Preliminary study of total flavonoids from Litsea coreana Levl. on experimental adjuvant-induced arthritis in rats

Litsea coreana Levl., a traditional Chinese medicine, has long been used for its diverse benefits such as detoxification and detumescence. Total flavonoids from Litsea coreana Levl. (TFLC) are the effective fraction of L. coreana. This study was designed to investigate the anti-inflammatory effects and mechanisms of TFLC against Feund's complete adjuvant (FCA)-induced arthritis in rats. Arthritis was evaluated by secondary paw swelling, polyarthritis index, body weight and histopathologic analysis. Con A- or LPS-stimulated splenocyte proliferation and cytokine (IL-1 and IL-2) production were assessed by MTT assay and activated mouse cell proliferation assay, respectively. The results indicate that therapeutic administration of TFLC (50, 100, 200 mg/kg, ig x 12 days) could significantly suppress secondary arthritis in rats with adjuvant-induced arthritis (AA). In vivo, TFLC (50, 100, 200 mg/kg, ig x 12 days) augmented splenocyte proliferation and increased IL-2 production in splenocytes, while reduced IL-1 activity in peritoneal macrophages (PM(Phi)) of AA rats. In vitro, TFLC at concentrations from 0.005 to 50 microg/ml exerted the same immunoregulatory effects on AA rats as those in vivo. In addition, an attractive feature of TFLC lies in its apparent lack of toxicity. These results suggest that TFLC without toxicity has a significant anti-arthritic effect on AA rats which could be associated with its anti-inflammatory and immunomodulatory properties.