Novel paeonol-matrine deep eutectic solvent: Physicochemical properties and cytotoxicity

Deep eutectic solvent (DES), as a new type of green solvent, showed great advantages of easy preparation and no need of purification after synthesis and has been widely investigated in various fields. Paeonol has been shown great potential applications due to its anti-inflammatory, antioxidant, and antibacterial functions. In this work, we designed a new DES based on paeonol and matrine with a series molar ratio of 3:7, 4:6, and 5:5. The interactions between matrine and paeonol were checked and verified by 1HNMR and FT-IR spectra. Thereafter, the physicochemical properties of DESs were investigated by various techniques in a temperature range from 303.15 K to 343.15 K. It has been shown that the viscosity, surface tension, and refractive index decline with the increasing temperature. DESs showed relatively lower inhibitory activity on tyrosinase as compared with the paeonol at the same concentration as that in DES. Moreover, DESs displayed lower cytotoxicity than that of paeonol. Therefore, this work provided fundamental information for the application of these DESs, which may be considered as potential candidates for transdermal delivery of paeonol.