 with minimum inhibitory concentration (MIC) values ranged between 0.5 and 1.9 mg ml-1. Fraction F4 recorded anticancer activity against HCT116, MCF7, and HePG2 with IC50 of 22.62, 24.43, and 102.52 µg ml-1, respectively. While fraction F7 had anticancer activity against HCT116 and MCF7 without any effect on the HePG2 cell line. GC-MS analysis of fractions F4 and F7 represented that the main compounds responsible for the bioactivity were Pentadeconic acid,4-hexadecyl ester, and 9-Octadecenoic acid in F4, while the main compounds in F7 were Quercetin 7,3',4'-trimethoxy and Methyl tetradecanoate. The study concluded that O. princeps DEE extract and fractions had a sufficient amount of bioactive compounds that possess antimicrobial and anticancer activity, which could be a promising source for pharmaceutical and nutraceutical ingredients.