Kratom alkaloid biosynthesis: how this plant epimerizes a highly conserved stereocenter.

All 3000 monoterpene indole alkaloids are made by a stereoselective Pictet Spengler reaction that leads to a tetrahydro-beta-carboline scaffold with a 3S stereocenter. Most monoterpene indole alkaloids retain this stereochemistry. However, 3R monoterpene indole alkaloids are found in the Kratom plant. Allwin discovered an oxidase and reductase that are responsible for epimerizing this center.

https://www.biorxiv.org/content/10.1101/2024.12.13.628308v1