Enzymatic production of enantiopure ketoprofen in a solvent-free two-phase system

Enhanced Production of (S)-2-arylpropionic Acids by Protein Engineering and Whole-Cell Catalysis

Esterases are important biocatalysts for chemical synthesis. Several bHSL family esterases have been used to prepare (S)-2-arylpropionic acids with stronger anti-inflammatory effects via kinetic resolution. Here, we presented the discovery of key residues that controlled the enantioselectivity of bHSL family esterases to ethyl 2-arylpropionates, through careful analysis of the structural information and molecular docking. A new bHSL family esterase, Est924, was identified as a promising catalyst for kinetic resolution of racemic ethyl 2-arylpropionates with slight (R)-stereopreference. Using Est924 as the starting enzyme, protein engineering was conducted at hotspots, and the substitution of A203 was proved to enhance the enantioselectivity. The stereopreference of the mutant M1 (A203W) was inverted to ethyl (S)-2-arylpropionates, and this stereopreference was further improved in variant M3 (I202F/A203W/G208F). In addition, the optimal variant, M3, was also suitable for the resolution of ibuprofen ethyl ester and ketoprofen ethyl ester, and their efficient (S)-isomers were synthesized. Next, the whole-cell catalyst harboring M3 was used to prepare (S)-ketoprofen. (S)-ketoprofen with 86%ee was produced by whole-cell catalyst with a single freeze-thaw cycle, and the cells could be reused for at least five cycles. Our results suggested that Est924 variants could kinetically resolve economically important racemates for industrial production and further offer the opportunity for the rational design of enzyme enantioselectivity. Moreover, it is an economical process to prepare optically pure (S)-ketoprofen and (S)-naproxen by using an engineered strain harboring M3 as the catalyst.

Solubility and thermodynamic analysis of ketoprofen in organic solvents

The solubility of the racemic solid phase of ketoprofen (KTP) in methanol, ethanol, isopropanol, butanol, acetonitrile, ethyl acetate, 1,4-dioxane and toluene has been determined between 273 and 303 K by a gravimetric method. FTIR and Raman spectroscopy, SEM and PXRD, have been used to characterise the solid phase. The melting data and heat capacity of solid and melt have been determined by DSC, and used to estimate fusion thermodynamics and the activity of the solid phase as functions of temperature. Empirical and semi-empirical models have been fitted to experimental solubility data. The solution activity coefficients reveal positive deviation from ideality in all solvents except for in dioxane, and very close to ideality in methanol. The solubility is fairly high in the alcohols but decrease with increasing hydrocarbon chain. Generally and due to the presence of the carboxylic acid group, KTP is more readily dissolved in polar protic solvents, followed in order by polar aprotic and non-polar solvents. However, the highest solubility is found in dioxane, classified as a non-polar solvent, but notably though the molecule having two strong hydrogen bond accepting functionalities, and no hydrogen bond donation capability.

Kinetic resolution of racemic naproxen methyl ester by magnetic and non-magnetic cross-linked lipase aggregates

In this study, the non-magnetic and the magnetic cross-linked enzyme aggregates (CLEAs) from Candida rugosa lipase were synthesized to catalyze the kinetic resolution reaction of naproxen methyl ester (NME). Magnetic iron oxide nanoparticles (MIONPs) were produced through co-precipitation method and their surfaces were modified by silanization reaction. The MIONPs were used as a platform to synthesize the magnetic CLEAs (M-CLEAs). The biocatalysts and MIONPs synthesized were characterized by FTIR spectroscopy and SEM analysis. The kinetic resolution of racemic NME was studied in aqueous buffer solution/isooctane biphasic system to compare the performance of M-CLEAs and CLEAs. The effects of reaction parameters such as temperature, pH, stirring rate on the enantiomeric excess of the substrate (ee_s%) were investigated in a batch reactor system. The activity recovery of CRL enzyme in CLEAs was higher than M-CLEAs. Compared with M-CLEAs, CLEAs biocatalysts had previously reached ee_s% values. Although both biocatalysts showed similar cavity structure from SEM analysis, the lower performance of M-CLEAs may be due to the different microenvironments of M-CLEAs from CLEAs. However, the reusability performance of M-CLEAs was higher than that of CLEAs. The optimal reaction conditions for M-CLEAs and CLEAs were found to be 37 °C, pH 7.5, and 300 rpm.

Relevance and bio-catalytic strategies for the kinetic resolution of ketoprofen towards dexketoprofen

This review presents the most relevant investigations concerning the biocatalytic kinetic resolution of racemic ketoprofen to dexketoprofen for the last 22 years. The advantages related to the administration of the dex-enantiomer in terms of human health, the so called "chiral switch" in the pharmaceutical industry and the sustainability of biotransformations have been the driving forces to develop innovative technology to obtain dexketoprofen. In particular, the kinetic resolution of racemic ketoprofen through enantiomeric esterification and hydrolysis using lipases as biocatalysts are thoroughly revised and commented upon. In this context, the biocatalysts, acyl-acceptors (alcohols), reaction conditions, conversion, enantiomeric excess, and enantiomeric ratio among others are discussed. Moreover, the investigations concerning scaling up processes in order to obtain an optically pure enantiomer of the profen are presented. Finally, some guidelines about perspectives of the technology and research opportunities are given.

Molecular recognition of an acyl–enzyme intermediate on the lipase B from Candida antarctica

Ketoprofen and serine form an acyl–enzyme intermediate species that vibrates at 1756 cm⁻¹ in the infrared spectra.