Activity study of a hydroxynaphthoquinone fraction from Arnebia euchroma in experimental arthritis

Although various drugs for the treatment of rheumatoid arthritis (RA) have been used in clinics, RA is not completely curable to date. Thus, to seek new drugs for the treatment of RA has been a hotspot. Hydroxynaphthoquinones are the major anti-inflammatory active constituents in Arnebia euchroma (Royle) Johnst. The present study aims to evaluate the anti-arthritic activity of a hydroxynaphthoquinone mixture (HM) of A. euchroma (Royle) Johnst, including its anti-inflammatory and analgesic effects. The anti-arthritic efficacy of HM was examined using complete Freund's adjuvant- and bovine type II collagen-induced arthritic models. The paw edema, polyarthritis index and histopathological change were evaluated. The analgesic effect was assessed using the chemical and thermal models of nociception. Results found that HM administered prophylactically and curatively showed marked anti-arthritic activity by suppressing the paw swelling and development of inflammation, lowering the levels of TNF-α and IL-1β and protecting cartilage and bone from damage. The protection of HM was superior to that of reference drugs such as prednisone acetate or etanercept, and showed no direct deleterious effect. Similarly, HM showed significant analgesic effects. In summary, HM possessed potent anti-arthritic activity. It could relieve inflammatory symptoms and protect against joint destruction. These findings indicate that HM would be a potential therapeutic agent for arthritic disease, which provide pharmacological evidence for its clinical application.