Pharmacological studies of indole alkaloids obtained from domostic plants, Uncaria rhynchophylla MIQ. and Amsonia elliptica ROEM. et SCHULT.

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Abstract
Pharmacological studies on hirsutine (HS), hirsuteine (HST), rhynchophylline (RP), isorhynchophylline (IRP) and dihydrocorynantheine (DCT) which were isolated from the domestic phant Uncaria rhynchophylla MIQ. and .beta.-yohimbine (.beta.-Y) which was isolated from the domestic phant Amsonia elliptica ROEM. et SCHULT. were carried out. These alkaloids showed a mild central depressive effect in mice, a week non-competitive antispasmodic action in the mouse intestine, and a hypotensive effect in rats. Since .beta.-Y showed .alpha.-adrenoceptor blocking action, the hypotensive effect of .beta.-Y may be partly due to the vasodilative effect induced by its .alpha.-adrenoceptor blocking action. HS and .beta.-Y showed a preventive effect on the development of gastric erosions in mice. HS had antiarrhythmic effects on both aconitine-induced arrhythmias in mice and ouabain-induced arrhythmias in guinea pigs. The potency of the antiarrhythmic effects induced by HS was approximately the same as that of ajmaline, an indole alkaloid. Since HS did not show .beta.-adrenoceptor blocking action, the antiarrhythmic effects of HS would not be due to its .beta.-adrenoceptor blocking effect.