Which plant is the natural source of the antihypertensive alkaloid reserpine?

Rauvolfia serpentina is the natural source of the antihypertensive alkaloid reserpine.

Rauvolfia serpentina, also called Indian snakeroot or sarpagandha, is a small evergreen shrub in the dogbane family, Apocynaceae. Its roots contain numerous indole alkaloids, including reserpine, ajmaline, ajmalicine, and serpentine. Reserpine became an important early antihypertensive drug after its isolation and introduction into modern medicine in the 1950s.

The compound lowers blood pressure by depleting storage vesicles of norepinephrine and other monoamine neurotransmitters in sympathetic nerve endings. This reduces sympathetic stimulation of the cardiovascular system, but the same mechanism can produce unwanted effects such as sedation, nasal congestion, gastrointestinal symptoms, and depression. Those adverse effects greatly limited its later use.

Rauvolfia serpentina has a long history in South Asian traditional medicine, where preparations of the root were used for conditions including snakebite, fever, and mental distress. A common confusion is with Catharanthus roseus, the Madagascar periwinkle, which supplies the anticancer alkaloids vincristine and vinblastine—not reserpine. Reserpine is also found in some other Rauvolfia species, but R. serpentina is the classic source named in pharmacognosy.