Lucigenin fluorescent assay of tyrosinase activity and its inhibitor screening

Tyrosinase is a key enzyme in melanin biosynthesis and its serum level is an important biomarker for some dermatoses such as vitiligo and melanoma. Thus, a sensitive and facile assay for tyrosinase activity is in urgent demands. Lucigenin is a well-known chemiluminescent luminophore, but has been rarely been employed for fluorescence detection. In this work, a facile method to detect tyrosinase activity based on lucigenin fluorescence has been reported for the first time. When tyrosinase was mixed with tyrosine, tyrosine was oxidized to generate melanin-like polymers which can effectively quench the fluorescence of lucigenin. A linear range of tyrosinase from 0.25 to 25 μg/mL was obtained with detection limit of 0.2 μg/mL. In addition, a useful platform for screening potential tyrosinase inhibitors was constructed based on the proposed system. The linear range is from 2.5 to 62.5 μg/mL and the detection limit is as low as 1.0 μg/mL for kojic acid, a typical tyrosinase inhibitor.