Monoamine Oxidase Inhibitors from Cinnamomi Cortex

Four compounds were isolated from the dichloromethane fraction of Cinnamomi Cortex through bioassay-guided isolation. Their structures were identified as coumarin (1), 3,3-dimethoxy-1-propenyl benzene (2), cinnamic acid (3) and o-methoxy cinnamaldehyde (4) on the basis of spectroscopic data. All four compounds showed inhibitory activities in vitro against monoamine oxidase (MAO) prepared by mouse brain. The $IC_{50}$ values were $41.4\;{\mu}M\;(1),\;110.6\;{\mu}M\;(2),\;252.5\;{\mu}M\;(3)\;and\;83.1\;{\mu}M$ (4), respectively.