Comparative Study of Anti-nociceptive Activity and Phenolic Content of the Ethanol Extracts of Piper nigrum and Piper longum Fruits

Abstract

The research was carried out for investigation of anti-nociceptive properties, and phenolic compound determination by HPLC-DAD method of the ethanol extracts of P. nigrum of two varieties (black and white pepper) and P. longum of two different biomes (local and foreign). The anti-nociceptive activity of the extracts was studied at different doses (250, 500 mg/kg body weight) using acetic acid induced writhing in mice and the phenolic compounds were analyzed by reverse phase HPLC method. For the evaluation of anti-nociceptive activity, the white pepper extract showed significant inhibitory effect (P<0.001) in comparison to the other extracts. At the dose 500 mg/kg body weight, the white pepper extract showed a significant anti-nociceptive activity in acetic acid induced writhing in mice showing 40.15% inhibition comparable to that produced by the standard drug, Diclofenac Na (49.25%). The HPLC results showed that black pepper extract contained a significant amount of catechin (114.68 mg per 100 g of dry weight) compared to white pepper and long pepper (local and foreign) (14.92, 8.51, and 26.87 mg per 100 g of dry extract, respectively). In addition, p- coumaric acid, rutin hydrate, and kaempferol were also determined in the extracts (black pepper-2.03, 6.82, 11.33 mg; white pepper-3.73, 12.63, 12.07 mg; long pepper local-2.17, 3.97, 14.04 mg; long pepper foreign-2.38, 5.36, 21.84 mg, respectively) in all the extracts. Therefore, the results tend to suggest that all the extracts of P. nigrum and P. longum exhibited anti-nociceptive properties and have polyphenolic compounds that might be responsible for this in vivo biological activity and justify its wide use in folkloric remedies.