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Abstract

Endophyte is a rich source of bioactive metabolites for medicinal exploitation as an increasing number of novel compounds with bioactive potential are now being isolated from this source. This study was conducted to characterize and explore endophytic fungi from marine weeds available in Bangladesh. The whole weed was used for isolation of endophytic fungi in the water agar media and the isolated fungi were identified through macroscopic and microscopic observation. Small scale cultivation was performed on liquid Wickersham media. Cytotoxicity, antibacterial, antioxidant activities were evaluated following brine shrimp lethality bioassay, disc diffusion method and DPPH free radical scavenging assay, respectively. A total of five endophytic fungi were isolated, purified and characterized from four seaweeds; Hypnea musciformis (HM), Sargassum crassifolium (SC), Dictyota dichotoma (DD) and Caulerpa peltata (CP). They were coded as HMWE-1, HMWE-2, SCWE-1, DDWE-1 and CPWE-1. The fungal strains HMWE-1 and SCWE-1 were identified morphologically as Fusarium sp., HMWE-2 and DDWE-1 as Penicillium sp. and CPWE-1 as Aspergillus sp. DDWE-1 fungal strain showed significant antioxidant activity in comparison to the standard, ascorbic acid. The fungal extracts CPWE-1 (LC 50 value of 2.85 µg/mL) and DDWE-1 (LC 50 value of 6.38 µg/mL) showed significant cytotoxic activity. The extracts exhibited weak to good activity against a wide range of human pathogenic microorganisms during anti-microbial activity screening. Preliminary chemical screening by thin-layer chromatography (TLC) indicated the presence of a number of secondary metabolites. Thus, this study explored the potential entophytes from marine weeds of the Bay of Bengal as a producer of leads for drugs.