Assessment of Antimicrobial and Antioxidant Potential of Oscillatoria sancta and Oscillatoria proteus Isolated from Chilika Lake.

Filamentous cyanobacteria are a promising source of biologically active secondary metabolites with antioxidant, antimicrobial, antiviral and anticancer properties. Previously, cyanobacteria isolated from fresh and marine water were studied extensively, but those isolated from brackish water were less investigated. The purpose of this study was to examine the antimicrobial activities as well as the potential antioxidant capacity of two cyanobacterial strains (Oscillatoria proteus and Oscillatoria sancta) obtained from Chilika Lake. The pigment and antioxidant was assayed using a spectrophotometer; antimicrobial activity was studied by minimum inhibitory concentration (MIC); and the presence of phytoconstituents was detected using gas chromatography mass spectrometry (GC-MS). The solvents used for extraction were methanol, acetone and benzene. The experimental data indicates that the total phenolic and flavonoid content was highest in O. sancta (58.26 ± 0.72 µg/g, 38.45 ± 0.79 µg/g, respectively). Similarly, the methanol extract of O. sancta presented the maximum antioxidant potential in both DPPH (83.18 ± 0.57%) and ABTS (68.42 ± 1.40%) radicals. Besides, more reducing power was also recorded in methanol extract of O. sancta as compared to O. proteus. Further, higher enzymatic activity (superoxide dismutase and catalase) was observed in O. sancta. The antimicrobial potential against bacterial and fungal pathogens demonstrated better activity in O. sancta. In GC-MS analysis seven major chemical classes have been detected. Differential results was found in the two species of Oscillatoria; however, both have potential antimicrobial and antioxidant properties. The findings have pharmaceutical and nutraceutical importance.

Antioxidant and antimicrobial activities and GC/MS-based phytochemical analysis of two traditional Lichen species Trypethellium virens and Phaeographis dendritica.

BACKGROUND: Lichens are complex plants living in symbiotic relationship between fungi and algae. They are used for human and animal nutrition and are used in folk medicine in many countries over a considerable period of time. In the present study, various solvent extracts of Trypethelslium virens and Phaeographis dendritica were tested for their antioxidant and antimicrobial activity. RESULTS: The phytochemical analysis by GC/MS revealed phenolics (1.273%), terpene (0.963%), hydrocarbons (2.081%), benzofurans (2.081%), quinone (1.273%), alkanes (0.963%), and aliphatic aldehydes (0.963%) as the predominant compounds in Trypethellium virens SPTV02, whereas secondary alcohol (1.184%), alkaloids (1.184%), and fatty acids (4.466) were the major constituents in Phaeographis dendritica. The antioxidant property of methanolic extract of T. virens and P. dendritica revealed the presence of total phenolic and terpenoids. The methanolic extracts of both the lichens exhibited encouraging DPPH antiradical activity, with the IC50 of 62.4 ± 0.76 µg/ml for T. virens and 68.48 ± 0.45 µg/ml for P. dendritica. Similarly, ferric reducing power assay result exhibited higher reducing activity. Further, the lichen extracts (methanolic) indicated promising antimicrobial activities against pathogens showing MIC from 62.5 to 500 µg/ml. CONCLUSION: The study results concludes that both the lichens could be used as new natural source of antioxidants and antimicrobial agents which can be exploited for pharmaceutical applications.