The pharmaceutical industry is continuously exploring innovative approaches to synthesize complex molecules more efficiently and sustainably. Enzyme engineering has become a pivotal tool in this endeavour, enabling the development of biocatalysts that facilitate the production of chiral intermediates essential for drug synthesis. Enzymaster has now been nominated as a finalist for the CPhI Pharma Awards 2024 in the category ‘API Development and Innovation’ for the development of green alternatives to traditional chemical methods in the synthesis of active pharmaceutical ingredients (APIs) such as Ezetimibe by application of Halohydrin dehalogenases (HHDHs).
Ezetimibe, a cholesterol-lowering medication, requires the synthesis of chiral intermediates such as the Evan’s auxiliary (S)-4-Phenyl-2-oxazolidinone. Conventional methods to produce this compound involve multiple steps and the use of environmentally harmful chemicals such as propionyl chloride, ethyl hydrogen sulfide, and methylbenzene. Using HHDHs instead not only reduces the environmental footprint of the synthesis process but also improves the overall efficiency and yield.
HHDHs exemplify the potential of enzyme engineering in the production of chiral intermediates. These enzymes naturally catalyse the reversible dehalogenation of (vicinal) halohydrins to epoxides. Utilizing the reverse reaction, a variety of chiral compounds is accessible via an enantio- and regioselective ring opening reaction by alternative nucleophiles. This selective ring-opening is crucial for the enantioselective synthesis of key API intermediates. By means of enzyme engineering, our scientists were able to improve the wildtype variant 10-fold regarding chemoselectivity with a 90-fold increase in substrate loading, creating a robust industrial catalyst that is used for tonne-scale production of the Ezetimibe Intermediate today.
The versatility of HHDHs combined with enzyme engineering underscores their potential as a platform technology for a wide range of chemoenzymatic reactions. Beyond Ezetimibe, these enzymes can be adapted to synthesize other pharmaceutical intermediates and fine chemicals such as intermediates for the APIs Mirabegron and Levamisole.
In conclusion, the integration of HHDHs into the synthesis of Ezetimibe API intermediates represents a significant leap forward in green chemistry. Enzyme engineering, by enabling the redesign and optimization of these and other biocatalysts, offers the pharmaceutical industry powerful means to achieve sustainable production. As research in this field continues, the potential for enzymes like HHDHs to revolutionize drug synthesis and beyond becomes increasingly evident.
