Ajmalicine is a monoterpenoid indole alkaloid with formula C21H24N2O3, isolated from several Rauvolfia and Catharanthus species. It is a selective alpha1-adrenoceptor antagonist used for the treatment of high blood pressure. It has a role as a vasodilator agent, an antihypertensive agent and an alpha-adrenergic antagonist. It is a methyl ester, an organic heteropentacyclic compound and a monoterpenoid indole alkaloid. It is a conjugate base of an ajmalicine(1+).