Screening of vasorelaxant activity of some medicinal plants used in Oriental medicines

Hexane, ethylacetate (EtOAC), and n-butanol (n-BuOH) extracts of medicinal plants traditionally used in the East Asia, such as China, Korea, and Japan were screened for their vasorelaxant activity using isolated rat aorta. Among the 60 solvent-extracts from 20 medicinal plants, hexane and n-BuOH extracts of Diospyros kaki and Polygonum aviculare, hexane, EtOAC, and n-BuOH extracts of Magnolia liliflora, nBuOH extract of Sorbus commixta, and EtOAC and n-BuOH extracts of Selaginella tamariscina were found to exhibit distinctive vasorelaxant activity. The activity disappeared by removal of functional endothelium or pre-treatment of the aortic tissues with N-G-nitro-(L)-arginine methyl ester (L-NAME), which is an inhibitor of nitric oxide synthase. These findings suggest that the medicinal plants relax vascular smooth muscle via endothelium-dependent nitric oxide. These results will be useful to further analyze those medicinal plants that contain the vasorelaxant activity in order to identify the active principles. (c) 2005 Elsevier Ireland Ltd. All rights reserved.