ANTI-INFLAMMATORY EFFECTS OF THE BARK OF PHELLODENDRON AMURENSE RUPR. IN EXPERIMENTAL MODELS

The objective of this study was to investigate the anti-inflammatory properties of n-hexane, ethyl acetate (EtOAc), dichloromethane (CH2Cl2), and aqueous extracts of Phellodendron amurense. The activity was evaluated in vitro by nitric oxide (NO) and prostaglandin E2 (PGE2) inhibition assays, and in vivo using carrageenan-induced paw edema and lipopolysaccharide (LPS)-induced endotoxemia models in rats. In vitro anti-inflammatory activity was assessed by measuring the inhibition of NO and PGE2 production using RAW 264.7 macrophage cells. Among the tested extracts, the CH2Cl2 extract exhibited the most potent activity, with IC50 values of 10.88 ± 2.88 µg/mL for NO inhibition and 10.82 ± 1.22 µg/mL for PGE2 inhibition, followed by the aqueous extract, which also inhibited NO and PGE2 production without causing cytotoxicity. The CH2Cl2 extract of P. amurense (CPA) was orally administered to rats in both LPS-induced endotoxemia and carrageenan-induced hind paw edema models. In the endotoxemia model, CPA significantly improved survival and markedly reduced serum IL-6 and IL-1β levels, as well as white blood cell counts. Consistently, in the carrageenan-induced paw edema model, CPA significantly suppressed edema formation, reducing paw-volume increase by 36%, 48%, and 55% at 2, 3, and 4 h, respectively, compared with the carrageenan control group (p < 0.05).