Ultrasound-Assisted Deep Eutectic Solvent Extraction of Flavonoids from Hovenia dulcis Thunb: Optimization,...

Hovenia dulcis Thunb. is a traditional medicinal and edible plant that is widely recognized for its hepatoprotective and hangover-alleviating properties, which are largely attributed to its rich flavonoid composition. The aim of this study was to develop an environmentally friendly ultrasonic-assisted deep eutectic solvent (UAE-DES) extraction method for the efficient extraction of bioactive flavonoids from Hovenia dulcis Thunb. A Box-Behnken design (BBD) was employed to systematically optimize the extraction parameters. Under optimal conditions (water content of 36%, liquid-to-solid ratio of 42:1 mL/g, extraction time of 42 min), the extraction yield reached a maximum of 9.09 ± 0.04%. Following purification using AB-8 macroporous resin, the phytochemicals were comprehensively characterized by UPLC-Q-Exactive Orbitrap-HRMS. A total of 12 flavonoids were identified. Bioassays demonstrated that the purified flavonoids exhibited strong, dose-dependent antioxidant activity against DPPH and ABTS radicals in vitro. Furthermore, the extract demonstrated significant anti-inflammatory activity by markedly inhibiting the excessive production of nitric oxide (NO) in RAW 264.7 macrophages induced by lipopolysaccharide (LPS), whilst exhibiting no cytotoxicity within the tested concentration range (0.06-0.96 mg/mL). These findings strongly confirm that the optimized UAE-DES method is a sustainable and efficient strategy for extracting structurally intact and pharmacologically active flavonoids from Hovenia dulcis Thunb, highlighting its immense potential for future applications in the functional food and pharmaceutical industries.