rauwolscine

Rauwolscine hydrochloride (Isoyohimbine hydrochloride) , a natural alkaloid, is a specific and reversible α2-adrenergic receptor antagonist (Ki: 12 nM) [1]. It is a stereoisomer of yohimbine, which potently antagonizes both α1- and α2-adrenergic receptors [1]. Rauwolscine hydrochloride also acts as a receptor antagonist at the serotonin 5-HT2B receptor (Ki: 14.3 nM) and as a weak partial agonist at 5-HT1A (IC50: 1.3 μM) [3]. The α2-adrenergic receptor has diverse physiological functions and antagonists like rauwolscine have numerous applications, including the modulation of mood and behavior [5].

L-654284 is an α2-adrenergic receptor antagonist characterized by its notable selectivity. It competes with 3H-clonidine and 3H-rauwolscine for binding in vitro, exhibiting Ki values of 0.8 nM and 1.1 nM, respectively. L-654284 effectively blocks the pre-ejaculatory effects of clonidine in isolated rat vas deferens, with a pA2 value of 9.1. The compound demonstrates significant selectivity for α2 over α1 adrenergic receptors, with a Ki value of 110 nM against 3H-prazosin binding. In vivo, L-654284 significantly increases the turnover of norepinephrine in the rat cerebral cortex, indicating its activity in blocking α2-adrenergic receptors within the central nervous system.