Sedative, Anticonvulsant and Analgesic activities of Fresh Leaf Essential Oil of Plectranthus aegyptiacus from Southwest Nigeria in Mice

Abstract

Background: The folkloric use of Plectranthus aegyptiacus (Forssk.) C. Chr. in the Southwest Nigeria includes; pain, sensory diseases, cough and fever. This study investigated the anxiolytic, sedative, anticonvulsant and analgesic activities of the essential oil of P. aegyptiacus in mice.

Methods: The oil was extracted by hydro-distillation. 5% Tween-80 (0.1 ml/10 g) was used as negative control and different standard drugs were used as positive controls depending on the model.  The effect of the oil (50, 100, 150 and 200 mg/kg, i.p., n=6) on anxiety, sedation, convulsion, and analgesic activities were assessed on elevated plus maze (EPM), ketamine-induced hypnosis (100 mg/kg, i.p.), pentylenetetrazole (PTZ) (85 mg/kg, i.p.), strychnine (2 mg/kg, i.p.), maximal electroshock (MES), acetic acid-induced(1% v/v)  writhings and the hot plate models respectively.

Results: The oil (50, 100 and150 mg/kg) significantly (p< 0.01, 0.05 and 0.01) increased the time spent on open arms of the EPM, completely blocked the hind limb tonic extension on the MES, and at 200 mg/kg, protected (100%) the mice against PTZ–induced mortality respectively. The oil at all tested doses significantly (p<0.01) shortened sleep latency and at (100 and 150 mg/kg) it significantly (p<0.05 and 0.01) prolonged total sleeping time respectively. The oil (150 mg/kg) significantly (p<0.05) reduced writhings, and at (50, 100 and 150 mg/kg) significantly (p<0.05, 0.01 and 0.05) increased the reaction time on the hot plate respectively.

Conclusion: The study concluded that the oil possessed anxiolytic, sedative, anticonvulsant and analgesic activities in mice.