Antinociceptive activity of Amaranthus spinosus in experimental animals

Aim of the study: 50% ethanol extract (ASE) of Amaranthus spinosus (whole plant) has been evaluated for antinociceptive and antiinflammatory activities. Materials and methods: Analgesic and antiinflammatory activities were studied by measuring nociception by formalin, acetic acid, hot plate, tail immersion method while inflammation was induced by carrageenan. Results: ASE had significant dose dependent percentage protection against acetic acid (0.6% of 10 ml) induced pain and the effects were also compared to aspirin, morphine and naloxone while formalin induced pain (0.05 ml of 2.5%) was significantly blocked only at higher dose (400 mg/kg) in first phase. ASE significantly blocked pain emanating from inflammation at all the doses in second phase. The reaction time in hot plate was increased significantly and dose dependently where as pretreatment with naloxone rigorously reduced the analgesic potentials of ASE. Further in tail immersion test the same dose dependent and significant activity was observed. Aspirin had no effect on thermal induced pain i.e. hot plate and tail immersion tests but showed an effect on writhing test. Conclusions: Our investigation show that Amaranthus spinosus possess significant and dose dependant and inflammatory activity, it has also central and peripheral analgesic activity. (C) 2009 Elsevier Ireland Ltd. All rights reserved.