Evaluation of Anti-depressant and Anti-anxiety Activity of Methanol Extract of Stachys annua L. in Mice

Background and objectives: Development of new medicines with fewer side effects and more efficacy is needed for treatment of depressive and anxiety disorders. The present study was designed to investigate the antidepressant and anti-anxiety effects of Stachys annua L. methanol extract in mice. Methods: The extract was prepared by maceration method and the total phenolic and flavonoid contents were determined by Folin-Ciocalteu and aluminum chloride methods, respectively. Elevated plus-maze (EPM) and open field tests (OFT) were applied to evaluate the anti-anxiety and locomotor activity of animals treated with the intraperitoneal (i.p.) extract (12.5, 25, 50, and100 mg/kg), respectively. Antidepressant activity was evaluated by forced swim test (FST) and tail suspension test (TST). Results:The total phenolic content of the extract was 54.13±0.01 mg of gallic acid equivalents per gram of dry extract and total flavonoid content was 67.89±0.005 mg of quercetin as equivalents/ g of extract. Intraperitoneal administration of the extract (50 and 100 mg/kg) significantly increased the percentage of time spent and the percentage of arm entries into the open arms of EPM and decreased locomotor activity, compared with the vehicle control group. In addition, the immobility time of animals significantly decreased in both FST and TST with doses of 25, 50, and 100 mg/kg of the extract, compared with the vehicle control group. Conclusion: The extract of Stachys annua L. might be used as an adjunct therapy in clinical studies for the treatment of depressive and anxiety disorders. However, determination of active ingredients needs further evaluation.