Mitragynine, an indole alkaloid, is the most abundant active alkaloid

Alkaloid

Alkaloids are a group of naturally occurring chemical compounds that contain mostly basic nitrogen atoms. This group also includes some related compounds with neutral and even weakly acidic properties. Also some synthetic compounds of similar structure are attributed to alkaloids...

 in the plant Mitragyna speciosa, commonly known as Kratom

Kratom

Kratom , Mitragyna speciosa, is a medicinal leaf harvested from a large tree in the Rubiaceae family native to Southeast Asia in the Indochina and Malesia floristic regions. The plant has been traditionally used for its medicinal properties.It was first formally documented by the Dutch colonial...

.

Pharmacology

In small doses its activity is reported to be stimulant-like, while in higher doses more opiate-like. These effects agree with the profile of mitragynine's actions developed by study of its action on the brain. It has been shown to be adrenergic (like some related alkaloids from yohimbe) at lower doses, while at higher doses mitragynine acts on the mu- and delta-opiate receptors. The mu-opiate receptors are responsible for the enjoyable effects of the opiates, analgesia, and physical dependence. Its potential for treating drug addiction, perhaps in combination with ibogaine

Ibogaine

Ibogaine is a naturally occurring psychoactive substance found in a number of plants, principally in a member of the Apocynaceae family known as Iboga . A hallucinogen with both psychedelic and dissociative properties, the substance is banned in some countries; in other countries it is being used...

, is being investigated. It is orally active.

Mitragynine itself acts primarily via μ-opioid receptors, although its oxidation product mitragynine-pseudoindoxyl, which is likely to be a major component of kratom that has been aged or stored for extended periods, acts as a fairly selective δ-opioid

Delta Opioid receptor

The δ-opioid receptors, also known as delta opioid receptor or simply delta receptor, abbreviated DOR, is an opioid receptor that has enkephalins as its endogenous ligands.-Function:...

 agonist

Agonist

An agonist is a chemical that binds to a receptor of a cell and triggers a response by that cell. Agonists often mimic the action of a naturally occurring substance...

 with little affinity for μ or κ receptors. Another alkaloid with a major contribution to the μ-opioid activity of the kratom plant is the related compound 7-hydroxymitragynine

7-Hydroxymitragynine

7-Hydroxymitragynine , an indole, is an active alkaloid in the plant Mitragyna speciosa, commonly known as Kratom. It has opioid agonistic activity. "The potency, calculated using pD values, was 30- and 17-fold higher than that of mitragynine and morphine, respectively...

, which while present in the plant in much smaller quantities than mitragynine, is a much more potent μ-opioid agonist.

Discovery

Mitragynine was isolated in 1907 by D. Hooper, a process repeated in 1921 by E. Field who gave the alkaloid its name. Its structure was first fully determined in 1964 by D. Zacharias, R. Rosenstein and E. Jeffrey.

Structure

It is structurally related to both the yohimbe alkaloid

Alkaloid

Alkaloids are a group of naturally occurring chemical compounds that contain mostly basic nitrogen atoms. This group also includes some related compounds with neutral and even weakly acidic properties. Also some synthetic compounds of similar structure are attributed to alkaloids...

s and, more distantly, voacangine

Voacangine

Voacangine is an alkaloid found predominantly in the rootbark of the Voacanga africana tree, as well as in other plants such as Tabernanthe iboga, Tabernaemontana africana, Trachelospermum jasminoides and Ervatamia yunnanensis...

. Chemically, mitragynine is 9-methoxy-corynantheidine.

Dose

Dry kratom leaf contains roughly 0.25% mitragynine. A typical dose ranges from 15 mg to 65 mg.

Chemical properties

Physically the freebase

Freebase (chemistry)

Freebase or free base refers to the pure basic form of an amine, as opposed to its salt form. The amine is usually an alkaloid natural product. Free base is commonly used in organic chemistry and pharmaceuticals to describe the unprotonated amine form of a compound.Most alkaloids are unstable in...

is a white, amorphous powder. It is soluble in alcohol, chloroform and acetic acid.