Over 25 alkaloids have been isolated from this tree (from mainly regions in Thailand). Mitragynine is the primary active alkaloid in the leaves of the plant .
Pharmacology studies show that mitragynine has opiate like effects in animals. It inhibits electrically stimulated ileum and the vas deferens. Through actions on centrally located opioid receptor, and reduces pain response.
Mitragynine has been described as producing both stimulant and sedative effects. At low doses, it produces stimulant effects, with users reporting increased alertness, physical energy, talkativeness and sociable behavior. At high doses, opiate effects are produced, in addition to sedative and euphoric effects.