Monoamine oxidase inhibition by Rhodiola rosea L. roots

Aim of the study: Rhodiola rosea L. (Crassulaceae) is traditionally used in Eastern Europe and Asia to stimulate the nervous system, enhance physical and mental performance, treat fatigue, psychological stress and depression. In order to investigate the influence of Rhodiola rosea L roots on mood disorders, three extracts were tested against monoamine oxidases (MAOs A and B) in a microtitre plate bioassay. Materials and methods: Methanol and water extracts gave the highest inhibitory activity against MAOs. Twelve compounds were then isolated by bioassay-guided fractionation using chromatographic methods. The structures were determined by H-1, C-13 NMR and HR-MS. Results: The methanol and water extracts exhibited respectively inhibitions of 92.5% and 84.3% on MAO A and 81.8% and 88.9% on MAO B, at a concentration of 100 mu g/ml. The most active compound (rosiridin) presented an inhibition over 80% on MAO B at a concentration of 10(-5) M (pIC(50) = 5.38 +/- 0.05). Conclusions: The present investigation demonstrates that Rhodiola rosea L roots have potent antidepressant activity by inhibiting MAO A and may also find application in the control of senile dementia by their inhibition of MAO B. (C) 2009 Elsevier Ireland Ltd. All rights reserved.