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, n-BuOH 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.