Biotransformation of halogenated nucleosides by immobilized Lactobacillus animalis 2′- N -deoxyribosyltransferase

Magnetic Multi-Enzymatic System for Cladribine Manufacturing

Enzyme-mediated processes have proven to be a valuable and sustainable alternative to traditional chemical methods. In this regard, the use of multi-enzymatic systems enables the realization of complex synthetic schemes, while also introducing a number of additional advantages, including the conversion of reversible reactions into irreversible processes, the partial or complete elimination of product inhibition problems, and the minimization of undesirable by-products. In addition, the immobilization of biocatalysts on magnetic supports allows for easy reusability and streamlines the downstream process. Herein we have developed a cascade system for cladribine synthesis based on the sequential action of two magnetic biocatalysts. For that purpose, purine 2′-deoxyribosyltransferase from Leishmania mexicana (LmPDT) and Escherichia coli hypoxanthine phosphoribosyltransferase (EcHPRT) were immobilized onto Ni2+-prechelated magnetic microspheres (MagReSyn®NTA). Among the resulting derivatives, MLmPDT3 (activity: 11,935 IU/gsupport, 63% retained activity, operational conditions: 40 °C and pH 5–7) and MEcHPRT3 (12,840 IU/gsupport, 45% retained activity, operational conditions: pH 5–8 and 40–60 °C) emerge as optimal catalysts for further synthetic application. Moreover, the MLmPDT3/MEcHPRT3 system was biochemically characterized and successfully applied to the one-pot synthesis of cladribine under various conditions. This methodology not only displayed a 1.67-fold improvement in cladribine synthesis (compared to MLmPDT3), but it also implied a practically complete transformation of the undesired by-product into a high-added-value product (90% conversion of Hyp into IMP). Finally, MLmPDT3/MEcHPRT3 was reused for 16 cycles, which displayed a 75% retained activity.

Green Production of Cladribine by Using Immobilized 2'-Deoxyribosyltransferase from Lactobacillus delbrueckii Stabilized through a Double Covalent/Entrapment Technology

Nowadays, enzyme-mediated processes offer an eco-friendly and efficient alternative to the traditional multistep and environmentally harmful chemical processes. Herein we report the enzymatic synthesis of cladribine by a novel 2'-deoxyribosyltransferase (NDT)-based combined biocatalyst. To this end, Lactobacillus delbrueckii NDT (LdNDT) was successfully immobilized through a two-step immobilization methodology, including a covalent immobilization onto glutaraldehyde-activated biomimetic silica nanoparticles followed by biocatalyst entrapment in calcium alginate. The resulting immobilized derivative, SiG_{PEI 25000}-LdNDT-Alg, displayed 98% retained activity and was shown to be active and stable in a broad range of pH (5-9) and temperature (30-60 °C), but also displayed an extremely high reusability (up to 2100 reuses without negligible loss of activity) in the enzymatic production of cladribine. Finally, as a proof of concept, SiG_{PEI 25000}-LdNDT-Alg was successfully employed in the green production of cladribine at mg scale.

New trends in the biocatalytic production of nucleosidic active pharmaceutical ingredients using 2'-deoxyribosyltransferases

Nowadays, pharmaceutical industry demands competitive and eco-friendly processes for active pharmaceutical ingredients (APIs) manufacturing. In this context, enzyme and whole-cell mediated processes offer an efficient, sustainable and cost-effective alternative to the traditional multi-step and environmentally-harmful chemical processes. Particularly, 2'-deoxyribosyltransferases (NDTs) have emerged as a novel synthetic alternative, not only to chemical but also to other enzyme-mediated synthetic processes. This review describes recent findings in the development and scaling up of NDTs as industrial biocatalysts, including the most relevant and recent examples of single enzymatic steps, multienzyme cascades, chemo-enzymatic approaches, and engineered biocatalysts. Finally, to reflect the inventive and innovative steps of NDT-mediated bioprocesses, a detailed analysis of recently granted patents, with specific focus on industrial synthesis of nucleoside-based APIs, is hereunder presented.

Decitabine bioproduction using a biocatalyst with improved stability by adding nanocomposites

A novel IDA-LaNDT derivative was able to reach the highest productivity in the biosynthesis of a well-known antitumoral agent called decitabine. However, the combination of two simple and inexpensive techniques such as ionic absorption and gel entrapment with the incorporation of a bionanocomposite such as bentonite significantly improved the stability of this biocatalyst. These modifications allowed the enhancement of storage stability (for at least 18 months), reusability (400 h of successive batches without significant loss of its initial activity), and thermal and solvent stability with respect to the non-entrapped derivative. Moreover, reaction conditions were optimized by increasing the solubility of 5-aza by dilution with dimethylsulfoxide. Therefore, a scale-up of the bioprocess was assayed using the developed biocatalyst, obtaining 221 mg/L·h of DAC. Finally, green parameters were calculated using the nanostabilized biocatalyst, whose results indicated that it was able to biosynthesize DAC by a smooth, cheap, and environmentally friendly methodology.

Biotransformation of cladribine by a nanostabilized extremophilic biocatalyst

Cladribine (2-chloro-2'-deoxy-β-d-adenosine) is a 2'-deoxyadenosine analogue, approved by the FDA for the treatment of hairy cell leukemia and more recently has been proved for therapeutic against many autoimmune diseases as multiple sclerosis. The biosynthesis of this compound using Thermomonospora alba CECT 3324 as biocatalyst is herein reported. This thermophilic microorganism was successfully entrapped in polyacrylamide gel supplemented with nanoclays such as bentonite. The immobilized biocatalyst (T. alba-Ac-Bent 1.00 %), was able to biosynthesize cladribine with a conversion of 89 % in 1 h of reaction and retains its activity for more than 270 reuses without significantly activity loss, showing better operational stability and mechanical properties than the natural matrix. A microscale assay using the developed system, could allow the production of at least 181 mg of cladribine in successive bioprocesses.

Biotransformation of cladribine by a magnetic immobilizated biocatalyst of Lactobacillus animalis

A stable biocatalyst with magnetic properties based on immobilized Lactobacillus animalis ATCC 35,046 to obtain 2-chloroadenine-2'-deoxyriboside, known as cladribine, is reported for the first time. This nucleoside analogue is an antitumor agent used in the treatment of a wide variety of types of leukemia. In this study, an eco-compatible and alternative bioprocess to obtain cladribine was developed. Product conversion was close to 90% at 2 h in optimized nonconventional reaction media. The microscale biosynthesis of the compound of interest afforded a total productivity close to 370 mg/L/h in the presence of DMSO, and it was stable at least for 30 days in storage conditions.

Sustainable production of nucleoside analogues by a high-efficient purine 2'-deoxyribosyltransferase immobilized onto Ni2+ chelate magnetic microparticles

The present work aims to develop a magnetic biocatalyst for customized production of nucleoside analogues using mutant His-tagged purine 2'-deoxyribosyltransferase from Trypanosoma brucei (TbPDT_V11S) immobilized onto Ni²⁺ chelate magnetic iron oxide porous microparticles (MTbPDT_V11S). Biochemical characterization revealed MTbPDT_V11S5 as optimal candidate for further studies (10,552 IU g^-1; retained activity 54% at 50 °C and pH 6.5). Interestingly, MTbPDT_V11S5 displayed the highest activity value described up to date for an immobilized NDT. Moreover, MTbPDT_V11S5 was successfully employed in the one-pot, one-step production of different therapeutic nucleoside analogues, such as cladribine or 2'-deoxy-2-fluoroadenosine, among others. Finally, MTbPDT_V11S5 proved to be stable when stored at 50 °C for 8 h and pH 6.0 and reusable up to 10 times without negligible loss of activity in the enzymatic production of the antitumor prodrug 2'-deoxy-2-fluoroadenosine.

Characterization of an atypical, thermostable, organic solvent- and acid-tolerant 2'-deoxyribosyltransferase from Chroococcidiopsis thermalis

In our search for thermophilic and acid-tolerant nucleoside 2'-deoxyribosyltransferases (NDTs), we found a good candidate in an enzyme encoded by Chroococcidiopsis thermalis PCC 7203 (CtNDT). Biophysical and biochemical characterization revealed CtNDT as a homotetramer endowed with good activity and stability at both high temperatures (50-100 °C) and a wide range of pH values (from 3 to 7). CtNDT recognizes purine bases and their corresponding 2'-deoxynucleosides but is also proficient using cytosine and 2'-deoxycytidine as substrates. These unusual features preclude the strict classification of CtNDT as either a type I or a type II NDT and further suggest that this simple subdivision may need to be updated in the future. Our findings also hint at a possible link between oligomeric state and NDT's substrate specificity. Interestingly from a practical perspective, CtNDT displays high activity (80-100%) in the presence of several water-miscible co-solvents in a proportion of up to 20% and was successfully employed in the enzymatic production of several therapeutic nucleosides such as didanosine, vidarabine, and cytarabine.