Analgesic and Anti-inflammatory Effects of Ethanol Extract from Arenga pinnata in Mice/Rats / 中国药房

ABSTRACT

OBJECTIVE： To investigate the analgesic and anti-inflammatory effects of ethanol extract from Arenga pinnata in mice/rats after intragastric administration. METHODS： The mice were randomly divided into A. pinnata ethanol extract group  and solvent control group （distilled water）， with 20 mice in each group. Maximal dosage method was used to observe the acute toxicity of ethanol extract from A. pinnata with intragastric administration. The mice were randomly divided into A. pinnata ethanol extract high-dose， medium-dose and low-dose groups [6.5， 3.25， 1.625 g/kg （by ethanol extract， similarly here in after）， i.g.]， positive control group （0.005 g/kg morphine， i.p.） and blank control group （distilled water， i.g.）. The analgesic effect was evaluated by hot plate method， and the licking latency was compared 30， 60 and 90 minutes after administration. The mice were randomly divided into A. pinnata ethanol extract high-dose， medium-dose and low-dose groups （6.5， 3.25， 1.625 g/kg， i.g.）， positive control group （loxoprofen sodium 0.023 g/kg， i.g.） and model control group （distilled water， i.g.）. The analgesic effect was evaluated by acetic acid writhing method. The writhing times within 20 minutes were compared and the writhing inhibition rate was calculated. The mice were randomly divided into A. pinnata ethanol extract high-dose， medium-dose and low-dose groups （6.5， 3.25， 1.625 g/kg， i.g.）， positive control group （morphine 0.005 g/kg， i.p.）， model control group （distilled water， i.g.）. The analgesic effect was evaluated by formalin-induced pain method. The total licking time was compared between 0-5 min and 10-40 min after formalin administration； the inhibition rate of licking was calculated. The mice were grouped according to acetic acid writhing test. The mice were given relevant medicine once a day for consecutive 3 days. The mice were given xylene to induce inflammation model， and the degree of ear swelling was compared. Rats were randomly divided into A. pinnata ethanol extract high-dose， medium-dose and low-dose groups （4.5， 2.25， 1.125 g/kg， i.g.）， positive control group （losoprofen sodium 0.016 g/kg， i.g.）， model control group （distilled water， i.g.） and blank control group （distilled water， i.g.）， once a day， for consecutive 3 days. The rats were given Freund’s complete adjuvant to induce inflammation model and then given relevant medicine for consecutive 7 d. The degree of paw swelling was compared before inflammation and within 7 days after inflammation. The number of mice/rats in each group was 8 to 14 in the analgesic and anti-inflammatory tests. RESULTS： Compared with solvent control group， the body weight of mice had no significant increase in A. pinnata ethanol extract group； no drug-induced toxicity was found. Compared with blank control group， licking latency in mice was significantly prolonged in A. pinnata ethanol extract high-dose group 30 and 60 minutes after medication （P＜0.01）. Compared with model control group， the times of writhing， total licking time and the degree of ear swelling of mice were decreased significantly in A. pinnata ethanol extract high-dose， medium-dose and low-dose groups （P＜0.05 or P＜0.01）. Compared with model control group， the degree of paw swelling began decrease significantly in A. pinnata ethanol extract high-dose group 4 h after inducing inflammation， and the effect lacted until the 7th day （P＜0.01）. CONCLUSIONS： A. pinnata ethanol extract has no significant acute oral toxicity， and possesses significant analgesic and anti-inflammatory effects.