MAO-A inhibitory activity of quercetin from Calluna vulgaris (L.) Hull.

Aim of the study: This study investigated MAO-A inhibitory activity of methanol extract of Calluna vulgaris (L) Hull., which traditionally has been used as a nerve calming remedy. Materials and methods: A methanolic extract of Calluna vulgaris was partitioned against heptane, ethyl acetate and water. The three fractions were tested in a photometric peroxidase linked MAO-A bioassay. The ethyl acetate phase showed the highest MAO-A inhibitory activity. Quercetin was isolated by VLC through bioassay-guided fractionation and purified by re-crystallisation. The structure was elucidated by LC-MS and (1)H NMR. Results:The IC(50)-value for MAO-A inhibition by quercetin was 18 +/- 0.2 mu M in an assay where the IC(50)-value for MAO-A inhibition by clorgylin was 0.2 +/- 0.02 mu M. Conclusion: The content of quercetin in Calluna vulgaris might explain the reported nerve calming effect of the plant. (c) 2008 Elsevier Ireland Ltd. All rights reserved.