Antioxidants are essential in the fight against free radicals which are linked to a number of diseases in humans. Synthetic antioxidants are stable and economical, but they come with health hazards. Mangrove cyanobacteria are being studied for their antioxidant properties in an effort to find natural substitutes. Desmonostoc salinum is isolated from industrial and mangrove sites in the study and antioxidant activity is evaluated. When compared to their industrial counterparts, mangrove isolates show better antioxidant qualities including a greater phenolic content and DPPH radical scavenging activity. Mangrove isolates' ethanolic extracts exhibit 1.42 times greater antioxidant activity than industrial extracts along with a 2.31-fold rise in DPPH scavenging activity. These results highlight the importance of cyanobacteria as a source of antioxidants for the food and pharmaceutical industries. The results of genetic research identify both isolates as Desmonostoc sp., indicating that the different antioxidant levels may be a result of their adaptability to different environments. This study highlights the potential of cyanobacteria as readily extracted, naturally occurring antioxidants that have significant opportunities for both industry and health.