Inhibitory effect on nitric oxide production and free radical scavenging activity of Thai medicinal plants in osteoarthritic knee treatment.

BACKGROUND: Thai medicine plants used for Osteoarthritis of knee (OA) treatment consist of twelve plants such as Crinumn asiaticum, Cleome viscosa, Drypetes roxburghii, Piper longum, Piper nigrum, Plumbago indica, Alpinia galanga, Curcuma aromatica, Globba malaccensis, Zingiber montanum, Zingiber officinale andZingiberzerumbet. They showedhighfrequency in OA formula. OBJECTIVE: To investigate inhibitory effect on LPS-induced nitric oxide (NO) release from RAW264. 7 cell and free radical scavenging activity usingDPPH assay of these ethanolic plant extracts. MATERIAL AND METHOD: Plant materials were extracted by maceration in 95% ethanol. Anti-inflammatory activity were tested on LPS-induced NO production. Free radical scavenging activity was performed by DPPH assay. RESULTS: All of ethanolic extracts exhibited potent inhibitory effect on NO release. The ethanolic extract of Z. zerumbet exhibited the highest inhibitory effect followed by Z. montanum and G. malaccensis, respectively. Except A. galanga and C. viscosa, all extracts possessed more influential than indomethacin (IC50 = 20.32±3.23 μLg/ml), a positive control. The investigation on antioxidant activity suggested that the ethanolic extracts of D. roxburghii, Z. officinale, Z. montanum, C. aromatic, A. galanga, P indica, G malaccensis, P nigrum exhibited antioxidant activity. By means ofD. roxburghii had the highest electron donating activity,followed by Z. officinale. Moreover both extracts were more effective than BHT apositive control (EC50 = 14.04±1.95 μg/ml). CONCLUSION: Thai medicinal plants had anti-inflammatory activity and could inhibit destruction of articular cartilage that corresponded to the traditional medicine and supported using these medicinal plants for OA treatment.