Characterization of selected marine cyanobacteria as a source of compounds with antioxidant activity

The usage of cyanobacteria as a promising source for new and safe bioactive compounds has drawn attention for research at current time. The cyanobacterial antioxidant potential from fresh water and soil was studied; however, such activity from the cyanobacteria from marine habitats poorly reported. Therefore, this study initiated to evaluate the enzymatic and non-enzymatic antioxidant activity and phytochemical analysis by quantitative as well as GC-MS and FTIR of two cyanobacterial strains (Oscillatoria boryana SB 15 and Oscillatoria pseudogeminata SB 20). The species are identified on morphological and molecular techniques. The pigment content was determined by estimating chlorophyll, carotenoid, and phycobiliproteins. The DPPH and ABTS radical scavenging activities were evaluated, and the IC50 recorded was 260.21 ± 0.94 and 362.03 ± 0.78 μg/ml for O. boryana and O. pseudogeminata. The FRAP assay revealed prominent reducing activity in O. boryana. The total phenol, flavonoid, tannins, and terpenes content was found in the methanol extract of both species. The Super Oxide Dismutase and Catalase activity was equally significant in both organisms. FTIR analysis detected functional groups like amines, alcohols, aldehydes, amides, alkynes, alkanes, aromatic groups, nitro compounds, aryls, and halides common to both species. In GC–MS analysis, compounds like aromatic carboxylic acid, flavonoids, fatty acids, carboxylic acids, terpenes, and some monounsaturated fatty acids were screened from O. boryana; likewise, organic alcohols, propionates, and aliphatic alcohols were found in O. pseudogeminata. The experimental results indicated that both the cyanobacteria have inherent antioxidant compounds, indicating them as potential agent for supply of antioxidant. Further isolation and evaluation of such compounds will indicate for commercial application especially as food pharmaceutical and cosmetic industries.