Apigenin 7-glucoside from Stachys tibetica Vatke and its anxiolytic effect in rats.

BACKGROUND

Stachys tibetica Vatke (Himalayan or mountain tea) grows abundantly in the tropical and subtropical locations of the world including India, Tibet and China. The traditional healers of Kargil and adjoining areas in Ladakh, Jammu and Kashmir in India use the drug to treat fever, cough, phobias and various mental disorders etc. in the form of a decoction or as a tea. Flavonoids are important components in most herbal teas and play an important role in the management of various brain disorders via mimicking the action of benzodiazepines or through benzodiazepine receptors.

OBJECTIVE

The present study aimed to isolate flavonoids from S. tibetica and to evaluate their anxiolytic potential in comparison to reference synthetic (diazepam) and natural (apigenin) molecules.

METHODS

S. tibetica root powder was extracted with 95% methanol for about 72 h using a soxhlet apparatus and the resultant extract was subjected to isolation procedures, resulting in the isolation of apigenin 7-glucoside and characterisation by various physical and spectrometric analyses. Apigenin 7-glucoside was evaluated for anxiolytic activity in rats in comparison with the reference compounds diazepam and apigenin using the elevated plus maze (EPM) model.

RESULTS

Phytochemical investigations of S. tibetica revealed the presence of tannins, phenolics, flavonoids, saponins, glycosides and carbohydrates. A flavonoid glucoside, apigenin 7-glucoside was isolated for the first time from the roots of S. tibetica Vatke. The percentage of time spent and arm entries in the open arms was increased while the arms entries and duration of time spent in closed arms were decreased in the groups treated with apigenin 7-glucoside (which dose). In a similar fashion, diazepam and apigenin also exhibited anxiolytic activity (*p<0.05, **p<0.01). Apigenin 7-glucoside significantly decreased the percentage of head dips in EPM. Apigenin 7-glucoside showed anxiolytic potential comparable to the reference drugs apigenin and diazepam.

CONCLUSIONS

Apigenin 7-glucoside could be an important molecule for the treatment of anxiety and further studies are required to elucidate its possible mechanism of action.