Antimicrobial and antioxidant activity and GC-MS metabolite profiling of cyanobacteria in the tersakan stream (Amasya, Türkiye)

Abstract

Cyanobacteria are photosynthetic prokaryotes with biologically active metabolites. The present work investigated the antimicrobial and antioxidant activities of extracts of six isolates (Cyanobacterium aponinum (0TA & Ccedil;3), Cylindrospermum moravicum (0TA & Ccedil;4), Nostoc sp. (0TA & Ccedil;5), Pseudoanabaena lonchoides (11TA & Ccedil;8), Cyanobium sp. (11TA & Ccedil;9), and Leptolyngbya sp. (11TA & Ccedil;13)) isolated from the Tersakan Stream. By applying the minimum inhibitory concentration (MIC) method, it was found that especially Pseudoanabaena lonchoides and Nostoc sp. extracts displayed strong antimicrobial activity (0.3125-10 mg/mL) on the tested microorganisms. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) scavenging and Ferric reducing antioxidant power assay (FRAP) were investigated for antioxidant activity screening. Cyanobacterium aponinum and Cyanobium sp. extracts showed strong DPPH (IC50: 0.497 and 0.479 mg/mL, respectively) scavenging and Fe3+ reducing activities (16.88 and 13.58 mg GAE/g extract, respectively). Additionally, the total phenolic content was determined spectroscopically. The antioxidant activities of the methanol extracts were found to be related to the total phenolic content. Cyanobacterium aponinum and Leptolyngbya sp. extracts had high phenolic content (28.99 and 26.42 mg GAE/g extract, respectively). Metabolite profiling was performed by gas chromatography-mass spectroscopy (GC-MS) after the methanol extracts were derivatized with a silylation agent. The GC-MS analysis detected primary and secondary metabolites (fatty acids, organic and inorganic acids, hydrocarbons, alkaloids, terpenes, etc.) that might contribute to biological activity. According to these results, it was revealed that the studied cyanobacteria have therapeutic agents that exhibit natural antimicrobial and antioxidant activity.