Characterization and Anti-Ultraviolet Radiation Activity of Proanthocyanidin-Rich Extracts from by Ultrasonic-Assisted Method.

The ultrasonic-assisted extraction (UAE) method was employed to separate proanthocyanidin-rich extracts (PCEs). This extraction process was optimized by the Box-Behnken design, and the optimal conditions, on a laboratory scale, were as follows: an ethanol concentration of 75%, a liquid-to-solid ratio of 24 mL/g, an ultrasonic time of 39 min, and an ultrasonic power of 540 W. Under the obtained conditions, the PCE yield extracted by UAE was higher than that from heat reflux extraction and soaking extraction. An ultra-performance liquid chromatography-tandem mass spectrometry analysis was employed to characterize the phloroglucinolysis products of the PCEs, by which epigallocatechin, catechin, epicatechin, and (-)-epigallocatechin-3--gallate were identified as the terminal units; epigallocatechin, epicatechin, and (-)-epigallocatechin-3--gallate were recognized as extension units. The PCEs possessed higher anti-ultraviolet activity in vitro compared with the commercially available sunscreen additive of benzophenone with respect to their ethanol solutions (sun protection factor of 27.01 ± 0.68 versus 1.96 ± 0.07 at a concentration of 0.09 mg/mL) and sunscreens (sun protection factor of 17.36 ± 0.62 versus 14.55 ± 0.47 at a concentration of 20%). These results demonstrate that PCEs possess an excellent ultraviolet-protection ability and are promising green sunscreen additives that can replace commercial additives.