[2] It also occurs in the leaves of Mitragyna speciosa (kratom) and Mitragyna tubulosa,[3] a tree native to Thailand.

Chemically, it is related to the alkaloid mitragynine.

Rhynchophylline is a non-competitive NMDA antagonist (IC50 = 43.2 μM) and a calcium channel blocker.

[4][5] Uncaria species have had a variety of uses in traditional herbal medicine, such as for lightheadedness, convulsions, numbness, and hypertension.

[6] These uses have been associated with the presence of rhynchophylline and have encouraged its investigation as a drug candidate for several cardiovascular and central nervous system diseases; however, few clinically relevant studies have been conducted.