The plant Tapinanthus globiferus has gained ethnomedicinal values to manage pain, rheumatism and cancer. The current experiment investigated the anti-nociceptive action of the ethanol extract of the plant T. globiferus (EETG) and its possible mechanisms of action. Phytochemical studies and oral median lethal dose (LD50) determination were conducted as per standard experimental protocols. The anti-nociceptive properties of the EETG (250, 500 and 1,000 mg/kg) were checked against acetic acid-elicited writhing, hot plate and formalin-produced pain models in mice. To establish the potential pathways of analgesic effects of the EETG, the animals were pre-administered with naloxone (2 mg/kg, i.p), prazosin (1 mg/kg, i.p), yohimbine (1 mg/kg, i.p), propranolol (20 mg/kg, i.p), metergoline (2 mg/kg, i.p), and glibenclamide (5 mg/kg, i.p) 30 min before the EETG (500 mg/kg) administration. The phytochemical results revealed flavonoids, cardiac glycosides, phenols, steroids, saponins, tannins and triterpenes. The oral LD50 was above 5,000 mg/kg in mice. The EETG effectively (P < 0.001) reduced the acetic acid-produced writhes independent of dose. Besides, it significantly (P < 0.05, P < 0.01 and P < 0.001) increased the pain latency in the thermally induced pain at 30, 60, and 120 min. The EETG at 500 mg/kg efficiently (P < 0.05) declined the second stage of formalin-caused pain response in comparison to the control animals. The pre-administration of the naloxone, prazosin and metergoline to the mice reversed the anti-nociceptive effect elicited by the EETG in the formalin-produced pain in the second stage. The experimental outcomes have revealed that the plant Tapinanthus globiferus possesses analgesic activity which could be related to the opioidergic, α1-adrenergic and serotonergic pathways.
