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2010 Volume 21 Issue 4
2010, 21(4): 381-384
doi: 10.1016/j.cclet.2009.11.033
Abstract:
A series of furoxan-based nitric oxide-releasing matrine derivatives(10a-f)were synthesized.The biological evaluation showed that compounds 10a,10b,10e and 10f had stronger cytotoxic activities than 5-fluorouracil against human hepatoma cells(HepG2) in vitro.
A series of furoxan-based nitric oxide-releasing matrine derivatives(10a-f)were synthesized.The biological evaluation showed that compounds 10a,10b,10e and 10f had stronger cytotoxic activities than 5-fluorouracil against human hepatoma cells(HepG2) in vitro.
2010, 21(4): 385-387
doi: 10.1016/j.cclet.2009.12.031
Abstract:
A novel series of protic tertiary pyrrolidinium surfaetants were prepared and characterized by different techniques.These compounds show good conductivity and efficient ability to reduce surface tension.Thermogravimetric analysis proves their high thermal stability at decomposition temperatures over 250℃.Their lyotropic and thermotropic liquid crystalline properties are also discussed.
A novel series of protic tertiary pyrrolidinium surfaetants were prepared and characterized by different techniques.These compounds show good conductivity and efficient ability to reduce surface tension.Thermogravimetric analysis proves their high thermal stability at decomposition temperatures over 250℃.Their lyotropic and thermotropic liquid crystalline properties are also discussed.
2010, 21(4): 388-390
doi: 10.1016/j.cclet.2009.12.016
Abstract:
A microwave-assisted solid phase synthesis for endothelin 1 is presented.Reduced endothelin 1 was synthesized efficiently on Wang resin under microwave irradiation using Fmoc/tBu orthogonal protection strategy.The whole peptide was cleaved from the resin and two disulphide bridges were formed under air oxidation at room temperature.The purity and efficiency of synthesizing the peptide is much higher than other methods used before.
A microwave-assisted solid phase synthesis for endothelin 1 is presented.Reduced endothelin 1 was synthesized efficiently on Wang resin under microwave irradiation using Fmoc/tBu orthogonal protection strategy.The whole peptide was cleaved from the resin and two disulphide bridges were formed under air oxidation at room temperature.The purity and efficiency of synthesizing the peptide is much higher than other methods used before.
2010, 21(4): 391-394
doi: 10.1016/j.cclet.2009.11.026
Abstract:
A general method was described to synthesize a highly hydrophobic cyclic peptide,cyclo[(L)W(L)W(L)W(L)W(L)Q]where underlines indicate D-configuration of the amino acid,by a two-step solid-phase/solution synthesis strategy.The linear decapeptide was assembled by standard Boc chemistry on solid-phase and subsequently cyclized in solution with high efficiency and reproducibility.In subsequent purification by semi-preparative HPLC,50%(v/v)DMF/H2O was employed as the solvent to overcome the difficulty of solubilization for the hydrophobic cyclic decapeptide and achieved a total yield of 30-35% with a purity of over 98%.
A general method was described to synthesize a highly hydrophobic cyclic peptide,cyclo[(L)W(L)W(L)W(L)W(L)Q]where underlines indicate D-configuration of the amino acid,by a two-step solid-phase/solution synthesis strategy.The linear decapeptide was assembled by standard Boc chemistry on solid-phase and subsequently cyclized in solution with high efficiency and reproducibility.In subsequent purification by semi-preparative HPLC,50%(v/v)DMF/H2O was employed as the solvent to overcome the difficulty of solubilization for the hydrophobic cyclic decapeptide and achieved a total yield of 30-35% with a purity of over 98%.
2010, 21(4): 395-398
doi: 10.1016/j.cclet.2009.12.015
Abstract:
Polyethylene glycol(PEG)was found to be an effective catalyst for the condensation of 1,2-diamines with 1,2-dicarbonyl compounds to afford the corresponding quinoxaline derivatives in excellent yields under mild reaction conditions.
Polyethylene glycol(PEG)was found to be an effective catalyst for the condensation of 1,2-diamines with 1,2-dicarbonyl compounds to afford the corresponding quinoxaline derivatives in excellent yields under mild reaction conditions.
2010, 21(4): 399-402
doi: 10.1016/j.cclet.2009.12.008
Abstract:
Silica-supported tin chloride and titanium tetrachloride were prepared by the reaction of tin chloride and titanium tetrachloride with activated silica gel in refluxing toluene.These solid acids have been employed as the catalysts for the synthesis of bisdihydropyrimidin-2(1H)-ones from aromatic dialdehydes,1,3-dicarbonyl compounds and urea at 90℃ under solvent-free conditions.
Silica-supported tin chloride and titanium tetrachloride were prepared by the reaction of tin chloride and titanium tetrachloride with activated silica gel in refluxing toluene.These solid acids have been employed as the catalysts for the synthesis of bisdihydropyrimidin-2(1H)-ones from aromatic dialdehydes,1,3-dicarbonyl compounds and urea at 90℃ under solvent-free conditions.
2010, 21(4): 403-406
doi: 10.1016/j.cclet.2009.11.017
Abstract:
Certain phenols and naphthols were nitrated regioselectively with Zn(NO3)2·6H2O/TCT in acetonitrile as solvent at room temperature and short reaction time in good yields.The reaction condition was mild.TCT is a cheap and commercially available reagent.It performed as an acid catalyst in this transformation.
Certain phenols and naphthols were nitrated regioselectively with Zn(NO3)2·6H2O/TCT in acetonitrile as solvent at room temperature and short reaction time in good yields.The reaction condition was mild.TCT is a cheap and commercially available reagent.It performed as an acid catalyst in this transformation.
2010, 21(4): 407-411
doi: 10.1016/j.cclet.2009.12.007
Abstract:
In this article,six new optically active copoly(amide-imide)s (10a-f) were synthesized through the direct polycondensation reaction of N-phthalimido-L-aspartic acid(4)with 1,5-diamino naphthalene(8),3,4-diainino benzophenone(9) in the presence of therphthalic acid(7),fumaric acid (6) and adipic acid (5) as a second diacid in a medium consisting of N-methyl-2-pyrrolidone,triphenyl phosphite,calcium chloride and pyridine.The resulting copolymers were fully characterized by means of FT-IR spectroscopy,elemental analyses,inherent viscosity,solubility tests and UV-vis spectroscopy.Thermal properties of resulting copolymers (10a-c) containing three different second diacid in the main chain were compared by using TGA and DTG thermograms.
In this article,six new optically active copoly(amide-imide)s (10a-f) were synthesized through the direct polycondensation reaction of N-phthalimido-L-aspartic acid(4)with 1,5-diamino naphthalene(8),3,4-diainino benzophenone(9) in the presence of therphthalic acid(7),fumaric acid (6) and adipic acid (5) as a second diacid in a medium consisting of N-methyl-2-pyrrolidone,triphenyl phosphite,calcium chloride and pyridine.The resulting copolymers were fully characterized by means of FT-IR spectroscopy,elemental analyses,inherent viscosity,solubility tests and UV-vis spectroscopy.Thermal properties of resulting copolymers (10a-c) containing three different second diacid in the main chain were compared by using TGA and DTG thermograms.
2010, 21(4): 412-416
doi: 10.1016/j.cclet.2009.11.035
Abstract:
A facile one-pot synthesis of 2-aminothiazoles has been carded in PEG-400 as a greener medium at room temperature.This method avoids the use of lachrymatric α-bromoketones as well as the volatile,toxic organic solvents.
A facile one-pot synthesis of 2-aminothiazoles has been carded in PEG-400 as a greener medium at room temperature.This method avoids the use of lachrymatric α-bromoketones as well as the volatile,toxic organic solvents.
2010, 21(4): 417-420
doi: 10.1016/j.cclet.2009.11.010
Abstract:
A novel acid dye acid was synthesized by the condensation reaction between bromamine acid and 2-amino-6-nitrobenzothiazole and its anti-UV protection properties were evaluated.The results showed that silk dyed with this dye had very good ultraviolet radiation protection capability and excellent dyeing performance.The UV-absorption mechanism of this dye was also discussed.
A novel acid dye acid was synthesized by the condensation reaction between bromamine acid and 2-amino-6-nitrobenzothiazole and its anti-UV protection properties were evaluated.The results showed that silk dyed with this dye had very good ultraviolet radiation protection capability and excellent dyeing performance.The UV-absorption mechanism of this dye was also discussed.
2010, 21(4): 421-425
doi: 10.1016/j.cclet.2009.10.020
Abstract:
A cheap and recyclable ZnO-beta zeolite was used as catalyst for the synthesis of benzothiazole derivatives.This method provides several advantages such as environmental friendliness,short reaction times,high yields,simple work-up procedure and catalyst was successfully reused for four cycles without significant loss of activity.
A cheap and recyclable ZnO-beta zeolite was used as catalyst for the synthesis of benzothiazole derivatives.This method provides several advantages such as environmental friendliness,short reaction times,high yields,simple work-up procedure and catalyst was successfully reused for four cycles without significant loss of activity.
2010, 21(4): 426-428
doi: 10.1016/j.cclet.2009.12.006
Abstract:
A series of ethyl 6-alkoxy-7-phenyl-4-hydroxy-3-quinolinecarboxylates were designed and synthesized.Their structures were confirmed by 1H NMR,13C NMR,IR and HRMS.The biological activities were primarily evaluated against Eimeria tenella according to Anticoccidial Index(ACI)method in vivo.The results showed that compounds 5e,5f and 5i exhibited anticoccidial activities against E.tenella at 27 mg kg-1.
A series of ethyl 6-alkoxy-7-phenyl-4-hydroxy-3-quinolinecarboxylates were designed and synthesized.Their structures were confirmed by 1H NMR,13C NMR,IR and HRMS.The biological activities were primarily evaluated against Eimeria tenella according to Anticoccidial Index(ACI)method in vivo.The results showed that compounds 5e,5f and 5i exhibited anticoccidial activities against E.tenella at 27 mg kg-1.
2010, 21(4): 429-432
doi: 10.1016/j.cclet.2009.11.012
Abstract:
A simple and efficient method has been developed; benzil/benzoin undergoes smooth condensation with various substituted aldehyde and ammonium acetate in the presence of potassium dihydrogen phosphate(KH2PO4)under mild reaction conditions to afford the corresponding trisubstituted imidazole in excellent yields.The method for synthesis of product,the reaction mixture was reflux in ethanol for 40-90 min.The present method is simple,efficient,and cost-effective.
A simple and efficient method has been developed; benzil/benzoin undergoes smooth condensation with various substituted aldehyde and ammonium acetate in the presence of potassium dihydrogen phosphate(KH2PO4)under mild reaction conditions to afford the corresponding trisubstituted imidazole in excellent yields.The method for synthesis of product,the reaction mixture was reflux in ethanol for 40-90 min.The present method is simple,efficient,and cost-effective.
2010, 21(4): 433-436
doi: 10.1016/j.cclet.2009.11.047
Abstract:
Two new ceramides,(2S,3S,4R)-2-N-[(2'R)-2'-hydroxypentacosanoylamino]-nonacosane-1,3,4-triol(1)and(2S,3S,4R,8E)-2-N-[(2'R)-2'-hydroxytetracosanoylamino]-8-eicosylene-1,3,4-triol(2)have been isolated from the stems of Piper betle L.collected from Baoshan city of Yunnan Province in China.Their structures were determined by spectroscopic and chemical methods.
Two new ceramides,(2S,3S,4R)-2-N-[(2'R)-2'-hydroxypentacosanoylamino]-nonacosane-1,3,4-triol(1)and(2S,3S,4R,8E)-2-N-[(2'R)-2'-hydroxytetracosanoylamino]-8-eicosylene-1,3,4-triol(2)have been isolated from the stems of Piper betle L.collected from Baoshan city of Yunnan Province in China.Their structures were determined by spectroscopic and chemical methods.
2010, 21(4): 437-439
doi: 10.1016/j.cclet.2009.12.009
Abstract:
A new glycoside named 6β-O-β-D-glucosylpaederosidic acid(1)was isolated from Paederia scandens and its structure was elucidated on the basis of spectroscopic and chemical evidence,together with four known iridoids,paederoside(2),paederosidic acid(3),paederosidic acid methyl ester(4),and deacetyl asperulosidic acid methyl ester(5).Compound 5 was isolated from this plant for the first time.
A new glycoside named 6β-O-β-D-glucosylpaederosidic acid(1)was isolated from Paederia scandens and its structure was elucidated on the basis of spectroscopic and chemical evidence,together with four known iridoids,paederoside(2),paederosidic acid(3),paederosidic acid methyl ester(4),and deacetyl asperulosidic acid methyl ester(5).Compound 5 was isolated from this plant for the first time.
2010, 21(4): 440-442
doi: 10.1016/j.cclet.2009.12.019
Abstract:
Two new tetrahydronaphthalenes,lα,2α-diol-4α-ethoxy-1,2,3,4-tetrahydronaphthalene(1)and lα,2α,4β-triol-1,2,3,4-tetrahydronaphthalene(2),were isolated from the stem of Impatiens balsamina L.Their structures were elucidated by various spectroscopic methods.
Two new tetrahydronaphthalenes,lα,2α-diol-4α-ethoxy-1,2,3,4-tetrahydronaphthalene(1)and lα,2α,4β-triol-1,2,3,4-tetrahydronaphthalene(2),were isolated from the stem of Impatiens balsamina L.Their structures were elucidated by various spectroscopic methods.
2010, 21(4): 443-445
doi: 10.1016/j.cclet.2009.12.030
Abstract:
A novel caged-prenylxanthone xanthone,neobractatin(1),was isolated from the twig of Garcinia bracteata.Its structure was elucidated by spectroscopic methods,especially 2D NMR techniques.
A novel caged-prenylxanthone xanthone,neobractatin(1),was isolated from the twig of Garcinia bracteata.Its structure was elucidated by spectroscopic methods,especially 2D NMR techniques.
2010, 21(4): 446-448
doi: 10.1016/j.cclet.2009.11.018
Abstract:
Microbial transformation of diosgenin(1)was carried out with the white-rot fungus,Coriolus versicolor.A new polyhydroxyl metabolite,(25R)-spirost-5-ene-3β,7β,21-triol(2),was obtained as a result of hydroxylation.Its structure was elucidated on the basis of 1D and 2D NMR as well as HR-ESI-MS spectroscopic analysis.
Microbial transformation of diosgenin(1)was carried out with the white-rot fungus,Coriolus versicolor.A new polyhydroxyl metabolite,(25R)-spirost-5-ene-3β,7β,21-triol(2),was obtained as a result of hydroxylation.Its structure was elucidated on the basis of 1D and 2D NMR as well as HR-ESI-MS spectroscopic analysis.
2010, 21(4): 449-452
doi: 10.1016/j.cclet.2009.12.029
Abstract:
One new triterpenoid sapoin with two known triterpenoid sapoins:3β-O-{α-L-rhamnopyranosyl-(1→3)-[β-D-xylopyranose-(1→2)]-β-D-glucopyranosyl-(1→4)-α-L-arabinopyranosyl}-3β-hydroxy-13β,28-epoxy-oleanan-16-oxo-30-al(1),3β-O-{α-Lrhamnopyranosyl-(1→3)-[(β-D-xylopyranosyl-(1→2)]-β-D-galactopyranosyl-(1→4)-[(β-D-glucopyranosyl-(1→2)]-α-L-arabinopyranoside}-16α-hydroxy-13,28-epoxy-oleanane(2)and cyclamiretin A 3β-O-α-L-rhamnopyranosyl-(1→3)-[β-D-xylopyranosyl-(1→2)]-β-D-glucopyranosyl-(1→4)-[β-D-glucopyranosyl-(1→2)]-α-L-arabinopyranoside(3)were isolated from Ardisia gigantifolia Stapf.Their structures were elucidated by means of 1H and 13C NMR spectroscopic studies,including2D-NMR technique.
One new triterpenoid sapoin with two known triterpenoid sapoins:3β-O-{α-L-rhamnopyranosyl-(1→3)-[β-D-xylopyranose-(1→2)]-β-D-glucopyranosyl-(1→4)-α-L-arabinopyranosyl}-3β-hydroxy-13β,28-epoxy-oleanan-16-oxo-30-al(1),3β-O-{α-Lrhamnopyranosyl-(1→3)-[(β-D-xylopyranosyl-(1→2)]-β-D-galactopyranosyl-(1→4)-[(β-D-glucopyranosyl-(1→2)]-α-L-arabinopyranoside}-16α-hydroxy-13,28-epoxy-oleanane(2)and cyclamiretin A 3β-O-α-L-rhamnopyranosyl-(1→3)-[β-D-xylopyranosyl-(1→2)]-β-D-glucopyranosyl-(1→4)-[β-D-glucopyranosyl-(1→2)]-α-L-arabinopyranoside(3)were isolated from Ardisia gigantifolia Stapf.Their structures were elucidated by means of 1H and 13C NMR spectroscopic studies,including2D-NMR technique.
2010, 21(4): 453-456
doi: 10.1016/j.cclet.2009.12.032
Abstract:
This paper proposes the use of novel surfactant additives for the separation of organic acids by ion-pair chromatography and studies the influences of surfactants on the chromatographic separation behaviors.Researches have been carried out on both silica gel matrix and polymer supporters in order to compare the two ordinary kinds of stationary phases,and the phenomenon is similar.Separation is based on differences in the stabilities of analyte-additive complexes in solution.Retention times of analytes can be varied over a large range by varying the additive concentration.The results indicate that the additives of proper concentrations can reduce the retention times of different organic acids while the resolution remains the same.The larger the molecular weight is,the greater the shift of the retention time is.This greatly expands the scope of macromolecular polar compounds that can be separated by ion-pair chromatography with the advantages of retention times being greatly reduced.
This paper proposes the use of novel surfactant additives for the separation of organic acids by ion-pair chromatography and studies the influences of surfactants on the chromatographic separation behaviors.Researches have been carried out on both silica gel matrix and polymer supporters in order to compare the two ordinary kinds of stationary phases,and the phenomenon is similar.Separation is based on differences in the stabilities of analyte-additive complexes in solution.Retention times of analytes can be varied over a large range by varying the additive concentration.The results indicate that the additives of proper concentrations can reduce the retention times of different organic acids while the resolution remains the same.The larger the molecular weight is,the greater the shift of the retention time is.This greatly expands the scope of macromolecular polar compounds that can be separated by ion-pair chromatography with the advantages of retention times being greatly reduced.
2010, 21(4): 457-460
doi: 10.1016/j.cclet.2009.10.021
Abstract:
Cyanide ion was studied as an effector of Jack bean urease(JBU)at 300 K in 30 mmol/L Tris buffer,pH 7 by isothermal titration calorimetry(ITC).The simple novel model was used for CN-+JBU interaction over the whole range of CN-concentrations.The binding parameters recovered from the simple novel model were attributed to the cyanide ion interaction.It was found that cyanide ion acted as a noncooperative inhibitor of JBU,and there is a set of 12 identical and independent binding sites for CN-ions.The dissociation equilibrium constant is 750 μmol/L.The molar enthalpy of binding is △H=-13.6 kJ mol-1.The technique used provided an accurate and quick assessment of the effectiveness of the compounds to inhibit Jack bean urease.
Cyanide ion was studied as an effector of Jack bean urease(JBU)at 300 K in 30 mmol/L Tris buffer,pH 7 by isothermal titration calorimetry(ITC).The simple novel model was used for CN-+JBU interaction over the whole range of CN-concentrations.The binding parameters recovered from the simple novel model were attributed to the cyanide ion interaction.It was found that cyanide ion acted as a noncooperative inhibitor of JBU,and there is a set of 12 identical and independent binding sites for CN-ions.The dissociation equilibrium constant is 750 μmol/L.The molar enthalpy of binding is △H=-13.6 kJ mol-1.The technique used provided an accurate and quick assessment of the effectiveness of the compounds to inhibit Jack bean urease.
2010, 21(4): 461-463
doi: 10.1016/j.cclet.2009.12.018
Abstract:
The chemokine CXCR4 receptor is over-expressed in a wide variety of tumors.AMD3100,which was a prototypenon-peptide antagonist of CXCR4 receptor,was labeled with 99mTC.99mTC-AMD3100 was verified by thin layer radiochromatography (TLRC).The tumor-localizing properties of 99mTc-AMD3100 were evaluated and proved in mice bearing Hep-G2 tumor xenograft.99mTc-AMD3100 was a promising,novel receptor-specific radiopharmaceutical with potentialapplication in the imaging of human tumors.
The chemokine CXCR4 receptor is over-expressed in a wide variety of tumors.AMD3100,which was a prototypenon-peptide antagonist of CXCR4 receptor,was labeled with 99mTC.99mTC-AMD3100 was verified by thin layer radiochromatography (TLRC).The tumor-localizing properties of 99mTc-AMD3100 were evaluated and proved in mice bearing Hep-G2 tumor xenograft.99mTc-AMD3100 was a promising,novel receptor-specific radiopharmaceutical with potentialapplication in the imaging of human tumors.
2010, 21(4): 464-467
doi: 10.1016/j.cclet.2009.11.028
Abstract:
Four 20-membered N2S4-monoazathiacrown ethers have been synthesized and explored as neutral ionophores for Ag+-selective electrodes.Potentiometric responses reveal that the flexibility of the ligands has great effect on the selectivity and sensitivity to Ag+ions.The electrode based on ionophore 9,10,20,25-tetrahydro-5H,12H-tribenzo[b,n,r][1,7,10,16,4,13]tetrathiadiaza cycloicosine6,13-(7H,14H)-dione(C)with 2-nitrophenyl octyl ether(ο-NPOE)as solvent in a poly(vinyl chloride)(PVC)membrane matrix shows a measuring range of 1.0×10-6 to 1.0×10-3 mol/L with a Nemstian slope of 54.9±0.3 mV/decade.This electrode has high selectivity for Ag+with negligible interference from many other cations and can be used in a wide pH range of 3.6-9.2.
Four 20-membered N2S4-monoazathiacrown ethers have been synthesized and explored as neutral ionophores for Ag+-selective electrodes.Potentiometric responses reveal that the flexibility of the ligands has great effect on the selectivity and sensitivity to Ag+ions.The electrode based on ionophore 9,10,20,25-tetrahydro-5H,12H-tribenzo[b,n,r][1,7,10,16,4,13]tetrathiadiaza cycloicosine6,13-(7H,14H)-dione(C)with 2-nitrophenyl octyl ether(ο-NPOE)as solvent in a poly(vinyl chloride)(PVC)membrane matrix shows a measuring range of 1.0×10-6 to 1.0×10-3 mol/L with a Nemstian slope of 54.9±0.3 mV/decade.This electrode has high selectivity for Ag+with negligible interference from many other cations and can be used in a wide pH range of 3.6-9.2.
2010, 21(4): 468-471
doi: 10.1016/j.cclet.2009.12.004
Abstract:
The amino acid at the 119th position of human basic fibroblast growth factor(hbFGF),lysine(K119),is a critical component for its mitogenic activity.However,little is known about the effects of the characteristics of this residue including charge on the mitogenic activity of hbFGE Herein,this basic residue was replaced with neutral glutamine residue and acidic glutamic acid residue to construct mutants hbFGFK119Q and hbFGFK119E,respectively.The mutants were produced by BL21(DE3)/pET3c expression system and purified to homogeneity by ionic exchange and heparin affinity chromatography from the supernatant of bacteria lysate.The mitogenic activity analysis showed that neutralization of charge at the 119th residue diminished the mitogenic activity of hbFGE whereas change of positive charge to negative charge at this residue had no significant effect on its mitogenic activity.Further MAP kinase activation assay revealed that the influence of different charge at the 119th position on the mitogenic activity of hbFGF was related to the signal molecular activation in MAPK pathway.It was deduced that the charge,either positive or negative,at the 119th position of hbFGF is crucial for its full mitogenic activity.
The amino acid at the 119th position of human basic fibroblast growth factor(hbFGF),lysine(K119),is a critical component for its mitogenic activity.However,little is known about the effects of the characteristics of this residue including charge on the mitogenic activity of hbFGE Herein,this basic residue was replaced with neutral glutamine residue and acidic glutamic acid residue to construct mutants hbFGFK119Q and hbFGFK119E,respectively.The mutants were produced by BL21(DE3)/pET3c expression system and purified to homogeneity by ionic exchange and heparin affinity chromatography from the supernatant of bacteria lysate.The mitogenic activity analysis showed that neutralization of charge at the 119th residue diminished the mitogenic activity of hbFGE whereas change of positive charge to negative charge at this residue had no significant effect on its mitogenic activity.Further MAP kinase activation assay revealed that the influence of different charge at the 119th position on the mitogenic activity of hbFGF was related to the signal molecular activation in MAPK pathway.It was deduced that the charge,either positive or negative,at the 119th position of hbFGF is crucial for its full mitogenic activity.
2010, 21(4): 472-475
doi: 10.1016/j.cclet.2009.12.005
Abstract:
An impedance immunosensor based on O-phenylenediamine modified gold electrode for the determination of phytohormone abscisic acid(ABA)was proposed.The operating pH,absorption time,absorption temperature and concentration of anti-ABA antibody were investigated to optimize the analytical performance.The calibration curve for the determination of ABA was obtained from this impedance immunosensor under optimal conditions.The results showed that the detection limit at about 1 ng/mL in the range of 10-5000 ng/mL.
An impedance immunosensor based on O-phenylenediamine modified gold electrode for the determination of phytohormone abscisic acid(ABA)was proposed.The operating pH,absorption time,absorption temperature and concentration of anti-ABA antibody were investigated to optimize the analytical performance.The calibration curve for the determination of ABA was obtained from this impedance immunosensor under optimal conditions.The results showed that the detection limit at about 1 ng/mL in the range of 10-5000 ng/mL.
2010, 21(4): 476-479
doi: 10.1016/j.cclet.2009.12.033
Abstract:
The photoisomerization abilities of secondary thioxopeptide bond(CS-NH)and thioxo prolyl bond(CS-N)incorporated into the C-terminal pentapeptide of insect kinin were compared.H-Phe-Phe-Ψ[CS-NH]-D-Ala-Trp-Gly-NHz and H-Phe-Tyr-Ψ[CS-N]-Pro-Trp-Gly-NH2 were studied by UV-vis absorption.The isomerization energy barriers of the two segments,Ac-Phe-Ψ[CS-NH]-D-Ala-NH2 and Ac-Tyr-Ψ[CS-N]-Pro-NH2 picked from the two peptides,were calculated using ab initio method.The cis isomer of CS-N is more stable than that of CS-NH due to higher energy barrier,so the former is more suitable in peptide structure-activity relationship studies.
The photoisomerization abilities of secondary thioxopeptide bond(CS-NH)and thioxo prolyl bond(CS-N)incorporated into the C-terminal pentapeptide of insect kinin were compared.H-Phe-Phe-Ψ[CS-NH]-D-Ala-Trp-Gly-NHz and H-Phe-Tyr-Ψ[CS-N]-Pro-Trp-Gly-NH2 were studied by UV-vis absorption.The isomerization energy barriers of the two segments,Ac-Phe-Ψ[CS-NH]-D-Ala-NH2 and Ac-Tyr-Ψ[CS-N]-Pro-NH2 picked from the two peptides,were calculated using ab initio method.The cis isomer of CS-N is more stable than that of CS-NH due to higher energy barrier,so the former is more suitable in peptide structure-activity relationship studies.
2010, 21(4): 480-483
doi: 10.1016/j.cclet.2009.11.042
Abstract:
The interaction mechanism between human serum albumin(HSA)and 1-phenyl-3(fluorenone-2-yl)-5-(9-ethylcarbazole-3-yl)-2-pyrazoline(PFEP)was investigated by fluorescence and absorption titration techniques in combination with molecular modeling method.Stern-Volmer plots at different temperatures proved that PFEP could quench the intrinsic fluorescence of HSA attributed to a static quenching procedure.The association constants were calculated in the range of 1×105-8×105 mol-1 at different pH conditions,and the stoicbiometric ratio of binding was 1:1 between PEEP and HSA.Molecular modeling study showed that the distance between indole moiety of the Trp214 residue and the carbazole group at the terminal of PFEP was 4.45 Å in the optimal model.
The interaction mechanism between human serum albumin(HSA)and 1-phenyl-3(fluorenone-2-yl)-5-(9-ethylcarbazole-3-yl)-2-pyrazoline(PFEP)was investigated by fluorescence and absorption titration techniques in combination with molecular modeling method.Stern-Volmer plots at different temperatures proved that PFEP could quench the intrinsic fluorescence of HSA attributed to a static quenching procedure.The association constants were calculated in the range of 1×105-8×105 mol-1 at different pH conditions,and the stoicbiometric ratio of binding was 1:1 between PEEP and HSA.Molecular modeling study showed that the distance between indole moiety of the Trp214 residue and the carbazole group at the terminal of PFEP was 4.45 Å in the optimal model.
2010, 21(4): 484-487
doi: 10.1016/j.cclet.2009.11.039
Abstract:
A type of triangular pyramid-shaped microparticles of puerarin was synthesized by using oil-in-oil microemulsion approach which is simple and economical under the action of copper substrate.The pyramid-shaped microparticles would be made up of deposit of nanospheres or nanorods and have two significant characters.One is its complex surface morphology like coral reef.The other is a lot of nanopores in existence in the microparticle body.Two possible formation routes were speculated.
A type of triangular pyramid-shaped microparticles of puerarin was synthesized by using oil-in-oil microemulsion approach which is simple and economical under the action of copper substrate.The pyramid-shaped microparticles would be made up of deposit of nanospheres or nanorods and have two significant characters.One is its complex surface morphology like coral reef.The other is a lot of nanopores in existence in the microparticle body.Two possible formation routes were speculated.
2010, 21(4): 488-491
doi: 10.1016/j.cclet.2009.11.038
Abstract:
Low-dielectric-constant poly(acetoxystyrenezhi-co-octavinyl-polyhedral oligomeric silsesquioxane)(PAS-POSS)organic-inorganic hybrid nanocomposite was successfully synthesized via one-step free radical polymerization and characterized by FTIR,high-resolution 1H NMR,29Si NMR,DSC,TGA,AFM,spectroscopic ellipsometry and dielectric constants measurements.The results show Tg and Tdec were elevated dramatically due to the incorporation of inorganic POSS cores.Spectroscopic ellipsometry and dielectric constants measurement display the incorporation of POSS into PAS homopolymer can apparently reduce the dielectric constant of materials due to the increase of relative porosity of the hybrid nanocomposites.
Low-dielectric-constant poly(acetoxystyrenezhi-co-octavinyl-polyhedral oligomeric silsesquioxane)(PAS-POSS)organic-inorganic hybrid nanocomposite was successfully synthesized via one-step free radical polymerization and characterized by FTIR,high-resolution 1H NMR,29Si NMR,DSC,TGA,AFM,spectroscopic ellipsometry and dielectric constants measurements.The results show Tg and Tdec were elevated dramatically due to the incorporation of inorganic POSS cores.Spectroscopic ellipsometry and dielectric constants measurement display the incorporation of POSS into PAS homopolymer can apparently reduce the dielectric constant of materials due to the increase of relative porosity of the hybrid nanocomposites.
2010, 21(4): 492-495
doi: 10.1016/j.cclet.2009.12.017
Abstract:
Homology models of the ligand binding domain of the wild-type and Y151S mutant brown planthopper(Nilaparvata lugens)α1and rat(Rattus norvegicus)β2 nicotinic acetylcholine receptor(nAChR)subunits were generated based on the crystal structure of acetylcholine binding protein of Lymnaea stagnalis.Neonicotinoid insecticide imidacloprid was docked into the putative binding site of wild-type and mutant α1β2 dimeric receptors by Surflex-docking,and the calculated docking energies were in agreement with experimental results.The resistance mechanisms and corresponding binding modes of imidacloprid on nAChRs containing the Y151S target-site mutation were discussed.
Homology models of the ligand binding domain of the wild-type and Y151S mutant brown planthopper(Nilaparvata lugens)α1and rat(Rattus norvegicus)β2 nicotinic acetylcholine receptor(nAChR)subunits were generated based on the crystal structure of acetylcholine binding protein of Lymnaea stagnalis.Neonicotinoid insecticide imidacloprid was docked into the putative binding site of wild-type and mutant α1β2 dimeric receptors by Surflex-docking,and the calculated docking energies were in agreement with experimental results.The resistance mechanisms and corresponding binding modes of imidacloprid on nAChRs containing the Y151S target-site mutation were discussed.
2010, 21(4): 496-500
doi: 10.1016/j.cclet.2009.11.025
Abstract:
In this work,by a combination of controlled ring-opening polymerization(CROP)and click reaction,we reported a facile and useful method to synthesize linear poly(ε-caprolactone)at attapulgite nanocomposites with well-defined structures.For this,first,the chlorine terminated attapulgite was prepared by the self-assembly of 3-chloropropyltrimethoxysilane from the surfaces of attapulgite.And then,the terminal chlorines of modified attapulgite were substituted with azido groups.As the second step,linear propargyl-terminated poly(ε-caprolactone)(PCLs)with different molecular weights were synthesized by the CROP of ε-CL monomer in toluene with Sn(Oct)2 as a catalyst and propargyl alcohol as an initiator.Finally,the azido-terminated attapulgites were reacted with propargyl-terminated PCLs via the click reactions.
In this work,by a combination of controlled ring-opening polymerization(CROP)and click reaction,we reported a facile and useful method to synthesize linear poly(ε-caprolactone)at attapulgite nanocomposites with well-defined structures.For this,first,the chlorine terminated attapulgite was prepared by the self-assembly of 3-chloropropyltrimethoxysilane from the surfaces of attapulgite.And then,the terminal chlorines of modified attapulgite were substituted with azido groups.As the second step,linear propargyl-terminated poly(ε-caprolactone)(PCLs)with different molecular weights were synthesized by the CROP of ε-CL monomer in toluene with Sn(Oct)2 as a catalyst and propargyl alcohol as an initiator.Finally,the azido-terminated attapulgites were reacted with propargyl-terminated PCLs via the click reactions.
2010, 21(4): 501-505
doi: 10.1016/j.cclet.2009.11.024
Abstract:
A unique ionic hybrid material[C6H12N5O]3[(PO4)W12O36]·5H2O has been synthesized from the reaction of((1H-tetrazole-5-yl)morphline and α-H3 [(PO4)W12O36]·21H2O.It has successfully been charactrized by elemental analysis.IR and 1HNMR spectroscopies,TGA and single-crystal X-ray diffraction method.Thetitle compound is constructed from the three [C6H12N5O]+cations and α-Keggin[(PO4)W12O36]3-polyoxoanion.The most remarkable structural feature of this hybrid can be described as two-dimensional inorganic infinite plane-like(2D/∞[(PO4)W12O36]3-)which forming via van der Waais interactions along the x axis.
A unique ionic hybrid material[C6H12N5O]3[(PO4)W12O36]·5H2O has been synthesized from the reaction of((1H-tetrazole-5-yl)morphline and α-H3 [(PO4)W12O36]·21H2O.It has successfully been charactrized by elemental analysis.IR and 1HNMR spectroscopies,TGA and single-crystal X-ray diffraction method.Thetitle compound is constructed from the three [C6H12N5O]+cations and α-Keggin[(PO4)W12O36]3-polyoxoanion.The most remarkable structural feature of this hybrid can be described as two-dimensional inorganic infinite plane-like(2D/∞[(PO4)W12O36]3-)which forming via van der Waais interactions along the x axis.
