In vivo Assessment of the Antinociceptive Activity of Ethanol Bark Extract of Thevetia peruviana (Family: Apocynaceae) in Swiss Albino Mice

Background: Thevetia peruviana, a common plant of Apocynaceae family has been used as Ayurvedic herbal medicine to treat hemorrhoids, hair loss, arthritis, and dysentery. The bark and leaf decoction has been used to loosen the bowels, as an emetic, and is said to be an effective curative agent for intermittent fevers. Aim of the study: The present study was an attempt to investigate the phytochemical constituents and to explore the antinociceptive activity of ethanol extract of the bark of Thevetia peruviana which is growing in Bangladesh. Methodology: The antinociceptive activity of ethanol extract of T. peruviana was evaluated by heat-induced (hot plate, tail immersion test) and chemical-induced (acetic acid induced writhing, formalin-induced nociception) pain models using Swiss albino mice as experimental animal. Results: The results of preliminary phytochemical screenings revealed that the extract contained alkaloids, tannins, terpenoids and flavonoids. For acetic acid-induced writhing test, the sample showed highest inhibition of writhing (40.04%) at the dose of 400 mg/kg body weight, whereas standard drug (Diclofenac sodium) showed 65.6% writhing inhibition. In formalin-induced nociception, extract of T. peruviana exhibited dose-dependent antinociceptive activity. On the other hand, ethanol extract of T. peruviana bark showed significant effect (p<0.05) in hot plate and tail immersion test in various phases. Conclusion: The ethanol extract of T. peruviana bark showed significant antinociceptive activity via multifactorial mechanism of action, indicating that the extract may be useful in the development of new analgesic drugs.