Protective effects of Cyclocarya paliurus on hyperuricemia and urate-induced inflammation

As a new and safe food resource, Cyclocarya paliurus (CP), rich in flavonoids, exhibits hypouricemic, anti-inflammatory and antioxidative properties. However, whether CP aqueous extract (CPA) still possesses the ameliorative effects on hyperuricemia (HUA) and urate-induced renal inflammation remains vacant. In HUA mice, CPA could significantly reduce serum uric acid (UA), alleviate kidney damage and liver steatosis, inhibit xanthine oxidase (XOD) activity, ameliorate renal urate transporters and renal inflammation by inhibiting NLRP3 inflammasome and interleukin-1β (IL-1β). Moreover, the flavonoids quercetin-3-O-β-D-galactopyranoside, quercetin-3-O-β-D-glucopyranoside, and quercetin-3-O-α-L-rhamnopyranoside from CPA could significantly reduce IL-1β and interleukin-6 (IL-6) in MSU-challenged THP-1 cells. Noticeably, quercetin-3-O-β-D-galactopyranoside could inhibit the intracellular XOD activity, reduce intracellular ROS and the expression of pro-IL-1β, IL-1β, and NLRP3 inflammasome. Collectively, CPA shows appreciable therapeutic effects on HUA and evoked renal inflammation. Quercetin-3-O-β-D-galactopyranoside, quercetin-3-O-β-D-glucopyranoside, and quercetin-3-O-α-L-rhamnopyranoside might be the major active compounds of CPA, which obtain the favorable effects through blocking the activation of ROS/NLRP3/IL-1β pathway.