Synergistic Analgesic Effects of Petroleum Ether Extract of Oxalis Corniculata with Tramadol and Pentazocine in Mice

Abstract

Introduction: Opioids are the drug of choice for acute and chronic painful conditions not responding to other pain killers. But evidence shows that a small proportion of patients with chronic pain do not get complete pain relief with opioids, thus necessitating the need for newer modalities of treatment. Oxalis corniculata is a herbal plant used for pain medication. Beta sitosterol present in Oxalis corniculata is responsible for the analgesic action. Beta sitosterol is extracted through petroleum ether to form petroleum ether extract of Oxalis corniculata using Soxhlet apparatus. Oxalis corniculata was found to be acting through opioid receptors. In this study, we aim to evaluate the synergistic analgesic effects of Petroleum ether extract of Oxalis corniculata (PEOC) with Tramadol and Pentazocine in mice.

Methods: This study was conducted in Albino mice (Swiss strain) in the animal house of our institute. Animals were divided into seven groups of six mice each (Total = 42). Drugs such as Tramadol, Pentazocine and PEOC were given at a dose of 50mg/kg i.p., 10 mg/kg i.p., 150 mg/kg p.o. respectively. Analgesic activity is evaluated using “Hot plate test”, “Tail immersion test”, “Tail flick test”, “Formalin induced paw licking test”, and “Acetic acid induced writhing test”.

Results: In Hot plate test at the end of 90 min, the reaction time was found to be increased in the Tramadol with extract (18.28+0.62) and the Pentazocine with extract (15.02+0.46 sec) than the other groups such as Tramadol, Pentazocine, PEOC, Olive oil and Distilled water group and was statistically significant. In tail immersion test, the tail withdrawal time was found to be better in the Tramadol with extract group (4.77+1.22 sec) and pentazocine with extract group (2.3+0.61 sec) compared to other groups. In Tail Flick test the tail flick latency was better in the Tramadol with extract group (10+0 sec) and Pentazocine with extract group (9.83+0.13 sec) compared to the control groups. In Formalin induced paw licking test, in both the phases (Phase I & II), the paw licking time was found to be reduced in the tramadol with extract group (44.83+15.67 sec & 16+4.78 sec) and pentazocine with extract group (66.33+7.57 sec & 44+8.61sec) compared to other groups. In acetic acid induced writhing test the number of writhing responses for a period of 30 minutes was found to be reduced in the tramadol with extract group (16.33+1.33), and pentazocine with extract group (22.17+3.04) compared to other groups.

Conclusion: Thus, from our study we conclude that Petroleum ether extract of Oxalis corniculata exhibits synergistic analgesic effect when given in combination with opioid analgesics such as tramadol and pentazocine in mice.