Comparative evaluation of Melissa officinalis L., Tilia europaea L., Passiflora edulis Sims. and Hypericum perforatum L. in the elevated plus maze anxiety test.

There are numerous plants that have been used for their 'tranquillising' properties in Portuguese folk medicine. This report will describe a comparative analysis of the effects of Melissa officinalis L., Tilia europaea L., Passiflora edulis Sims. and Hypericum perforatum L. on the performance of mice in the elevated plus maze, open-field, and horizontal-wire tests. We have tested lyophilised aqueous extracts with doses ranging from 5-100 mg/kg prepared according to traditional folk medicine. The results indicate that Hypericum perforatum L. and Tilia europaea L. induced significant raise in immobility time, diminution of rearing and other parameters, suggesting a clear sedative effect at doses ranging from 10-100 mg/kg. Below these doses, Tilia europaea L. did not induce any significant change in the tests mentioned, while Hypericum perforatum L. (5 mg/kg) increased the time spent in the open areas of the elevated plus maze and the percentage of unprotected head-dips and stretch-approach postures, thus indicating an anxiolytic effect. For this dose, there were no significant changes in motor activity as measured by classical parameters for the tests used. As the infused H. perforatum L. tested was devoid of hyperforin, it can be stated that the observed effects cannot be attributed to this substance.