Antinociceptive and hypnotic effects of Premna tomentosa L. (Verbenaceae) in experimental animals.

Medicinal plants are believed to be an important source of new chemical substances with potential therapeutic effects. The research into plants with alleged folklore use as pain relievers should therefore be viewed as a fruitful and logical research strategy in the search of new analgesic drugs. In the present inquiry, antinociceptive effects of Premna tomentosa (PT) leaf extract (in methanol) were explored in experimental animals by acetic acid-induced writhing, tail flick and tail clip tests. Oral administration of PT extract at different doses (100, 200, 400 and 500 mg/kg) led to significant antinociceptive effects. The extract was also tested for hypnotic effects. Treatment with extracts at different doses (100, 200, 400 and 500 mg/kg) decreased the locomotor activity and potentiated the pentobarbitone-induced sleep time. The responses were dose-dependent. On the basis of the present finding, we can conclude that PT possesses antinociceptive and hypnotic activities.