Effects of Curcuma drugs on vasomotion in isolated rat aorta

The effectiveness of Curcuma drugs against "Oketsu" and the differences in their efficacy were evaluated by examining their vasomotional effects as one index. Since nitric oxide (NO) is the relaxation factor of vascular smooth muscle and also an inhibitor of platelet aggregation in blood vessels, substances showing NO-dependent relaxation are thought to be effective in improving Oketsu. In this study, five Curcuma drugs derived from Curcuma longa, C. kwangsiensis, C. phaeocaulis, C. wenyujin, and C. zedoaria were used. Methanol extracts exhibited intense effects on relaxation in rings precontracted by prostaglandin F_2α (PGF_2α) despite pretreatment with and without N^G-nitro-l-arginine methyl ester (L-NAME) as an inhibitor of NO synthesis. The maximal activities were approximately 80% at 10^-3 g/ml. From these methanol extracts, curcumin and eight sesquiterpenes were isolated. Since all these compounds showed NO-independent relaxation effects with almost the same intensities, the relaxation effects of Curcuma drugs can be estimated by the total amounts of curcumin and sesquiterpenes. Polysaccharides, the main constituents of methanol-insoluble compounds of water extracts, in contrast, showed contraction effects; only polysaccharides in C. zedoaria showed NO-dependent relaxation as well as contraction. All water extracts showed relaxation effects as sum of the methanol-soluble compounds-induced relaxation and polysaccharides-induced contraction. Therefore, all Curcuma drugs tested in the present study can be effective for vasodilation. Moreover, the drug derived from C. zedoaria has potential to cure Oketsu with its various acting points.