Evaluation of antinociceptive, in-vivo & in-vitro anti-inflammatory activity of ethanolic extract of Curcuma zedoaria rhizome

BACKGROUND The present study was aimed to investigate the antinociceptive and anti-inflammatory activity of the Curcuma zedoaria (family Zingiberaceae) ethanolic rhizome extract in laboratory using both in vitro and in vivo methods so as to justify its traditional use in the above mentioned pathological conditions. METHODS Phytochemical screening was done to find the presence of various secondary metabolites of the plant. In vivo antinociceptive activity was performed employing the hot plate method, acidic acid induced writhing test and formalin induced writhing test on Swiss albino mice at doses of 250 and 500 mg/kg body weight. Anti-inflammatory activity test was done on Long Evans rats at two different doses (250 and 500 mg/kg body weight) by using carrageenan induced paw edema test. Finally in vitro anti-inflammatory test by protein-denaturation method was followed. Data were analyzed by one-way analysis of variance (ANOVA) and Dunnett's t-test was used as the test of significance. P value <0.05 was considered as the minimum level of significance. RESULTS Phytochemical screening revealed presence of tannins, saponins, flavonoids, gums & carbohydrates, steroids, alkaloids, reducing sugars and terpenoids in the extract. In the hot plate method, the extract increased the reaction time of heat sensation significantly to 61.99% and 78.22% at the doses of 250 and 500 mg/kg BW respectively. In acetic acid induced writhing test, the percent inhibition of writhing response by the extract was 48.28% and 54.02% at 250 and 500 mg/kg doses respectively (p < 0.001). The extract also significantly inhibited the licking response in both the early phase (64.49%, p < 0.01) and the late phase (62.37%, p < 0.01) in formalin induced writhing test. The extract significantly (p < 0.05, p < 0.01 and p < 0.001) inhibited carrageenan induced inflammatory response in rats in a dose related manner. In in-vitro anti-inflammatory test, the extract significantly inhibited protein denaturation of 77.15, 64.43, 53.04, 36.78 and 23.70% for doses of 500, 400, 300, 200 and 100 μg/mL respectively. CONCLUSIONS The results obtained from the tests indicate that the plant might have one or more secondary metabolite(s) having central and peripheral analgesic and anti-inflammatory activity.