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

Abstract 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 μM in an assay where the IC 50 -value for MAO-A inhibition by clorgylin was 0.2 ± 0.02 μM. Conclusion The content of quercetin in Calluna vulgaris might explain the reported nerve calming effect of the plant.