Biological Activity of the Cyanobacterium Oscillatoria brevis Extracts as a Source of Nutraceutical and Bio-preservative Agents

Background and Objective: Recently nutraceutical and bio-preservative agents from algae, as a natural source have received a great attention.The study aimed to evaluate the antibacterial, antifungal activities and the cytotoxicity, of both Oscillatoria brevis extracts and their fractions.Materials and Methods: Different extracts of O. brevis were examined for their activities against different types of food pathogens and mycotoxigenic fungi.In vitro cytotoxicity assay against human hepatocellular carcinoma cell line (HepG2), colon cancer cell line (HCT116) and breast cancer cell line (MCF7) was monitored.Experimental results were expressed as Mean±Standard Error for three replicates using SAS 6.03.Results: Diethyl ether crude extract (DEE) and diethyl ether fraction No. 4 (F4) inhibited the growth of all tested bacterial and fungal species, where the inhibition zone ranged from 10.2 to 32 mm and from 7 to 10 mm, respectively.Regarding to the in vitro cytotoxicity, DEE exhibited high activity against HCT116 and MCF7 cell lines, with IC 50 values of 22.0 and 39.7 µg mLG 1 , respectively.Interestingly, the cytotoxicity of F4 against MCF7 cell lines was doubled with an IC 50 value of 20.6 µg mgG 1 .The GC/MS analysis revealed the presence of 10 compounds in the F4, most of them have been reported as bioactive agent against different pathogenic bacterial and fungal strain.The detected cytotoxicity was attributed to the presence of phenol, 2,4-bis(1,1-dimethylethyl)-, 9,12-octadecadienoic acid, methyl ester and quercetin.Conclusion: It is concluded that diethyl ether extract of O. brevis had high antimicrobial activity against common food pathogens.It had also anticancer activity especially against breast cancer cell lines.