This study was conducted to evaluate the antimicrobial activities and cytotoxicity of both crude extracts of Scenedesmus obliquus and their fractions. In vitro cytotoxicity assay against human hepatocellular carcinoma (HepG2), colon cancer (HCT116) and breast cancer (MCF7) cell line was monitored. The highest inhibition was observed using diethyl ether crude extract (DEE) recording between 12.5 and 19.5 mm inhibition zone against all tested bacteria and between 8.7 and 18.3 mm against tested fungi. The highest anticancer effect of DEE was observed at IC50 against HCT116 and HepG2 cell lines using just 24.6 and 42.8 μg ml-1, respectively. While, high concentration, 93.8 μg ml-1, was required to exhibit its effect against MCF7. Column chromatography technique was used to separate DEE crude extract to its main components using 7 different mobile phases. Fractions F1 and F7 were the highest fractions that had antimicrobial activity against tested bacteria and fungi. High IC50 > 80 μg ml-1 were required to exhibit anticancer activity at IC50 against the tested cancer cell lines. The main compounds responsible for the bioactivity were identified using GC-MS, nonadecane and butylated hydroxytoluene in F1 and 9-octadecadienoic acid and quercetin 7,3',4'-trimethoxy in F7 were identified. The current study highlights the potential use of S. Obliquus extract and their fractions as a source of antimicrobial and anticancer compounds.
Keywords: Cancer research; Microbiology; Natural product chemistry.