Harnessing two-dimensional magnetic Poly(deep eutectic solvents) for matrix solid-phase dispersion extraction of polyphenols from roselle: Promoting antiphotoaging strategy

The calyxes of roselle are rich in polyphenols and have excellent antioxidant capacities. However, because polyphenols are unstable, it is challenging to develop a method to efficiently obtain and maintain the activity of polyphenols from roselle. Herein, a method for preparing polyphenol extract from roselle is developed. A two-dimensional (2D) magnetic Poly(deep eutectic solvents) (PDES) based on magnetic graphene oxide is prepared as an adsorbent for extracting polyphenols from roselle, and roselle polyphenol extract is efficiently prepared by matrix solid-phase dispersion method. Under the conditions of sample/dispersant ratio of 1:4, grinding time of 3 min, and ultrasonic elution of 60 % ethanol for 5 min, the polyphenol content extracted from roselle is 30.362 ± 1.224 mg/g. Density functional theory calculations show that the 2D-MPDES can efficiently adsorb polyphenols via π–π stacking owing to the numerous benzene ring structures on its surface. Ultra-performance liquid chromatography quadrupole time-of-flight mass spectroscopy shows that the active substance prepared using the 2D-MPDES contains 39 compounds. Finally, the antioxidant capacity and antiphotoaging potential of the roselle polyphenol extract prepared using the 2D-MPDES are investigated. Results show that the roselle polyphenol extract prepared using the 2D-MPDES exhibits good antioxidant capacity and can be used to treat photoaging of HaCaT cells from ultraviolet-B-induced. Our results show that the 2D-MPDES can be used to prepare active substances in roselle–roselle polyphenol extract, which provides a research idea for preparing polyphenol components from natural products. In addition, the successful application of DES helps to maintain the stability of the material and improve its reuse rate, which has a broad application prospect in industrial production.