Anti-inflammatory and anti-ulcerogenic effect of ethanol extract of coconut ( Cocos nucifera ) on experimental rats

摘要

The effect of the ethanol extract of coconut on egg albumin- induced inflammation in rat hind paw, hypotonicity induced haemolysis of human red blood cells and indomethacin – induced gastric ulcer in Wistar rats, was studied. Fifty adult rats of either sex of weight 120-200g were divided into ten experimental groups of five rats each; five groups were used for the inflammation test, while the other five groups were used for ulcer test. Inflammation was induced by injecting 0.1ml undiluted fresh egg albumin (philogistic agent) into the subplantar surface of the right hind paw of the rats. Ethanol extract of coconut with doses of 100, 200 and 400mg/kg, and indomethacin (100mg/kg) were administered intraperitoneally to separate groups of the rats one hour before inducing inflammation. The control group received equivalent volume of normal saline (vehicle). Ulcer was induced in the rats by the administration of indomethacin (50mg/kg) (p.o.) using standard procedures. Coconut extract with doses of 100, 200 and 400mg/kg, and ranitidine (100mg/kg) were administered orally to separate groups of the rats thirty minutes before inducing ulcer. The control group received equivalent volume of normal saline (vehicle). The percentage ulcer inhibition was taken as the measure of the protection against ulcer offered by the coconut extract. The effect of the coconut extract on haemolysis induced by distilled water was evaluated by incubating various concentrations of the extract with red blood cells and distilled water. The effect of the standard antiinflammatory drug, indomethacin was determined as a positive control. Changes in absorbance were used to assess the extent of haemolysis, hence membrane stabilization. From the results obtained, rats treated with 100 and 200mg/kg of the extract showed significant reduction of oedema at the later phase of inflammation and also reduced the ulcer induced by indomethacin, with 100mg/kg and 200mg/kg doses having an ulcer inhibition of 65.4% and 67.9% respectively; 400mg/kg of the extract increased the paw oedema of the animals and also evinced an increase in ulceration when compared to control. The coconut extract gave a dose dependent reduction in the haemolysis induced by distilled water. This suggests that the extract at low doses has potential anti-inflammatory and anti-ulcerogenic effect. Key words: Coconut extract, ulcer, inflammation, haemolysis