Kinetic resolution of ketoprofen ester catalyzed by lipase from a mutant of CBS 5791

Lipase Assisted (S)-Ketoprofen Resolution from Commercially Available Racemic Mixture

Ketoprofen is a commercially available drug sold as a racemic mixture that belongs to the family of non-steroidal anti-inflammatory drugs known as profens. It has been demonstrated (in vitro) that (S)-ketoprofen is around 160 times more potent than its enantiomer (R)-ketoprofen, while accumulation of (R)-ketoprofen can cause serious side effects, such as dyspepsia, gastrointestinal ulceration/bleeding, pain, salt and fluid retention, and hypertension. In this work, four commercially available lipases were systematically assessed. Parameters such as conversion, enantiomeric excess, and enantioselectivity were considered. Among them, and by evaluating lipase load, temperature, solvent, and alcohol, Candida rugosa lipase exhibited the best results in terms of enantioselectivity E = 185 ((S)-enantiopreference) with esterification conversions of c = 47% (out of 50%) and enantiomeric excess of 99%. The unreacted (R)-enantiomer was recovered by liquid-liquid extraction and racemized under basic media, which was recycled as starting material. Finally, the (S)-alkyl ketoprofen ester was successfully enzymatically hydrolyzed to the desired (S)-ketoprofen with c = 98.5% and 99% ee. This work demonstrated the benefit and efficiency of using Candida rugosa lipase to kinetically resolve racemic ketoprofen by an environmentally friendly protocol and with the recycling of the undesired (R)-ketoprofen.

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.

Chemoenzymatic synthesis of the chiral herbicide: (S)-metolachlor

A chemoenzymatic approach for the production of (S)-metolachlor, one of the most widely used herbicides, has been developed. The starting material (S)-N-(2-ethyl-6-methylphenyl)alanine was obtained by the use of lipase-catalyzed hydrolytic kinetic resolution. Under the optimal conditions, the good activity and excellent enantioselectivity of lipase B from Candida antarctica (CAL-B,E > 100) are achieved in diethyl ether – water (15% v/v), which is about 9.7-fold more enantioselective than that in a pure buffered aqueous solution (E = 12.1). After a simple extraction procedure is used to separate the acid product from the remaining ester, the remaining ester is racemized, providing the basis for the continuous resolution process. Then (S)-metolachlor is synthesized by a simple chemical method using the enantiomerically pure (S)-acid.Key words: (S)-metolachlor, herbicide, CAL-B, (S)-N-(2-ethyl-6-methylphenyl)alanine, resolution.