Chiang Mai Journal of Science

 Tyrosinase is the most important enzyme that can approach towards controlling melanin production for hyperpigmentation treatment. The 104 samples were extracted from 54 fungi which were isolated from organic soil at Sirindhorn peat swamp forest, Narathiwat province, Thailand. They were screened on tyrosinase inhibition. From the results, four samples as SPSF318BE, SPSF011BE, SPSF318CE and SPSF045BE showed the potent tyrosinase inhibitory activity with more than 50% at 20 μg/ml. Their tyrosinase inhibitions were 78.83±2.72%, 75.80±2.65%, 72.45±3.55% and 58.04±1.46%, respectively. While positive controls as the water extract of Artocarpus lakoocha wood and kojic acid could inhibit this enzyme with 94.26±0.65% and 80.18±0.84%, respectively. The most active sample was selected for further study, the fungus SPSF318 was identified by using molecular method as Aspergillus flavus. The crude extracts of A. flavus were evaluated for inhibition of cellular tyrosinase, melanin synthesis on B16F1 melanoma cells, pigmentation inhibitory effects on zebrafish, antioxidant and anti-microbial activities against Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis, Pseudomonas aeruginosa and Escherichia coli. In addition, A. flavus has to further study of chemical constituents in order to figure out the active compound which might be the lead compound for whitening agent. Therefore, isolated soil fungi in this area could be considered as good sources of various bioactive natural products, especially, to identify new inhibitor with drug-like properties on tyrosinase enzyme activity.