¹³C- and ²H-Labeled Deoxyxylulose as a Tool in Study of Kinetics and Mechanism of Salvinorin A Biosynthesis

Salvinorin A, diterpenoid isolated from Mexican sage Salvia divinorum, is the most potent naturally occurring kappa opioid agonist [1]. Biosynthetically derived from DOXP pathway [2], salvinorin A is produced in glandular trichomes located on the abaxial side of the leaf [3]. A specific precursor of the DOXP pathway, deoxyxylulose (DOX) was used as a probe for measuring the rate of its incorporation into the final product, salvinorin A. We observed that deuterium atoms can significantly decrease the level of DOX incorporation, especially when associated with reactions of bond making and bond breaking. Carbon −13 had no effect on rate of incorporation, however. Deuterium labelled glucose was also used to study the mechanism of geranylgeranyl pyrophosphate cyclization in the early steps of the salvinorin biosynthesis. Determination of the GGPP cyclization mechanism was studied by NMR and MS methods. References: [1] Roth BL, et al. (2002) PNAS 99: 11934–11939. [2] Kutrzeba LM, et al. (2007) Phytochemistry 68: 1872–1881. [3] Siebert D. (2004) Ann. Bot. 93: 763–771.