Pharmacological Evaluation of 25-MHA Underlying Anti-nociceptive Properties in Animals Models

Abstract

The 25-MHA obtained from Poncirus trifoliate have several traditional applications such as anti-allergic, anti-cancer, anti-platelet and against GIT ulcers. The 25-MHA is currently evaluated against the CFA, Carrageenan, formalin and acetic acid induced nociception. The 25-MHA was evaluated against the both acute and chronic CF-induced mechanical hyperalgesia, mechanical allodynia, and thermal hyperalgesia. The pre-treatment of 25-MHA significantly reduced the mechanical hyperalgesia, allodynia and thermal hyperalgesia in both acute and chronic doses. Similarly, the 25-MHA also exhibited remarkable inhibition on the Carrageenan-induced hyperalgesia compared to the negative control. Formalin-induced nociception is an acute inflammatory pain model and served as screening tool to investigate the anti-nociceptive activity of new drug. The 25-MHA treatment significantly reduced the formalin-induced biphasic nociceptive responses i.e. inflammatory and neurogenic. The intraperitoneal administration of acetic acid is associated with the production of writhing response characterized by the contraction of abdominal muscles and extension of hind limbs and serve as acute visceral pain model to screen the anti-nociceptive potential of new drug entity. The intraperitoneal administration of 25-MHA significantly inhibited the acetic acid induced writhing response when compared to the negative control. The inflammatory cytokines are associated with sensitization of nociceptors and reducing the pain threshold. During inflammatory process several inflammatory cytokines are released, however, the most important cytokines that are implicated in most painful conditions are IL-1β, IL-6, tumour necrosis factor-α (TNF-α) and growth factor like vascular endothelial growth factor (VEGF). The 25-MHA treatment significantly reduced the mRNA expression levels of these inflammatory cytokines compared to the treatment with negative control. Furthermore, the mRNA expression level of anti-oxidant enzyme were also assessed using Quantitative Real Time polymerase chain reaction (qRT-PCR). The most important anti-oxidant enzymes implicated in the various oxidative stress conditions are nuclear factor erythroid 2 (NFE2)-related factor 2 (Nrf2), Heme Oxygenase-1 (HO-1) and Sulphur oxide dismutase (SOD2). The mRNA expression levels of these anti-oxidant enzymes were significantly increased by the 25-MHA treatment when compared to the negative control. The Nitric oxide (NO) is an important mediators of inflammation and its level in significantly increased in many inflammatory conditions. The NO production was assessed in the plasma of animals in different treatment groups. The 25-MHA treated group significantly inhibited the NO production when compared to the negative control, thus, indicates the strong anti-inflammatory activity of 25-MHA. Many available analgesics like NSAIDs and opioids are associated with various intractable side effects such as GIT ulceration and addiction respectively. The 25-MHA was also assessed for any potential side effects against the liver, kidney damage and any toxic effect on the muscle strength and co-ordination. The 25-MHA treatment did not exhibited any side effect on the liver, kidney and muscle strength when compared to the negative control. The 25-MHA mechanism by which it produced analgesia was also studied in the current study.