Characterization of Bioactive Compounds with Antioxidant Activity and Antimicrobial Activity from Freshwater Cyanobacteria

Cyanobacteria are one of the most promising candidates for production of alternative biomolecules that can be used for biotechnological applications. In the current study the methanolic extract from four cyanobacterial isolates were screened for their total phenolics, total flavonoids contents, antioxidant and antimicrobial activities. The highest total phenolic content ) 14.33 +/- 0.76 mg GAE/g DW) was detected in Oscillatoria sancta SN2 (MZ504750) extract while the highest flavonoid content (3.13 +/- 0.04 mgQE/g DW) was recorded for Limnothrix planktonica SN4 (MZ504752). All extracts were discovered to have antioxidant activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and the IC50 values ranged between 1.61 mg/ml to 5.68 mg/ml for Limnothrix planktonica SN3 (MZ504751) and Oscillatoria sancta (SN2 MZ504750) respectively. The extracts were examined for antimicrobial activity and showed varying degrees of activity against various gram negative, gram positive bacteria and yeast. GC/MS analysis showed that all extracts contain numerous active biomolecules including 3Allyl-6-methoxyphenol, cis-Vaccenic acid, cis-13-Eicosenoic acid, Tetradecanoic acid "Myristic acid", Phytol, Palmitoleic acid, Palmitic acid methyl ester, n-Hexadecanoic acid "Palmitic acid", Linolenic acid methyl ester, Linolenic acid, and other compounds which exerts antimicrobial and antioxidant activities.