Biol. Pharm. Bull. 29(12) 2415—2418 (2006)

Cinnamomi Cortex is a crude drug used therapeutically in Asia and Europe. Its main component is cinnamaldehyde. There are many reports on the pharmacological effects of Cinnamomi Cortex. Mainly, the sedative effect of decreasing spontaneous motor activity, anti-inflammatory effects related to cyclooxygenase-2, and antibacterial activity against Escherichia coli and Pseudomonas aeruginosa have been reported. In addition, in oriental medicine, Cinnamomi Cortex is often used to improve blood circulation. In regard to the circulatory system, a catecholamine-releasing effect of cinnamaldehyde, a reducing effect on platelet aggregation due to suppression of the release of arachidonic acid from platelets, and an inhibitory effect of collagen-induced platelet aggregation have been reported. However, reports concerning the direct effect against vasomotion by components of Cinnamomi Cortex are few, except in relation to cinnamtannin. In the present study, the vasorelaxant effects of cinnamaldehyde were studied by the organ bath method, and the mechanisms of vasorelaxation were evaluated.