Lipase-catalyzed Acylation Research Articles

Impacts of ionic liquids on enzymatic synthesis of glucose laurate and optimization with superior productivity by response surface methodology

As biosurfactants derived from naturally renewable resources, sugar fatty acid esters have broad applications in food, cosmetic and pharmaceutical industries. Glucose laurate was synthesized by a lipase-catalyzed acylation of glucose with vinyl laurate in ionic liquid (IL) systems. 16 ILs were screened for investigating the impact of the IL’s compositions on both the solvent properties of the IL and the synthetic process. The conversions obtained in ILs showed a bell-shaped relationship with their log P values. ILs that carry hydrophobic cations and hydrophilic anions seemed to favor the sugar ester synthesis. 1-Hexyl-3-methylimidazolium trifluoromethylsulfonate ([HMIm][TfO]) was selected both as a pure solvent and as a co-solvent with 2-methyl-2-butanol (2M2B) for this application, and the influence of the affecting factors (such as reaction temperature, enzyme amount, molar ratio of the two substrates, and reaction time) has been studied. Response surface methodology (RSM) was applied to optimize the [HMIm][TfO]/2M2B bisolvent system, and an optimal productivity of 14.2mmol/L/h was achieved, which is superior to other literature results.

Easy preparation of enantiomerically enriched heteroaromatic alcohols through lipase-catalyzed acylation with succinic anhydride under unconventional activation.

This study reports the lipase-catalyzed resolution of heteroaromatic secondary alcohols by succinic anhydride under different activation conditions by convenient procedure with succinic anhydride. The effects of succinic anhydride and the nature of the heteroatom are discussed in standard conditions in the kinetic resolution with lipases. The results recorded under microwave activation and ultrasonication is compared. (R)-4-chromanol was obtained in optically pure form (ee > 99%) with a high selectivity E > 200 by Pseudomonas cepacia lipase (PCL) in diethyl ether, using microwave radiation and under ultrasonication. The reaction time is reduced compared to the conventional heating with a better control of the selectivity of the lipase PCL. A significant effect of the nature of the heteroatoms on the reactivity and selectivity of the lipase with succinic anhydride has been disclosed, regardless the conditions of activation. This method proved to be clean, fast, interesting alternative, and facilitates the use of a cyclic anhydride, by microwave or ultrasound especially with secondary alcohols. The process is a valuable prerequisite for the preparative scale production of enantiomerically heteroaromatic alcohols in sustainable chemistry.

ChemInform Abstract: Chemoenzymatic Synthesis of the Macrolide Antibiotic (‐)‐A26771B.

The formal and total syntheses of the macrolide antibiotic (−)-A26771B have been developed wherein the stereochemistries at its C-5 and C-15 centres were installed using the lipase-catalyzed acylation of suitable MeCH(OH) and allylic secondary carbinol centres. A lipase-catalyzed chemoselective and hazard-free acrylation protocol, and a ring-closing metathesis reaction were used to construct the macrocyclic skeleton.

Asymmetric synthesis of the constitutive C22-carboxylic acid of macroviracin A

An efficient asymmetric synthesis of the C22-trihydroxy fatty acid component of macroviracin A has been developed. The key steps were highly enantioselective (i) lipase-catalyzed acylation, (ii) InCl3-(S)-BINOL mediated allylation, and (iii) asymmetric dihydroxylation (ADH) reaction. The moderate diastereoselectivity of the ADH reaction was overridden by converting the resultant diol diastereomers to the required epoxide enantiomer.

Lipase-catalyzed asymmetric acylation of boron cluster-containing secondary alcohols

The lipase-catalyzed asymmetric acetylation of secondary alcohols containing a carborane (boron cluster) moiety was investigated. Most lipases examined showed poor catalytic activity toward carborane-containing secondary alcohol 1a, but lipase TL efficiently catalyzed the acetylation of 1a with high enantioselectivity, to afford (R)-3a. This selectivity is similar to that of the general lipase-catalyzed acylation of secondary alcohols. Utilizing lipase TL, we succeeded in the resolution of carborane-containing alcohol 5, synthesized as a progesterone receptor ligand candidate, and evaluated the activities of the two enantiomers.

Highly Efficient and Enzymatic Regioselective Undecylenoylation of Gastrodin in 2-Methyltetrahydrofuran-Containing Systems

Highly efficient and regioselective acylation of pharmacologically interesting gastrodin with vinyl undecylenic acid has been firstly performed through an enzymatic approach. The highest catalytic activity and regioselectivity towards the acylation of 7′-hydroxyl of gastrodin was obtained with Pseudomonas cepacia lipase. In addition, it was observed the lipase displayed higher activity in the eco-friendly solvent 2-methyltetrahydrofuran-containing systems than in other organic solvents. In the co-solvent mixture of tetrahydrofuran and 2-methyltetrahydrofuran (3/1, v/v), the reaction rate was 60.6 mM/h, substrate conversion exceeded 99%, and 7′-regioselectivity was 93%. It was also interesting that the lipase-catalyzed acylation couldn’t be influenced by the benzylic alcohol in gastrodin. However, pseudomonas cepacia lipase displayed different regioselectivity towards gastrodin and arbutin.

Lipase-Catalyzed Esterification of Phloridzin: Acyl Donor Effect on Enzymatic Affinity and Antioxidant Properties of Esters

Lipase-catalyzed acylation of phloridzin with a wide range of fatty acids and antioxidant activities of synthesized esters were investigated in this study. Polar solvents were suitable reaction media for esterification, and the highest yield was achieved in acetonitrile. By using statistically designed optimization of key experimental factors for the synthesis of phloridzil oleate as the model reaction, great improvements in achieved conversion and yield per enzyme mass were enabled. The most significant progress has been made in the cost-effectiveness of the reaction, since the specific yield of 5.45 mmol g–1 was obtained at 58 °C, with 0.09 M phloridzin, 1.17 M oleic acid, and only 0.5% (w/v) biocatalyst. All examined fatty acids were suitable acyl donors, since the chain length and unsaturation degree had slight effects on esterification and all products yielded over 70%. Phloridzil caprate, myristate, and oleate exhibited the highest antioxidant activities among the obtained esters.

A chemoenzymatic synthesis of hept-6-ene-2,5-diol stereomers: application to asymmetric synthesis of decarestrictine L, pyrenophorol, and stagonolide E.

The stereomers of hept-6-ene-2,5-diol derivatives were conceived as useful chiral intermediates and were synthesized starting from sulcatol using two lipase-catalyzed acylation reactions as the key steps. The versatility of the intermediates was demonstrated by converting them to the titled tetrahydropyran, macrolide, and macrodiolide compounds using standard synthetic protocols.

Potential Anti-Influenza Virus Agents Based on Coffee Ingredients and Natural Flavonols

Natural phenolic compounds have been reported to directly inhibit influenza virus. Nonetheless, there have been no reports on the direct inhibitory effects of coffee ingredients. Here, we fractionated the hydrophobic and hydrophilic components of coffee. The hydrophobic fraction directly inhibited both a seasonal influenza A/Puerto Rico/8/24(H1N1) virus and a neuraminidase-resistant influenza A/Yokohama/77/2008(H1N1) virus infection in a dosedependent manner, while the hydrophilic fraction did not show any inhibitory effects, even at concentrations above 100 μg/ml. The HPLC profile of the hydrophobic fraction indicated that caffeine is the major component. Indeed, caffeine alone showed comparable anti-influenza virus activity. Interestingly, caffeic acid also inhibited viral infection, while chlorogenic acid, which is an ester of caffeic acid and (-)-quinic acid, showed no obvious antiviral effect at less than 2 mg/ml. We previously reported a method for enhancing the anti-influenza virus activity of epigallocatechin gallate, a major tea catechin, by lipase-catalyzed acylation. Using this methodology, we synthesized fatty acid esters of caffeic acid and evaluated their influenza virus-inhibitory effects. It was found that dioctanoyl ester of caffeic acid exhibited approximately 38-fold higher direct antiviral activity. To understand the essential structure required for virus inhibition, we further examined the antiviral activity of natural flavonoids containing either the caffeic acid skeleton or its analogous structure. Flavonols (quercetin, myricetin and morin) and hexahydrobenzophenone containing extended planar pi-conjugated systems efficiently inhibited the virus infection. Flavonoids possessing both radical scavenging activity and cytotoxicity tended to show higher antiviral activity, probably due to their affinity with viral surface factors. On the other hand, there was no apparent correlation between their antiviral activity and antioxidative activity. These findings provide insight into the design of anti-influenza virus agents from natural polyphenols.

Effect of Binary Organic Solvent Mixtures on Lipase-Catalyzed Regioselective Acylation of 6-Azauridine with Various Structural Vinyl Esters

Effect of Binary Organic Solvent Mixtures on Lipase-Catalyzed Regioselective Acylation of 6-Azauridine with Various Structural Vinyl Esters

Lipase-catalyzed acylation of microbial mannosylerythritol lipids (biosurfactants) and their characterization

Culturing Pseudozyma aphidis on glucose as main carbon source and soybean oil as co-substrate the mannosylerythritol lipids MEL-A and MEL-B were produced. Based on their excellent surface/interfacial active behavior they possess a high potential among all known biosurfactants. The components of a microbial MEL mixture were purified by medium pressure liquid chromatography (MPLC) and were used as substrates for in vitro enzymatic modifications. Lipase-catalyzed acylations of MEL-A and MEL-B with uncommon fatty acids from other microbial glycolipids—3-hydroxydecanoic acid from rhamnolipids and 17-hydroxyoctadecanoic acid from classical sophorolipids—yielded functionalized products at the C-1 position of the erythritol. The novel products were purified by MPLC and their structures elucidated by 1H and 13C nuclear magnetic resonance spectroscopy and mass spectrometry. In physicochemical characterization experiments two of the three new glycoconjugates lowered the surface tension of water from 72mNm−1 to 27–38mNm−1. Moreover the novel compounds inhibited the growth of gram-positive bacteria and showed a potential for anti-tumor-promoting activity.

Lipase-catalyzed acylation of lily polysaccharide in ionic liquid-containing systems

A comparative study was made of immobilized Burkholderia cepacia lipase (PSL-C)-catalyzed acylation of lily polysaccharide (LP) with vinyl acetate in organic solvents, ionic liquids (ILs) and IL-containing systems. The degree of substitution (DS) of the modified LP was used to evaluate the extent of acylation and thus enzymatic activity. In this manner, an eco-friendly solvent, 2-methyltetrahydrofuran (MeTHF), was found to be the most suitable organic reaction medium. However, compared to MeTHF, enhanced enzyme activity was observed when 1-butyl-3-methylimidazolium tetrafluorobrate ([C4MIm][BF4]) was used as the solvent. To further enhance the DS of the modified LP product, co-solvent mixtures of [C4MIm][BF4] and MeTHF were investigated. Among the various MeTHF–[C4MIm][BF4] systems examined, 20% (v/v) MeTHF–[C4MIm][BF4] produced the highest DS. In this reaction medium, the optimal water activity, reaction temperature and time were 0.33, 55°C and 18h, respectively, producing a product DS as high as 0.67. The PSL-C enzyme exhibited a much higher stability in the IL-containing system. Additionally, PSL-C-catalyzed acylation of LP was highly regioselective, causing acylation of only C6OH.

Lipase-catalyzed acylation in a continuous down-flow fixed-bed reactor

The kinetic resolution of racemic 1-phenylethanol with ethyl acetate was investigated in a down-flow fixed-bed reactor operated in a continuous mode mainly at the molar ratio of 1: 3 in 400 mL toluene at 70°C. The catalytic activity of the immobilized lipase was studied by: (i) changing the flow rates, (ii) utilizing different substrate concentrations, (iii) applying step changes using ethyl acetate, ethyl benzene, acetic acid, acetophenone etc., (iv) investigating the inhibitory effect of either the desired or the stoichiometric products (R)-1-phenylethyl acetate and ethanol, respectively), (v) elucidating the effect of water on the activity and stability of the immobilized lipase. The residence time distribution and the reactor hydrodynamics were also discussed along with kinetic modelling. The results were linked to the one-pot reactions.

A chemoenzymatic asymmetric synthesis of (+)-strictifolione

A chemoenzymatic asymmetric synthesis of the title compound has been developed using an efficient lipase-catalyzed acylation and a chiral reagent-directed diastereoselective allylation as the key steps for incorporating the stereogenic centers. A cross metathesis was employed to obtain the required E-olefin geometry of the target compound.

Examination of spacer effects on stereochemical recognition of a remote sterically hindered chiral center in lipase-catalyzed acylation

Abstract To date, the enzyme-catalyzed kinetic resolution of the secondary alcohol [Ar-C*H(CH 3 )OH, Ar = 2′,4′,6′-triisopropylphenyl] has not been available, due to high steric hindrance around the hydroxy group. To achieve resolution, the reaction site was extended by the introduction of two kinds of spacers, [ C( O)CH 2 ] and [ C( O)C**HCN ]. In the first substrate, the recognition of remote chirality [Ar C*H(CH 3 )O C( O)CH 2 OH] by acylation with Burkholderia cepacia lipase was examined by changing reaction conditions and acyl donors. An E = 22 in the preference of (1′ R )-isomer, was recorded with vinyl acetate as an acyl donor at 25 °C. In the second substrate, there was a matched enantiomeric pair [stereoselective ratio at C-1′ = 15, in the preference of (1′ R )-isomer] and a mismatched pair [stereoselective ratio at C-1′ = 2.5, in the preference of (1′ S )-isomer] based on the relative stereochemistry between the two chiral centers [Ar C*H(CH 3 )O C( O)C**HCN OH].

Regioselective Enzymatic Acylation of Aureolic Acids to Obtain Novel Analogues with Improved Antitumor Activity

A variety of aureolic acids was efficiently obtained by lipase-catalyzed regioselective acylation reactions of mithramycin and its analogues mithramycin SK and mithramycin SDK. The acylation took place in the aglycone moiety or in the B sugar unit, depending on the substrate, lipase and acyl donor considered. Most of the novel acylated derivatives showed antitumor activity at double digit nanomolar concentrations, in some cases significantly improving the activity of the parent drugs.

Lipase-catalyzed preparation of chromomycin A3 analogues and biological evaluation for anticancer activity

Several acyl derivatives of the aureolic acid chromomycin A3 were obtained via lipase-catalyzed acylation. Lipase B from Candida antarctica (CAL-B) was found to be the only active biocatalyst, directing the acylation regioselectively towards the terminal secondary hydroxyl group of the aglycone side chain. All new chromomycin A3 derivatives showed antitumor activity at the micromolar or lower level concentration. Particularly, chromomycin A3 4′-vinyladipate showed 3–5 times higher activity against the four tumor cell lines assayed as compared to chromomycin A3.

Efficient 1–5 regioselective acylation of primary hydroxyl groups of fermentative derived xylitol catalyzed by an immobilized Pseudomonas aeruginosa lipase

The experiment described in this paper synthesizes xylitol acylated products from fermentative derived xylitol and acid anhydrides of various chain lengths in the presence of Tetrahydrofuran (THF) and acetonitrile using immobilized Pseudomonas aeruginosa (PL) lipase as a biocatalyst (97% residual activity up to five cycles) at 37°C, 200 rpm. This study examines a number of different acid anhydrides for their highly selective and efficient lipase-catalyzed acylation of primary hydroxyl groups in xylitol. Of those studied, the best results are obtained with butanoic anhydride, 80.12% after 4 h in acetonitrile followed by vinyl acetate, which results in 77.79% conversion after 8 h of incubation in THF as analyzed through high performance liquid chromatography (HPLC).

Efficient synthesis of Guanfu base G via highly regioselective lipase-catalyzed acylation in non-aqueous phase

Lipase-catalyzed acylation of Guanfu alcohol-amine (GFAA) with vinyl acetate (VA) was performed in non-aqueous system for the preparation of Guanfu base G (GFG), a plant-originated alkaloid with significant antiarrhythmic activity. Among the eight lipases from different origins, Novozym 435 was found to be the best biocatalyst. The most suitable molecular sieve amount, substrate concentration, molar ratio of VA to GFAA, enzyme amount and reaction temperature were proved to be 40mg/mL, 6μmol/mL, 10:1, 2mg/mL and 50°C, respectively. A maximum GFG yield of 37.4% was achieved under the selected conditions with methanol served as the optimal reaction medium. The structure of the acetylated product was elucidated by 1H NMR and 13C NMR analysis.

Preparation of (S)-1-Cyclopropyl-2-methoxyethanamine by a Chemoenzymatic Route Using Leucine Dehydrogenase

(S)-1-Cyclopropyl-2-methoxyethanamine is a key chiral intermediate for the synthesis of a corticotropin-releasing factor-1(CRF-1) receptor antagonist. Resolution of the racemic amine by transaminase from Vibrio fluvalis gave a 38% yield of the S-amine with 53% ee. Resolution by lipase-catalyzed acylation provided the S-amine in 35% yield with 91% ee. With limited success of these resolution approaches, an efficient chemo-enzymatic route to (S)-1-cyclopropyl-2-methoxyethanamine was devised starting from methylcyclopropyl ketone. Permanganate oxidation of the ketone gave cyclopropylglyoxylic acid, which was converted to (S)-cyclopropylglycine by reductive amination using leucine dehydrogenase from Thermoactinomyces intermedius with NADH cofactor recycling by formate dehydrogenase from Pichia pastoris. Both enzymes were cloned and expressed in recombinant E. coli. (S)-Cyclopropylglycine obtained from enzymatic reductive amination was isolated as the N-Boc derivative and converted to the desired amine by redu...