The present study has been carried out to evaluate the antidepressant activity of a pharmacopoeal Unani drug Majoon Najah (MN) in experimental animals. Tetrabenazine antagonism test and Yohimbine toxicity enhancement test were used to study the antidepressant activity in mice divided into 4 groups of 6 animals each. Animals in Group I, II and III were treated with distilled water, 50% alcoholic extract of MN in 260 mg/kg (single dose) and 520 mg/kg (double dose), orally, respectively. Group IV was treated with standard drugs Imipramine (20 mg/kg per oral) and Desipramine-Hcl (10 mg/kg i.p.) in both the tests, respectively. The effect of test drug was observed on duration of catalepsy, degree of ptosis and the mortality rate of the animals.

MN demonstrated antagonist effect in Tetrabenazine induced catalepsy and ptosis. Cataleptic score and degree of ptosis were significantly reduced (p<0.001) in Group II and III in a dose dependent manner, and no significant difference was found between Group III and IV. In Yohimbine toxicity enhancement test, the mortality rate increased significantly (p<0.001) in Group II & III; and at 24 hr significant difference was observed when mortality rate was compared among the groups, between I & III (p<0.011), and between I & IV (p<0.05), between II & III (p< 0.011). The mean time of mortality in group III was observed significantly less (p<0.0001) when compared with group I, II & IV.

The study demonstrated that the test drug possesses significant anti depressant. It has most likely produced its effect by inhibiting the monoamine uptake through adrenergic, serotonergic and monoamine oxidase inhibiting mechanisms.