Tyrosinase inhibition mechanism of polyphenols from Porphyra haitanensis extracted by cyclic subzero temperature

Abstract

Porphyra haitanensis, is cultivated plants in seawater, and contains health-promoting phenolic compounds that inhibit tyrosinase activity and reduce melanin levels. In this study, the extraction process of P. haitanensis polyphenols (PPE) by cyclic subzero temperature was optimized and the tyrosinase inhibition mechanism and anti-melanotic effect were investigated. The optimal extraction conditions for polyphenols were liquid-solid 50:1, freezing time 6.12 h, and thawing temperature 47.73 °C, getting an extraction yield of 4.903 mg GAE/g and tyrosinase inhibition rate of 53.20 %. 15 phenolic compounds such as catechin, naringenin and coumarin were identified. Catechin accounting for 92.46 %, as the major phenolic compound, played a major role in anti-tyrosinase activity. Further studies revealed catechin might alter the tyrosinase conformation and prevent substrate binding, thus inhibiting the catalytic activity of tyrosinase. Moreover, PPE showed significant inhibitory effects on melanin content and cellular tyrosinase activity. This study provided a reliable basis for the development of anti-tyrosinase drugs and melanin inhibitors from P. haitanensis.