Evaluation of Analgesic and Anti-inflammatory Activities of Methanolic Leaf and Root Extracts of Gomphocarpus purpurascens A. Rich (Asclepiadaceae) in Mice.

Abstract

Regardless of the availability of drugs many people still experienced pain and inflammation because current medications often trigger potentially serious adverse effects. A range of medicinal plants with analgesic and anti-inflammatory properties have been widely used by traditional healers. Among them, Gomphocarpus purpurascens is one however there are no experimental studies that support this traditional use. This study aimed to evaluate the analgesic and anti-inflammatory activities of 80% methanolic leaf and root extracts of G. purpurascens. Air-dried leaves and roots of G. purpurascens were extracted with 80% methanol and an acute oral toxicity study was conducted for the 80% methanolic extract of G. purpurascens according to OECD guideline version eighteen. Preliminary phytochemical screening for the presence of different constituents was carried out. The hot plate method was used to evaluate centrally mediated analgesic activity while peripheral analgesic activity was tested by an acetic acid-induced writhing test. Carrageenan-induced paw edema test and formalin-induced pedal edema test were used to evaluate anti-inflammatory activity. Dose-dependent inhibition of acetic acid-induced writhing test was observed in mice by 100 mg/kg, 200 mg/kg, and 400 mg/kg of root extract with respective values of 16.6%, 68.9%, and 83%. In the hot plate method, the root extract at doses of 200mg/kg and 400 mg/kg showed a significant (p < 0.05) analgesic effect. Maximum anti-inflammatory effects by all doses of leaf extracts were observed from 2-4hr post-induction in carrageenan-induced paw edema; and all tested doses of the extract inhibited the formalin-induced inflammation significantly (p < 0.001, p < 0.01). The presence of saponins, alkaloids, flavonoids, tannins, terpenoids, anthraquinone, steroids, and phenols might be responsible for these activities. This study shows that the extract had potential analgesic and anti-inflammatory activity which supports the traditional claim.