Improving the xanthine oxidase and adenosine deaminase inhibitory activities of Flos Sophorae Immaturus by ultrasound-assisted heating treatments

Flos Sophorae Immaturus (FSI) is consumed as a natural food rich in flavonoids and exhibits potential xanthine oxidase (XOD) and adenosine deaminase (ADA) inhibitory activities. Therefore, ultrasound and heating treatments were applied to improve the XOD and ADA inhibitory effects of FSI, and the mechanisms were revealed by tracking the changes of flavones. Results showed that ultrasound (480 W, 60 min) assisted heating treatments (180 °C, 60 min) significantly improved the XOD (from 40.97% to 83.47%) and ADA (6.64%–23.28%) inhibition rates. Meanwhile, ultrasound and heat treatment caused significant variations in total polyphenols and flavonoid contents and altered the flavonoid composition of FSI. Specifically, rutin, kaempferol–3–o–rutinoside, and narcissoside of FSI converted to quercetin, kaempferol, and isorhamnetin during heating treatments. However, the model experiment revealed that ultrasound treatment did not cause the conversion of flavones and just promoted the dissolution of FSI flavones. Furthermore, quercetin, kaempferol, and isorhamnetin possessed better XOD and ADA inhibitory activities than rutin, kaempferol–3–o–rutinoside, and narcissoside at a concentration from 0.025 mg/mL to 1.0 mg/mL, implying de-glycosylation is a feasible approach for enhancing XOD and ADA activity. The present study provides a promising strategy for the processing of FSI. [Display omitted] •UAHT caused the breakage of 3-o-rutinoside bond of FSI flavones.•Quercetin, isoquercitrin, kaempferol, and isorhamnetin were generated during UAHT.•The highest flavone conversion rate of FSI occurred at 180 °C.•Newly formed flavones possessed better enzyme activity inhibitory properties.•Ultrasound treatment exhibited a synergistic effect with heating treatment.