共查询到20条相似文献,搜索用时 15 毫秒
1.
Highly regioselective acylation of helicid with fatty acid vinyl esters catalyzed by the lipase from Thermomyces lanuginosus has been successfully performed for the first time. For the enzymatic caproylation of helicid, under the optimal conditions, initial reaction rate was 33.2 mM/h, and substrate conversion and regioselectivity were greater than 99%. In addition, the acyl recognition of the enzyme in the regioselective acylation of helicid was investigated. The results showed that although 6’-O-acyl derivatives of helicid were exclusively obtained with all the tested acyl donors, the enzymatic reaction rate varied widely with different acyl donors, presumably owing to their different interactions with the active site of the lipase. It is also interesting that the different configuration of only one hydroxyl group at C-3 in helicid couldn’t affect the lipase-catalyzed esterification and helicid has the same regioselectivity as that of D-glucose and arbutin. 相似文献
2.
Pseudomonas sp. lipase was immobilized onto glutaraldehyde-activated Florisil® support via Schiff base formation and stabilized by reducing Schiff base with sodium cyanoborohydride. The immobilization performance was evaluated in terms of bound protein per gram of support (%) and recovered activity (%). A 4-factor and 3-level Box–Behnken design was applied for the acylation of (±)-2-(propylamino)-1-phenylethanol, a model substrate, with vinyl acetate and the asymmetric acylations of other (±)-2-amino-1-phenylethanols with different alkyl substituents onto nitrogen atom such as (±)-2-(methylamino)-1-phenylethanol, (±)-2-(ethylamino)-1-phenylethanol, (±)-2-(butylamino)-1-phenylethanol and (±)-2-(hexylamino)-1-phenylethanol were performed under the optimized conditions. The optimal conditions were bulk water content of 1.8%, reaction temperature of 51.5 °C, initial molar ratio of vinyl acetate to amino alcohol of 1.92, and immobilized lipase loading of 47 mg mL?1. (R)-enantiomers of tested amino alcohols were preferentially acylated and the reaction purely took place on the hydroxyl group of 2-amino-1-phenylethanols. The increase of alkyl chain length substituted onto nitrogen atom caused an increase in the acylation yield and ee values of (S)-enantiomers. Enantiomeric ratio values were >200 for all the reactions. Our results demonstrate that the immobilized lipase is a promising biocatalyst for the preparation of (S)-2-amino-1-phenylethanols and their corresponding (R)-esters via O-selective acylation of (±)-2-amino-1-phenylethanols with vinyl acetate. 相似文献
3.
《Journal of Molecular Catalysis .B, Enzymatic》2007,44(1):1-7
Controllable selective synthesis strategy of polymerizable N-acyl and O-acylpropranolol vinyl derivatives was developed by enzyme-catalyzed acylation of propranolol using divinyl dicarboxylates with different carbon chain length as acyl donor. The influence of parameters including enzyme, solvents and chain length of acyl donor on the reaction was investigated in detail. Lipase AY30 in diisopropyl ether demonstrated high selectivity towards the amino group of propranolol, while lipase M from Mucor javanicus in dioxane acylated selectively the hydroxyl group of propranolol. N-Acylpropranolol (3a–3c) and O-acylpropranolol vinyl (4a–4c) derivatives were obtained successfully, and can be used for preparing functional macromolecular prodrugs of beta-blockers drugs. N-(Vinyladipoyl)propranolol (NVAP) was copolymerized with methyl methacrylate (MMA) using AIBN as initiator. The obtained polymeric prodrug was characterized with IR, NMR and GPC. The poly(NVAP-co-MMA) has Mn of 3.23 × 104, and Mw/Mn of 1.66. 相似文献
4.
The rate constants for hydrolysis of the enantiomers of amino acid p-nitrophenyl esters catalyzed by bifunctional comicellar catalysts containing the imidazolyl and hydroxyl groups have been determined at pH 7.30, 0.02 m phosphate buffer, and 25°C. The kinetic analysis suggests a reaction scheme which involves acylation followed by deacylation at the imidazolyl group. Although no appreciable cooperative catalytic efficiencies are observed between the bifunctional groups in the acylation step, it is found that the deacylation rates are thus accelerated by surfactant hydroxyl groups, and some of the stereoselective acyl transfer reaction occurs from the imidazolyl to the hydroxyl group in optically active comicellar systems. 相似文献
5.
Previous studies on the lipase-mediated acylation of 6-azauridine with vinyl stearate in organic solvents revealed that while
preparing a potential prodrug, 3′-O-stearoyl-6-azauridine, a lipase from Burkholderia cepacia showed high regioselectivity toward the second hydroxyl group. The most suitable reaction solvent, molar ratio of vinyl stearate
to 6-azauridine, and reaction temperature were anhydrous acetone, 15:1, and 45°C, respectively. Under these conditions, the
initial reaction rate, 3′-regioselectivity, and maximum substrate conversion were as high as 10.4 mM/h, 86.0, and 99.0%, respectively. 相似文献
6.
Hai-Yang Wang Chao Li Na Wang Kun Li Xing-Wen Feng Ting He Xiao-Qi Yu 《Bioorganic & medicinal chemistry》2009,17(5):1905-1910
Ketoprofen–saccharide conjugates were synthesized by selectively enzymatic hydrolysis and acylation. Firstly, the (S)-ketoprofen vinyl ester was prepared by enzymatic hydrolysis of (R,S)-ketoprofen vinyl ester. Then enzymatic transesterification of (S)-ketoprofen vinyl ester with a series of saccharides were performed by the catalysis of a commercial protease from Bacillus licheniformis (BLP) in organic medium mixture of pyridine and tert-butanol. The ketoprofen was selectively conjugated onto the primary hydroxyl group of saccharides and with high yield after 72 h. Partition coefficient determination showed that all the products have better water solubility than parent ketoprofen. Chemical hydrolysis experiment indicated that 50% ketoprofen could be release from ketoprofen glucoside and maltoside in aqueous buffer (pH 7.4) within 48 h. 相似文献
7.
A facile, high regioselective enzymatic synthesis approach for the preparation of amphipathic prodrugs with saccharides of mephenesin and chlorphenesin was developed. Firstly, transesterification of two drugs with divinyl dicarboxylates with different carbon chain length was performed under the catalysis of Candida antarctica lipase acrylic resin and Lipozyme in anhydrous acetone at 50 degrees C, respectively. A series of lipophilic derivatives with vinyl groups of mephenesin and chlorphenesin were prepared. The influences of different organic solvents, enzyme sources, reaction time, and the acylation reagents on the synthesis of vinyl esters were investigated. And then, protease-catalyzed high regioselective acylation of D-glucose and D-mannose with vinyl esters of mephenesin and chlorphenesin gave drug-saccharide derivatives in good yields. The studies of lipophilicity and hydrolysis in vitro of prodrugs verified that drug-saccharide derivatives had amphipathic properties, and both lipophilic and amphipathic drug derivatives had obvious controlled release characteristics. 相似文献
8.
We established a facile regioselectively chemo-enzymatic synthesis procedure for the preparation of mutual derivatives of nucleosides and pyrimidines by sequential Markovnikov addition and acylation. Firstly, pyrimidine derivatives containing vinyl ester group were synthesized from pyrimidines and divinyl esters through Markovnikov addition catalyzed by K2CO3 in DMSO at 80 °C, and the yields were ranged from 50% to 87%. Then regioselective acylation of ribavirin and cytarabine with pyrimidine vinyl ester was catalyzed by CAL-B (immobilized lipase from Candida antarctica) in anhydrous acetone. Reaction conditions of enzymatic acylation including enzyme resource and solvents were optimized. A series of mutual derivatives of nucleosides and pyrimidines were synthesized successfully and characterized with NMR, IR, and HRMS. This chemo-enzymatic protocol involving sequential Markovnikov addition and acylation provided a novel way of synthesizing complicated functional compounds regioselectively which was hard to be achieved either by chemical or by enzymatic methods. 相似文献
9.
Flavonoids such as (+)catechin can be efficiently solubilised in supersaturated solutions prepared with donor glycosides, e.g., p-nitrophenyl glycosides, di- and higher oligosaccharides, and poly(ethylene glycol) dimethyl ether in sufficiently high concentration for their efficient enzymatic glycosylation. Under these conditions several glycosidases readily accept (+)catechin as substrate and the target glycosides were prepared in one step in up to 26% yields. The regioselectivity of the reaction depends on the enzyme and substrate combination used; three positions, 5, 7, and 4', in the flavonoid can be glycosylated. The resulting and similar flavonoid glycosides were further modified by regioselective acylation with vinyl esters of arylpropenoic acids using lipases as biocatalyst. The efficiency of acylation was found to diminish in the order of vinyl cinnamate > vinyl ferulate > vinyl coumarate. This work demonstrates the feasibility of assembling complex flavonoid glycoside esters in just two steps by sequential use of commercially available glycosidases and lipases. 相似文献
10.
Efficient protocols for the selective synthesis of monosaccharide derivatives and polymeric prodrugs of 5-fluorouridine (5-FUR) have been developed. Firstly, transesterification of 5-FUR and divinyl dicarboxylates ranging from 4 to 10 carbon atoms were performed under the catalysis of Candida antarctica lipase acrylic resin in anhydrous THF at 50 °C, respectively. A series of vinyl 5-FUR esters were prepared, with high acylation regioselectivity at 5′-OH. The influences of reaction parameters including enzyme, solvents, molar ratio of substrates, reaction time, the carbon length of acyl donor and reaction temperature were investigated in details. And then, protease-catalyzed highly regioselective acylation of d-glucose, d-mannose and d-galactose with vinyl esters of 5-FUR gave 5-FUR-saccharide derivatives successfully. Moreover, a series of polymeric prodrugs of 5-FUR with the different linker lengths were prepared by the chemo-polymerization of vinyl 5-FUR esters in DMF initiated by azobisisobutyronitrile (AIBN). 相似文献
11.
Swati Misra Shailendra Raghuwanshi Pritesh Gupta R. K. Saxena 《Biotechnology and Bioprocess Engineering》2012,17(2):398-406
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). 相似文献
12.
Eric Husson Catherine Humeau Cédric Paris Régis Vanderesse Xavier Framboisier Ivan Marc Isabelle Chevalot 《Process Biochemistry》2009,44(4):428-434
The enzymatic acylation of polar dipeptides was investigated. First, the Novozym435®-catalyzed acylation of Lys-Ser, HCl exhibiting three potential acylable sites was carried out in organic media (2-methyl-2-butanol, oleic acid) and in an ionic liquid ([Bmim]+[PF6]?). In these reactions, the chemo-selectivity of the acylation was exclusively in favour of the N?-lysine acylation and the efficiency (substrate conversion) was demonstrated to be under control of the peptide solubility. The use of [Bmim]+[PF6]? permitted to significantly improve the dipeptide solubility, and to enhance both substrates conversion and initial rates of acylation reaction. In the three reaction media used, the O-acylated derivative of the dipeptide was never detected suggesting a weak reactivity of the serine hydroxyl group due to its molecular environment and particularly to the presence of a free carboxylic group known for its electroattractor property.Last, the acylation of a natural dipeptide (carnosine), exhibiting a very low solubility in organic solvents, was also performed. Carnosine was successfully N-acylated in 2-methyl-2-butanol, and a yield of 39% was obtained when improving the substrate solubility: a better dispersibility was obtained by application of a high pressure on the reaction medium just before starting the reaction. 相似文献
13.
Maria Cristina Pinna Andrea Salis Maura Monduzzi 《Journal of Molecular Catalysis .B, Enzymatic》2004,27(4-6):233-236
The 1-O-lauroyl-
-mannitol, a non-ionic surfactant, was synthesised via a chemo-enzymatic pathway starting from the 1,2:4,5-di-O-isopropylidene-
-mannitol and vinyl laurate as acylation agent. The high hydrophobicity of the substrates allowed the enzymatic reaction to occur both in n-hexane and in solvent free conditions. The immobilised Candida antarctica lipase B was used as the catalyst of the enzymatic step. This enzyme acts differently depending on the position of the hydroxyls with respect to the isopropylidene groups. The acid selective hydrolysis of the isopropylidene groups gave the non-ionic surfactant without the presence of isomers. 相似文献
14.
A facile control of the acylation position at the primary hydroxyl and amino of acyclovir, respectively, was achieved and five polymerizable acyclovir prodrugs were synthesized. Various reaction conditions were studied in detail. Thus, lipase acrylic resin from Candida antarctica (CAL-B) in pyridine or acetone showed high chemo-selectivity toward the primary hydroxyl of acyclovir. However, lipase PS 'Amano' (PS) in DMSO selectively acylated the amino group. The selectivity of PS could be adjusted by changing reaction solvents. The acyclovir vinyl derivatives obtained would be important monomers used for the preparation of macromolecular nucleoside drugs. 相似文献
15.
Acylation of (hydroxyalkyl)phenols with vinyl esters by lipase B from Candida antarctica proceeded smoothly in a highly chemoselective manner, affording their alkyl esters exclusively or at least predominantly. The enzyme therefore discriminates between an alcoholic hydroxyl from a phenolic hydroxyl in addition to having versatile catalytic abilities for organic synthesis. 相似文献
16.
Ruud ter Haar Henk A. Schols Lambertus A.M. van den Broek Dilek Sağlam August E. Frissen Carmen G. Boeriu Harry Gruppen 《Journal of Molecular Catalysis .B, Enzymatic》2010,62(2):183-189
The cause of discrepancies in the literature regarding the specificity of immobilized Candida antarctica lipase B in the acylation of oligosaccharides was examined. Molecular sieves, generally used to control the water content during acylation reactions, turned out to have an important role in this. It was proven that molecular sieves alone can catalyze the acylation of fructose oligomers using vinyl laurate, leading to multiple substitution of the oligomers. This effect was the most profound at conditions unfavorable for the enzyme, because this resulted in a relatively high concentration of the chemically produced adducts. The enzyme alone catalyzed the formation of monosubstituted oligomers. It was proven that even solvent pre-drying by molecular sieves already causes the release of catalyzing compounds to the liquid, leading to subsequent catalysis. These findings should be taken into account when applying molecular sieves in this type of reactions in the future. Molecular sieves could, moreover, be used as a catalyst when multiple substitution is desired. 相似文献
17.
Bryan Colin Nicholas Morgan Jones Claire Simons Hisao Nishimura Jiri Zemlicka 《Nucleosides, nucleotides & nucleic acids》2013,32(3-5):431-434
Abstract Anti-HIV agent (±)-cytallene (1b + 2b) was resolved by enantioselective acylation of (±)-N4-benzoylcytallene (1d + 2d) with vinyl butyrate in tetrahydrofuran catalyzed by lipase AK from Pseudomonas sp. and subsequent deacylation of 4d and 1d with ammonia in methanol. Optically pure enantiomers 1b and 2b were obtained. 相似文献
18.
In this investigation, poly(vinyl alcohol) was chemically modified by the introduction of different amounts of N-phthaloyl-l-phenylalanine. The modification was carried out by the reaction of PVA hydroxyl groups with (2S)-3-phenyl-2-phthalimidylpropanoyl
chloride using N,N-dimethyl acetamide/lithium chloride as a reaction media. The novel copolymers obtained were characterized by spectroscopic
techniques, elemental analysis, X-ray diffraction and thermal methods. Optical rotation and viscosities were also measured.
The degree of esterification was determined by 1H-NMR. The influence of reagent molar ratio on the degree of modification was also evaluated. The vinyl(3-phenyl-2-phthalimidopropanoate)
content in the copolymer was attained up to 52%. Thermal stability of the copolymers was checked by thermogravimetric analysis
and differential thermogravimetric analysis. All copolymers displayed improved thermal stability compared to the parent polymer. 相似文献
19.
Stefanie Mädler 《Analytical biochemistry》2010,398(1):123-125
In order to clarify whether arginine has a promoting effect on the acylation of hydroxyl groups of serine, threonine, or tyrosine by homobifunctional cross-linking agents in aqueous solution, we carried out systematic experiments with model peptides, comparing relative reaction yields with covalently protected and unprotected arginines by MALDI-MS. The guanidinium group could be demonstrated to contribute to the reactivity of hydroxyl groups toward N-hydroxysuccinimide esters and catalyze the nucleophilic substitution, probably via hydrogen bonds. 相似文献
20.
Particulate enzyme preparations of cotton fibers catalyze the acylation of exogenous steryl glucoside to form acylated steryl glucoside. The acyl transferase involved in this reaction was solubilized by treatment of the membrane fractions with Triton X-100 and was partially purified by chromatography on DEAE-cellulose and gel filtration. This solubilized enzyme had an absolute requirement for Triton X-100 and phospholipid in order to catalyze the acylation of the steryl glucoside. The best phospholipid substrate was phosphatidylethanolamine but egg and soybean phosphatidylcholine were also active. The phospholipid was shown to function as an acyl donor by demonstrating that [14C]fatty acid from 14C-labeled phospholipid could be transferred to steryl-[3H]glucoside to form [14C,3H]acylated steryl glucoside. Saponification of this compound yielded [14C]fatty acid and steryl-[7H]glucoside. 相似文献