Mitragyna Speciosa, also known as Kratom, is a large tree in the Rubiaceae family native to Southeast Asia in the Indochina and Malesia floristic regions. It was first documented by Pieter Korthals, a Dutch colonial botanist. The leaf of the tree contains mirtragynine and was traditionally used for its ethnobotanical and medicinal properties. The leaves of kratom have been used by the indigenous people as a stimulant in low doses, a sedative in large doses, an anti-diarrheal and pain killer. It is said that Kratom affects the human brain similarly to an opiate although there is no conclusive clinical data proving how the alkaloids works in relation to the human brain.
Kratom contains more than 25 alkaloids including mitragynine and 7-hydroxymitragynine. These alkaloids act as mu-opioid receptor antagonist. The three most abundant indoles are mitragynine (9-methoxy-corynantheidine) which is responsible for 1/2 of the alkaloid content, paynanthine, and speciogynine. The two most abundant oxindoles are mitraphylline and speciofoline. Other alkaloids present include ajmalicine, corynanthedine, mitraversine, rhychophylline, and stipulatine. Mitragynine is believed, but has not been proven to be, the primary active alkaloid in Mitragyna Speciosa.