Punarnavine, an alkaloid isolated from ethanolic extract of Boerhaavia diffusa Linn. reverses depression-like behaviour in mice subjected to chronic unpredictable mild stress.

Punarnavine (20 and 40 mg/kg) and fluoxetine (20 mg/kg) per se administered orally for 14 successive days significantly decreased immobility periods of both unstressed and stressed mice in forced swim test. These drugs also significantly decreased sucrose preference in both stressed and unstressed mice as compared to their respective controls, indicating significant antidepressant-like activity. The drugs did not show any significant effect on locomotor activity of mice. The alkaloid also significantly decreased monoamine oxidase (MAO-A) activity, malondialdehyde levels in both unstressed and stressed mice; and significantly reversed the stress-induced decrease in reduced glutathione and catalase activity. It also significantly attenuated the stress-induced increase in plasma nitrite and corticosterone levels. Thus, punarnavine showed antidepressant-like activity in unstressed and stressed mice probably through inhibition of brain MAO-A activity, decrease in plasma nitrite levels and due to its antioxidant activity. In addition, punarnavine also showed antidepressant-like activity in stressed mice possibly through decrease in plasma corticosterone levels.