Methanolysis of ethyl esters of N-acetyl amino acids catalyzed by cyclosophoraoses isolated from Rhizobium meliloti

Methanolysis of four ethyl esters, N-acetyl-L-phenylalanine ethyl ester, N-acetyl-l-tyrosine ethyl ester, N-acetyl-l-tryptophan ethyl ester, and ethyl phenylacetate was catalyzed by a mixture of microbial cyclooligosaccharides termed cyclosophoraoses isolated from Rhizobium meliloti. Cyclosophoraoses [cyclic-(1-->2)-beta-d-glucans, collectively 'Cys'] are a mixture of large-ring molecules consisting of various numbers of glucose residues (17-27) linked by beta-(1-->2)-glycosidic bonds. Cys as a catalytic carbohydrate enhanced the methanolysis about 233-fold for N-acetyl-L-tyrosine ethyl ester in comparison with a control. The effect of dry organic solvents on the methanolysis of N-acetyl-L-tyrosine ethyl ester was investigated by high-performance liquid chromatography (HPLC), and it was found that the rate enhancement correlated closely with the hydrophobicity of the solvent.     

粉绿铁线莲挥发油成分分析

利用气相色谱－质谱联用技术对青海粉绿铁线莲的挥发油成分进行了研究,共鉴定出59种组分,其中主要成分为十六酸乙酯,9,12,15－十八三烯酸乙酯,亚油酸乙酯,十九烷,正二十五烷,正二十六烷,6,10,14－三甲基－2－十五烷酮,双（2－乙基己基）邻苯二甲酸酯,十八烷酸乙酯,N－苯基－萘胺等,其中十六酸乙酯的含量最高,占挥发油成分总量的24．06％,检出成分占挥发油总量的87．8％。     

An efficient synthesis of acyclic N7- and N9-adenine nucleosides via alkylation with secondary carbon electrophiles to introduce versatile functional groups at the C-1 position of acyclic moiety

The introduction of versatile functional groups, allyl and ester, at the C-1 position of the acyclic chain in acyclic adenine nucleosides was achieved for the first time directly by alkylation of adenine and N6-potected adenine. Thus, the C-1'-substituted N9-adenine acyclic nucleoside, adenine-9-yl-pent-4-enoic acid ethyl ester (11), was prepared by direct alkylation of adenine with 2-bromopent-4-enoic acid ethyl ester (6), while the corresponding N7-regioisomer, 2-[6-(dimethylaminomethyleneamino)-purin-7-yl]-pent-4-enoic acid ethyl ester (10), was obtained in one step by the coupling of N, N-dimethyl-N'- (9H-purin-6-yl)-formamidine (9) with 2-bromopent-4-enoic acid ethyl ester (6). The functional groups, ester and allyl, were converted to the desired hydroxymethyl and hydroxyethyl groups, and subsequently to phosphonomethyl derivatives and corresponding pyrophosphorylphosphonates.     

（S）-（-）-β-羟基苯丙酸乙酯的微生物法合成

采用酿酒酵母CGMCC No．2266菌体,不对称还原β-羰基苯丙酸乙酯制备光学纯（S）-（-）-β-羟基苯丙酸乙酯。结果表明：采用初始pH为8．0的液体发酵培养基培养的CGMCCNo．2266菌体经过50℃预热处理30min后用于生物转化获得的（S）-（-）-G-羟基苯丙酸乙酯对映体过剩值可以达到100％ee。确定了合成（S）-（-）-β-羟基苯丙酸乙酯的较佳转化条件为pH7．0,温度30℃,转化时间24h,底物浓度为3．63mmol／L,菌体用量为86g/L（干重／反应体积）。以10％葡萄糖为辅助底物,产率比不加辅助底物时提高了75．4％。在最佳转化条件下反应转化率及（S）-（-）-β-羟基苯丙酸乙酯对映体过剩值可分别达到98．4％和100％ee。     

发酵无花果香料的挥发性成分分析

利用微生物发酵无花果开发特色香料,并采用同时蒸馏萃取装置收集挥发性成分并用气相色谱一质谱仪对生物技术制备的无花果香料挥发性成分进行分离和鉴定,经毛细管色谱分离出47种组分,确认了其中的45种成分,并用面积归一化法测定了各种成分的百分含量,其主要成分为：9,12-十八碳二烯酸乙酯(27．34％)、十六酸乙酯(23．99％)、邻苯二甲酸二丁酯(6．18％)、邻苯二甲酸二异丁酯(5．52％)、9,12-十八碳二烯酸甲酯(4．72％)、十六酸甲酯(4．67％)、9,12,15-十八碳三烯酸乙酯(4．48％)、9-十八碳烯酸乙酯(3．80％)、糠醛(2．53％)、9,12,15-十八碳三烯酸甲酯(1．85％)、十八酸乙酯(1．42％)、9-十八碳烯酸甲酯(1．26％)等。     

不同小麦品种（系）叶片表面蜡质对两种麦蚜取食的影响

采用气质联用(GC-MS)和生物测定法,探讨了不同小麦品种(系)叶片表面蜡质对麦长管蚜和禾谷缢管蚜取食的影响.结果表明:SN80、SN18和ZM12叶片表面蜡质对2种蚜虫取食具有刺激作用,而SN87叶片表面蜡质无刺激作用.对4种小麦材料叶片表面蜡质进行GC-MS分析发现,其表面蜡质化学组分有所不同,但主要组分均为长链烷烃,其它组分包括7-十四碳烯、8-十五烷酮、十四烷酸乙酯和十六烷酸乙酯等.生物测定结果表明:长链烷烃(>C17)、7-十四碳烯及8-十五烷酮对两种蚜虫取食具有显著的刺激作用;而乙基柠檬酸、十四烷酸乙酯和十六烷酸乙酯对麦长管蚜取食无刺激作用;十四烷酸乙酯和十六烷酸乙酯对禾谷缢管蚜取食也无刺激作用.     

Analysis of proteases involved in phagocytic activity of macrophages through the use of various amino acid esters

Inhibitory effects of various amino acid esters on the phagocytic activity of guinea pig peritoneal macrophages were studied with sensitized 51Cr-sheep erythrocytes (51Cr-EAb) as well as 125I-alpha-amylase complexed with homologous IgG2 antibody (Ag-Ab complex). The intracellular uptake of 51Cr-EAb was markedly inhibited by N-acetyl-L-phenylalanine ethyl ester (Ac-Phe-OEt), N-acetyl-L-tryptophan ethyl ester (Ac-Trp-OEt) and N-benzoyl-L-tyrosine ethyl ester (Bz-Tyr-OEt), but not by N-acetyl-L-tyrosine ethyl ester (Ac-Tyr-OEt), N-alpha-acetyl-L-arginine methyl ester (Ac-Arg-OMe), N-alpha-benzoyl-L-arginine ethyl ester (Bz-Arg-OEt) or N-alpha-acetyl-L-lysine methyl ester (Ac-Lys-OMe). When phagocytosis of the Ag-Ab complex was assayed by measuring the amount of digested products released from macrophage cells, Ac-Tyr-OEt also inhibited it as markedly as Ac-Phe-OEt, Ac-Trp-OEt, and Bz-Tyr-OEt did, whereas Bz-Arg-OEt again did not show any effect. The results of analysis of the intracellular fate of the Ag-Ab complex taken up by macrophages through the use of analytical density gradient fractionation of the homogenized cells suggest that Ac-Phe-OEt inhibits the ingestive process since the distribution of Ag-Ab complex showed a single peak, closely accompanying the plasma membrane. Ac-Tyr-OEt, on the other hand, caused a marked accumulation of Ag-Ab complex in the lysosome fraction, reflecting the inhibition of intralysosomal digestion of the complex.(ABSTRACT TRUNCATED AT 250 WORDS)     

Inhibitory activities of aromatic amino acid esters and peptides against ovalbumin permeation through Caco-2 cell monolayers

Trp, Phe, and Tyr ethyl esters and their dipeptides with Gly at the C-terminals inhibited ovalbumin (OVA) permeation through Caco-2 monolayers. The inhibitory activity of Trp ethyl ester was the highest at near the concentration of 10(-6) M. It was suggested that Trp ethyl ester inhibited transcellular permeation of OVA.     

Directed evolution of an esterase for the stereoselective resolution of a key intermediate in the synthesis of epothilones

The directed evolution of an esterase from Pseudomonas fluorescens using the mutator strain Epicurian coli XL1-Red was investigated. Mutants were assayed for their ability to hydrolyze a sterically hindered 3-hydroxy ester, which can serve as a building block in the synthesis of epothilones. Screening was performed by plating esterase producing colonies derived from mutation cycles onto minimal media agar plates containing indicator substances (neutral red and crystal violet). Esterase-catalyzed hydrolysis of the 3-hydroxy ester (ethyl or glycerol ester) was detected by the formation of a red color due to a pH decrease caused by the released acid. Esterases isolated from positive clones were used in preparative biotransformations of the ethyl ester. One variant containing two mutations (A209D and L181V) stereoselectively hydrolyzed the ethyl ester resulting in 25% ee for the remaining ester.     

Polyethylene glycol-modified papain catalyzes peptide bond formation in benzene

Summary Papain modified with 2,4-bis(O-methoxypolyethylene glycol)-6-chloro-s-triazine (activated PEG₂) was soluble in benzene and retained the enzymic activity. Acid-amide bond formation by the modified enzyme proceeded efficiently in benzene; N-benzoyl-L-alanine alkylamides were synthesized from N-benzoyl-L-alanine methyl ester and various alkylamines, and N-benzoyl-L-alaninyl(oligo)leucine ethyl ester was formed from N-benzoyl-L-alanine methyl ester and L-leucine ethyl ester.     

Isolation of an esterase-producing Trichosporon brassicae and its catalytic performance in kinetic resolution of ketoprofen

A yeast strain CGMCC 0574, identified as Trichosporon brassicae, was selected from 92 strains for its high (S) selectivity in the hydrolysis of ketoprofen ethyl ester. The effective strains of the microorganisms were isolated from soil samples with the ester as the sole carbon source. The ethyl ester proved to be the best substrate for resolution of ketoprofen among several ketoprofen esters examined. The resting cells of CGMCC 0574 could catalyze the hydrolysis of ketoprofen ethyl ester with an enantiomeric ratio of 44.9, giving (S)-ketoprofen an enantiomeric excess of 91.5% at 42% conversion.     

Chemical modification of chitosan. Part 15: synthesis of novel chitosan derivatives by substitution of hydrophilic amine using N-carboxyethylchitosan ethyl ester as an intermediate

The Michael type reaction of chitosan with ethyl acrylate has been investigated. Although this reaction was quite slow in the case of chitosan, the reiteration of the reaction was an effective means for increasing the degree of substitution (DS) of ethyl ester. The N-carboxyethylchitosan ethyl ester as an intermediate was successfully substituted with various hydrophilic amines, although the simultaneous hydrolysis of the ester to carboxylic acid also occurred. Water-soluble chitosan derivatives were obtained by substitution with hydroxyalkylamines and diamines.     

An Efficient Synthesis Of Acyclic N7- and N9-Adenine Nucleosides Via Alkylation With Secondary Carbon Electrophiles to Introduce Versatile Functional Groups At the C-1 Position of Acyclic Moiety

The introduction of versatile functional groups, allyl and ester, at the C-1 position of the acyclic chain in acyclic adenine nucleosides was achieved for the first time directly by alkylation of adenine and N⁶-protected adenine. Thus, the C-1′-substituted N⁹-adenine acyclic nucleoside, adenine-9-yl-pent-4-enoic acid ethyl ester (11), was prepared by direct alkylation of adenine with 2-bromopent-4-enoic acid ethyl ester (6), while the corresponding N⁷-regioisomer, 2-[6, (dimethylaminomethyleneamino)-purin-7-yl]-pent-4-enoic acid ethyl ester (10), was obtained in one step by the coupling of N,N-dimethyl-N′- (9H-purin-6-yl)-formamidine (9) with 2-bromopent-4-enoic acid ethyl ester (6). The functional groups, ester and allyl, were converted to the desired hydroxymethyl and hydroxyethyl groups, and subsequently to phosphonomethyl derivatives and corresponding pyrophosphorylphosphonates.     

Oxidase-peroxidase enzymes of Datura innoxia. Oxidation of formylphenylacetic acid ethyl ester.

An enzyme system from Datura innoxia roots oxidizing formylphenylacetic acid ethyl ester was purified 38-fold by conventional methods such as (NH4)2SO4 fractionation, negative adsorption on alumina Cy gel and chromatography on DEAE-cellulose. The purified enzyme was shown to catalyse the stoicheiometric oxidation of formylphenylacetic acid ethyl ester to benzoylformic acid ethyl ester and formic acid, utilizing molecular O2. Substrate analogues such as phenylacetaldehyde and phenylpyruvate were oxidized at a very low rate, and formylphenylacetonitrile was an inhilating agents, cyanide, thiol compounds and ascorbic acid. This enzyme was identical with an oxidase-peroxidase isoenzyme. Another oxidase-peroxidase isoenzyme which separated on DEAE-chromatography also showed formylphenylacetic acid ethyl ester oxidase activity, albeit to a lesser extent. The properties of the two isoenzymes of the oxidase were compared and shown to differ in their oxidation and peroxidation properties. The oxidation of formylphenylacetic acid ethyl ester was also catalysed by horseradish peroxidase. The Datura isoenzymes exhibited typical haemoprotein spectra. The oxidation of formylphenylacetic acid ethyl ester was different from other peroxidase-catalysed reactions in not being activated by either Mn2+ or monophenols. The oxidation was inhibited by several mono- and poly-phenols and by catalase. A reaction mechanism for the oxidation is proposed.     

Semisynthetic ‘acid-esterase’: Conformational modification of ribonuclease

Bovine pancreatic ribonuclease has been modified by exposure to acidic conditions, addition of indole propionic acid and crosslinking with glutaraldehyde. The ‘acid-esterase’ generated was purified up to 100-fold by ammonium sulphate fractionation and gel filtration on Biogel P-30. The partially purified acid-esterase hydrolysed tryptophan ethyl ester (TrEE) and $\text{N-}\text{benzoyl}\text{-}\text{l}\text{-}\text{arginine}$ ethyl ester (BAEE) effectively at pH 6.0–6.3, but it had very little activity towards glycine ethyl ester and lysine ethyl ester. Hydrolysis of TrEE was competitively inhibited by tryptophan. The acid-esterase exhibited amidase activity towards benzoyl-l-arginine p-nitroanilide.     

Oxidase-peroxidase enzymes of Datura innoxia. Oxidation of reduced nicotinamide-adenine dinucleotide in the presence of formylphenylacetic acid ethyl ester.

The oxidase-peroxidase from Datura innoxia which catalyses the oxidation of formylphenylacetic acid ethyl ester to benzoylformic acid ethyl ester and formic acid was also found to catalyse the oxidation of NADH in the presence of Mn2+ and formylphenylacetic acid ethyl ester. NADH was not oxidized in the absence of formylphenylacetic acid ethyl ester, although formylphenylacetonitrile or phenylacetaldehyde could replace it in the reaction. The reaction appeared to be complex and for every mol of NADH oxidized 3-4 g-atoms of oxygen were utilized, with a concomitant formation of approx. 0.8 mol of H2O2, the latter being identified by the starch-iodide test and decomposition by catalase. Benzoylformic acid ethyl ester was also formed in the reaction, but in a nonlinear fashion, indicating a lag phase. In the absence of Mn2+, NADH oxidation was not only very low, but itself inhibited the formation of benzoylformic acid ethyl ester from formylphenylacetic acid ethyl ester. A reaction mechanism for the oxidation of NADH in the presence of formylphenylacetic acid ethyl ester is proposed.     

Changes in ester compounds and higher alcohols of awamori during aging

The total contents of ethyl acetate, ethyl caproate, ethyl caprylate, isoamyl caproate, ethyl caprate, isoamyl caprylate, ethyl laurate, isoamyl caprate, ethyl myristate, ethyl palmitate, ethyl stearate, ethyl oleate, ethyl linoleate and β-phenethyl acetate in awamori ranged from 70.67 to 569.72 mg per l a t 100 per cent alcohol. The ratio of ethyl acetate content to the total content of 14 ester compounds (ethyl acetate/total esters) ranged from 0.59 to 0.86, and that of ethyl caprylate to the total esters was from 0.98 ×10⁻² to 8.26 × 10⁻². Ethyl acetate was the main component of ester compounds followed in descending order by ethyl caprate, ethyl palmitate and ethyl caprylate. Of the higher alcohols, awamori contained only β-phenethyl alcohol in significant quantity.On aging in kame 13 of 16 ester compounds tended to decrease distinctly and the remaining 3 components to show no distinct change, while 3 of 5 higher alcohols tended to increase distinctly. On aging in non-porous containers, however, 3 of 16 ester compounds decreased distinctly, and 3 of 5 higher alcohols increased distinctly. In the process of aging, esters underwent hydrolysis in kame but not in non-porous containers.     

Transesterification of canola oil in mixed methanol/ethanol system and use of esters as lubricity additive

Transesterification of canola oil was carried out with methanol, ethanol, and various mixtures of methanol/ethanol, keeping the molar ratio of oil to alcohol 1:6 and using KOH as a catalyst. Mixtures of alcohol increased the rate of transesterification reaction and produced methyl as well as ethyl esters. The increased rate was result of better solubility of oil in reaction mixture due to better solvent properties of ethanol than methanol and equilibrium due to methanol. With 3:3 molar ratio of methanol to ethanol {MEE (3:3)} the amount of ethyl ester formed was 50% that of methyl ester. Properties (acid value, viscosity, density) of all esters including mixed esters were within the limits of ASTM standards. Lubricities of these esters are in the order: ethyl ester>methyl ethyl ester>methyl ester.     

印度獐牙菜挥发油化学成分的研究

研究了印度獐牙菜(Swertia chitayita Buch-Ham．)挥发油的化学成分。采用水蒸气蒸馏法提取、毛细管气相色谱-质谱联用技术对印度獐牙菜挥发性化学成分进行了分离,经计算机质谱谱库检索对分离的化合物进行鉴定,并用已知烃类进行标定,共确定了其中63种化合物,所鉴定出的化合物含量占全挥发油的81．36％;用峰面积归一化法测定了各化学成分的相对含量。研究结果表明,印度獐牙菜的主要化学成分为：十六烷酸乙酯(19．54％)、4-(苯甲基)哌啶(11．72％)、油酸乙酯(7．82％)、丁基化羟基甲苯(6．70％)、亚油酸乙酯(5．80％)、丁二酸二乙酯(3．21％)、3a,6a-二氢-2(3H,4H)环戊二烯并[b]呋喃酮(2．13％)等。     

Divergent effects of eicosapentaenoic and docosahexaenoic acid ethyl esters, and fish oil on hepatic fatty acid oxidation in the rat

The physiological activity of fish oil, and ethyl esters of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) affecting hepatic fatty acid oxidation was compared in rats. Five groups of rats were fed various experimental diets for 15 days. A group fed a diet containing 9.4% palm oil almost devoid of n-3 fatty acids served as a control. The test diets contained 4% n-3 fatty acids mainly as EPA and DHA in the form of triacylglycerol (9.4% fish oil) or ethyl esters (diets containing 4% EPA ethyl ester, 4% DHA ethyl ester, and 1% EPA plus 3% DHA ethyl esters). The lipid content of diets containing EPA and DHA ethyl esters was adjusted to 9.4% by adding palm oil. The fish oil diet and ethyl ester diets, compared to the control diet containing 9.4% palm oil, increased activity and mRNA levels of hepatic mitochondrial and peroxisomal fatty acid oxidation enzymes, though not 3-hydroxyacyl-CoA dehydrogenase activity. The extent of the increase was, however, much greater with the fish oil than with EPA and DHA ethyl esters. EPA and DHA ethyl esters, compared to the control diet, increased 3-hydroxyacyl-CoA dehydrogenase activity, but fish oil strongly reduced it. It is apparent that EPA and DHA in the form of ethyl esters cannot mimic the physiological activity of fish oil at least in affecting hepatic fatty acid oxidation in rat.