Evidence for involvement of the monoaminergic system in antidepressant-like activity of an ethanol extract of Boerhaavia diffusa and its isolated constituent, punarnavine, in mice.

CONTEXT

Boerhaavia diffusa Linn. (Nyctaginaceae) roots possess potent antioxidant, antistress, and anticonvulsant activities. It is used as a medicinal plant in Ayurvedic and natural herbal medicines.

OBJECTIVE

To evaluate the effect of Boerhaavia diffusa root ethanol extract and its active constituent, punarnavine, on depression in Swiss albino mice.

MATERIALS AND METHODS

Ethanol extract (50, 100, and 200 mg/kg, p.o.) and punarnavine (20 and 40 mg/kg, p.o.) were separately administered to 22 and 17 groups of mice, respectively, for 14 successive days followed by testing in the tail suspension and forced swim tests (FST). About 2% w/v gum acacia and double distilled water were used as controls for the extract and punarnavine, respectively.

RESULTS

Antidepressant-like effect of the lowest dose (50 mg/kg) of the extract and lower dose (20 mg/kg) of punarnavine were found to be comparable to fluoxetine. The ED50 value of the ethanol extract was 26.30 mg/kg (FST) and 33.11 mg/kg (tail suspension test); and of punarnavine was 15.14 mg/kg (FST) and 17.38 mg/kg (tail suspension test). The drugs did not show any significant effect on locomotor activities of mice. Prazosin (α1-adrenoceptor antagonist), sulpiride (selective D2-receptor antagonist), para-chlorophenylalanine) (p-CPA) (tryptophan hydroxylase inhibitor), and baclofen (GABAB agonist) significantly attenuated the extract and punarnavine induced-antidepressant-like effect in the tail suspension test. The extract and punarnavine also significantly reduced mouse brain monoamine oxidase (MAO)-A levels, but there was no significant effect on plasma corticosterone levels.

CONCLUSION

Ethanol extract of Boerhaavia diffusa and punarnavine produced an antidepressant-like effect in mice probably through interaction with monoaminergic and GABAergic systems.