Cyanobacteria are natural enormous sources of various biologically active compounds with great contributions in different industries. They are immense sources of several pharmacological compounds such as flavonoids and carotenoids with anti-inflammatory and antioxidant activity.
This study aimed to introduce molecular and biochemical characterization for six novel cyanobacterial isolates obtained from qalyubia irrigated drainage canals. Besides, in-vitro antioxidant activity of the isolates was evaluated by radical scavenging assay. According to the antioxidant activity, the possible prophylactic activity of S. aphanizomenoides, the most potent, against hydrogen peroxide-induced oxidative stress in rat model was evaluated in-vivo. Immunohistochemistry of Caspase-3, apoptotic marker, was investigated. Moreover, the effects of H2O2 and S. aphanizomenoides on the mRNA levels of two antioxidant enzyme encoding genes, manganese superoxide dismutase (Mn/SOD) and catalase (CAT), were determined via qRT-PCR.
The obtained accession numbers were KY250420.1, KY321359.1, KY296359.1, KY296358.1, KU212886.1 and KU373076.1 of Nostoc calcicola, Leptolyngbya sp, Nostoc sp, Cronbergia siamensis, Sphaerospermopsis aphanizomenoides and Nostoc sp., respectively. The isolate Leptolyngbya sp (KY321359.1) showed the lowest identity (90%) with other deposited sequences in database. While the isolate S. aphanizomenoides (KU212886.1) revealed the highest total phenolic content as well as the highest levels of caffeic, ferulic and gallic acids. Consequently, it appeared the highest antioxidant scavenging activity. Administration of S. aphanizomenoides against H2O2 in redox rats was marked by amelioration on liver function (AST, ALT), a decrease in oxidative stress markers (MDA, GSSG, NO), increase in endogenous antioxidant defense enzymes and the expression of their related genes (Mn-SOD, CAT). Moreover, immunohistochemistry of Caspase-3 displayed complete amelioration of Caspase3 expression in response to administration of S. aphanizomenoides. Thus, the novel isolate S. aphanizomenoides evidenced a potential in-vitro and in-vivo antioxidant activity against redox rat model.
Keywords: cyanobacteria, Molecular identification, Antioxidant activity, Total phenolic, S. aphanizomenoides, oxidative stress, Redox rats, gene expression.