In the present study, we evaluated the anti-inflammatory effect of 4-methoxy-5- hydroxycanthin-6-one (CAN), a natural alkaloid isolated from Picrasma quassioides. CAN significantly inhibited the production of NO and the release of TNF-alpha induced by LPS in macrophage RAW 264.7. Western blot showed that CAN can downregulate the expression of iNOS protein. After oral administration, CAN (3, 9, and 27 mg/kg) reduced the development of carrageenan-induced paw edema and complete Freund's adjuvant (CFA)-induced chronic arthritis in rats. The observed results indicated that pre-treatment with CAN might be an effective therapeutic intervention against inflammatory diseases including chronic arthritis. (C) 2012 Elsevier GmbH. All rights reserved.