The mangrove fungi provide a vast and unexplored source of diverse and unique chemicals and biological properties. The plant Aegiceras corniculatum (L.) Blanco and its endophytic fungus aspergillus species were collected from different sites of the Baleswar river region in Sundarban. Hence, we compared the antioxidant properties of the associated fungus ACSF-1 and the methanolic bark extract of Aegiceras corniculatum (MBAC) by measuring the total phenolic content (TPC), total flavonoid content (TFC), and DPPH free radical assay. Subsequently, antimicrobial activity was measured using the disc diffusion method, and cytotoxic activity was measured using the brine shrimp lethality bioassay. The results showed that MBAC has even more DPPH scavenging activity (IC