Buddleja officinalis as a natural xanthine oxidase inhibitor in a murine hyperuricemia model

Buddleja officinalis Maxim. is rich in flavonoids and polyphenols, which exhibits pronounced antioxidant activity. Given that B. asiatica, a related species, has been noted to inhibit xanthine oxidase (XO) in vitro, the urate-lowering effects of B. officinalis have not been confirmed. Thus, this study aimed to screen the XO inhibition of extracts in vitro and to confirm the most active urate-lowering fraction of B. officinalis in vivo. Ethanol extracts were partitioned into n-hexane (HEX), ethyl acetate (EA), n-butanol (BuOH), and aqueous fractions. The EA fraction of B. officinalis extracts exhibited the highest XO inhibitory activity, with it significantly surpassing that of the other fractions (P<0.05). Consequently, the EA fraction was selected for further in vivo evaluation in a mouse model of hyperuricemia, which was induced through intraperitoneal injection of potassium oxonate (PO, 250 mg/kg/day for 7 days). Mice were divided into six groups, including not treated, PO, PO + allopurinol, and low (PO + EA-L), medium (PO + EA-M), and high (PO + EA-H) EA dose groups. EA fractions of B. officinalis extracts were orally administered 1 hr after PO injection. Compared with in the PO group, the serum uric acid levels were significantly reduced in the PO + EA-M, PO + EA-H, and PO + allopurinol groups (P<0.05). These findings support the potential of B. officinalis as a natural XO inhibitor and an adjunctive supplement for hyperuricemia.