mitragynine

Mitragynine is a **naturally occurring indole alkaloid** and the principal active compound in the leaves of *Mitragyna speciosa* (commonly known as kratom). Isolated first in 1921, mitragynine exists as a white amorphous crystalline solid. Its chemical formula is C23H30N2O4. Mitragynine exhibits **dose-dependent pharmacological effects**: at low doses, it acts as a stimulant, while higher doses confer sedative-narcotic and analgesic effects[1][4][6]. Traditionally, it has been used in Southeast Asia to combat fatigue, treat pain, diarrhea, cough, diabetes, and as an opioid substitute to alleviate withdrawal symptoms[1][3][7][9]. There is no approved medical use for mitragynine in modern medicine, but it is widely self-administered for pain management and opioid withdrawal[1][6][9]. The mechanism involves agonism at the **mu-opioid receptor** with lower affinity partial agonism or antagonism at delta and kappa opioid receptors. Mitragynine also binds to alpha-2 adrenergic, dopamine D2, adenosine, and serotonin 5-HT2C/5-HT7 receptors, though the physiological significance of these interactions is not fully established[3][4][7]. Notably, mitragynine is believed to have a lower risk of inducing respiratory depression than conventional opioids due to bias against beta-arrestin pathway activation[4][7]. Mitragynine is metabolized in the liver to the more potent 7-hydroxymitragynine[7]. Adverse effects of mitragynine or kratom consumption may include nausea, constipation, dizziness, and in rare cases hepatotoxicity[3]. The substance is not legally approved for medical use in most countries, though it is regulated in some[1].

Other names

(E)-16,17-didehydro-9,17-dimethoxy-17,18-seco-20α-yohimban-16-carboxylic acid methyl ester9-methoxycorynantheidine