Aim: Assessment of antidepressive effect of aqueous extract (AE) of common vervain and its main constituent – verbascoside and elucidation of underlying mechanism of action.
Introduction: Common vervain is a plant used in traditional medicine. Its AE contains a vast number of compounds, hence its significant pharmacological potential.
The monoamine hypothesis is the central theory of depression, and a majority of conventional antidepressants act on the monoaminergic system.
Methods: Experiments were conducted on Swiss albino sexually mature male mice. There were 6-8 animals in each of 5 subgroups (imipramine; fluoxetine; two different doses of AE – AE I, II; and VS;). Forced Swimming Test (FST) and Tail Suspension Test (TST) were used to assess the antidepressive effect.
Molecular docking experiments were performed using the programme AutoDock 4.2, with 3D structures of crystallized proteins from the PDB database and 3D structures of ligands generated by the software Avogadro 2 0.8.0.
Results: Immobilisation time (IT) in FST after the administration of imipramine was shorter than the control, same as for subgroups treated with AE I, II and VS. In the subgroup treated with fluoxetine, IT in TST was shorter than the control time, and the same was observed in subgroups treated with AE I, II and VS.
Significant binding energies were found for Serotonin Reuptake Transporter (SERT) and verbenalin (−7.20kcal/mol) and verbascoside (−6.61kcal/mol), and for the Leucine Transprter (LeuT), the homologue of the noradrenaline reuptake transporter, and verbenalin (−6.27kcal/mol) and caffeic acid (−5.85kcal/mol).
Conclusion: In both pharmacodynamic tests the antidepressive effect of AE and VS has been confirmed. Verbenalin and verbascoside binding energies and poses in interaction with SERT were similar to those of paroxetine. For LeuT, verbenalin showed both a similar binding energy and pose to that of imipramine, whereas caffeic acid showed only a similar binding energy.1,2,3,4
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