Pain Alleviating Potential of Ethanol Extract of Vernonia amygdalina Del. on Writhing in Male Wistar Rats

Non-steroidal anti-inflammatory drugs and central analgesics are both effective pain relievers, but they have limitations and possible adverse effects. In African, Indian, and Chinese folkloric medicine, Vernonia amygdalina (VA) is known widely for its pharmacological benefits including antioxidant, antibacterial, and anti-cancer properties. The models, acetic acid-induced writhing, hot-plate latency, and tail-flick response, were utilized in this study for assessing the anti-inflammatory and analgesic potential of VA, alongside its toxicological study. The toxicology results showed no sign of toxicity, including mortality, salivation, diarrhea, or abnormal weight loss or gain. The serum AST and ALT were within the reference range (ALT:7-45 U/l; AST: 6-38 U/l). The analgesic effect of VA extract was highly demonstrated after 3 days of pretreatment at the two highest doses (400 and 800 mg/kg) in a dose-dependent manner. Despite being less effective than the larger doses, an analgesic effect was also observed at 200 mg/kg, which implies that VA may still have some analgesic effects at lower doses. The higher doses of VA were as effective and provided a prolonged analgesic effect that was comparable to the conventional medications (Diclofenac and Aspirin) used. The analgesic effect of VA has been suggested to be associated with its rich alkaloid constituent, which has been reported to exert an analgesic effect via mechanisms such as opioid receptor activation, neurotransmitter modulation, inhibition of pro-inflammatory cytokines, and ion channel modulation, among others. Hence, this study supports the utilization of VA as alternative therapeutic approach for the alleviation of pain and its symptoms.