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

Abstract

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 antiinflammatory 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 proinflammatory 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.