Diterpenoid alkaloid mesaconitine

Mesaconitine, an aconite-type Ci9-diterpenoid alkaloid, inhibited phenylephrine-induced contraction in the endothelium-intact but not endothelium-denuded, aortic rings [76]. Compounds named sharwuphinine A, lycoctonine, and deoxymethylenelycoctonine were tested when phenylephrine (PE) 3x10 M was applied to thoracic aortic rings with endothelium after achieving a maximal response. Only sharwuphinine A showed a moderate vasorelaxant activity (40% relaxation at 10 " M) and that vasodilation may be influenced by the hydrophobicity of a nitrogen atom [40]. 

The most toxic alkaloids of aconite, such as aconitine, mesaconitine, hypaconitine, etc., are known to possess arrhythmogenic effect. Aconitine itself has long been used to induce arrhythmia in experimental models [38, 39]. Aconitine and its structural analogues induce ventricular ectopics, ventricular tachycardia, torsades de pointes, and ventricular fibrillation in a dose-dependent manner. Aconitine has a positive inotropic effect on the heart. It has hypotensive and bradycardic actions [40]. Another group of diterpenoid alkaloids possessing C18 and C19 skeleton, such as lappaconitine, A -deacetyllappac(Miitine, heteratisine, and 6-benzoylheteratisine, are... 

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