Search Results (25)

Biocatalysis is fundamental to biological processes and sustainable chemical productions. Over time, the biocatalysis strategy has been widely researched. Initially, biomanufacturing and catalysis of high-value chemicals were carried out through direct immobilization and application of biocatalysts, including natural enzymes and living cells. With the evolution of green chemistry and environmental concern, hybrid photoelectro-biocatalysis (HPEB) platforms are seen as a new approach to enhance biocatalysis. This strategy greatly expands the domain of natural biocatalysis, especially for bio-based components. The selective valorization of renewable furan derivatives, such as 5-hydroxymethylfurfural (HMF) and furfural, is central to advancing biomass-based chemical production. Biocatalysis offers high chemo-, regio-, and stereo-selectivity under mild conditions compared with traditional chemical catalysis, yet it is often constrained by the costly and inefficient regeneration of redox cofactors like NAD(P)H. Photoelectrocatalysis provides a sustainable means to supply reducing equivalents using solar or electrical energy. In recent years, hybrid systems that integrate biocatalysis with photoelectrocatalysis have emerged as a promising strategy to overcome this limitation. This review focuses on recent advances in such systems, where photoelectrochemical platforms enable in situ cofactor regeneration to drive enzymatic transformations of furan-based substrates. We critically analyze representative coupling strategies, materials and device configurations, and reaction engineering approaches. Finally, we outline future directions for developing efficient, robust, and industrially viable hybrid catalytic platforms for green biomass valorization. Full article

Spirocyclic architectures, which feature two rings sharing a single atom, are common in natural products and exhibit beneficial biological and material properties. Due to the significance of these architectures, biocatalytic dearomative spirocyclization has recently emerged as a powerful approach for constructing three-dimensional spirocyclic frameworks under mild, sustainable conditions and with exquisite stereocontrol. This review surveys the latest advances in biocatalyzed spirocyclization of all-carbon arenes (phenols and benzenes), aza-aromatics (indoles and pyrroles), and oxa-aromatics (furans). We highlight cytochrome P450s, flavin-dependent monooxygenases, multicopper oxidases, and novel metalloenzyme platforms that effect regio- and stereoselective oxidative coupling, epoxidation/semi-pinacol rearrangement, and radical-mediated cyclization to produce diverse spirocycles. Mechanistic insights gleaned from structural, computational, and isotope-labeling studies are discussed where necessary to help the readers further understand the reported reactions. Collectively, these examples demonstrate the transformative potential of biocatalysis to streamline access to spirocyclic scaffolds that are challenging to prepare through traditional methods, underscoring biocatalysis as a transformative tool for synthesizing pharmaceutically relevant spiroscaffolds while adhering to green chemistry paradigms to ultimately contribute to a cleaner and more sustainable future. Full article

Cytochrome P450 enzymes (CYPs) are versatile heme-containing monooxygenases involved in the metabolism of endogenous and exogenous compounds, as well as natural product biosynthesis. Their ability to catalyze regio- and stereoselective oxidation reactions makes them valuable in pharmaceuticals, fine chemicals, and biocatalysis. However, wild-type CYPs suffer from low catalytic efficiency, limited substrate specificity, and instability under industrial conditions. Recent advances in protein engineering—rational design, semi-rational design, and directed evolution—have enhanced their activity, stability, and substrate scope. These strategies have enabled CYPs to be engineered for applications like C–H functionalization, carbene transfer, and complex molecule biosynthesis. Despite progress, challenges remain in optimizing efficiency, expanding substrate ranges, and scaling production for industrial use. Future directions include integrating CYPs with other biocatalysts, improving high-throughput screening, and applying machine learning to enzyme design. This review highlights recent developments and the promising future of engineered CYPs in sustainable chemistry, drug development, and high-value chemical production. Full article

Three fungal strains were employed for the stereoselective oxidation of the cheap and commercially available substrate 2-phenylethanol, which resulted in chiral building blocks being received. The whole-cell biocatalysts were as follows: Beauveria bassiana DSM 1344, Beauveria brongniartii DSM 6651, and Rhizopus arrhizus DSM 1185. The main product of Beauveria bassiana bioconversion was 1-phenylethane-1,2-diol, obtained, depending on the form of the biocatalyst, as an R-enantiomer (e.g., 99.9%) with fresh biomass application or as a racemic mixture in cases of immobilization in agar-agar. The best and most innovative results for the synthesis of the R-enantiomer of diol were received under precisely defined conditions as a result of a scaling study conducted on an automatic batch reactor. This is a pioneering result, since, in previous studies, fresh mycelium of Aspergillus niger resulted in this product being received as the (S) enantiomer. Also, the use of Rhizopus arrhizus DSM 1185 (immobilized in polyurethane foams) presented important results, as the bioconversion of phenyl ethanol led, indeed, to the racemic mixture of 1-phenylethane-1,2-diol but was accompanied by a noticeable tyrosol synthesis, which had not been reported previously. Full article

Dihydroxyacetone phosphate (DHAP)-dependent aldolases catalyze the aldol addition of DHAP to a variety of aldehydes and generate compounds with two stereocenters. This reaction is useful to synthesize chiral acyclic nucleosides, which constitute a well-known class of antiviral drugs currently used. In such compounds, the chirality of the aliphatic chain, which mimics the open pentose residue, is crucial for activity. In this work, three DHAP-dependent aldolases: fructose-1,6-biphosphate aldolase from rabbit muscle, rhanmulose-1-phosphate aldolase from Thermotoga maritima, and fuculose-1-phosphate aldolase from Escherichia coli, were used as biocatalysts. Aldehyde derivatives of thymine and cytosine were used as acceptor substrates, generating new acyclic nucleoside analogues containing two new stereocenters with conversion yields between 70% and 90%. Moreover, structural analyses by molecular docking were carried out to gain insights into the diasteromeric excess observed. Full article

Flavin-dependent monooxygenases (FMOs) have raised substantial interest as catalysts in monooxygenation reactions, impacting diverse fields such as drug metabolism, environmental studies, and natural product synthesis. Their application in biocatalysis boasts several advantages over conventional chemical catalysis, such as heightened selectivity, safety, sustainability, and eco-friendliness. In the realm of biomedicine, FMOs are pivotal in antibiotic research, significantly influencing the behavior of natural products, antimicrobial agents, and the pathways critical to drug synthesis They are also underscored as potential pharmaceutical targets, pivotal in opposing disease progression and viable for therapeutic intervention. Additionally, FMOs play a substantial role in environmental science, especially in pesticide processing and in preserving plant vitality. Their involvement in the biosynthesis of compounds like polyethers, tropolones, and ω-hydroxy fatty acids, with remarkable regio- and stereoselectivity, renders them indispensable in drug discovery and development. As our comprehension of FMOs’ catalytic mechanisms and structures advances, through the use of cutting-edge biotechnologies like computational design and directed evolution, FMOs are poised to occupy an increasingly significant role in both scientific exploration and industrial applications. Full article

Objective: Optically active (R)-ethyl 4-chloro-3-hydroxybutyrate ((R)-CHBE) is a useful chiral building block for the synthesis of pharmaceuticals. Recently, there has been great interest in the synthesis of (R)-CHBE via the highly stereoselective bioreduction of ethyl 4-chloro-3-oxobutanoate (COBE) under mild conditions. Methods: A highly efficient bioreduction process for transforming COBE into (R)-CHBE was developed in a biocompatible organic solvent–deep eutectic solvent–water reaction medium. Results: Recombinant Escherichia coli containing carbonyl reductase (CgCR) and glucose dehydrogenase (GDH) was successfully constructed and characterized. In addition, the feasibility of the asymmetric bioreduction of COBE to (R)-CHBE was verified in an organic solvent–deep eutectic solvent–water (ethyl acetate-betaine/lactic acid-water) system. At pH 7.0 and 30 °C, the kinetic constants Km and kcat of COBE were 20.9 mM and 56.1 s⁻¹, respectively. A high (R)-CHBE yield (≥90%) was achieved by catalyzing COBE (1000 mM) in 12 h with E. coli CgCR cells in the presence of Ni²⁺ (7 mM) and glucose (3.5 mM glucose/mM COBE) in an ethyl acetate-betaine/lactic acid-H₂O (50/7/43, v/v/v) system. The effects of organic solvents and DESs on whole-cell permeability were analyzed. Conclusions: An efficient bioreduction system was constructed for biologically transforming COBE to (R)-CHBE via whole-cell biocatalysis, and the established bioprocess has potential application in future. Full article

Tetrahydroprotoberberines (THPBs) are plant-specific alkaloids with significant medicinal value. They are present in trace amounts in plants and are difficult to chemically synthesize due to stereoselectivity and an unfavorable environment. In this study, a selective methylation strategy was developed for the biocatalysis of seven high-value-added THPB compounds using 4’-O-methyltransferase (Cj4’OMT), norcoclaurine 6-O-methyltransferase (Cj6OMT), and (S)-scoulerine 9-O-methyltransferase (SiSOMT and PsSOMT) in engineered E. coli. The methyltransferases Cj4’OMT, Cj6OMT, PsSOMT, and SiSOMT were expressed heterologously in E. coli. Compound 1 (10-methoxy-2,3,9-tetrahydroxyberbine) was synthesized using the recombinant E. coli strain Cj4’OMT and the substrate 2,3,9,10-tetrahydroxyberbine. Compound 2 (9-methoxy-2,3,10-tetrahydroxyberbine) was produced in the recombinant Escherichia coli (E. coli) strain PsSOMT, and compounds 2 and 3 (discretamine) were produced in the recombinant E. coli strain SiSOMT. Compounds 4 (9,10-methoxy-2,3-tetrahydroxyberbine) and 5 (corypalmine) were obtained by co-culturing the recombinant strains Cj4’OMT and SiSOMT with substrate. Compounds 6 (scoulerine) and 7 (isoscoulerine) were produced by co-culturing the substrate with the recombinant strains Cj4’OMT and Cj6OMT. To increase the yield of novel compound 2, the flask culture conditions of the engineered SiSOMT strain were optimized, resulting in the production of 165.74 mg/L of this compound. This study thus presents an enzymatic approach to the synthesis of high-value-added THPBs with minimum environmental wastage. Full article

Different approaches can be undertaken to realise a stereoselective electrochemical synthesis. Significant contributions to enantioselective electrochemical organic synthesis have been reported and largely reviewed in recent years. However, the development of general strategies for the electrochemical enantiocontrol of a transformation still presents considerable challenges; in particular, relatively few contributions of highly enantioselective catalytic electrochemical reactions have been reported to date. In this review article, the most recent examples of asymmetric electrochemical catalysis are discussed. The article is organised by the three types of enantioselective catalysis: metal-based catalysis, organocatalysis and biocatalysis; in each section, the most significant and recent advances are presented and discussed. Full article

The biocatalytic asymmetric reduction of prochiral ketones for the production of enantiopure alcohols is highly desirable due to its inherent advantages over chemical methods. In this study, a new bacterial strain capable of transforming ketones to corresponding alcohols with high activity and excellent enantioselectivity was discovered in a soil sample. The strain was subsequently identified as Bacillus cereus TQ-2 based on its physiological characteristics and 16S rDNA sequence analysis. Under optimized reaction conditions, the resting cells of B. cereus TQ-2 converted acetophenone to enantioenriched (R)-1-phenylethanol with 99% enantiometric excess following anti-Prelog’s rule, which is scarce in biocatalytic ketone reduction. The optimum temperature for the cells was 30 °C, and considerable catalytic activity was observed over a broad pH range from 5.0 to 9.0. The cells showed enhanced catalytic activity in the presence of 15% (v/v) glycerol as a co-substrate. The catalytic activity can also be substantially improved by adding Ca²⁺ or K⁺ ions. Moreover, the B. cereus TQ-2 cell was highly active in reducing several structurally diverse ketones and aldehydes to form corresponding alcohols with good to excellent conversion. Our study provides a versatile whole-cell biocatalyst that can be used in the asymmetric reduction of ketones for the production of chiral alcohol, thereby expanding the biocatalytic toolbox for potential practical applications. Full article

Stereoselective synthesis has been emerging as a resourceful tool because it enables the obtaining of compounds with biological interest and high enantiomeric purity. Flavonoids are natural products with several biological activities. Owing to their biological potential and aiming to achieve enantiomerically pure forms, several methodologies of stereoselective synthesis have been implemented. Those approaches encompass stereoselective chalcone epoxidation, Sharpless asymmetric dihydroxylation, Mitsunobu reaction, and the cycloaddition of 1,4-benzoquinone. Chiral auxiliaries, organo-, organometallic, and biocatalysis, as well as the chiral pool approach were also employed with the goal of obtaining chiral bioactive flavonoids with a high enantiomeric ratio. Additionally, the employment of the Diels–Alder reaction based on the stereodivergent reaction on a racemic mixture strategy or using catalyst complexes to synthesise pure enantiomers of flavonoids was reported. Furthermore, biomimetic pathways displayed another approach as illustrated by the asymmetric coupling of 2-hydroxychalcones driven by visible light. Recently, an asymmetric transfer hydrogen-dynamic kinetic resolution was also applied to synthesise (R,R)-cis-alcohols which, in turn, would be used as building blocks for the stereoselective synthesis of flavonoids. Full article

Cytochrome P450s are heme-containing enzymes capable of the oxidative transformation of a wide range of organic substrates. A protein scaffold that coordinates the heme iron, and the catalytic pocket residues, together, determine the reaction selectivity and regio- and stereo-selectivity of the P450 enzymes. Different substrates also affect the properties of P450s by binding to its catalytic pocket. Modulating the redox potential of the heme by substituting iron-coordinating residues changes the chemical reaction, the type of cofactor requirement, and the stereoselectivity of P450s. Around hundreds of P450s are experimentally characterized, therefore, a mechanistic understanding of the factors affecting their catalysis is increasingly vital in the age of synthetic biology and biotechnology. Engineering P450s can enable them to catalyze a variety of chemical reactions viz. oxygenation, peroxygenation, cyclopropanation, epoxidation, nitration, etc., to synthesize high-value chiral organic molecules with exceptionally high stereo- and regioselectivity and catalytic efficiency. This review will focus on recent studies of the mechanistic understandings of the modulation of heme redox potential in the engineered P450 variants, and the effect of small decoy molecules, dual function small molecules, and substrate mimetics on the type of chemical reaction and the catalytic cycle of the P450 enzymes. Full article

In a metagenome mining-based search of novel thermostable hydroxysteroid dehydrogenases (HSDHs), enzymes that are able to selectively oxidize/reduce steroidal compounds, a novel short-chain dehydrogenase/reductase (SDR), named Is2-SDR, was recently discovered. This enzyme, found in an Icelandic hot spring metagenome, shared a high sequence similarity with HSDHs, but, unexpectedly, showed no activity in the oxidation of the tested steroid substrates, e.g., cholic acid. Despite that, Is2-SDR proved to be a very active and versatile ketoreductase, being able to regio- and stereoselectively reduce a diversified panel of carbonylic substrates, including bulky ketones, α- and β-ketoesters, and α-diketones of pharmaceutical relevance. Further investigations showed that Is2-SDR was indeed active in the regio- and stereoselective reduction of oxidized steroid derivatives, and this outcome was rationalized by docking analysis in the active site model. Moreover, Is2-SDR showed remarkable thermostability, with an apparent melting temperature (T_M) around 75 °C, as determined by circular dichroism analysis, and no significant decrease in catalytic activity, even after 5 h at 80 °C. A broad tolerance to both water-miscible and water-immiscible organic solvents was demonstrated as well, thus, confirming the potential of this new biocatalyst for its synthetic application. Full article

Hydrolases, being most prominent enzymes used in industrial processes have left no stone unturned in fascinating the pharmaceutical industry. Lipases, being a part of acyl hydrolases are the ones that function similarly to esterases (except an interfacial action) wherein they generally catalyze the hydrolysis of ester bonds. Be it in terms of stereoselectivity or regioselectivity, lipases have manifested their promiscuous proficiency in rendering biocatalytic drug synthesis and intermediates thereof. Industrial utilization of lipases is prevalent since decades ago, but their distinctive catalytic competencies have rendered them suitable for maneuverability in various tides of biocatalytic industrial process development. Numbers of exquisite catalysts have been fabricated out of lipases using nanobiotechnology whereby enzyme reusability and robustness have been conferred to many of the organic synthesis procedures. This marks a considerable achievement of lipases in the second wave of biocatalysis. Furthermore, in the third wave an advent of genetic engineering has fostered an era of customized lipases for suitable needs. Be it stability or an enhanced efficacy, genetic engineering techniques have ushered an avenue for biocatalytic development of drugs and drug intermediates through greener processes using lipases. Even in the forthcoming concept of co-modular catalytic systems, lipases may be the frontiers because of their astonishing capability to act along with other enzymes. The concept may render feasibility in the development of cascade reactions in organic synthesis. An upcoming wave demands fulfilling the vision of tailored lipase whilst a far-flung exploration needs to be unveiled for various research impediments in rendering lipase as a custom fit biocatalyst in pharmaceutical industry. Full article

Multi-step cascade reactions have gained increasing attention in the biocatalysis field in recent years. In particular, multi-enzymatic cascades can achieve high molecular complexity without workup of reaction intermediates thanks to the enzymes’ intrinsic selectivity; and where enzymes fall short, organo- or metal catalysts can further expand the range of possible synthetic routes. Here, we present two enantiocomplementary (chemo)-enzymatic cascades composed of either a styrene monooxygenase (StyAB) or the Shi epoxidation catalyst for enantioselective alkene epoxidation in the first step, coupled with a halohydrin dehalogenase (HHDH)-catalysed regioselective epoxide ring opening in the second step for the synthesis of chiral aliphatic non-terminal azidoalcohols. Through the controlled formation of two new stereocenters, corresponding azidoalcohol products could be obtained with high regioselectivity and excellent enantioselectivity (99% ee) in the StyAB-HHDH cascade, while product enantiomeric excesses in the Shi-HHDH cascade ranged between 56 and 61%. Full article