Ultrahigh pressure enhances the extraction efficiency, antioxidant potential, and hypoglycemic activity of flavonoids from Chinese sea buckthorn leaves

Ultrahigh pressure extraction (UHPE) is an emerging non-thermal extraction technology, but whether this technology can be used for extracting flavonoids from sea buckthorn leaves remains unelucidated. This study optimized the processing conditions for flavonoid extraction from Chinese sea buckthorn leaves through UHPE and compared the results obtained with those of ultrasonic-assisted extraction (UAE) and conventional solvent extraction (CSE). The optimum parameters for UHPE were as follows: ethanol concentration, 50%; liquid-solid ratio, 41:1; pressure, 143 MPa; temperature, 44 degrees C; and holding time, 3 min. Compared with the UAE and CSE extracts the UHPE extracts had a higher content of total flavonoids and flavonol monomers, and the advantages of UPHE were primarily observed in the extraction of flavonoid monosaccharide chain glycosides and flavonoid aglycones. In total, 36 flavonoids were identified in the three extracts, with 33, 30, and 28 flavonoids identified in UHPE, UAE and CSE, respectively. Additionally, the UHPE extracts had a greater ferric reducing antioxidant power (FRAP), oxygen radical absorption capacity (ORAC), alpha-amylase inhibitory activity, and alpha-glucosidase inhibitory activity. In conclusion, the efficiency of UHPE to extract flavonoids from sea buckthorn leaves was significantly higher than those of UAE and CSE.