Synergistic effects of components in deep eutectic solvents relieve toxicity and improve the performance of steroid biotransformation catalyzed by Arthrobacter simplex

Abstract

BACKGROUND The discovery of deep eutectic solvents (DESs) has introduced a new class of promising green solvents to overcome many drawbacks associated with organic solvents. In this study, the synergistic effects of the components in the form of DESs on bacterial viability, membrane integrity, and retention of metabolic activity as well as the efficiency of Δ1,2‐dehydrogeneration of cortisone acetate (CA) using whole cells of Arthrobacter simplex were investigated. RESULTS The agar disc diffusion method, viability assays and the retention of sugar metabolic activity were used to investigate their toxicity to A. simplex. The results indicated that colinium salts were more toxic than the corresponding hydrogen bond donor (HBDs), but their deleterious effect could be weakened by incorporating them into DESs. Moreover, the best catalytic performance was found in the ChCl:U(DES)‐containing system when Δ1,2‐dehydrogeneration using A. simplex was carried out in three different systems followed by the addition of DES, their components and their mixtures, respectively. In addition, metabolites with significantly changed concentration were identified by means of gas chromatography–mass spectrometry (GC–MS) and principal component analysis, which revealed five compounds that may be used as potential indicators to discriminate the effects of different concentrations of DESs on A. simplex. CONCLUSION The cholinium salts used in this study were toxic to A. simplex to some extent, while synergistic effects were observed after DES formation. The efficient biotransformation in DESs especially in the ChCl:U(DES)‐containing system potentially offers a promising strategy for the production of many different steroids. © 2018 Society of Chemical Industry

Designing a biocatalytic process involving deep eutectic solvents

“…These studies indicated that a DEScontaining system can result in a remarkable improvement in the reaction efficiency in respect to the substrate solubility and loading and, consequently, improve the productivity of the biocatalytic process. 35,68,69 For example, DESs used as co-solvents enhanced the efficiency of C1,2-dehydrogeneration by improving the solubility of the highly hydrophobic substrate. 35 To be more precise, the solubility of cortisone acetate in Ch:U (1:2 mol mol −1 ) was improved to 0.0436 mg mL −1 , in comparison with solubility in water (0.0215 mg mL −1 ) and ethanol (0.0280 mg mL 1 ).…”

“…35,68,69 For example, DESs used as co-solvents enhanced the efficiency of C1,2-dehydrogeneration by improving the solubility of the highly hydrophobic substrate. 35 To be more precise, the solubility of cortisone acetate in Ch:U (1:2 mol mol −1 ) was improved to 0.0436 mg mL −1 , in comparison with solubility in water (0.0215 mg mL −1 ) and ethanol (0.0280 mg mL 1 ). Xu et al 69 , when studying asymmetric reduction of 3-chloropropiophenone with immobilised Acetobacter sp.…”

“…As substrate solubility and loading are the key parameters influencing biocatalytic process productivity, several research groups have investigated the differences in optimal substrate concentration in DESs compared with referent solvents (buffer or organic solvents). These studies indicated that a DES‐containing system can result in a remarkable improvement in the reaction efficiency in respect to the substrate solubility and loading and, consequently, improve the productivity of the biocatalytic process 35,68,69 . For example, DESs used as co‐solvents enhanced the efficiency of C1,2‐dehydrogeneration by improving the solubility of the highly hydrophobic substrate 35 .…”

The Versatile Applications of DES and Their Influence on Oxidoreductase-Mediated Transformations

“…Viability assays were carried out and the researchers concluded that the cell membrane of A. simplex in the presence of cholinium chloride was less stable compared to its presence with the different HBDs. The group also found out that the ChCl:Ur mixture was a good co-solvent in the steroid dehydrogenation reaction, and that the initial reaction rate for this reaction was higher compared to the ones that were performed in the DES individual components [42].…”

Positive Impact of Natural Deep Eutectic Solvents on the Biocatalytic Performance of 5-Hydroxymethyl-Furfural Oxidase

“…Several examples have been described in which a (NA)DES was applied in the presence of different types of biocatalysts [27][28][29][30], including their use in redox biotransformations [31,32]. Specifically, NADESs have been employed in selective reductions catalyzed by alcohol dehydrogenases [33][34][35], as well as in oxidations using different types of enzymes [36][37][38][39][40]. Yet, until recently, no examples of the application of DESs as cosolvents in reactions catalyzed by flavin-containing oxidases have been reported.…”