Effects of Different Extraction Methods on Biological Activities of Pearl Powder Extracts

Pearl powder has been used in medicine and beauty treatment since ancient times in China. However, it is still unclear whether the biological activities of pearl powder are affected by different extraction methods or not. In this study, we determine the total protein yield, protein molecular weight and biological activities including antioxidant, tyrosinase inhibition and melanogenesis inhibition activities and cytotoxicity of different pearl powder extracts prepared by five different preparation methods. The ultrasonic-assisted extraction (UAE) and microwave-assisted extraction (MAE) of pearl powder were optimized by the response surface method based on total protein yield. Compared with solid-liquid extraction (SLE), the optimized UAE and MAE increased the total protein yield without changing protein molecular weight. In addition, the extract by MAE enhanced the tyrosinase inhibition activity and anti-melanogenesis activity slightly. Acidolysis hydrolyzes macromolecular protein into small molecules with obvious cytotoxicity and low activities. Enzymolysis can hydrolyze macromolecular protein into small molecules with high protein yield and improvement of bioactivities. In the determination of the antioxidant assay, the extract prepared by the enzymolysis showed significant activity. These results suggest that protein molecules of the pearl powder extract are degraded appropriately by enzymolysis to smaller molecules to obtain the enhanced biological activities that can be applied in the cosmetic industry.