There are 40 compounds found in Kratom leaves ncluding many alkaloids such as mitragynine (once thought to be the primary active constituent), mitraphylline, and 7-hydroxymitragynine. Other active chemicals include raubasine and some yohimbe alkaloids such as corynantheidine. Kratom (Mitragyna speciosa) also contains at least one alkaloid called rhynchophylline (NMDA antagonist) that is a calcium channel blocker.
One analysis of kratom, using liquid chromatography-electrospray ionization mass spectrometry found mitragynine at levels of 1-6% and 7-hydroxymirtrogynine at levels of 0.01-0.04%. The chemical structure of mitragynines incorporate the nucleus of the tryptamine, and these may be responsible for the molecules which are observed in the serotonin and adrnergic systems. In mitragynine, the phenolic methyl ether is considered to be stronger in analgesic paradigms according to some studies.