Tyrosinase inhibitory activity of supernatant and semi-purified extracts from squid pen fermented with Burkholderia cepacia TKU025

摘要

Reports of tyrosinase inhibitors from microorganisms are rare. The tyrosinase inhibitory activity was found from the culture supernatant of Burkholderia cepacia TKU025 with 1 % squid pen as the sole carbonitrogen source. The fourth-day supernatant showed the strongest tyrosinase inhibitory activity (500 U/ml) and the highest total phenolic content (789 mu g/ml GAE). The supernatant was further purified by liquid-liquid partition, and it was found that the methanol extract exhibited the lowest IC50 value of 2 mu g/ml in the tyrosinase inhibitory activity assay and was compared with the positive control kojic acid and vitamin C. Significant associations between the tyrosinase inhibitory potency and the total phenolic content were found for the supernatant, extract, and fractions. The tyrosinase inhibitory activity persisted even when it was treated with acidic or alkaline conditions of pH 2 or 12. The tyrosinase inhibitory activity remained at 100 %, even after treatment at 100 degrees C for 60 min. The tyrosinase inhibitor also showed antimicrobial activity against Escherichia coli, Bacillus cereus, Aspergillus fumigatus, and Fusarium oxysporum.