Ajmalicine (Raubasine) is found in herbs of Catharanthus roseus, is an antihypertensive drug used in the treatment of high blood pressure, decreases peripheral resistance and blood pressure[1].Ajmalicine (Raubasine) is an adrenolytic drug which preferentially blocks alpha 1-adrenoceptor than alpha 2-adrenoceptor[2].Ajmalicine (Raubasine) is an reversible non-competitive nicotine receptor antagonist with an IC50 of 72.3 μM[3].Ajmalicine (Raubasine) acts preferentially at postsynaptic sites, competitively antagonizes the effect of noradrenaline on postsynaptic alpha-adrenoceptor with a pA2 value of 6.57, blocks the inhibitory effect of clonidine with an pA2 value of 6.2[4].
[1]. Wink, Michael; Roberts, M. W. (1998). Alkaloids: biochemistry, ecology, and medicinal applications. New York: Plenum Press. ISBN 0-306-45465-3. [2]. Roquebert J, et al. Inhibition of the alpha 1 and alpha 2-adrenoceptor-mediated pressor response in pithed rats by raubasine, tetrahydroalstonine and akuammigine. Eur J Pharmacol. 1984 Oct 30;106(1):203-5. [3]. Pereira DM, et al. Pharmacological effects of Catharanthus roseus root alkaloids in acetylcholinesterase inhibition and cholinergic neurotransmission. Phytomedicine. 2010 Jul;17(8-9):646-52. [4]. •Demichel P, et al. Effects of raubasine stereoisomers on pre- and postsynaptic alpha-adrenoceptors in the rat vas deferens. Br J Pharmacol. 1984 Oct;83(2):505-10