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1.
Adverse effects associated with synthetic drugs in diabetes therapy has prompted the search for novel natural lead compounds with little or no side effects. Effects of phenolic compounds from Carpobrotus edulis on carbohydrate-metabolizing enzymes through in vitro and in silico methods were assessed. Based on the half-maximal inhibitory concentrations (IC50), the phenolic extract of the plant had significant (p < 0.05) in vitro inhibitory effect on the specific activity of alpha-amylase (0.51 mg/mL), alpha-glucosidase (0.062 mg/mL) and aldose reductase (0.75 mg/mL), compared with the reference standards (0.55, 0.72 and 7.05 mg/mL, respectively). Molecular interactions established between the 11 phenolic compounds identifiable from the HPLC chromatogram of the extract and active site residues of the enzymes revealed higher binding affinity and more structural compactness with procyanidin (−69.834 ± 6.574 kcal/mol) and 1,3-dicaffeoxyl quinic acid (−42.630 ± 4.076 kcal/mol) as potential inhibitors of alpha-amylase and alpha-glucosidase, respectively, while isorhamnetin-3-O-rutinoside (−45.398 ± 4.568 kcal/mol) and luteolin-7-O-beta-d-glucoside (−45.102 ± 4.024 kcal/mol) for aldose reductase relative to respective reference standards. Put together, the findings are suggestive of the compounds as potential constituents of C. edulis phenolic extract responsible for the significant hypoglycemic effect in vitro; hence, they could be exploited in the development of novel therapeutic agents for type-2 diabetes and its retinopathy complication.  相似文献   

2.
Pumpkin seeds has long been used as a source of nutrition. Based on its content, it is possible that part of this plant used as immunonutrient. The purpose of this research is to study the immunomodulatory activity of pumpkin seeds. It effects on the non-specific immune response was determined through carbon clearance test, organ indexes (liver, spleen and thymic gland) and mice peritoneal exudate activity (PEA). The effects on specific immune response were determined through total antibody titre, delayed type of hypersensitivity (DTH) reaction and number of lymphocytes. On non specific immune response test, pumpkin seed at a low dose (PLD-3.8 g/kg bw) and at a high dose (PHD-7.6 g/kg bw) showed immunostimulanting effect with phagocytic index of 1.219 and 1.347, respectively. PHD increased PEA activity (p<0.01) in lysing microbes. On specific immune response test, PLD and PHD showed immunostimulation effect indicated through 50% haemaglutination activity (HA titre) i.e., 1:512 and 1:2048, respectively compared to than that of control (1:256) for secondary antibody titre. Through cellular immunity test, 48 hours after challenged, PHD showed significant (p<0.05) increased in footpad thickness. After 7 days administration, both doses of pumpkin increased lymphocytes number significantly (p<0.05). Based on the data it can be concluded that, pumpkin seeds have immunomodulatory effects, and can therefore be used as immunonutrient  相似文献   

3.
Oxidative stress has a crucial role in diabetic pathophysiology, therefore consuming naturally derived antioxidants as a remedial target. This study examines the naturally occurring antioxidant and antidiabetic of Olea europaea L. ethanolic leaves extract. Olea europaea L. leaves were macerated (OLE) by using absolute ethanol. Phytochemical and physiochemical analysis of OLE was screened using standard methods. The antioxidant effects were examined by DPPH (1, 1-diphenyl-2-picrylhydrazil) radical scavenging assay. In vitro antidiabetic was assayed by α-amylase enzyme inhibition study. Ethanolic extraction of OLE by maceration technique, 10% yield. Loss on drying, foreign organic matters and total ash value of OLE showed 2%, 0.2% and 16.5%, respectively. Phytochemical test on OLE confirmed saponin, flavonoid, glycoside, tannin, phenol and carbohydrate presences. The total phenolic and flavonoid contents of OLE is 490 mg GAE/g and 855 mg RUE/g of extract, respectively. OLE (IC50 38.37 ± 0.26 µg/ml) showed functional DPPH scavenging assay comparable to ascorbic acid (IC50 30.37 ± 0.17 µg/ml). In the alpha-amylase inhibitory activity, Acarbose showed an IC50 value of 20.06 ± 0.19 µg/ml, while OLE portrayed an IC50 value of 37.99 ± 0.15 µg/ml. The kinetic studies revealed that all samples at high concentrations reacted within a very short time, and a steady state was reached almost immediately. The lowest concentration showed slow kinetic behaviour implied longer periods before the constant state was reached. Molecular docking studies evidenced that most of the phenolic compounds of OLE interact with the active site of Human pancreatic α-amylase through the hydrogen bonding and hydrophobic interaction confirming the alpha-amylase inhibitory effect. The results suggest that Olea europaea L. has been a conceivable natural bioactive source as an antioxidant and an antidiabetic agent.  相似文献   

4.
Synthesis of nanoparticles by green synthesis has a large number of biomedical applications worldwide. In this study, Selenium Nanoparticles (SeNPs) were synthesized by using sodium salt of selenium and Solanum lycopersicum (tomato) fruit juice and seeds extract. The plant extracts were used as a reducing agent in ratio 1:4 i.e. sodium selenite salt (Na2SeO3). SeNPs were characterized by UV–visible spectrophotometry, FTIR and Zeta Sizer analysis. The UV-graphs indicated the highest peak of absorbance at 350 nm. Whereas, FTIR analysis of SeNPs indicated absorbance bands at 3262.35–1633.72 cm?1. Zeta sizer analysis showed the average size of SeNPs for Fruit juice extract as 1020 d.nm. with PDI 0.432. In case of seeds extract, average size was 1155 d.nm. with PDI 0.761; and the PDI value for both extracts showed polyderse nature of these NPs. SeNPs possessed significant antimicrobial activity against selected strains of E. coli, S. aureus, M. luteus, S. enterica, B. subtilis, K. pneumoniae and P. aureginosa. The α-amylase inhibitory assay of these SeNPs indicated that they had antidiabetic role with IC50 value 24.4642 µg/mL. The DPPH assay showed that SeNPs of Solanum lycopersicum have antioxidant activity with IC50 value of 20.7398 µg/mL.  相似文献   

5.
Withania frutescens L. is a wild perennial woody plant used by the local population for diverse therapeutic purposes. This work aims to study for the first time the potential inhibitory effect of this plant hydroethanolic extract on α-amylase and α-glucosidase activities using in vitro methods and its antidiabetic and antihyperglycemic activities using alloxan-induced diabetic mice as a model for experimental diabetes. Two doses were selected for the in vivo study (200 and 400 mg/kg) and glibenclamide, a well-known antidiabetic drug (positive control) in a subacute study (28 days) where the antihyperglycemic activity was also assessed over a period of 12 h on diabetic mice. The continuous treatment of diabetic mice with the extract of Withania frutescens for 4 weeks succeeded to slowly manage their high fasting blood glucose levels (after two weeks), while the antihyperglycemic test result revealed that the extract of this plant did not control hyperglycemia in the short term. No toxicity signs or death were noted for the groups treated with the plant extract, and it shows a protective effect on the liver and kidney. The in vitro assays demonstrated that the inhibition of alpha-amylase and alpha-glucosidase might be one of the mechanisms of action exhibited by the extract of this plant to control and prevent postprandial hyperglycemia. This work indicates that W. frutescens have an important long term antidiabetic effect that can be well established to treat diabetes.  相似文献   

6.
The influences of urea, yeast extract, and nitrate as the nitrogen source on heterotrophic growth of four strains of Chlorella protothecoides were investigated in 9-day feed-batch cultures. Biomass dry weight concentration (DWC) and lipid yield (LY) of the four strains in all media were compared. The highest LY in 9 days was 654 mg/L/day by UTEX 255 in 2.4 g/L KNO3 medium with a biomass DWC of 11.7 g/L and lipid content of 50.5%. Using green autotrophic seeds instead of yellow heterotrophic seeds improved the biomass DWC (13.1 vs. 11.7 g/L), LY (850 vs. 654 mg/L/day), and lipid to glucose consumption ratio (0.607 vs. 0.162). Moreover, 17.0 g/L DWC and 489 mg/L/day LY were obtained from the sequentially mixed-nitrogen medium, and the lipid to glucose consumption ratio was improved to 0.197 from 0.162 in 2.4 g/L nitrate medium and from 0.108 in 4.2 g/L yeast extract medium in the first batch.  相似文献   

7.
The effect of the CHCl3 and MeOH extracts from aerial parts from the Northwestern Argentina endemic species Ixorhea tschudiana Fenzl. on germination of the dicot tomato and the monoct onion and on soil microbial activity was studied by calorimetric and calorespirometric experiments. The CHCl3 extract inhibited seedling growth of tomato which increased with increasing concentrations. Seeds imbibed with 250 mg dm?3 extract germinated 24 h later than control and those imbibed with 100 and 500 mg dm?3 extract. This was reflected in the calculated low specific seedling growth rate (pSGΔHB) as determined from calorespirometric experiments. On the other hand, seedlings obtained in 500 mg dm?3 extract showed shorter and thicker hairy roots than control with significantly higher pSGΔHB. Probably, the extract induces inhibition of water uptake by seedling roots. Germination was reduced 50% in onion seeds imbibed with 500 mg dm?3 CHCl3 extract which apparently is due to higher rate of imbibition during the first stages as determined for calorimetry. On the other hand, 83 and 250 mg kg?1 of the MeOH and CHCl3 extract seem to selectively inhibit the growth of certain microorganisms and to enhance the activity of soil actinomycetes. Two actinobacteria were isolated from soil treated with these concentrations of both extracts: Kocuria sp. and Kocuria rosea; this latter species is known as a keratinolytic agent and seems to degrade complex carbon compounds of the soil and those incorporated by the MeOH extract. Both Kocuria specie seem to be beneficial for the soil converting substrate into biomass and thus I. tschudiana could be used as a soil phytoremediator.  相似文献   

8.
Universal behavior of the magnetocaloric effect along with structural and critical exponent analysis in mixed manganite La0.67Ca0.33Mn1xCrxO3 (x = 0.1, 0.25), [LCMCr0.1 and LCMCr0.25] exhibiting second order phase transition are investigated. Structural study using Reitveld refinement of XRD patterns indicates orthorhombic structure with Pnma space group. Modified Arrott plot method has been adopted to study the critical behavior of the compounds at their transition region, which gives values of β = 0.555(6), γ = 1.17(4) and δ = 2.7096(7) at TC = 232.5 K for LCMCr0.1 and β = 0.68 (1), γ = 1.09(3) and δ = 2.9362(4) at TC = 202.5 K for LCMCr0.25. The values are close to those expected for mean field ferromagnets with long range order. With increase in Cr content, the temperature corresponding to the maximum entropy change as well as the magnetic transition temperature gradually shifts to low temperatures. The maximum magnetic entropy change was found to be 3.5 J/kg K for x = 0.1 and 2.2 J/kg K for x = 0.25 for a field change of 5 T. The field dependence of the magnetic entropy change is also analyzed, which shows the power law dependence namely, ?SM ∝ Hn, n = 0.9086(5) at TC = 232.5 K and n = 0.849(7) at TC = 202.5 K for LCMCr0.1 and LCMCr0.25 respectively. Relative cooling power was found to be about 147 J/kg for LCMCr0.1 and 88 J/kg for LCMCr0.25. The field dependence of the relative cooling power for both the compounds shows a H1+1/δ dependence with the δ values in agreement with the mean field model.  相似文献   

9.
《Solid State Sciences》2012,14(10):1399-1404
New oxonickelates(I), Rb3NiO2 and Cs3NiO2, were prepared via the azide/nitrate route, starting from stoichiometric mixtures of azides, nitrates and NiO as precursors. The mixtures were heated steadily in a controlled heating regime up to 723 K and annealed at this temperature for 50 h (30 h for cesium compound) in specially designed containers with silver inlays. The crystal structures of Rb3NiO2 and Cs3NiO2 were solved and refined by X-ray powder methods. Room temperature α-Rb3NiO2 (P41212, Z = 4, a = 6.2651(2) Å, b = 14.7438(3) Å; Rwp = 6.30%) and high temperature β-Rb3NiO2 (at 523 K P42/mnm, Z = 2, a = 6.2750(2) Å, b = 7.5088(3) Å; Rwp = 7.85%) were found to be isostructural to room and high temperature α- and β-K3NiO2, respectively. Cs3NiO2 crystallizes at room temperature isostructural with the β-K3NiO2 (P42/mnm, Z = 2, a = 6.4336(3) Å, b = 8.0844(4) Å; Rwp = 5.21%). A3NiO2 (A = K, Rb, Cs) are paramagnetic in the whole temperature range investigated. The magnetic susceptibility data have been evaluated by the Curie–Weiss law, where the calculated magnetic moments are as expected for a d9 system (μ = 1.73–2.20μB). Negative values of Weiss constants are indicative for antiferromagnetic interactions in this family of compounds.  相似文献   

10.
Silver nanoparticles (AgNPs) have attracted considerable attention owing to their unique biological applications. AgNPs synthesized by plant extract is considered as a convenient, efficient and eco-friendly material. In this work, the aqueous extract of Areca catechu L. nut (ACN) was used as the reducing and capping agents for one-pot synthesis of AgNPs, and their antioxidant and antibacterial activities were investigated. UV (Ultra Violet)-visible spectrum and dynamic light scattering (DLS) analysis revealed that the size of AgNPs was sensitive to the synthesis conditions. The synthesized AgNPs were composed of well-dispersed particles with an small size of about 10 nm under the optimal conditions (pH value of extract was 12.0; AgNO3 concentration was 1.0 mM; reaction time was 90 min). In addition, scanning electron microscope with energy dispersive X-ray (SEM-EDX), transmission electron microscopy (TEM) and X-ray diffraction (XRD) results further verified that the synthesized AgNPs had a stable and well-dispersed form (Zeta potential value of ?30.50 mV and polydispersity index of 0.328) and a regular spherical shape (average size of 15–20 nm). In addition, Fourier transform infrared spectrometry (FTIR) results revealed that phytochemical constituents in ACN aqueous extract accounted for Ag+ ion reduction, capping and stabilization of AgNPs. The possible reductants in the aqueous extract of Areca catechu L. nut were identified by high-performance liquid chromatography-electrospray ionization-quadrupole-time of flight-mass spectrometry (HPLC-ESI-qTOF/MS) method. More importantly, the synthesized AgNPs indicated excellent free radical scavenging activity of 1,1-diphenyl-2-picrylhydrazyl (DPPH, IC50 = 11.75 ± 0.29 μg/mL) and 2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS+, IC50 = 44.85 ± 0.37 μg/mL), which were significant higher than that of ascorbic acid. Moreover, AgNPs exhibited an enhanced antibacterial activity against six selected common pathogens (especially Escherichia coli and Staphylococcus aureus) compared with AgNO3 solution. In a short, this study showed that the Areca catechu L. nut aqueous extract could be applied for eco-friendly synthesis of AgNPs.  相似文献   

11.
Colourless, water- and air-stable single crystals of cerium(III) oxoarsenate(III) Ce[AsO3] were prepared by the reaction of cerium metal (Ce) and arsenic sesquioxide (As2O3) in the presence of cesium chloride (CsCl) as fluxing agent at 750 °C in an evacuated silica ampoule. Ce[AsO3] crystallizes monoclinically (a = 902.89(8), b = 782.54(7), c = 829.68(7) pm, β = 103.393(3)°, Z = 8) in the space group P21/c and is isotypic with α-Pb[SeO3]. There are two crystallographically different Ce3+ positions. (Ce1)3+ is coordinated by nine oxygen atoms (d(Ce–O) = 244–286 pm) and (Ce2)3+ by only eight (d(Ce–O) = 239–273 pm). Both crystallographically different As3+ cations form discrete ψ1 tetrahedra [AsO3]3− (d(As–O) = 174–179 pm), which are attached to the Ce3+ cations via edges and corners. The second monoclinic modification of Ce[AsO3] with the lattice parameters a = 439.32(4), b = 529.21(5), c = 617.34(6) pm and β = 105.369(3)° with Z = 2 was obtained by high-pressure synthesis (11 GPa, 1200 °C) and has both a higher density (6.31 vs. 6.13 g · cm−3) and a higher calculated Madelung part of the lattice energy (15,155 vs. 15,132 kJ · mol−1). It adopts the space group P21/m, crystallizing isotypically with La[AsO3], β-Pb[SeO3], Pb[SO3] (scotlandite) or K[ClO3] and exhibits nine-fold coordinated Ce3+ cations exclusively (d(Ce–O) = 254–287 pm) along with tripodal [AsO3]3− anions (d(As–O) = 175–176 pm). Raman spectroscopy on both phases of Ce[AsO3] shows stretching vibrations between 769 and 731 cm−1 as well as asymmetric vibrations in the range of 659–617 cm−1. The symmetric bending mode vibrations emerge in an interval from 340 to 410 cm−1 and the asymmetric bending modes range between 230 and 290 cm−1.  相似文献   

12.
The intermetallic phase Yb11Bi10 − xSnx (x = 0 and 4.8) crystallizing in the Ho11Ge10 structure type was synthesized and characterized. The crystal structure was established by single-crystal X-ray diffraction data in the tetragonal space group I4/mmm (no.139), Pearson code tI84, Z = 4, a = 12.2043(4) Å, c = 17.7227(9) Å, and V = 2639.7(2) Å3, Rgt(F) = 0.040, 763 observed reflections for Yb11Bi10, and a = 12.0183(5) Å, c = 17.413(1) Å, and V = 2515.1(2) Å3, Rgt(F) = 0.027, 762 observed reflections for Yb11Bi5.2Sn4.8. The crystal structure of Yb11Bi10 contains three discrete anionic moieties: isolated Bi3− anions, Bi24− dimers and Bi44− squares. In Yb11Bi5.2Sn4.8, the square units are formed solely by Sn, and the structure shows a mixed Bi/Sn occupancy at the 8i and 16m Wyckoff sites. Magnetization measurements show that the title phase contains ytterbium exclusively in the 4f14 configuration up to 400 K. The Yb-LIII X-ray absorption spectrum attests also the presence of Yb with a 4f14 (Yb2+) configuration for Yb11Bi10, while the average valence of ytterbium was found to be 2.09 for Yb11Bi5.2Sn4.8.  相似文献   

13.
A new paratungstate-A-based organic–inorganic hybrid compound with the chemical formula of [Co(en)3]2[H2W7O24]·8H2O (en = ethylenediamine) (1) has been hydrothermally synthesized and structurally characterized by the elemental analysis, IR, TG, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic space group P21/c with a = 17.216(3) Å, b = 14.986(3) Å, c = 23.088(8) Å, β = 128.151(2)°, V = 4684.2 Å3, Z = 1, R1 = 0.0484, and wR2 = 0.1087. The structure of 1 consists of the [H2W7O24]4− building blocks and [Co(en)3]2+ metal-organic cationic moieties, which are packed together via the electrostatic forces and extensive hydrogen-bonding interactions to form a three-dimensional supramolecular framework. Interestingly, compound 1 represents the first structurally-defined hybrid compound based on the metastable paratungstate-A polyoxoanions and metal–organic units. The degradation of Rhodamine-B (RhB) under UV irradiation with 1 as the heterogeneous photocatalyst has been investigated, showing a good photocatalytic property of 1 for RhB degradation.  相似文献   

14.
《印度化学会志》2021,98(10):100170
Morus rubra (red mulberry) is a folk medicine used in management of diabetes. The aim of this article to investigate the antidiabetic activity of hydro alcoholic leaf extracts of Morus rubra in the sprague dawley male rats (SD) model. Authentication of plant material, total Phenolic contents, total flavonoid contents, HPLC analysis, in-vitro antioxidant activity, acute toxicity, in-vivo oral glucose tolerance test, in-vivo STZ induced antidiabetic activity along with biochemical parameters (triglycerides, low-density lipoprotein, high-density lipoprotein, total cholesterol, serum glutamate phosphotransferase, serum glutamate oxaloacetic acid transferase, urea and creatinine). The total phenolic contents 60.32 ​± ​0.80 ​mg/g GAE (gallic acid equivalent) were found higher in ethanolic extract. The total flavonoids 16 ​± ​0.42 ​mg/g QE (quercetin equivalent) were found in petroleum ether extract. M. rubra leaf extracts were tested by HPLC for qualitative and quantitative analysis. 100 ​mg of the dried powder of Morus leaves was dissolve in methanol: water (80:20, v/v) for analysis. Chromatograms of HPLC show the presence of chlorogenic acid 0.55 mg/gm, quercetin 1.90 ​mg/g, isoquercetin 0.68 mg/gm and rutin 0.10 mg/gm. IC50 (Inhibitory concentration) value has been found higher in chloroform extract (92.89 ​μg/ml). Metformin drug is used for positive control, which causes 14.6% improvement in glucose tolerance while M. rubra has been found 11.4. % at the dose of 300 ​mg/kg body wt in normal rats. In STZ treated diabetic rats, it reduces 13.0% blood glucose level while metformin reduces 21.9% up to dosing level of 300 ​mg/kg body wt. It produces reduction in biochemical parameters like, total cholesterol (TC), triglycerides (TG), SGPT, LDL, urea, creatinine and SGOT while HDL has been increased. Results show the hydro-alcoholic leaves extract of Morus rubra exhibited antidiabetic, antioxidant and hypolipidemic properties. This suggests that M. rubra has great potential to develop novel antidiabetic drug to manage this disastrous disease.  相似文献   

15.
《Solid State Sciences》2012,14(9):1338-1342
Lead free 0.95[(K0.5Na0.5)1−xAgxNbO3]–0.05LiSbO3 (KNAN–LS) ceramics with x = 0, 0.02, 0.04, 0.06 and 0.08 have been synthesized by conventional solid state reaction route (CSSR). X-ray diffraction (XRD) analysis confirmed the transformation of mixed structure to pure tetragonal structure with the increase in Ag content in KNN–LS ceramics. The Curie temperature (Tc) of the ceramics decreased from 385.5 °C to 331 °C with the increase in silver (Ag) content. The poling temperature was optimized for better piezoelectric properties. The KNAN–LS ceramics with x = 0.06 showed better piezoelectric and ferroelectric properties (d33 = 227 pC/N, kp = 42.5%, Tc = 368 °C and Pr = 21.9 μC/cm2).  相似文献   

16.
Global public health is seriously threatened by diabetes and its complications. Although several synthetic drugs are currently employed for managing diabetes, however, the adverse effects associated with their use cannot be underestimated. Thus, the quest for a safe and cost-effective alternative is highly imperative. In the present study, the phenolic contents, antioxidant, antidiabetic, and cytotoxic potentials of 70% ethanolic crude extract of Myrtus communis ‘Variegatha’ were investigated using in vitro biochemical protocols. The total polyphenols content was 116.44 mg GAE/g, flavonols (6.74 mg QE/g), flavanols (2.46 mg CE/g) and the ferric reducing antioxidant power (FRAP) value was 1267.28 µmol AAE/g, 2,2-diphenyl-1-picrylhydrazyl (DPPH) (1165.37 µmol TE/g), and Trolox equivalent antioxidant capacity (TEAC) (775.52 µmol TE/g). High-resolution ultra-performance liquid chromatography coupled with electrospray ionisation/quadrupole-time-of-flight-mass spectrometry (UPLC-ESI-QTOF-MS) was explored to identify the phenolic compounds, most of which were flavonoids. The extract demonstrated a strong α-glucosidase inhibition potential in a concentration-dependent manner with IC50 (3.159 µg/mL), which was higher than epigallocatechin gallate (EGCG) (6.208 µg/mL), a positive control antidiabetic drug. A slight increase in glucose utilization was observed after 24 h of treatment in C3A hepatocytes at 25 μg/mL whereas an increase in glucose uptake was recorded at 25 and 50 μg/mL. The extract exhibited a cytotoxic effect (IC50 76.85 µg/mL) against C3A hepatocytes at 100 µg/mL, which correlates to the glucose utilization and uptake recorded. The findings from the study show the prospect of M. communis ‘Variegatha’ as a promising source of bioactive compounds that could be used in the development of new anti-diabetic agents, thus, further research into the plant is recommended.  相似文献   

17.
This study was conducted to evaluate the method performance of a rapid procedure for the measurement of alpha-amylase activity in flours and microbial enzyme preparations. Samples were milled (if necessary) to pass a 0.5 mm sieve and then extracted with a buffer/salt solution, and the extracts were clarified and diluted. Aliquots of diluted extract (containing alpha-amylase) were incubated with substrate mixture under defined conditions of pH, temperature, and time. The substrate used was nonreducing end-blocked p-nitrophenyl maltoheptaoside (BPNPG7) in the presence of excess quantities of thermostable alpha-glucosidase. The blocking group in BPNPG7 prevents hydrolysis of this substrate by exo-acting enzymes such as amyloglucosidase, alpha-glucosidase, and beta-amylase. When the substrate is cleaved by endo-acting alpha-amylase, the nitrophenyl oligosaccharide is immediately and completely hydrolyzed to p-nitrophenol and free glucose by the excess quantities of alpha-glucosidase present in the substrate mixture. The reaction is terminated, and the phenolate color developed by the addition of an alkaline solution is measured at 400 nm. Amylase activity is expressed in terms of Ceralpha units; 1 unit is defined as the amount of enzyme required to release 1 micromol p-nitrophenyl (in the presence of excess quantities of alpha-glucosidase) in 1 min at 40 degrees C. In the present study, 15 laboratories analyzed 16 samples as blind duplicates. The analyzed samples were white wheat flour, white wheat flour to which fungal alpha-amylase had been added, milled malt, and fungal and bacterial enzyme preparations. Repeatability relative standard deviations ranged from 1.4 to 14.4%, and reproducibility relative standard deviations ranged from 5.0 to 16.7%.  相似文献   

18.
《Solid State Sciences》2004,6(6):593-598
The solution-mediated syntheses and single crystal structures of C6N2H10·Zn(HPO3)2 (I) and (C6N2H8)0.5·ZnHPO3 (II) are reported. Slight variation of the synthesis conditions led to two quite different phases. I contains infinite chains of ZnO4 and HPO3 groups with the protonated organic moiety acting as a template and interacting with the chains by NH⋯O hydrogen bonds and possible CH⋯O interactions. In II, the neutral 1,4-diamino benzene molecule bonds to Zn (as a ligand) and an unusual composite, “pillared”, structure results, with the organic species bridging 63 polyhedral sheets, although NH⋯O bonds are also present. Similarities and differences to other zinc phosphites and phosphates are briefly discussed for I and II. Crystal data: C6N2H10·Zn(HPO3)2, Mr=335.48, monoclinic, C2/c (No. 15), a=17.2471 (14) Å, b=9.0720 (8) Å, c=7.6529 (6) Å, β=103.752 (2)°, V=1163.09 (7) Å3, Z=4, R(F)=0.038, wR(F2)=0.084. (C6N2H8)0.5·ZnHPO3, Mr=199.42, orthorhombic, Pbca (No. 61), a=8.0314 (16) Å, b=8.1299 (16) Å, c=18.830 (4) Å, V=1229.5 (4) Å3, Z=8, R(F)=0.026, wR(F2)=0.055.  相似文献   

19.
Investigations into the formation of new ettringite-type phases with a range of trivalent and tetravalent cations were carried out to further study the potential this structure type has to incorporate cations covering a range of ionic radii (0.53–0.69 Å). We report the synthesis and structural characterisation of a new ettringite-type phase, Ca6[Ga(OH)6·12H2O]2(SO4)3·2H2O, which was indexed in space group P31c with the unit cell parameters a = 11.202(2) Å, c = 21.797(3) Å and two new thaumasite-type phases Ca6[M(OH)6·12H2O]2(SO4)2(CO3)2, M = Mn, Sn which were indexed in space group P63 with the unit cell parameters a = 11.071(5) Å, c = 21.156(8) Å and a = 11.066(1) Å, c = 22.420(1) Å respectively. These new phases show the versatility of the ettringite family of structures to tolerate a large range of cation sizes on the octahedral M site and highlights the preference of tetravalent cations to crystallise with the thaumasite structure over the ettringite structure.  相似文献   

20.
《中国化学快报》2022,33(7):3527-3530
Two tetravalent uranium silicate and germanate M2UIVT3O9 (M = K, Cs; T = Si, Ge) crystals were crystalized under inert gas by molten salt flux growth method. K2USi3O9 (1) crystallizes in the monoclinic space group P121/n1 with lattice parameters a = 7.1076 Å, b = 10.4776 Å, c = 12.2957 Å, γ = 120° and V = 915.67 Å3. Cs2UGe3O9 (2) crystallizes in a hexagonal space group P-6 with lattice constants of a = 7.5138 Å, b = 7.5138 Å, c = 11.0114 Å, γ = 120° and V = 538.38 Å3. Bond valence calculations indicate tetravalent uranium in both structures, which contain three-membered single-ring T3O96? trimers. K2USi3O9 is the first uranium silicate that contains the Si3O96? trimers.  相似文献   

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