Biosynthetic conversion of thebaine to codeine

High-Efficiency Biocatalytic Conversion of Thebaine to Codeine

An enzymatic biosynthesis approach is described for codeine, the most widely used medicinal opiate, providing a more environmentally sustainable alternative to current chemical conversion, with yields and productivity compatible with industrial production. Escherichia coli strains were engineered to express key enzymes from poppy, including the recently discovered neopinone isomerase, producing codeine from thebaine. We show that compartmentalization of these enzymes in different cells is an effective strategy that allows active spatial and temporal control of reactions, increasing yield and volumetric productivity and reducing byproduct generation. Codeine is produced at a yield of 64% and a volumetric productivity of 0.19 g/(L·h), providing the basis for an industrially applicable aqueous whole-cell biotransformation process. This approach could be used to redirect thebaine-rich feedstocks arising from the U.S. reduction of opioid manufacturing quotas or applied to enable total biosynthesis and may have broader applicability to other medicinal plant compounds.

A microbial biomanufacturing platform for natural and semisynthetic opioids

Opiates and related molecules are medically essential, but their production via field cultivation of opium poppy Papaver somniferum leads to supply inefficiencies and insecurity. As an alternative production strategy, we developed baker's yeast Saccharomyces cerevisiae as a microbial host for the transformation of opiates. Yeast strains engineered to express heterologous genes from P. somniferum and bacterium Pseudomonas putida M10 convert thebaine to codeine, morphine, hydromorphone, hydrocodone and oxycodone. We discovered a new biosynthetic branch to neopine and neomorphine, which diverted pathway flux from morphine and other target products. We optimized strain titer and specificity by titrating gene copy number, enhancing cosubstrate supply, applying a spatial engineering strategy and performing high-density fermentation, which resulted in total opioid titers up to 131 mg/l. This work is an important step toward total biosynthesis of valuable benzylisoquinoline alkaloid drug molecules and demonstrates the potential for developing a sustainable and secure yeast biomanufacturing platform for opioids.

Analgesia: morphine-pathway block in top1 poppies

The opium poppy is a source of the pharmaceuticals codeine, morphine and their derived analgesics. Here we describe the initial characterization of the poppy mutant known as top1 (for 'thebaine oripavine poppy 1'), which accumulates the morphine and codeine precursors thebaine and oripavine and does not complete their biosynthesis into morphine and codeine. The original discovery of top1 stimulated a re-engineering of the opioid industry in the island state of Tasmania, which grows over 40% of the world's licit opiates, in order to produce thebaine and oripavine efficiently from morphine-free poppy crops to provide precursors for highly effective analgesics and for treatment of opioid addiction.

Purification and properties of codeinone reductase (NADPH) from Papaver somniferum cell cultures and differentiated plants

Codeinone reductase (NADPH), which catalyzes the stereospecific reduction of (-)codeinone to (-)codeine, was detected and purified to electrophoretic homogeneity from a cytosolic fraction of Papaver somniferum L. cell cultures. The purification involved ammonium sulfate precipitation (40-80%), affinity chromatography (matrex red A), gel filtration (fractogel TSK HW 55S), affinity chromatography (fractogel TSK AF Blue), ion-exchange chromatography (DEAE-Sephacel) and native PAGE. The purified codeinone reductase was found to be a monomeric protein of 35 +/- 1 kDa that is highly substrate-specific, reducing only the C6 oxo group of codeinone and morphinone as well as a few analogues. The physiological forward reaction has a pH optimum at 7.0, the reverse reaction at 9.1. The temperature optimum is at 40 degrees C and the isoelectric point (p1) at 4.4. The apparent Km values (forward reaction) for codeinone and NADPH are 23 microM and 168 microM, respectively. Using capsule tissue of differentiated P. somniferum plants as an enzyme source, two codeinone reductase (NADPH) isoenzymes were detected and purified to homogeneity. These isoenzymes could not be separated for characterization and showed slightly different kinetic features (Km values: codeinone 9 microM; NADPH 81 microM) compared with the cell culture enzyme.