Antioxidant and antimicrobial screening of an unidentified yellow pigmented marine-derived fungus

Abstract

The exploration of fungal secondary metabolites has increased significantly since the first discovery of penicillin. In addition, pigment derived from marine fungi attracts plenty of attention due to its complex and unusual chemical structures, which have tremendous antioxidants and antimicrobial activities. Hence, our current work aimed to characterize the crude pigment extract of an unidentified fungus SUCCF0001 and its potential as an antioxidant and antimicrobial agent. The fungus was cultivated on two semi-solid media namely MEA and PDA for 14 days at 25 °C, and two different liquids media namely MEB and PDB for 14 days at 25 °C with agitation at 150 r.p.m. The semi-solid medium and the fungal mycelium from the broth culture were extracted with methanol, while the liquid medium using ethyl acetate. The crude extracts were characterized using TLC plates and then visualized using DPPH, vanillin-H2SO4, and FeCL3. The presence of carotenoid pigment was detected using TLC with β-carotene as a marker. Antioxidant bioassay was screened using the DPPH method; while antimicrobial activity bioassay was conducted using the paper disc method against Bacillus subtilis, Escherichia coli, Micrococcus luteus, Pseudomonas aeruginosa and Candida tropicalis. The results showed that only the PDB extract had radical scavenging activity (RSA) > 50% for antioxidant activity. On the other hand, antimicrobial bioassay showed that only MEB extract had antimicrobial activity against B. subtilis. TLC analysis indicated the presence of antioxidants, terpenoids and phenols in both PDB and MEB extract. However, the result of fungal pigment characterization using TLC concluded that the pigment was not a β-carotene.