Yohimbine is a naturally occurring substance from the group of indole alkaloids, mainly in the leaves and bark of the yohimbe tree (Pausinystalia yohimbe). In addition, yohimbine can also be found in the roots of numerous snake roots (Rauvolfia species). The Rauvolfia alkaloids named after this species include not only yohimbine but also reserpine, mitragynine, serpentine and ajmaline, for example. Yohimbine is used therapeutically for erectile dysfunction.
Yohimbine is a highly potent antagonist of α2-adrenoceptors, which among other things. found in the smooth muscles of blood vessels. A blockage of these smooth muscle receptors leads to an expansion of the blood vessels. Yohimbine also quickly crosses the blood-brain barrier and increases blood pressure and heart rate through central mechanisms. It also increases motor activity and causes tremors.
Also described are an antiemetic, antidiuretic, local anesthetic and monoaminooxidase-inhibiting effect.
The aphrodisiac effect of yohimbine is said to be due on the one hand to the blockade of α2-adrenoceptors on blood vessels in the male genital organs and on the other hand to the blockage of α2-adrenoceptors in the central nervous system. In addition, yohimbine interacts with numerous serotonin (5-HT) receptors.