Analgesic Effects of Vigna unguiculata subsepecies dekindtiana in Mice

Abstract

In the present study, we investigated the antinociceptive effects of the plant Vigna unguiculata spp dekindtiana using chemical and thermal tests in mice. The peripheral and the central analgesic activities of the methanol extract and its fractions were investigated in-vivo in albino mice using acetic acid induced-writhing test and hot plate models respectively. The result of the central analgesic effect showed that the methanol extract (VUME) at 400 mg/kg produced a significant (p<0.05) delay in reaction time in mice on hot plate compared to the control. Various fractions of the extract showed more potency compared to the crude extract. In acetic writhing model, the extract and the fractions demonstrated dose dependent reduction in writhing reaction induced by acetic acid in mice. The reduction was significant when compared to control which was suggestive of the analgesic effect of the plant. It was also seen that the extract and fractions showed an improved analgesic effect compared to diclofenac used as positive control in this model. Yohimbine (alpha adrenergic receptor antagonist) and cyproheptadine (serotonergic receptor antagonist) reversed the antinociceptic effect of the fractions in the hot plate model demonstrating the possibility of adrenergic and serotonergic involvement in eliciting the analgesic effect. Naloxone on the other hand, caused a reversal only in the butanol fraction meaning that this fraction may contain active principles that may mediate their analgesic effect through the opioid mechanism. In the writhing test, yohimbine abolished the analgesic effect of both hexane and butanol fractions. This may therefore, suggest that the analgesic effect of these fractions may be mediated through adrenergic pathway. In conclusion, the plant V. unguiculata subspecies dekindtiana possesses active principles with potential analgesic activity, establishing the folkloric use of the plant in managing pain.