Chemoenzymatic Kinetic resolution of (R)-malathion in aqueous media

Abstract

BackgroundMalathion (R,S)-diethyl-2-[(dimethoxyphosphorothioyl)sulfanyl]butanedioate is a chiral organophosphorus compound used widely as pesticide for suppression of harmful insects such as mosquitoes. It is well known that in biological systems (R)-malathion is the active enantiomer, therefore a sustainable approach could be the use of only the biologically active enantiomer. The resolution of the commercial racemic mixture to obtain the pure active enantiomer combined with a recycling of the undesired enantiomer through a racemization process could be an attractive alternative to reduce the environmental impact of this pesticide. Thus, this work evaluates the use of four commercially available lipases for enantioselective hydrolysis and separation of malathion enantiomers from the commercial racemic mixture.ResultsSeveral lipases were methodologically assessed, considering parameters such as enzyme concentration, temperature and reaction rates. Among them, Candida rugosa lipase exhibited the best performance, in terms of enantioselectivity, E = 185 (selective to the (S)-enantiomer). In this way, the desired unreacted (R)-enantiomer was recovered in a 49.42 % yield with an enantiomeric excess of 87 %. The monohydrolized (S)-enantiomer was recovered and racemized in basic media, followed by esterification to obtain the racemic malathion, which was recycled. In this way, an enantioenriched mixture of (R)-malathion was obtained with a conversion of 65.80 % considering the recycled (S)-enantiomer.ConclusionThis work demonstrated the feasibility of exploiting Candida rugosa lipase to kinetically resolve racemic malathion through an environmentally friendly recycling of the undesired (S)-enantiomer.Graphical AbstractLipase catalyzed enantioselective resolution of (R)-malathion in aqueous solvent.

Enantioselective Conversion of Racemic Sotalol to R(-)-Sotalol by Lipase AP6

“…Enantiomeric purity of sotalol after incubation with the whole-cell as well as immobilized-cell cultures for 10 d. % EE is enantiomeric excess, E is enantiomeric ratio, % C is conversion yield and * E-value is considered as worst (1-5), poor (5)(6)(7)(8)(9)(10), moderate (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20), good (20-100) and excellent (>100) compared to that of the reaction catalysed by wholecell cultures. The results obtained in the present study were also in line with Wang et al [39] .…”

“…This step is promoted by serine, histidine and aspartate residues (catalytic triad) of the enzyme lipase. The acyl-enzyme intermediate then reacts with a nucleophile like water, alcohol or amine regenerating the enzyme along with the product [17] . Hence one pure enzyme, lipase AP6 (triacylglycerol lipase from A. niger) [18] has also been employed in the present study as a biocatalyst to chiral switch the racemic sotalol.…”

Quiralidade: a outra face dos medicamentos: conceituação e contextualização

“…Com o Malathion racêmico em mãos, a reação biocatalítica escolhida é a reação de hidrólise, por meio das enzimas lipases (Figura 73) 89 . A lipase escolhida foi a Candida rugosa, com uma atividade catalítica de 31,8 U.g -1 .…”

Nuclear magnetic resonance chiral discrimination of fipronil and malathion agrochemicals: A case study

“…26,27 Moreover, NMR provides the possibility to assess the absolute configuration of novel chiral compounds and/or degradation intermediates. [28][29][30] Based on the necessity to develop simple and practical methods to evaluate the enantiomers ratio, herein we disclose an NMR protocol for chiral discrimination of fipronil and malathion commercial agrochemicals (Figure 1), 31,32 exploring the highly abundance nuclei, 1 H, 31 P, and 19 F. These agrochemicals were chosen due the physicochemical properties differences, which imply in distinct routes to provide an effective NMR chiral discrimination protocol. As mentioned, few procedures use this technique, 26,27 and this report affords an optimization study with distinct chiral solvent agents (CSAs) in organic solvents and chiral host-guest interactions with cyclodextrins in aqueous media to provide a readily available procedure for agrochemical enantiomers ratio.…”