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1.
A new adsorbent is proposed for the solid-phase extraction of phenol and 1-naphthol from polluted water. The adsorbent (TX-SiO2) is an organosilica composite made from a bifunctional immobilized layer comprising a major fraction (91%) of hydrophilic
diol groups and minor fraction (9%) of the amphiphilic long-chain nonionic surfactant Triton X-100 (polyoxyethylated isooctylphenol)
(TX). Under static conditions phenol was quantitatively extracted onto TX-SiO2 in the form of a 4-nitrophenylazophenolate ion associate with cetyltrimethylammonium bromide. The capacity of TX-SiO2 for phenol is 2.4 mg g−1 with distribution coefficients up to 3.4 × 104 mL g−1; corresponding data for 1-naphthol are 1.5 mg g−1 and 3 × 103 mL g−1. The distribution coefficient does not change significantly for solution volumes of 0.025–0.5 L and adsorbent mass less than
0.03 g; 1–90 μg analyte can be easily eluted by 1–3 mL acetonitrile with an overall recovery of 98.2% and 78.3% for phenol
and 1-naphthol, respectively. Linear correlation between acetonitrile solution absorbance (A
540) and phenol concentration (C) in water was found according to the equation A
540 = (6 ± 1) × 10−2 + (0.9 ± 0.1)C (μmol L−1) with a detection range from 1 × 10−8 mol L−1 (0.9 μL g−1) to 2 × 10−7 mol L−1 (19 μL g−1), a limit of quantification of 1 μL g−1 (preconcentration factor 125), correlation coefficient of 0.936, and relative standard deviation of 2.5%. A solid-phase colorimetric
method was developed for quantitative determination of 1-naphthol on adsorbent phase using scanner technology and RGB numerical
analysis. The detection limit of 1-naphthol with this method is 6 μL g−1 while the quantification limit is 20 μL g−1. A test system was developed for naked eye monitoring of 1-naphthol impurities in water. The proposed test kit allows one
to observe changes in the adsorbent color when 1-naphthol concentration in water is 0.08–3.2 mL g−1. 相似文献
2.
Dorota Swiatla-Wojcik 《Research on Chemical Intermediates》2009,35(4):519-530
The effect of pH and associated ionic strength on the primary yields in the radiolysis of pressurised water has been assessed
by diffusion-kinetic calculations for temperatures in the range 100–300°C. Account has been taken for ionic strength I up to 0.1 mol kg−1, assuming that the counter ions of H+ in acid solutions and of OH− in base solutions have unit charge. In acid solutions, the H+ ions react with e−
aq. The decrease in G(e−
aq) and the increase in G(H) with decreasing pH becomes substantial for [H+] ≥ 1 × 10−4 m, but the primary yields of oxidising species are almost constant. In alkaline solutions, the OH− anions affect the spur chemistry of radiation-generated protons and hydroxyl radicals for [OH−] ≥ 1 × 10−4 m. The scavenging of H atoms and hydrogen peroxide becomes significant for [OH−] ≥ 1 × 10−2 m. The total yields G(OH) + G(O−) and G(H2O2) + G(HO2
−) are independent of base concentration below 0.01 m. In more alkaline solutions, G(OH) + G(O−) increases, whereas G(H2O2) + G(HO2
−) decreases with increasing [OH−]. Calculations showed the substantial yield of the reaction O− + e−
aq in 0.1 m base solution. Spur chemistry in alkaline hydrogenated water is not affected by the presence of H2 if less than 0.001 m of hydrogen is added. 相似文献
3.
J. H. Wang Q. Li M. H. Wu G. Xu Ch. Li B. R. Bao W. F. Zheng H. He Sh. D. Zhang 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(1):249-254
N,N-dimethylhydroxylamine (DMHA) is a novel salt-free reducing reagent used in the separation U from Pu and Np in the reprocessing
of power spent fuel. This paper reports on the radiolysis of aqueous DMHA solution and its radiolytic liquid organics. Results
show that the main organics in irradiated DMHA solution are N-methyl hydroxylamine, formaldehyde and formic acid. The analysis
of DMHA and N-methyl hydroxylamine were performed by gas chromatography, and that of formaldehyde was performed by ultraviolet–visible
spectrophotometry. The analysis of formic acid was performed by ion chromatography. For 0.1–0.5 mol L−1 DMHA irradiated to 5–25 kGy, the residual DMHA concentration is (0.07–0.47) mol L−1, the degradation rate of DMHA at 25 kGy is 10.1–30.1%. The concentrations of N-methylhydroxylamine, formaldehyde and formic acid are (8.25–19.36) × 10−3, (4.20–36.36) × 10−3 and (1.35–10.9) × 10−4 mol L−1, respectively. The residual DMHA concentration decreases with the increasing dose. The concentrations of N-methylhydroxylamine and formaldehyde increase with the dose and initial DMHA concentration, and that of formic acid increases
with the dose, but the relationship between the concentration of formic acid and initial DMHA concentration is not obvious. 相似文献
4.
Reactions of radiolytically generated CO3
•− with some ferric heme proteins, catalase, cytochrome c, and horseradish peroxidase (HRP), were studied. Carbonate radical
anion oxidized amino acid residues of these proteins, but did not react directly with heme iron. HRP and catalase lost about
30% and 20% of their activity, respectively, after the reaction with 100 μM of CO3
•−. The rate constants of the reactions of CO3
•− with the investigated proteins measured by the pulse radiolysis method at pH 8–8.4 and 10 varied from 1.0 × 108 M−1 s−1 (for cytochrome c) to 3.7 × 109 M−1 s−1 (for catalase). 相似文献
5.
Barbora Drtinová Milan Pospíšil 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(3):631-636
Behavior of cadmium(II) in aqueous solutions irradiated by accelerated electrons was studied. A concentration of 8.8 × 10−4 mol L−1 of cadmium dissolved from Cd(NO3)2 requires dose of 15 kGy to be effectively removed from the system containing 1 × 10−2 mol L−1 of HCOOK as a scavenger of OH radicals. The positive effect of deaeration with N2O or N2 was observed in the range of lower doses. The addition of solid modifiers (bentonite, active carbon, zeolite, Cu2O, NiO, TiO2 and CuO) reduced the effectivity of radiation removal of cadmium. Product of irradiation is CdCO3. On the contrary, in the system with cadmium dissolved from CdCl2 radiation reduction takes place. Systems contained organic complexants (ethylene diamine tetraacetic acid–EDTA, citric acid)
were also studied. The solutions of Cd(NO3)2 containing initial concentration 2.37 × 10−4 mol L−1 of CdII were mixed with 3 × 10−4 mol L−1 EDTA. In this system the efficient degradation proceeds up to 90% at a dose of 45 kGy with addition of 5 × 10−3 mol L−1 carbonate (pH 10.5). The product of irradiation is CdCO3. The presence of 1 × 10−2 mol L−1 of HCOOK in the solution is necessary for radiation removal of cadmium complexed with citric acid (1 × 10−3 mol L−1) at pH 8. With increasing concentration of HCOOK (up to 5 × 10−2 mol L−1) decreases the pH value necessary for the radiation induced precipitation of cadmium. The best result was obtained in the
system containing zeolite as a solid modifier. 相似文献
6.
Jonathan F. Ojo Jide Ige Grace O. Ogunlusi Olanrewaju Owoyomi Esan S. Olaseni 《Transition Metal Chemistry》2006,31(6):782-785
The kinetics of the reactions between Fe(phen)
3
2+
[phen = tris–(1,10) phenanthroline] and
Co(CN)5X3− (X = Cl, Br or I) have been investigated in aqueous acidic solutions at I = 0.1 mol dm−3 (NaCl/HCl). The reactions were carried out at a fixed acid concentration ([H+] = 0.01 mol dm−3) and the second-order rate constants for the reactions at 25 °C were within the range of (0.151–1.117) dm3 mol−1 s−1. Ion-pair constants K
ip for these reactions, taking into consideration the protonation of the cobalt complexes, were 5.19 × 104, 3.00 × 102 and 4.02 × 104 mol−1 dm−3 for X = Cl, Br and I, respectively. Activation parameters measured for these systems were as follows: ΔH* (kJ K−1 mol−1) = 94.3 ± 0.6, 97.3 ± 1.0 and 109.1 ± 0.4; ΔS* (J K−1) = 69.1 ± 1.9, 74.9 ± 3.2 and 112.3 ± 1.3; ΔG* (kJ) = 73.7 ± 0.6, 75.0 ± 1.0 and 75.7 ± 0.4; E
a
(kJ) = 96.9 ± 0.3, 99.8 ± 0.4, and 122.9 ± 0.3; A (dm3 mol−1 s−1) = (7.079 ± 0.035) × 1016, (1.413 ± 0.011) × 1017, and (9.772 ± 0.027) × 1020 for X = Cl, Br, and I respectively. An outer – sphere mechanism is proposed for all the reactions. 相似文献
7.
A new high α1A adrenoreceptor (α1AAR) expression cell membrane chromatography (CMC) method was developed for characterization of α1AAR binding interactions. HEK293 α1A cell line, which expresses stably high levels of α1AAR, was used to prepare the stationary phase in the CMC model. The HEK293 α1A/CMC-offline-HPLC system was applied to specifically recognize the ligands which interact with the α1AAR, and the dissociation equilibrium constants (K
D) obtained from the model were (1.87 ± 0.13) × 10−6 M for tamsulosin, (2.86 ± 0.20) × 10−6 M for 5-methylurapidil, (3.01 ± 0.19) × 10−6 M for doxazosin, (3.44 ± 0.19) × 10−6 M for terazosin, (3.50 ± 0.21) × 10−6 M for alfuzosin, and (7.57 ± 0.31) × 10−6 M for phentolamine, respectively. The competitive binding study between tamsulosin and terazosin indicated that the two drugs
interacted at the common binding site of α1AAR. However, that was not the case between tamsulosin and oxymetazoline. The results had a positive correlation with those
from radioligand binding assay and indicated that the CMC method combined modified competitive binding could be a quick and
efficient way for characterizing the drug–receptor interactions. 相似文献
8.
A new H2O2 biosensor was fabricated on the basis of nanocomposite films of hemoglobin (Hb), silver nanoparticles (AgNPs), and multiwalled
carbon nanotubes (MWNTs)–chitosan (Chit) dispersed solution immobilized on glassy carbon electrode (GCE). The immobilized
Hb displayed a pair of well-defined and reversible redox peaks with a formal potential (E
θ′) of −22.5 mV in 0.1 M pH 7.0 phosphate buffer solution. The apparent heterogeneous electron transfer rate constants (k
s) in the Chit–MWNTs film was evaluated as 2.58 s−1 according to Laviron’s equation. The surface concentration (Γ*) of the electroactive Hb in the Chit–MWNTs film was estimated to be (2.48 ± 0.25) × 10−9 mol cm−2. Meanwhile, the Chit–MWNTs/Hb/AgNPs/GCE demonstrated excellently electrocatalytical ability to H2O2. Its apparent Michaelis–Menten constant (K
Mapp) for H2O2 was 0.0032 mM, showing a good affinity. Under optimal conditions, the biosensors could be used for the determination of H2O2 ranging from 6.25 × 10−6 to 9.30 × 10−5 mol L−1 with a detection limit of 3.47 × 10−7 mol L−1 (S/N = 3). Furthermore, the biosensor possessed rapid response to H2O2 and good stability, selectivity, and reproducibility. 相似文献
9.
I. M. Piskarev I. P. Ivanova S. V. Trofimova N. A. Aristova 《High Energy Chemistry》2012,46(5):343-348
The chemical effects of self-sustained spark discharge with an energy per pulse of 5.9 × 10−2 J, a pulse repetition frequency of 10 Hz, and a spark-gap breakdown voltage of 6 kV have been studied. The discharge generated a UV photon flux of (2.5 ± 0.3) × 1015 cm−2 s−1 with an energy density of (2 ± 0.3) × 10−3 J cm−1 s−1 and the emission spectrum maximum at 220 nm. The action of the discharge on water samples leads to a decrease in pH and to buildup of oxidizing and reducing species. The formation of HO2· radicals with an initial yield of (1.2 ± 0.3) × 10−6 mol L−1 s−1 has been detected in the liquid. The initial yields of acid residues (increment in [H+]), oxidants, and reducing agents are (5.8 ± 1.6) × 10−7, (3.3 ± 1) × 10−6, and (4.2 ± 1) × 10−7 mol equiv L−1s−1, respectively. The formation of NO3− and NO4+ ions, nitrosamines, and organic compounds has been established. 相似文献
10.
H. Faghihian D. Rahi M. Mostajaboddavati 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(2):711-717
In this study the concentration of natural radionuclides has been investigated in soil and water of Karun river by using a
high resolution (HPGe detector, n-type) γ-spectrometry. The concentrations range in water sample was 47.6 ± 5.6–130.8 ± 6.3,
0.0–23.4 ± 0.5 and 0–6.4 ± 2.0 Bq L−1 for 40K, 232Th and 226Ra respectively. For soil samples the concentration range of 275.7 ± 8.6–458.6 ± 6.8, 19.2 ± 5.35–41.1 ± 3.95 and 29.9 ± 1.53–50 ± 1.54 Bq kg−1 was obtained respectively for 40K, 232Th and 238U. 137Cs was also detected in some part of the region in soil samples. The mean concentration of 137Cs was 5.5 ± 0.6 Bq kg−1. The origin of this activity is unknown. The average absorbed dose rate in outdoor air at a height of 1 m above the ground
was found to be 54.3 ± 3.7 nGy h−1. The results of this study indicate that the area has standard background radiation level. 相似文献
11.
Dazhang Zhu Shilong Wang Xiaoyu Sun Yaming Ni Side Yao 《Frontiers of Chemistry in China》2007,2(4):354-358
The reaction mechanism between isoquinoline and ·OH radical in aqueous dilute solutions under different conditions was studied
by pulse radiolysis. The main characteristic peaks in these transient absorption spectra were attributed and the growth-decay
trends of several transient species were investigated. Under neutral or alkaline conditions, the reaction of ·OH radical and
isoquinoline produces OH-adducts with respective rate constants of 3.4 × 109 and 6.6 × 109 mol−1 · dm3 · s−1 while under acidic conditions, the isoquinoline was firstly protonated and then ·OH added to the benzene ring and produced
protonated isoquinoline OH-adducts with a rate constant of 3.9 × 109 mol−1 · dm3 · s−1. With a better understanding on radiolysis of isoquinoline, this study is of help for its degradation and for environmental
protection.
__________
Translated from Journal of Fudan University (Natural Science), 2006, 45(6): 774–778 [8BD1;81EA: 590D;65E6;5B66;62A5;(自然科学版)] 相似文献
12.
Mark A. W. Lawrence Sonia E. Thomas Paul T. Maragh Tara P. Dasgupta 《Transition Metal Chemistry》2011,36(5):553-563
The kinetics of the intra-molecular electron transfer of an adduct of l-ascorbic acid and the [Fe3IIIO(CH3COO)6(H2O)3]+ cation in aqueous acetate buffer was studied spectrophotometrically, over the ranges 2.55 ≤ pH ≤ 3.74, 20.0 ≤ θ ≤ 35.0 °C,
at an ionic strength of 0.50 and 1.0 mol dm−3 (NaClO4). The reaction of l-ascorbic acid and the complex cation involves the rapid formation of an adduct species followed by a slower reduction in
the iron centres through consecutive one-electron transfer processes. The final product of the reaction is aqueous iron(II)
in acetate buffer. The proposed mechanism involves the triaqua and diaqua-hydroxo species of the complex cation, both of which
form adducts with l-ascorbic acid. At 25 °C, the equilibrium constant for the adduct formation was found to be 86 ± 15 and 5.8 ± 0.2 dm3 mol−1 for the triaqua and diaqua-hydroxo species, respectively. The kinetic parameters derived from the rate expression have been
found to be: k
0 = (1.12 ± 0.02) × 10−2 s−1 for the combined spontaneous decomposition and k
1 = (4.47 ± 0.06) × 10−2 s−1 (ΔH
1‡ = 51.0 ± 2.3 kJ mol−1, ΔS
1‡ = −100 ± 8 J K−1 mol−1), k
2 = (4.79 ± 0.38) × 10−1 s−1 (ΔH
2‡ = 76.5 ± 0.8 kJ mol−1, ΔS
2‡ = 6 ± 3 J K−1 mol−1) for the triaqua and diaqua-hydoxo species, respectively. 相似文献
13.
Ahmad Soleymanpour Bahram Garaili S. Masoud Nabavizadeh 《Monatshefte für Chemie / Chemical Monthly》2008,139(12):1439-1445
Three platinum(II) complexes were synthesized and studied to characterize their ability as an anion carrier in a PVC membrane electrode. The polymeric membrane electrodes (PME) and also coated glassy carbon electrodes (CGCE) prepared with
one of these complexes showed excellent response characteristics to perchlorate ions. The electrodes exhibited Nernstian responses to ClO4
− ions over a wide concentration range from 1.5 × 10−6 to 2.7 × 10−1 M for PME and 5.0 × 10−7 to 1.9 × 10−1 M for CGCE with low detection limits (9.0 × 10−7 M for PME and 4.0 × 10−7 M for CGCE). The electrodes possess fast response time, satisfactory reproducibility, appropriate lifetime and, most importantly,
good selectivity toward ClO4
− relative to a variety of other common anions. The potentiometric response of the electrodes is independent of the pH of the test solution in the pH range 2.0–9.0. The proposed sensors were used in potentiometric determination of perchlorate ions in mineral water and urine
samples.
Correspondence: Ahmad Soleymanpour, Department of Chemistry, Damghan Basic Science University, Damghan, Iran. 相似文献
14.
The effects of temperature and common ions on binding of puerarin to bovine serum albumin (BSA) are investigated. The binding
constants (K
a) between puerarin and BSA are 1.13×104 L⋅mol−1 (20 °C) and 1.54×104 L⋅mol−1 (30 °C), and the number of binding sites (n) is (0.95±0.02). However, at a higher temperature (40 °C) the stability of the puerarin–BSA system decreases, which results
in a lower binding constant (1.58×103 L⋅mol−1) and number of binding sites (n=0.73) of the puerarin–BSA system. However, the presence of Cu2+ and Fe3+ ions increases the binding constants and the number of binding sites in the puerarin–BSA complex. 相似文献
15.
A flow injection method is described for the determination of iron in fresh water based on potassium permanganate chemiluminescence
detection via oxidation of formaldehyde in aqueous hydrochloric acid. Total iron concentrations are determined after reducing
Fe(III) to Fe(II) using hydroxylamine hydrochloride. The detection limit (three standard deviations of blank) is 1.0 nM, with
a sample throughput of 120 h−1. The calibration graph was linear over the range (2–10) × 10−7 M (r
2 = 0.9985) with relative standard deviations (n = 5) in the range 1.0–2.3%. The effect of interfering cations (Ca(II), Mg(II), Zn(II), Ni(II), Co(II), Fe(III), Mn(II), Pb(II),
and Cu(II)) and common anions (Cl−, SO
4
2−
, PO
4
3−
, NO
3
−
, NO
2
−
, I−, F−, and SO
3
2−
) was studied at their maximum admissible concentrations in fresh water. The method was applied to fresh-water samples from
the Quetta Valley, and the results obtained (0.04 ± 0.001–0.11 ± 0.01 mg/L Fe(II)) were in reasonable agreement with those
obtained using the spectrophotometric reference method (0.05 ± 0.01–0.12 ± 0.02 mg/L Fe(II)).
The text was submitted by the authors in English. 相似文献
16.
Neetu Bansal 《Transition Metal Chemistry》2010,35(4):483-490
A kinetic method for the determination of organosulfur compounds by UV spectrophotometry is described. Organosulfur compounds
have been shown to inhibit the Hg(II)-catalyzed substitution of cyanide in hexacyanoferrate(II) by 2-methylpyrazine (2-Mepz).
The inhibitory effect is proportional to the concentration of inhibitor and can be used as the basis for the determination
of trace amounts of organosulfur compounds such as cysteine, 2,3-dimercaptopropanol (DMP) and thioglycolic acid (TGA). Both
the influence of the reaction variables and interference of a variety of ions have been studied. A mechanism for the inhibition
process is proposed. The determination range depends on the amount of Hg(II) added and stability of the Hg(II)–ligand complex.
Kinetic parameters were determined from Lineweaver–Burk plots, obtained in the absence and presence of the inhibitor. Excellent
linearity is observed for all analytes over their respective concentration ranges with correlation coefficient >0.9. The condition
calibration curves were linear in the range of 5 × 10−6–15 × 10−6 M for cysteine, 1 × 10−7–7 × 10−7 M for DMP and 1 × 10−6–10 × 10−6 M for TGA. The detection limits were 1.18 × 10−7 M for cysteine, 4.16 × 10−8 M for DMP and 1.30 × 10−7 M for TGA. The effects of amino acids that can interfere in the determination of cysteine were studied. 相似文献
17.
Eduardo Marafon Lauro T. Kubota Yoshitaka Gushikem 《Journal of Solid State Electrochemistry》2009,13(3):377-383
SiO2/ZrO2/C carbon ceramic material with composition (in wt%) SiO2 = 50, ZrO2 = 20, and C = 30 was prepared by the sol–gel-processing method. A high-resolution transmission electron microscopy image
showed that ZrO2 and the graphite particles are well dispersed inside the matrix. The electrical conductivity obtained for the pressed disks
of the material was 18 S cm−1, indicating that C particles are also well interconnected inside the solid. An electrode modified with flavin adenine dinucleotide
(FAD) prepared by immersing the solid SiO2/ZrO2/C, molded as a pressed disk, inside a FAD solution (1.0 × 10−3 mol L−1) was used to investigate the electrocatalytic reduction of bromate and iodate. The reduction of both ions occurred at a peak
potential of −0.41 V vs. the saturated calomel reference electrode. The linear response range (lrr) and detection limit (dl)
were: BrO3
−, lrr = 4.98 × 10−5–1.23 × 10−3 mol L−1 and dl = 2.33 μmol L−1; IO3
−, lrr = 4.98 × 10−5 up to 2.42 × 10−3 and dl = 1.46 μmol L−1 for iodate. 相似文献
18.
E. A. Skrypnikova S. A. Kaluzhina E. V. Orlova 《Russian Journal of Electrochemistry》2011,47(11):1231-1235
The effect of glycine, α-alanine, and asparagine acid on the kinetics of anode processes occurring for copper in alkali electrolytes
is studied. The experiments are performed in a background solution of 1 × 10−2 M NaOH (pH 12). The concentrations of glycine and α-alanine are varied in the range of 1 × 10−6-1 × 10−1 M, and the concentration of asparagine acid is varied in the range of 1 × 10−5-1 × 10−3 M. All amino acids used in this work have been found to stimulate anode oxidation of passivated copper, initiating local
activation (LA) of the metal. Depending on the nature of amino acids, this effect occurs in various concentration ranges:
for glycine and α-alanine, it takes place at c= 5 × 10−3-2 × 10−2 M, while for asparagine acid, at c = 1 × 10−5−1 × 10−3 M. In addition to this general regularity, several individual peculiarities have been revealed: in the systems containing
a monobasic amino acid additive, local activation occurs at E = 0.10–0.20 V, while in the presence of a dibasic amino acid, the local activation is observed at two potentials, E
LA1 = 0.20–0.30 V and = E
LA2 = 0.80–0.90 V, separated by the repassivation region. 相似文献
19.
A sensitive and selective HPLC–UV method established for determination of picroside I in dog plasma has been used to study
the pharmacokinetics of the drug after intravenous administration of three different doses. Sample pretreatment consists in
deproteination by addition of acetonitrile; l-ascorbic acid was used to improve the stability of picroside I. The lower limit of quantification of picroside I was 0.05 μg mL−1. The recovery of the method was up to 90%. After intravenous administration to dogs picroside I was mainly distributed in
the central compartment and was rapidly eliminated from the plasma; the mean elimination half-life was 30.54 ± 4.34, 30.20 ± 3.78,
and 34.02 ± 1.88 min for doses of 2.5, 5, and 15 mg kg−1, respectively, and the respective values of AUC
0–∞ were 81.04 ± 19.95, 198.50 ± 27.77, and 586.44 ± 103.08 μg min mL−1. The different doses had no significant effect on the main pharmacokinetic data and the kinetics seemed to be linear in dosage
range 2.5–15 mg kg−1. 相似文献
20.
Maneerat Yodjun Aphichart Karnchanatat Polkit Sangvanich 《Applied biochemistry and biotechnology》2012,166(8):2037-2050
Ammonium sulphate cut protein extracts, and their pepsin hydrolysates, from the rhizomes of 15 plants in the Zingiberaceae
family were screened for their in vitro angiotensin I-converting enzyme inhibitory (ACEI) activity. The protein extract from
Zingiber ottensii had the highest ACEI activity (IC50 of 7.30 × 10−7 mg protein/mL) and was enriched for by SP Sepharose chromatography with five NaCl step gradients 0, 0.25, 0.50, 0.75 and
1 M NaCl collecting the corresponding five fractions. The highest ACEI activity was found in the F75 fraction, which appeared
to contain a single 20.7-kDa protein, suggesting enrichment to or near to homogeneity. The ACEI activity of the F75 fraction
was moderately thermostable (−20–60 °C), showed >80% activity across a broad pH range of 4–12 (optimal at pH 4–5) and appeared
as a competitive inhibitor of ACE (K
i of 9.1 × 10−5 mg protein/mL). For the pepsin hydrolysates, that from Zingiber cassumunar revealed the highest ACEI activity (IC50 of 0.38 ± 0.012 mg/mL), was enriched to a single active hexapeptide by RP-HPLC with a strong ACEI activity (IC50 of 0.011 ± 0.012 mg/mL) and acted as a competitive inhibitor of ACE (K
i of 1.25 × 10−6 mg protein/mL). 相似文献