Recent Advances in Developing Chemoenzymatic Processes for Active Pharmaceutical Ingredients

Photobiocatalytic Strategies for Organic Synthesis

Biocatalysis has revolutionized chemical synthesis, providing sustainable methods for preparing various organic molecules. In enzyme-mediated organic synthesis, most reactions involve molecules operating from their ground states. Over the past 25 years, there has been an increased interest in enzymatic processes that utilize electronically excited states accessed through photoexcitation. These photobiocatalytic processes involve a diverse array of reaction mechanisms that are complementary to one another. This comprehensive review will describe the state-of-the-art strategies in photobiocatalysis for organic synthesis until December 2022. Apart from reviewing the relevant literature, a central goal of this review is to delineate the mechanistic differences between the general strategies employed in the field. We will organize this review based on the relationship between the photochemical step and the enzymatic transformations. The review will include mechanistic studies, substrate scopes, and protein optimization strategies. By clearly defining mechanistically-distinct strategies in photobiocatalytic chemistry, we hope to illuminate future synthetic opportunities in the area.

Landscape and opportunities for active pharmaceutical ingredient manufacturing in developing African economies

This review will highlight the opportunities that exist in the localization of cutting-edge manufacturing technologies within an African context.

Biocatalytic approaches towards the stereoselective synthesis of vicinal amino alcohols

The global need for clean manufacturing technologies and the management of hazardous chemicals and waste present new research challenges to both chemistry and biotechnology.

Application of ω-Transaminases in the Pharmaceutical Industry

Chiral amines are valuable building blocks for the pharmaceutical industry. ω-TAms have emerged as an exciting option for their synthesis, offering a potential "green alternative" to overcome the drawbacks associated with conventional chemical methods. In this review, we explore the application of ω-TAms for pharmaceutical production. We discuss the diverse array of reactions available involving ω-TAms and process considerations of their use in both kinetic resolution and asymmetric synthesis. With the aid of specific drug intermediates and APIs, we chart the development of ω-TAms using protein engineering and their contribution to elegant one-pot cascades with other enzymes, including carbonyl reductases (CREDs), hydrolases and monoamine oxidases (MAOs), providing a comprehensive overview of their uses, beginning with initial applications through to the present day.

Lipase-Catalyzed Kinetic Resolution of Novel Antifungal N-Substituted Benzimidazole Derivatives

A series of new N-substituted benzimidazole derivatives was synthesized and their antifungal activity against Candida albicans was evaluated. The chemical step included synthesis of appropriate ketones containing benzimidazole ring, reduction of ketones to the racemic alcohols, and acetylation of alcohols to the esters. All benzimidazole derivatives were obtained with satisfactory yields and in relatively short times. All synthesized compounds exhibit significant antifungal activity against Candida albicans 900028 ATCC (% cell inhibition at 0.25 μg concentration > 98%). Additionally, racemic mixtures of alcohols were separated by lipase-catalyzed kinetic resolution. In the enzymatic step a transesterification reaction was applied and the influence of a lipase type and solvent on the enantioselectivity of the reaction was studied. The most selective enzymes were Novozyme SP 435 and lipase Amano AK from Pseudomonas fluorescens (E > 100).

Recent Advances in Lipase-Mediated Preparation of Pharmaceuticals and Their Intermediates

Biocatalysis offers an alternative approach to conventional chemical processes for the production of single-isomer chiral drugs. Lipases are one of the most used enzymes in the synthesis of enantiomerically pure intermediates. The use of this type of enzyme is mainly due to the characteristics of their regio-, chemo- and enantioselectivity in the resolution process of racemates, without the use of cofactors. Moreover, this class of enzymes has generally excellent stability in the presence of organic solvents, facilitating the solubility of the organic substrate to be modified. Further improvements and new applications have been achieved in the syntheses of biologically active compounds catalyzed by lipases. This review critically reports and discusses examples from recent literature (2007 to mid-2015), concerning the synthesis of enantiomerically pure active pharmaceutical ingredients (APIs) and their intermediates in which the key step involves the action of a lipase.

Solvents and sustainable chemistry

Solvents are widely recognized to be of great environmental concern. The reduction of their use is one of the most important aims of green chemistry. In addition to this, the appropriate selection of solvent for a process can greatly improve the sustainability of a chemical production process. There has also been extensive research into the application of so-called green solvents, such as ionic liquids and supercritical fluids. However, most examples of solvent technologies that give improved sustainability come from the application of well-established solvents. It is also apparent that the successful implementation of environmentally sustainable processes must be accompanied by improvements in commercial performance.

The Industrial Age of Biocatalytic Transamination

During the last decade the use of ω-transaminases has been identified as a very powerful method for the preparation of optically pure amines from the corresponding ketones. Their immense potential for the preparation of chiral amines, together with their ease of use in combination with existing biocatalytic methods, have made these biocatalysts a competitor to any chemical methodology for (asymmetric) amination. An increasing number of examples, especially from industry, shows that this biocatalytic technology outmaneuvers existing chemical processes by its simple and flexible nature. In the last few years numerous publications and patents on synthetic routes, mainly to pharmaceuticals, involving ω-transaminases have been published. The review gives an overview of the application of ω-transaminases in organic synthesis with a focus on active pharmaceutical ingredients (APIs) and the developments during the last few years.

Recent Developments in Chemical Synthesis with Biocatalysts in Ionic Liquids

Over the past decade, a variety of ionic liquids have emerged as greener solvents for use in the chemical manufacturing industries. Their unique properties have attracted the interest of chemists worldwide to employ them as replacement for conventional solvents in a diverse range of chemical transformations including biotransformations. Biocatalysts are often regarded as green catalysts compared to conventional chemical catalysts in organic synthesis owing to their properties of low toxicity, biodegradability, excellent selectivity and good catalytic performance under mild reaction conditions. Similarly, a selected number of specific ionic liquids can be considered as greener solvents superior to organic solvents owing to their negligible vapor pressure, low flammability, low toxicity and ability to dissolve a wide range of organic and biological substances, including proteins. A combination of biocatalysts and ionic liquids thus appears to be a logical and promising opportunity for industrial use as an alternative to conventional organic chemistry processes employing organic solvents. This article provides an overview of recent developments in this field with special emphasis on the application of more sustainable enzyme-catalyzed reactions and separation processes employing ionic liquids, driven by advances in fundamental knowledge, process optimization and industrial deployment.

Miniaturization in biocatalysis

The use of biocatalysts for the production of both consumer goods and building blocks for chemical synthesis is consistently gaining relevance. A significant contribution for recent advances towards further implementation of enzymes and whole cells is related to the developments in miniature reactor technology and insights into flow behavior. Due to the high level of parallelization and reduced requirements of chemicals, intensive screening of biocatalysts and process variables has become more feasible and reproducibility of the bioconversion processes has been substantially improved. The present work aims to provide an overview of the applications of miniaturized reactors in bioconversion processes, considering multi-well plates and microfluidic devices, update information on the engineering characterization of the hardware used, and present perspective developments in this area of research.

Utilizing Simple Biochemical Measurements to Predict Lifetime Output of Biocatalysts in Continuous Isothermal Processes

The expected product yield of a biocatalyst during its useful lifetime is an important consideration when designing a continuous biocatalytic process. One important indicator of lifetime biocatalyst productivity is the dimensionless total turnover number (TTN). Here, a method is proposed for estimating the TTN of a given biocatalyst from readily-measured biochemical quantities, namely the specific activity and the deactivation half-life, measured under identical conditions. We demonstrate that this method may be applied to any enzyme whose thermal deactivation follows first-order kinetics, regardless of the number of unfolding intermediates, and that the TTN method circumvents the potential problems associated with measuring specific catalyst output when a portion of the enzyme is already unfolded. The TTN estimation was applied to several representative biocatalysts to demonstrate its applicability in identifying the most cost-effective catalyst from a pool of engineered mutants with similar activity and thermal stability.

Candida spp. redox machineries: an ample biocatalytic platform for practical applications and academic insights

The use of oxidoreductases as biocatalysts for the production of a wide number of chiral building blocks is presently a mature (bio-)technology. In this context some industrial applications are currently performed by means of those enzymatic approaches, and new examples are expected to be realized. Moreover, oxidoreductases provide an interesting academic platform to undertake fundamental research in enzymology, to acquire a better understanding on catalytic mechanisms, and to facilitate the development of new biocatalytic applications. Within this area, a wide number of oxidoreductases from genus Candida spp. have been characterized and used as biocatalysts. These enzymes are rather diverse, and are able to carry out many useful reactions, like highly (enantio)selective keto-reductions, (de)racemizations and stereoinversions, and promiscuous catalytic imine reductions. In addition, some Candida spp. dehydrogenases are very useful for regenerating the cofactors, with the aid of sacrificial substrates. Addressing those features, the present paper aims to give an overview of these enzymes, by focusing on practical applications that these biocatalysts can provide. Furthermore, when possible, academic insights on the enzymatic performances will be discussed as well.

The locks and keys to industrial biotechnology

The sustainable use of resources by Nature to synthesize the required products at the right place, when they are needed, continues to be the role model for total synthesis and production in general. The combination of molecular and engineering science and technology in the biotechnological approach needs no protecting groups at all and has therefore been established for numerous large-scale routes to both natural and synthetic products in industry. The use of biobased raw materials for chemical synthesis, and the economy of molecular transformations like atom economy and step economy are of growing importance. As safety, health and environmental issues are key drivers for process improvements in the chemical industry, the development of biocatalytic reactions or pathways replacing hazardous reagents is a major focus. The integration of the biocatalytic reaction and downstream processing with product isolation has led to a variety of in situ product recovery techniques and has found numerous successful applications. With the growing collection of biocatalytic reactions, the retrosynthetic thinking can be applied to biocatalysis as well. The introduction of biocatalytic reactions is uniquely suited to cost reductions and higher quality products, as well as to more sustainable processes. The transfer of Nature's simple and robust sensing and control principles as well as its reaction and separation organization into useful technical systems can be applied to different fermentations, biotransformations and downstream processes. Biocatalyst and pathway discovery and development is the key towards new synthetic transformations in industrial biotechnology.