(RS)-coclaurine and tetrandrine

A series of O- and/or N-substituted derivatives of (+/-)-coclaurine (1a) were synthesized as simplified structural mimics of the antihypertensive alkaloid tetrandrine (2) and assayed for binding to brain cortical sites labeled with the alpha(1)-adrenergic radioligand [(3)H]prazosin or the calcium channel radioligand [(3)H]diltiazem. The introduction of O-benzyl groups on the coclaurine molecule, which exhibits only adrenergic antagonist activity, led to the appearance of calcium channel blocking activity comparable to that of tetrandrine while retaining adrenolytic activity in the same concentration range. Contraction of aortal rings with noradrenaline or KCl was relaxed more potently by some of these coclaurine derivatives than by tetrandrine, suggesting leads for the development of novel antihypertensive drugs with a dual mechanism of action.

Topics: Alkaloids; Antihypertensive Agents; Benzylisoquinolines; Calcium Channel Blockers; Combinatorial Chemistry Techniques; Diltiazem; Inhibitory Concentration 50; Isoquinolines; Molecular Conformation; Molecular Mimicry; Molecular Structure; Prazosin; Stereoisomerism; Structure-Activity Relationship