Anti-inflammatory, anti-nociceptive, and anti-psychiatric effects by the rhizomes of Alpinia officinarum on complete Freund's adjuvant-induced arthritis in rats

Abstract

Ethnopharmacological relevance Alpinia officinarum Hance (Zingiberaceae) is an annual plant. Its rhizome has long been used as an anti-inflammatory, an analgesic, a stomachic and a carminative in traditional medicine. Objective The aim of this study was to test the anti-inflammatory effects of Alpinia officinarum rhizomes on acute and chronic arthritis in SD rats. Methods Alpinia officinarum rhizomes were extracted by refluxing using 80% ethanol. The fractions were prepared by the fractionation of ethyl acetate (EtOAc), n-butanol, and water. This extract was administrated to rats by peroral injection. Acute arthritis was induced by a subcutaneous injection of carrageenan into the hind paw of SD rats. Chronic arthritis was stimulated by a subcutaneous injection of complete Freund's adjuvant (CFA) into the hind paw of SD rats. The paw volume was measured using a plethysmometer, thermal hyperalgesia was tested using a thermal plantar tester, hyperalgesia was evaluated by ankle flexion evoked vocalizations, and the expression of c-Fos in the brain hippocampus was measured with the avidin–biotin-peroxidase technique. Nitric oxide (NO) production was evaluated on nitrite by a Griess assay in lipopolysaccharide (LPS)-induced murine macrophage RAW 264.7 cells. Results An 80% ethanolic extract showed acute anti-inflammatory activity that it reduced the edema volume in carrageenan-stimulated arthritis and inhibited NO generation in LPS-induced RAW 264.7 cells. In addition, this extract showed chronic anti-rheumatic and analgesic activities by suppressing the swelling volume, by recovering the paw withdrawal latency, and by inhibiting the flexion scores in CFA-induced arthritis. Particularly, this medicine had potent meaningful effects on the second signal of the left hind paw in the form of an immunological reaction compared to its effects on the first signal in the right hind paw after the CFA treatment. This also shows an anti-psychiatric effect through control of the expression of the c-Fos protein of the brain hippocampus in CFA-stimulated arthritis. On the other hand, each fraction showed acute anti-inflammatory effects; the action of the EtOAc fraction may have resulted from the suppression of NO production. Conclusions Alpinia officinarum rhizomes may be viable therapeutic or preventive candidates for the treatment of acute and chronic arthritis.