Biological evaluation of 3-hydroxybenzyl alcohol, an extrolite produced by Aspergillus nidulans strain KZR-132.

AIMS: The aim of the study was to purify and characterize a bioactive compound from Aspergillus nidulans strain KZR-132 and its biological evaluation. METHODS AND RESULTS: A bioactive extolite was purified from A. nidulans strain KZR-132, and its chemical structure was elucidated as 3-hydroxylbenzyl alcohol (3-HBA) based on 1 H and 13 C NMR, FT-IR and mass spectroscopic analysis. The antimicrobial efficacy of 3-HBA was established against Gram-positive, Gram-negative bacteria and different Candida strains. It also showed promising antibiofilm activity against various tested microbial strains. Reactive oxygen species induced by 3-HBA treatment on different Candida strains killed most of the cells and showed necrotic effect. It also exhibited dose-dependent antioxidant and anti-inflammatory activities. CONCLUSIONS: This bioactive extrolite produced by A. nidulans isolated from a niche habitat was demonstrated to possess significant biotechnological and pharmacological potential since it exhibited broad-spectrum antimicrobial and antibiofilm activities which are reported for the first time. SIGNIFICANCE AND IMPACT OF THE STUDY: The overall study demonstrates that 3-HBA produced by A. nidulansKZR-132 is a promising bioactive metabolite and possibly can function as a pharmacologically suitable broad-spectrum antimicrobial drug candidate against various dreaded human-related bacterial and fungal pathogens.

Physicochemical characterization and antioxidant activity of melanin from a novel strain of Aspergillus bridgeri ICTF-201.

AIMS: The aim of the study is to isolate and characterize a melanin pigment from a new strain of Aspergillus bridgeri isolated from rhizosphere soil of Eucalyptus tree and to investigate its antioxidant activity. METHODS AND RESULTS: The extracellular pigment was alkali soluble, acid-resistant and insoluble in organic solvents and water. The pigment was precipitated on treatment with FeCl(3), ammoniacal AgNO(3) and potassium ferricyanide and was bleached in the presence of oxidants and reductants. It was confirmed as melanin based on the Fourier transform infrared and electron paramagnetic resonance spectroscopy techniques apart from chemical analysis. Inhibition of melanin production by inhibitors like tricyclazole, 6-hydroxyflavanone, 4-hydroxy-7-methoxy-3-phenyl-coumarin, 7-hydroxy-4-phenyl-coumarin and 7-hydroxy-3,4,8-trimethylcoumarin confirmed that melanin produced by A. bridgeri is synthesized by 1,8-dihydroxynaphthalene (DHN)-melanin pathway. The melanin showed good free radical scavenging activity by DPPH method with an EC(50) of 54.12 µg ml(-1). CONCLUSIONS: The results of the study indicate that the melanin produced by the newly isolated A. bridgeri strain is a member of DHN melanin family and exhibited significant free radical scavenging activity. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report on characterization of DHN melanin produced by a novel strain of A. bridgeri and may find potential application as a natural antioxidant in the cosmetic and pharmaceutical industries.