Evaluation of the analgesic effect of Umbelliprenin and Umbelliprenin-morphine co-administration on the acute, chronic and neuropathic pain

Background and purpose: Neuropathic Pain (NP) is a complex and chronic pain which is accompanied by nerve injury. Umbelliprenin (UMB) is a naturally occurring prenylatedcoumarin with anticancer, antioxidant, anti-inflammatory, antibacterial and antileishmanial activities. This study aimed to investigate the antinociceptive effects of UMB on acute, chronic and neuropathic pain and its combination therapy with morphine on the neuropathic pain. Methods: Albino mice weighing 20-25 g were randomly divided into 13 groups (n=7), subjected to hot plate with groups including morphine 1 mg+UMB (0.01 μM/kg), morphine (1 mg/kg, i.p.), UMB (0.01 mM/kg), Imipramin 40 mg/kg and NS (normal saline) (0.9%) as vehicle), formalin test with groups including (NS, Imipramine (40 mg/kg, i.p.), morphine (9 mg/kg, i.p.) and UMB (0.01 μM/kg)) and morphine tests with groups including (NS (0.9%), imipramine (40 mg/kg, i.p.), morphine (1 mg/kg, i.p.)+UMB (0.01 mM/kg) and morphine (1 mg/kg, i.p.).The acute and neuropathic pain were evaluated using hot-plate and formalin and morphine tests. Results: Administration of UMB single dose (0.01 mM) reduced NP significantly (p<0.05) compared to the negative control and didn’t change acute pain against Diclofenac. Antinociceptive effects of UMB were comparable to Imipramine as a standard positive control. UMB potentiated morphine 1 mg/kg response on NP. Conclusion: This research indicates that UMB alone reduces NP and its combination with morphine potentiates morphine effects. Therefore, UMB-morphine co-administration is proposed to be used instead of conventional treatment.