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1.
Acylation of quercetin with cinnamic acid catalyzed by Candida antarctica lipase B (CAL-B) or Pseudomonas cepacia lipase C (PCL-C) was investigated. Specifically, the effects of reaction duration, incubation temperature, and molar ratio of substrates on bioconversion yield, initial rate of reaction, and regioselectivity were investigated. Three new acylated quercetin analogues were produced: quercetin 4′-cinnamate (C24H16O8), quercetin 3′,4′-dicinnamate (C33H22O9), and quercetin 7,3′,4′-tricinnamate (C42H28O10). The effects of the lipase-catalyzed acylation conditions on the bioconversion yields varied across the conditions. The initial rate of reaction of acylation of quercetin with cinnamic acid catalyzed by CAL-B and PCL-C was similar. In the presence of CAL-B, acylation mainly took place at the C-4′-OH, generating mostly quercetin 4′-cinnamate; whereas with PCL-C, acylation mainly took place at both the 4′- and 3′-hydroxyls, generating quercetin 3′,4′-dicinnamate. Thin-layer-chromatography analysis showed that the three acylated quercetin analogues had higher lipophilicity when compared with quercetin. In silico investigation revealed that quercetin 4’-cinnamate and quercetin 3′,4′-dicinnamate are likely to be orally active pharmacological drugs. 相似文献
2.
Impact of Chiral Bioanalytical Methods on the Bioequivalence of Ibuprofen Products Containing Ibuprofen Lysinate and Ibuprofen Base
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Alfredo García‐Arieta Juan Manuel Ferrero‐Cafiero Montse Puntes Ignasi Gich Susana Morales‐Alcelay Maite Tarré Xavier Font Rosa Maria Antonijoan 《Chirality》2016,28(5):429-433
The purpose was to assess the impact of the use of a chiral bioanalytical method on the conclusions of a bioequivalence study that compared two ibuprofen suspensions with different rates of absorption. A comparison of the conclusion of bioequivalence between a chiral method and an achiral approach was made. Plasma concentrations of R‐ibuprofen and S‐ibuprofen were determined using a chiral bioanalytical method; bioequivalence was tested for R‐ibuprofen and for S‐ibuprofen separately and for the sum of both enantiomers as an approach for an achiral bioanalytical method. The 90% confidence interval (90% CI) that would have been obtained with an achiral bioanalytical method (90% CI: Cmax: 117.69–134.46; AUC0t: 104.75–114.45) would have precluded the conclusion of bioequivalence. This conclusion cannot be generalized to the active enantiomer (90% CI: Cmax: 103.36–118.38; AUC0t: 96.52–103.12), for which bioequivalence can be concluded, and/or the distomer (90% CI: Cmax: 132.97–151.33; AUC0t: 115.91–135.77) for which a larger difference was observed. Chiral bioanalytical methods should be required when 1) the enantiomers exhibit different pharmacodynamics and 2) the exposure (AUC or Cmax) ratio of enantiomers is modified by a difference in the rate of absorption. Furthermore, the bioequivalence conclusion should be based on all enantiomers, since the distomer(s) might not be completely inert, in contrast to what is required in the current regulatory guidelines. In those cases where it is unknown if the ratio between enantiomers is modified by changing the rate of absorption, chiral bioanalytical methods should be employed unless enantiomers exhibit the same pharmacodynamics. Chirality 28:429–433, 2016. © 2016 Wiley Periodicals, Inc. 相似文献
3.
Lipase-catalyzed synthesis of potential multifunctional ribavirin derivatives was performed in acetone. Divinyl dicarboxylates with different chain lengths (C4, C6, C9, C10) were used as acyl donors and the reactions were catalyzed by lipase immobilized on acrylic resin from Candida antarctica (CAL-B). Ribavirin was regioselectivly acylated at the primary hydroxyl groups and the corresponding vinyl esters (C4, C6, C9, C10) were prepared in respective yields of 48%, 65%, 54%, 55%. 相似文献
4.
Studies on the application of commercially available enzymes to resolution of the racemic unsaturated γ-lactones: 5-(3-methylbutylidene)-4-methyl-tetrahydrofuran-2-one (1a) and 5-(3,3-dimethylbutylidene)-4-methyl-tetrahydrofuran-2-one (2a) are presented. Lipase PS, Rhizopus niveus lipase, Rhizopus arrhizus lipase, porcine pancreas lipase and hog liver esterase transformed substrates into their respective γ-keto acids with good efficiency (50–75%). Three of them hydrolysed the studied lactones with moderate enantioselectivity. Enantiomeric excesses determined by GC for the unreacted lactones were in the range of 20–60%. Lipase PS preferentially hydrolysed the (+) enantiomers of lactones 1a and 2a whereas R. niveus lipase hydrolysed the (?) enantiomers, respectively. 相似文献
5.
The enantioselective liquid–liquid extraction of 4‐nitro‐D,L‐phenylalanine (D,L‐Nphy) using PdCl2{(s)‐BINAP} as extractant in dichloroethane was studied experimentally in a countercurrent cascade of 10 centrifugal contactor separators (CCSs) at 5°C, involving flow ratio, extractant concentration, and Cl? concentration. The steady‐state enantiomeric excess (ee) in both stream exits was 90.86% at a 93.29% yield. The predicted value was modeled using an equilibrium stage approach. The correlation between model and experiment was satisfactory. The model was applied to optimize the production of both enantiomers in >97% ee and >99% ee. 14 stages and 16 stages are required for 97% ee and 99% ee for both enantiomers, respectively. Chirality 27:75–81, 2015. © 2014 Wiley Periodicals, Inc. 相似文献
6.
Jennifer Cunniff Glynis Jones Michael Charles Colin P. Osborne 《Global Change Biology》2017,23(1):380-393
Limitation of plant productivity by the low partial pressure of atmospheric CO2 (Ca) experienced during the last glacial period is hypothesized to have been an important constraint on the origins of agriculture. In support of this hypothesis, previous work has shown that glacial Ca limits vegetative growth in the wild progenitors of both C3 and C4 founder crops. Here, we present data showing that glacial Ca also reduces grain yield in both crop types. We grew four wild progenitors of C3 (einkorn wheat and barley) and C4 crops (foxtail and broomcorn millets) at glacial and postglacial Ca, measuring grain yield and the morphological and physiological components contributing to these yield changes. The C3 species showed a significant increase in unthreshed grain yield of ~50% with the glacial to postglacial increase in Ca, which matched the stimulation of photosynthesis, suggesting that increases in photosynthesis are directly translated into yield at subambient levels of Ca. Increased yield was controlled by a higher rate of tillering, leading to a larger number of tillers bearing fertile spikes, and increases in seed number and size. The C4 species showed smaller, but significant, increases in grain yield of 10–15%, arising from larger seed numbers and sizes. Photosynthesis was enhanced by Ca in only one C4 species and the effect diminished during development, suggesting that an indirect mechanism mediated by plant water relations could also be playing a role in the yield increase. Interestingly, the C4 species at glacial Ca showed some evidence that photosynthetic capacity was upregulated to enhance carbon capture. Development under glacial Ca also impacted negatively on the subsequent germination and viability of seeds. These results suggest that the grain production of both C3 and C4 crop progenitors was limited by the atmospheric conditions of the last glacial period, with important implications for the origins of agriculture. 相似文献
7.
Summary The synthesis of poly(3-hydroxyalkanoates) [P(3HA)] by a new Alcaligenes species was investigated. The new species was grown on various carbon sources such as n-alkanoic acids of carbon numbers ranging from C2 to C22, plant oils and animal fats, and accumulated P(3HA) within the cells. When the bacterium was cultured in mineral media containing sodium salts of n-alkanoic acids, the homopolymer of poly(3-hydroxybutyrate) [P(3HB)] was produced from n-alkanoates of even carbon numbers, whereas the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate units [P(3HB-co-3HV)] was produced from n-alkanoates of odd carbon numbers. Relatively high yields of both dry cells and P(3HA) were obtained by the use of n-alkanoates from C12 to C16 as the sole carbon source.
Correspondence to: Y. Doi 相似文献
8.
《Biocatalysis and Biotransformation》2013,31(5-6):303-308
Immobilized Candida antarctica lipase B, Novozym® 435, was used in the esterification of adipic acid and alcohols with different chain lengths (C1–C18). Optimum conditions for the synthesis of adipate esters were obtained using response surface methodology (RSM) with respect to important reaction parameters including time, temperature, substrate molar ratio and amount of enzyme. Alcohol chain length specificity of the enzyme in the synthesis of adipate esters was also determined. Minimum reaction time (215 min) for achieving maximum ester yield was obtained for butyl alcohol. Methanol required an increased time (358 min) and enzyme amount (10.2%, w/w) for attaining maximum yield. The maximum required temperature and time of 65°C and 523 min, respectively, were obtained for the synthesis of dioctadecyl adipate. The results demonstrate that alcohol chain length is a determining parameter in optimization of the lipase-catalyzed synthesis of adipate esters. Reactions under optimized conditions yielded a high percentage of esterification (>97%). The optimum conditions can be used to scale up the process. 相似文献
9.
Enantioselective assay of β-receptor antagonists present in microdialysis and plasma samples of rats
The enantiomers of alprenolol, metoprolol, and propranolol have been separated on an enantioselective cellulase column and analysed using a fully automated HPLC system involving coupled column chromatography and fluorescence detection. The assays had sufficient selectivity and sensitivity to investigate the disposition of these β2-receptor antagonists in blood and brain extracellular fluid of rats. A cellulase column was used as the first column to separate the enantiomers giving separation factors between 2.9 and 4.3. After the separation, the enantiomers were trapped on two small precolumns by the use of a switching valve and were then introduced on an achiral C18 analytical column by eluting the small columns backward. The enantiomers in blood and brain tissue dialysates were analysed by direct injection of 8 μl samples. The limit of quantitation was 0.025–0.4 μg/ml of the different enantiomers. Plasma samples were analysed after a simple extraction procedure. The intraassay precision of the lowest quality control plasma samples (0.2–0.8 μg rac drug/ml) was 4–8% for the different enantiomers. © 1995 Wiley-Liss, Inc. 相似文献
10.
Juciane Lauren Cavalcanti Cardoso Vera Lucia Lanchote Maria Paula Marques Pereira Jorge Manuel Vieira Capela José Salvador Lepera 《Chirality》2013,25(3):206-210
Fluoxetine is used clinically as a racemic mixture of (+)‐(S) and (–)‐(R) enantiomers for the treatment of depression. CYP2D6 catalyzes the metabolism of both fluoxetine enantiomers. We aimed to evaluate whether exposure to gasoline results in CYP2D inhibition. Male Wistar rats exposed to filtered air (n = 36; control group) or to 600 ppm of gasoline (n = 36) in a nose‐only inhalation exposure chamber for 6 weeks (6 h/day, 5 days/week) received a single oral 10‐mg/kg dose of racemic fluoxetine. Fluoxetine enantiomers in plasma samples were analyzed by a validated analytical method using LC‐MS/MS. The separation of fluoxetine enantiomers was performed in a Chirobiotic V column using as the mobile phase a mixture of ethanol:ammonium acetate 15 mM. Higher plasma concentrations of the (+)‐(S)‐fluoxetine enantiomer were found in the control group (enantiomeric ratio AUC(+)‐(S)/(–)‐(R) = 1.68). In animals exposed to gasoline, we observed an increase in AUC0‐∞ for both enantiomers, with a sharper increase seen for the (–)‐(R)‐fluoxetine enantiomer (enantiomeric ratio AUC(+)‐(S)/(–)‐(R) = 1.07), resulting in a loss of enantioselectivity. Exposure to gasoline was found to result in the loss of enantioselectivity of fluoxetine, with the predominant reduction occurring in the clearance of the (–)‐(R)‐fluoxetine enantiomer (55% vs. 30%). Chirality 25:206–210, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
11.
Anu Arya Divya Mathur Abhilash Tyagi Rajesh Kumar Vinod Kumar Carl E. Olsen 《Nucleosides, nucleotides & nucleic acids》2013,32(12):646-659
An efficient protocol has been developed for the synthesis of a small library of 3′-deoxy-3′-(4-substituted-triazol-1-yl)-5-methyluridine using Cu(I)-catalyzed Huisgen–Sharpless–Meldal 1,3-dipolar cycloaddition reaction of 3′-azido-3′-deoxy-5-methyluridine with different alkynes under optimized condition in an overall yields of 76%–92%. Here, the azido precursor compound, i.e., 3′-azido-3′-deoxy-5-methyluridine was chemoenzymatically synthesized from D-xylose in good yield. Some of the alkynes used in cycloaddition reaction were synthesized by the reaction of hydroxycoumarins or naphthols with propargyl bromide in acetone using K2CO3in excellent yields. All synthesized compounds were unambiguously identified on the basis of their spectral (IR, 1H-, 13C NMR spectra, and high-resolution mass spectra) data analysis. 相似文献
12.
Pseudomonas mendocina strain 0806 was isolated from oil-contaminated soil and found to produce polyesters consisting of medium chain length 3-hydroxyalkanoates (mclPHAs). The monomers of mclPHAs contained even numbers of carbon atoms, such as 3-hydroxyhexanoate (HHx or C6), 3-hydroxyoctanoate (HO or C8), and/or 3-hydroxydecanoate (HD or C10) as major components when grown on many carbon sources unrelated to their monomeric structures, such as glucose, citric acid, and carbon sources related to their monomeric structures, such as myristic acid, octanoate, or oleic acid. On the other hand, PHA containing both even and odd numbers of hydroxyalkanoates (HA) monomers was synthesized when the strain was grown on tridecanoic acid. The molar ratio of carbon to nitrogen (C/N) had a significant effect on PHA composition: the strain produced PHAs containing 97–99% of HD monomer when grown in a glucose ammonium sulfate medium of C/N<20, and 20% HO, and 80% of the HD monomer when growth was conducted in media containing C/N>40. It was demonstrated that the HO/HD ratio in the polymers remained constant in media with a constant C/N ratio, regardless of the glucose concentration. Up to 3.6 g/L cell dry weight containing 45% of PHAs was produced when the strain was grown for 48 h in a medium containing 20 g/L glucose with a C/N ratio of 40. 相似文献
13.
Experimental and Model Studies on Continuous Separation of 2‐Phenylpropionic Acid Enantiomers by Enantioselective Liquid–Liquid Extraction in Centrifugal Contactor Separators
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Multistage enantioselective liquid–liquid extraction (ELLE) of 2‐phenylpropionic acid (2‐PPA) enantiomers using hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) as extractant was studied experimentally in a counter‐current cascade of centrifugal contactor separators (CCSs). Performance of the process was evaluated by purity (enantiomeric excess, ee) and yield (Y). A multistage equilibrium model was established on the basis of single‐stage model for chiral extraction of 2‐PPA enantiomers and the law of mass conservation. A series of experiments on the extract phase/washing phase ratio (W/O ratio), extractant concentration, the pH value of aqueous phase, and the number of stages was conducted to verify the multistage equilibrium model. It was found that model predictions were in good agreement with the experimental results. The model was applied to predict and optimize the symmetrical separation of 2‐PPA enantiomers. The optimal conditions for symmetric separation involves a W/O ratio of 0.6, pH of 2.5, and HP‐β‐CD concentration of 0.1 mol L?1 at a temperature of 278 K, where eeeq (equal enantiomeric excess) can reach up to 37% and Yeq (equal yield) to 69%. By simulation and optimization, the minimum number of stages was evaluated at 98 and 106 for eeeq > 95% and eeeq > 97%. Chirality 28:235–244, 2016. © 2016 Wiley Periodicals, Inc. Research highlights are as follows:
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14.
A sensitive and selective high performance liquid chromatographic method using an automated column switching technique for the determination of FCE 28833 enantiomers in gerbil plasma was developed. After solid-liquid extraction using a Supelcosil C18 cartridge FCE 28833 was eluted on a clean-up column (Spherisorb CN) and the enantiomers were separated using an analytical chiral column (Crownpack CR(+)). The mobile phase (15% methanol in HClO4 1 mM) was directed through the columns at a flow rate of 1 ml/min and the fraction eluted between 13 and 40 min was transferred from the clean-up column into the analytical column. FCE 28833 enantiomers were monitored at 257 nm. The limit of quantitation of the method was 20 ng/ml plasma for both enantiomers and proved to be linear, precise, and accurate for the assay of both enantiomers in the 20–6,000 ng/ml concentration range. No interference from the blank gerbil plasma sample was observed. The suitability of the method was assessed using plasma samples obtained from male gerbils treated with a single oral dose (400 mg/kg) of FCE 28833. Chirality 9:133–138, 1997. © 1997 Wiley-Liss, Inc. 相似文献
15.
A proof‐of‐concept study to evaluate the biological removal of hydrocarbons (naphthalene, n‐hexadecane, and fuel oil #2) from contaminated wood (Southern yellow pine) was conducted using 14C‐labeled tracers and gas chromatography. Contaminated wood was brought in contact with n‐hexadecane‐degrading Pseudomonas aeruginosa PG201 or naphthalene degrading environmental isolates by the application either on mineral medium agar or filter paper containing a previously grown biomass (“overlay” technique). The experiments showed a significant acceleration of naphthalene removal by biomass. Due to biodegradation combined with evaporation, naphthalene was nearly completely removed (up to 90–98 %) in 4–8 days from freshly contaminated 6 mm‐ and 17 mm‐thick wood samples. The removal of a less volatile hydrocarbon, n‐hexadecane, was less efficient, at 40–60% in 20–40 days, with the only variable significantly affecting this pollutant's removal rate being the moisture content of the medium. Biodegradation experiments with standard heating fuel oil #2 (a representative real‐world contaminant) resulted in significant removal of light hydrocarbons (C10–C16), i.e., more mobile/volatile substrates, in 3 weeks (up to 70 %) whereas heavier hydrocarbons (C17–C19) were less affected. Pollutant mobility in both wood and aqueous media was shown to be the crucial factor affecting the removal efficiency. These results point toward a promising technique to reclaim wooden structures contaminated with volatile and semi‐volatile chemicals. 相似文献
16.
17.
Arife Pınar Ekinci Nimet Baltaş Ahmet Adıgüzel 《Journal of enzyme inhibition and medicinal chemistry》2016,31(2):325-331
The lipase was partially purified by ion exchange chromatography and gel filtration column chromatography, and was characterized from Geobacillus stearothermophilus AH22 strain. The lipase was purified 18.3-folds with 19.7% recovery. The lipase activity was determined by using p-nitrophenyl esters (C2–C12) as substrates. The Km values of the enzyme for these substrates were found as 0.16, 0.02, 0.19 and 0.55?mM, respectively, while Vmax values were 0.52, 1.03, 0.72 and 0.15?U?mg?1. The enzyme showed maximum activity at 50?°C and between pH 8.0 and 9.0. The enzyme was found to be quite stable at pH range of 4.0–10.0, and thermal stability between 50 and 60?°C. It was found that the best inhibitory effect of the enzyme activity was of Hg2+. The inhibitory effect as orlistat, catechin, propyl paraben, p-coumaric acid, 3,4-dihydroxy hydro-cinnamic acid was examined. These results suggest that G. stearothermophilus AH22 lipase presents very suitable properties for industrial applications. 相似文献
18.
Chen-Li Chiang 《Biotechnology Techniques》1999,13(7):453-457
The stability of Candida rugosa lipase, which catalyzes the hydrolysis reaction of olive oil in AOT/isooctane reverse micelles, decreased with the increase of 0 (defined as the molar ratio of water to surfactant) and Aerosol-OT concentration. The addition of a non-ionic cosurfactant, tetraethylene glycol dodecyl ether (C12E4), preserved enzymatic activity. The residual activity of the lipase was 53% after 24 h, while the enzyme completely lost its activity within 6 h in the absence of C12E4 addition. The stabilizing effect of C12E4 resulted in the increase of conversion. The enhancement of the activity and stability of lipase in reverse micelles by the addition of C12E4 may contribute to increase the rigidity of the micellar matrix stabilizing the enzyme structure. 相似文献
19.
Russell K. Monson Robert O. Littlejohn Jr. George J. Williams III 《Photosynthesis research》1982,3(2):153-159
The quantum yield for CO2 uptake was measured in C3 and C4 monocot species from several different grassland habitats. When the quantum yield was measured in the presence of 21% O2 and 340 cm3 m-3 CO2, values were very similar in C3 monocots, C3 dicots, and C4 monocots (0.045–0.056 mole CO2 · mole-1 quanta absorbed). In the presence of 2% O2 and 800 cm3 m-3 CO2, enhancements of the quantum yield values occurred for the C3 plants (both monocots and dicots), but not for C4 monocots. A dependence of the quantum yield on leaf temperature was observed in the C3 grass, Agropyron smithii, but not in the C4 grass, Bouteloua gracilis, in 21% O2 and 340 cm3 m-3 CO2. At leaf temperatures between 22–25°C the quantum yield values were approximately equal in the two species. 相似文献
20.
Tetrahydroberberine (THB), a racemic mixture of (+)‐ and (?)‐enantiomer, is a biologically active ingredient isolated from a traditional Chinese herb Rhizoma corydalis (yanhusuo). A chiral high performance liquid chromatography method has been developed for the determination of THB enantiomers in rat plasma. The enantioseparation was carried out on a Chiral®‐AD column using methanol:ethanol (80:20, v/v) as the mobile phase at the flow rate 0.4 ml/min. The ultraviolet detection was set at 230 nm. The calibration curves were linear over the range of 0.01–2.5 μg/ml for (+)‐THB and 0.01‐5.0 μg/ml for (?)‐THB, respectively. The lower limit of quantification was 0.01 μg/ml for both (+)‐THB and (?)‐THB. The stereoselective pharmacokinetics of THB enantiomers in rats was studied after oral and intravenous administration at a dose of 50 and 10 mg/kg racemic THB (rac‐THB). The mean plasma levels of (?)‐THB were higher at almost all time points than those of (+)‐THB. (?)‐THB also exhibited greater Cmax, and AUC0–∞, smaller CL and Vd, than its antipode. The (?)/(+)‐enantiomer ratio of AUC0–∞ after oral and intravenous administration were 2.17 and 1.43, respectively. These results indicated substantial stereoselectivity in the pharmacokinetics of THB enantiomers in rats. Chirality, 2012. © 2012 Wiley Periodicals, Inc. 相似文献