Analgesic and anti-inflammatory effects of Portolaca oleracea extracts in mice and rat

ABSTRACT

Portolaca oleracea is a plant, which is used as vegetable in some parts of Iran and also is a well-known herbal medicine. Several effects such as smooth and skeletal muscle relaxant effect, cardiac muscle relaxant effect, analgesic and anti-inflammatory effect have been reported for this plant. This study was performed to investigate the analgesic and anti-inflammatory effects of the portolaca oleracea. Aerial parts of plant [stem and leaves] were collected and dried in shadow. The dried parts then were powdered and ethanolic and aqueous extracts were prepared by suxhelet. Analgesic effects were assessed by hot plate and tail flick tests at 0, 30, 60 and 90 minutes after treatment of animals. For each test sixty white mice with about 25- 30 g body weight were randomly divided into six groups. Groups A and B were received 200 and 400 mg/kg of aqueous extract respectively, groups B and C received 200 and 400 mg/kg of ethanolic extract respectively and groups E and F were received normal saline [as negative control] and morphine 9 mg/kg [as positive control]. To determine anti-inflammatory effect, 32 Wistar - Albino rats with 250- 300 g B.W were divided into 4 groups; experimental groups received 400 mg/kg B.W of aqueous and / or ethanolic extracts, and control groups were received 10 mg/kg B.W diclofenac sodium [positive control] or saline [negative control] one hour prior to caraggeenan injection to induce foot paw edema. Foot volume to a strict drawn line on leg when immersed in a 25 ml cylinder was measured before caraggeenan injection and 1and 3 hours after injection; the increase in swollen paw were determined for each rat. The results were determined and compared by an analysis of variances [ANOVA] for all groups and changes were compared by Tukey-Kramer test. The difference was considered to be significant when the P value was less than 0.05. Both aqueous and ethanolic extracts at 400 mg/kg B.W showed analgesic effects, which was significant as compared to that of negative control [P<0.001 for both tests]. The maximum effect was determined at 60 minutes after injection. The analgesic effects of both extracts at 60 minutes were equal to 60% of morphine [hot plat]. The differences between aqueous and ethanolic extracts were not significant. Both aqueous and athanolac extracts significantly decreased paw edema at 1 [P<0.01] and 3 [P<0.001] hours after caraggeenan injection in treated rats. The results of this study demonstrated that Portolaca oleracea at the dose of 400 mg/kg have a considerable analgesic and anti-inflammatory effects and thus may be used as oral or topical anti-inflammatory and analgesic products