Tyrosinase Inhibitory Activity of Extracts from Prunus persica

Abstract

The demand for skin-whitening agents is high across the world, including Asian countries. An extensive screening using a tyrosinase inhibition assay was performed in order to discover novel plant materials. In our research program investigating a safe and effective agent, 50% ethanolic extracts prepared from discarded parts of Prunus persica were screened for in vitro tyrosinase inhibitory activity. Among the extracts tested, twig extract showed the most potent inhibitory activity: 38% inhibition at 500 µg/mL. The investigation of active compounds in twig extract found four flavanones that acted as moderate inhibitors, including (−)-prunin, persiconin, (+)-dihydrokaempferol, and (−)-naringenin. These compounds were only observed in the twig extract following preliminary quantification by HPLC, with the following concentrations: (−)-prunin, 1.8 mg/g sample; persiconin, 0.8 mg/g sample; (+)-dihydrokaempferol, 0.8 mg/g sample; (−)-naringenin, 1.7 mg/g sample. These results suggest that twig extracts can be more useful for skin-whitening compared with other parts of the plant. In addition, a new constituent of twig extract was identified, namely isoquercitrin, which suggests that twig extract can be a potent source of flavones and flavanones. Further studies on the identification of novel compounds from twig extract are now underway in our laboratory.