Enhancement of the Antioxidant, Anti-Tyrosinase, and Anti-Hyaluronidase Activity of Morus alba L. Leaf Extract by Pulsed Electric Field Extraction.

In this study we aimed to compare the chemical composition and biological activity between Morus alba L. leaf extract obtained with 95% v/v ethanol using a pulsed electric field (PEF) and the conventional maceration method. Extracts of M. alba leaves collected from Chiang Mai (CM), Sakon Nakon (SK), and Buriram (BR), Thailand, were investigated for 1-deoxynojirimycin content by high-performance liquid chromatography and for total phenolic content by the Folin-Ciocalteu method. Antioxidant activity was investigated by 2,2'-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azinobis-3-ethylbenzothiazoline-6-sulphonate (ABTS), and ferric reducing antioxidant power (FRAP) assay. Anti-tyrosinase and anti-hyaluronidase activity was investigated by in vitro spectrophotometry. The results show that this is the first study to indicate PEF as a novel method for enhancing the phenolic content and antioxidant, anti-tyrosinase, and anti-hyaluronidase activity of M. alba leaf extract (P < 0.05). PEF extract of M. alba leaves collected from BR had comparable ABTS^•+ scavenging activity to l-ascorbic acid and comparable anti-tyrosinase activity to kojic acid (P > 0.05). On the other hand, PEF extract of M. alba leaves collected from SK exhibited significantly high anti-hyaluronidase activity, comparable to that of oleanolic acid (P > 0.05). Therefore, PEF is suggested for further M. alba leaf extraction in the production of natural whitening and anti-aging cosmetic ingredients.