Corynanthine, also known as rauhimbine, is an alkaloid

Alkaloid

Alkaloids are a group of naturally occurring chemical compounds that contain mostly basic nitrogen atoms. This group also includes some related compounds with neutral and even weakly acidic properties. Also some synthetic compounds of similar structure are attributed to alkaloids...

 found in the Rauwolfia

Rauwolfia

Rauvolfia is a genus of evergreen trees and shrubs in the dogbane family, Apocynaceae. The genus is named to honor Leonhard Rauwolf. The approximately 85 species in the genus can mainly be found in tropical regions...

and Pausinystalia

Pausinystalia

Pausinystalia, formerly known as Corynanthe is a largely African genus of plant in family Rubiaceae. At least one species in the genus contains a powerful alkaloid known as yohimbine used in some herbal remedies, that being Pausinystalia yohimbe...

(formerly known as Corynanthe) genera of plants. It is one of the two diastereoisomers of yohimbine

Yohimbine

Yohimbine is an alkaloid with stimulant and aphrodisiac effects found naturally in Pausinystalia yohimbe . It is also found naturally in Rauwolfia serpentina , Alchornea floribunda , along with several other active alkaloids...

, the other being rauwolscine

Rauwolscine

Rauwolscine, also known as isoyohimbine, α-yohimbine, and corynanthidine, is an alkaloid found in various species within the genera Rauwolfia and Pausinystalia . It is a stereoisomer of yohimbine...

. It is also related to ajmalicine

Ajmalicine

Ajmalicine, also known as δ-yohimbine or raubasine, is an antihypertensive drug used in the treatment of high blood pressure. It has been marketed under numerous brand names including Card-Lamuran, Circolene, Cristanyl, Duxil, Duxor, Hydroxysarpon, Iskedyl, Isosarpan, Isquebral, Lamuran, Melanex,...

.

Corynanthine acts as an α₁-adrenergic

Alpha-1 adrenergic receptor

The alpha-1 adrenergic receptor is a G protein-coupled receptor associated with the Gq heterotrimeric G-protein. It consists of three highly homologous subtypes, including α1A-, α1B-, and α1D-adrenergic...

 and α₂-adrenergic receptor

Alpha-2 adrenergic receptor

The alpha-2 adrenergic receptor is a G protein-coupled receptor associated with the Gi heterotrimeric G-protein. It consists of three highly homologous subtypes, including α2A-, α2B-, and α2C-adrenergic. Some species other than humans express a fourth α2D-adrenergic receptor as well...

 antagonist

Receptor antagonist

A receptor antagonist is a type of receptor ligand or drug that does not provoke a biological response itself upon binding to a receptor, but blocks or dampens agonist-mediated responses...

 with approximately 10-fold selectivity

Binding selectivity

Binding selectivity refers to the differing affinities with which different ligands bind to a substrate forming a complex. A selectivity coefficient is the equilibrium constant for the reaction of displacement by one ligand of another ligand in a complex with the substrate...

 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

Stimulant

Stimulants are psychoactive drugs which induce temporary improvements in either mental or physical function or both. Examples of these kinds of effects may include enhanced alertness, wakefulness, and locomotion, among others...

 (or an aphrodisiac

Aphrodisiac

An aphrodisiac is a substance that increases sexual desire. The name comes from Aphrodite, the Greek goddess of sexuality and love. Throughout history, many foods, drinks, and behaviors have had a reputation for making sex more attainable and/or pleasurable...

 for that matter), but a depressant

Depressant

A depressant, or central depressant, is a drug or endogenous compound that depresses the function or activity of a specific part of the brain...

, and likely plays a role in the antihypertensive

Antihypertensive

The antihypertensives are a class of drugs that are used to treat hypertension . Evidence suggests that reduction of the blood pressure by 5 mmHg can decrease the risk of stroke by 34%, of ischaemic heart disease by 21%, and reduce the likelihood of dementia, heart failure, and mortality from...

 properties of Rauwolfia extracts. Like yohimbine and rauwolscine, corynanthine has also been shown to possess some activity at serotonin receptors.