Corynanthine
Corynanthine, also known as rauhimbine, is an alkaloid found in the Rauvolfia and Pausinystalia genera of plants. It is one of the two diastereoisomers of yohimbine, the other being rauwolscine. It is also related to ajmalicine.
Corynanthine acts as an α1-adrenergic and α2-adrenergic receptor antagonist with approximately 10-fold selectivity for the former site over the latter. This is in contrast to yohimbine and rauwolscine which have around 30-fold higher affinity for α2-adrenergic over α1-adrenergic. As a result, corynanthine is not a stimulant, but a depressant, and likely plays a role in the antihypertensive properties of Rauvolfia extracts. Like yohimbine and rauwolscine, corynanthine has also been shown to possess some activity at serotonin receptors.
