Anti-infammatory, anti-nociceptive and antipyretic activity of young and old leaves of Vernonia amygdalina

Abstract

Background: Both young and old leaves of Vernonia amygdalina (VA) are traditionally used to treat inflammation, pain and fever. However, the efficacy of young and old leaves for treating these ailments has not been compared till date. Aim: To ascertain the efect of young and old leaves of VA in managing inflammation, pain and fever. Methods: Both quantitative and qualitative phytochemical screening of ethanol extracts of young (EthYL) and old (EthOL) leaves of VA were performed. The anti-infammatory activity of orally administered EthYL and EthOL (50–200 mg/kg) and Diclofenac (10 mg/kg) were evaluated in carrageenan-induced inflammation model in rats. Antipyretic activity of EthYL, EthOL and Aspirin (25 mg/kg) were assessed in the Baker’s yeast-induced pyrexia model. Anti-allodynic effect of both extracts was evaluated by inserting infamed paws of rats in cold water. Antinociceptive property of the extracts was assessed using tail withdrawal and formalin-induced nociception test. Histopathological examination of the paws was performed, in addition to formalin test to understand the possible mechanism of action of the extracts. Negative control rats received 2 ml/kg normal saline in all tests. Results: The amount of flavonoids, alkaloids, tannins, and phenolics were signifcantly (p < 0.05) higher in EthOL than EthYL, while saponins were signifcantly higher (p < 0.05) in EthYL than EthOL. The antioxidant ability and total antioxidant capacity were signifcantly (p < 0.05) higher in EthYL than EthOL. However, this was signifcantly (p < 0.05) lower than the anti-oxidant activity of Ascorbic acid. A dose-dependent increase in anti-infammatory, antipyretic and antinociceptive properties were observed in both EthYL and EthOL, similar to the standard drugs. Mast cell degranulation accompanied by vasodilatation and high leukocytosis were observed in the negative control, but were markedly low in extract treated groups. Both extracts mediated their analgesic effect through opioidergic and nitric oxide pathways with EthYL additionally implicating the muscarinic cholinergic system. Conclusion: Although both EthYL and EthOL alleviate infammation, pyrexia and nociception, EthYL of VA was found to be more potent than EthOL