Early and Late Steps of Quinine Biosynthesis.

The enzymatic basis for quinine biosynthesis was investigated. Transcriptomic data from the producing plant led to the discovery of three enzymes involved in the early and late steps of the pathway. A medium-chain alcohol dehydrogenase (CpDCS) and an esterase (CpDCE) yielded the biosynthetic intermediate dihydrocorynantheal from strictosidine aglycone . Additionally, the discovery of an -methyltransferase specific for 6'-hydroxycinchoninone suggested the final step order to be cinchoninone hydroxylation, methylation, and keto-reduction.