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+).

Vincamine is a plant alkaloid used clinically as a peripheral vasodilator that increases cerebral blood flow and oxygen and glucose utilization by neural tissue to combat the effect of aging. Vincamine has contractile and relaxant actions on the guinea pig trachealis, may be due to the generation of prostaglandins and to changes in the membrane Ca2+ fluxes and/or the intracellular Ca2+ distribution. Vincamine alleviates Amyloid-β 25-35 peptides-induced cytotoxicity in PC12 cells. Vincamine is a methyl ester, a vinca alkaloid, an organic heteropentacyclic compound, an alkaloid ester and a hemiaminal. It has a role as a metabolite, a vasodilator agent and an antihypertensive agent. It is functionally related to an eburnamenine.