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1.
Comparison of antioxidant abilities of magnolol and honokiol to scavenge radicals and to protect DNA 总被引:3,自引:0,他引:3
The antioxidant properties of magnolol and honokiol were evaluated in the experimental systems of reducing ONOO− and 1O2, bleaching β-carotene in linoleic acid (LH) emulsion, and trapping 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) cationic radical (ABTS+) and 2,2′-diphenyl-1-picrylhydrazyl radical (DPPH), and then were applied to inhibit the oxidation of DNA induced by Cu2+/glutathione (GSH) and 2,2′-azobis(2-amidinopropane hydrochloride) (AAPH). Magnolol and honokiol were active to reduce ONOO− and 1O2. Honokiol showed a little higher activity to protect LH and to inhibit Cu2+/GSH-induced oxidation of DNA than magnolol. In addition, honokiol exhibited higher activities to trap ABTS+ and DPPH than magnolol. In particular, honokiol trapped 2.5 radicals while magnolol only trapped 1.8 radicals in protecting DNA against AAPH-induced oxidation. The obtained results suggested that low antioxidant ability of magnolol may be related to the intramolecular hydrogen bond formed between di-ortho-hydroxyl groups, which hindered the hydrogen atom in hydroxyl group to be abstracted by radicals. Therefore, the antioxidant capacity of magnolol was lower than that of honokiol. 相似文献
2.
Chalcones with or without a para-hydroxyl group were condensed with phenylhydrazine-related compounds to form 1,3,5-triphenyl-1H-pyrazole (TPP), 4-(1,5-diphenyl-1H-pyrazol-3-yl)phenol (APP), 4-(1,3-diphenyl-1H-pyrazol-5-yl)phenol (BPP), and 4-(3,5-diphenyl-1H-pyrazol-1-yl)phenol (CPP), in which the phenyl group formed a dendritic structure with pyrazole as the core. Thus, the aim of this work was to explore the antioxidant capacities of TPP, APP, BPP, and CPP in trapping 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) cationic radical (ABTS+?) and 2,2′-diphenyl-1-picrylhydrazyl radical (DPPH) and in inhibiting Cu2 +/glutathione (GSH)-, ?OH-, and 2,2′-azobis(2-amidinopropane hydrochloride) (AAPH)-induced oxidation of DNA. TPP can react with ABTS+? and DPPH, indicating that the N atom in pyrazole possesses radical-scavenging ability. Moreover, APP, BPP, and CPP can trap 1.71, 1.81, and 1.58 radicals, respectively, in protecting DNA against AAPH-induced oxidation. Thus, the combination of pyrazole with a phenyl group exerted antioxidant ability although only one phenolic hydroxyl group was involved. However, these compounds showed weak protective effect against Cu2 +/GSH-induced oxidation of DNA and even a pro-oxidant effect on ?OH-induced oxidation of DNA. 相似文献
3.
Caroline Prouillac Patricia Vicendo Jean-Christophe Garrigues Romuald Poteau Ghassoub Rima 《Free radical biology & medicine》2009,46(8):1139-1148
Thiol and aminothiol compounds are among the most efficient chemical radioprotectors. To increase their efficiency, we synthesized two new classes of thiol and aminothiol compounds derived from benzothiazole (T1, T2, AM1, AM2) and thiadiazole (T3, T4, AM3) structures. We examined them for their ability to scavenge free radicals (DPPH·, ABTS·+, ·OH). Thiol derivatives with a thiadiazole structure are the most active compounds scavenging DPPH· and ABTS·+ free radicals, with an IC50 of 0.053 ± 0.006 and 0.023 ± 0.002 mM, respectively, for the derivative T3. Moreover, compounds T1, T2, and T3 at 60 μM gave 83% protection against 2-deoxyribose degradation by ·OH. The ability of these compounds to protect DNA against ·OH produced by a Fenton reaction and γ-irradiation (15 Gy)-induced strand breaks was also evaluated on pBR322 plasmid DNA. In both tests thiol derivatives were the most efficient compounds. Derivatives T2 and T3 totally inhibit DNA strand breaks at the concentration of 50 μM. The protection afforded by these derivatives was comparatively higher than that of the radioprotectors WR-2721 and WR-1065. Our data indicate that these two compounds are free radical scavengers and potential antioxidant agents. Finally, DFT and QSAR studies were performed to support the experimental observations. 相似文献
4.
Hoi-Ling Seng Sze-Tin Von Kong-Wai Tan Mohd Jamil Maah Seik-Weng Ng Raja Noor Zaliha Raja Abd Rahman Ignez Caracelli Chew-Hee Ng 《Biometals》2010,23(1):99-118
Crystal structure analysis of the zinc complex establishes it as a distorted octahedral complex, bis(3-methylpicolinato-κ2
N,O)2(1,10-phenanthroline-κ2
N,N)-zinc(II) pentahydrate, [Zn(3-Me-pic)2(phen)]·5H2O. The trans-configuration of carbonyl oxygen atoms of the carboxylate moieties and orientation of the two planar picolinate ligands above
and before the phen ligand plane seems to confer DNA sequence recognition to the complex. It cannot cleave DNA under hydrolytic
condition but can slightly be activated by hydrogen peroxide or sodium ascorbate. Circular Dichroism and Fluorescence spectroscopic
analysis of its interaction with various duplex polynucleotides reveals its binding mode as mainly intercalation. It shows
distinct DNA sequence binding selectivity and the order of decreasing selectivity is ATAT > AATT > CGCG. Docking studies lead
to the same conclusion on this sequence selectivity. It binds strongly with G-quadruplex with human tolemeric sequence 5′-AG3(T2AG3)3-3′, can inhibit topoisomerase I efficiently and is cytotoxic against MCF-7 cell line. 相似文献
5.
Gao E Guan F Gao X Zhu M Liu L Wang C Zhang W Sun Y 《Journal of biological inorganic chemistry》2012,17(2):263-274
Two novel palladium(II) complexes with a thiosalicylic acid (HSC6H4CO2H) ligand, with the formulas [Pd(TSA)(L)]·mH2O (TSA is thiosalicylic acid; in complex 1, L is 1,10-phenanthroline and m = 1; in complex 2, L is 2,2′-bipyridine and m = 2), have been synthesized and characterized. The coordination geometry of both palladium atoms is square planar; they are
four-coordinated and each is coordinated in an N,N,O−,S− mode. There is a sigmoid oxygen chain in complex 1, but an oxygen ring in complex 2. The competitive binding of the complexes to HeLa cell DNA (HL-DNA) has been investigated by fluorescence spectroscopy. The
results show that the two complexes have the ability to bind with HL-DNA. Viscosity studies suggest that the complexes bind
to DNA by intercalation. Gel electrophoresis assay demonstrated the ability of the complexes to cleave the HL-DNA. The two
complexes exhibit cytotoxic specificity and a significant cancer cell inhibitory rate. The apoptosis tests indicated that
the complexes have an apoptotic effect. Furthermore, complex 1 exhibits more biological activity than complex 2, which is mainly because the area of the aromatic ring of 1,10-phenanthroline is larger than that of 2,2′-bipyridine. 相似文献
6.
Six 1,2,4-oxadiazole derivatives were prepared in order to compare their abilities to protect DNA against radical-mediated oxidation and to scavenge radicals. These derivatives had a structure based on disubstituted 1,2,4-oxadiazole, in which a vanillin group (A ring) and a substituted benzene group (B ring) were the substituents. The functional group at B ring was assigned as ortho- or meta-hydroxylbenzene group, ortho-chlorobenzene group, no group contained, and pyridine group or vanillin group at B ring. It was found that the compound with two vanillin groups attaching to oxadiazole can trap 2.05 radicals in protecting DNA against 2,2′-azobis(2-amidinopropane hydrochloride) (AAPH)-induced oxidation, and the compound with an ortho-hydroxylbenzene group at B ring can trap 1.78 radicals. The compound with an ortho-chlorobenzene group at B ring exhibited the highest ability to inhibit ·OH-induced oxidation of DNA, while the compound with a meta-hydroxylbenzene group at B ring inhibited Cu2+/glutathione (GSH)-induced oxidation of DNA efficiently. The ortho- and para-hydroxylbenzene groups at B ring made the compounds possess the highest rate constant (k) in scavenging 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) cationic radical (ABTS+.) and 2,2′-diphenyl-1-picrylhydrazyl radical (DPPH). Therefore, only a few hydroxyl groups can markedly enhance the activity of the core-branched antioxidant, which may be a novel structural feature in designing antioxidant. 相似文献
7.
Two zinc(II) terpyridine complexes Zn(atpy)2(PF6)2 (1) (atpy = 4′-p-N9′-adeninylmethylphenyl-2,2′:6,2′′-terpyridine) and Zn(ttpy)2(PF6)2 (2) (ttpy = 4′-p-tolyl-2,2′:6,2′′-terpyridine) have been synthesized and characterized by elemental analysis, 1H NMR and electrospray mass spectroscopy. The structure of complex 2 was also determined by X-ray crystallography, which revealed a ZnN6 coordination in an octahedral geometry with two terpyridine acting as equatorial ligands. The circular dichroism data showed
that complex 1 exhibited an ICD signal at around 300 nm and induced more evident disturbances on DNA base stacking than complex 2, reflecting the impact of the adenine moiety on DNA binding modes. Complex 1 exhibited higher cleavage activity to supercoiled pUC 19 DNA than complex 2 under aerobic conditions, suggesting a promotional effect of adenine moiety in DNA nuclease ability. Interestingly, both
complexes demonstrated potent in vitro cytotoxicity against a series human tumor cell lines such as human cervix carcinoma
cell line (HeLa), human liver carcinoma cell line (HepG2), human galactophore carcinoma cell line (MCF-7) and human prostate
carcinoma cell line (pc-3). The cytotoxicity is averagely 10 times more active than the anticancer drug cisplatin.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
8.
Novel 2-oxo-1,2-dihydroquinoline-3-carbaldehyde (4′-methylbenzoyl) hydrazone (H2L) (1) and its two copper(II) complexes have been synthesized. Single-crystal X-ray diffraction studies revealed that the structure
of the new copper(II) chloride complex, [Cu(H2L)Cl2]·2H2O (2), is square pyramidal and that of the copper(II) nitrate complex, [Cu(HL)NO3]·DMF (3), is square planar. In 2, the copper atom is coordinated by the ligand with ONO donor atoms, one chloride ion in the apical position, and the other
chloride in the basal plane. In 3, the ligand coordinates as a uninegative tridentate ONO− species and with one nitrate ion in the basal plane. DNA binding experiments indicated that the ligand and copper(II) complexes
can interact with DNA through intercalation. Bovine serum albumin binding studies revealed that the compounds strongly quench
the intrinsic fluorescence of bovine serum albumin through a static quenching process. Antioxidative activity tests showed
that 1 and its copper(II) complexes have significant radical scavenging activity against free radicals. Cytotoxic activities of
the ligand and copper(II) complexes showed that the two copper(II) complexes exhibited more effective cytotoxic activity against
HeLa and HEp-2 cells than the corresponding ligand. The entire biological activity results showed that the activity order
was 1 < 2 < 3. 相似文献
9.
The interactions between a series of platinum complexes, including (pyridyl)(6-phenyl-2,2-bipyridine)platinum(II) hexafluorophosphate (1), three dinuclear bis[(6-phenyl-2,2-bipyridine)platinum(II)] complexes (2–4), and (4-aminopyridine)(4,6-diphenyl-2,2-bipyridine)platinum(II) perchlorate (5) with DNA have been investigated. All Pt(II) complexes, except 5, were demonstrated to be DNA intercalators, based on viscosity measurements. Absorption and fluorescence titration results indicated that the addition of a phenyl ring to the 6-phenyl-2,2-bipyridine ligand dramatically reduced the DNA binding of the Pt(II) complex
5. The dinuclear complexes
2–4 exhibited multiple binding modes of mono/bisintercalation and groove binding, as revealed by viscosity and fluorescence titration measurements. While complexes
2–4 bound to DNA with significantly enhanced affinities as compared to 1, compounds
1 and 2–4 showed similar IC50 values against a panel of cancer cell lines. In addition, these complexes showed similar cellular uptakes. The results indicated that the cytotoxicity of these (6-phenyl-2,2-bipyridine)platinum compounds may not be mediated through DNA binding but may involve interacting mechanisms with cellular components other than DNA.Electronic Supplementary Material Supplementary material is available for this article if you access the article at . A link in the frame on the left on that page takes you directly to the supplementary material.Abbreviations AO
acridine orange
- ampy
4-aminopyridine
- bipy
2,2-bipyridine
- bp
base pair
- CNN
6-phenyl-2,2-bipyridine
- ctDNA
calf thymus DNA
- EB
ethidium bromide
- EI
electron ionization
- en
ethylenediamine
- FAB
fast atomic bombardment
- H33342
Hoechst 33342
- IC50
inhibitory concentration 50%
- ICP-AES
inductively coupled plasma–atomic emission spectroscopy
- MTT
3-(4,5-dimethylthiazol-2-yl)-2,5-tetrazolium bromide
- 4-PhCNN
4,6-diphenyl-2,2-bipyridine
- phen
1,10-phenanthroline
- terpy
2,2:6,2-terpyridine
- Tris
tris(hydroxymethyl)aminomethane 相似文献
10.
11.
12.
A. V. Loskutov G.-Q. Song K. C. Sink 《In vitro cellular & developmental biology. Plant》2008,44(4):239-245
Callus selection (CS) and the flamingo-bill explant (FB) methods were evaluated for efficacy in transformation for celery.
Agrobacterium tumefaciens strains EHA105 and GV3101, each with the bar gene under the promoters NOS (pGPTV-BAR) or 35S (pDHB321.1), were used. Leaf explants were inoculated and co-cultivated for
2 d in the dark. Calluses emerged on the explants on callus medium (C), Murashige and Skoog (MS) medium + 2,4-Dichlorophenoxyacetic
acid (2,4-D) (2.3 μM) + kinetin (2.8 μM) + timentin (300 mg·l−1). Calluses 4- to 6-wk-old were selected for glufosinate (GS) resistance by a two step method. First, calluses were transferred
to C medium + GS 0.35, 0.5, 1, 2, 5, or 10 mg·l−1; calluses formed only with 0, 0.35 and 0.5 mg·l−1 GS. All growing calluses from 0 and 0.35 mg·l−1 and a few from 0.5 mg·l−1, were divided and placed back on C + GS 0.35–0.5 mg·l−1 for another 5–6 wk. Second, tolerant clones were again divided and placed on C + GS 1–50 mg·l−1. When cultivar XP85 was inoculated with both strains, using pGPTVBAR, 19 glufosinate resistant (GR) callus clones were selected,
but shoots regenerated only for strain EHA105 inoculations. When both of the strains (each with pDHB321.1) were inoculated
on cv. XP166, 3 and 12 GR calluses occurred for EHA105 and GV3101, respectively. Using CS, a total of 34 GR callus clones
were selected, and shoots were regenerated from over 50% of them on Gamborg B5 medium + 6-(γ, γ-dimethylallylamino) purine
2ip (4.9 μM) + naphthaleneacetic acid (NAA; 1.6 μM) and rooted on MS in 5–6 mo total time. Conversely, using FB with inoculation
by GV3101/pDHB321.1 on cv. XP166 yielded putative transgenic celery plants confirmed by polymerase chain reaction (PCR) in
just 6 wk. Transformation of the bar gene into celery was confirmed by PCR for 5 and 6 CS and FB lines, respectively. Southern blot analyses indicated 1–2 copies
in CS lines and 1 copy in FB lines. Herbicide assays on whole plants with 100 and 300 mg·l−1 glufosinate indicated a range of low to high tolerance for lines derived by both methods. The bar gene was found to be Mendelian inherited in one self-fertile CS derived line. 相似文献
13.
Simin Mohseni Shirin Emtenani Shamsi Emtenani Ahmad Asoodeh 《Journal of peptide science》2014,20(6):429-437
Human catestatin CgA352–372 (SL21) is an endogenous neuropeptide with multiple biological functions. The present study aimed to evaluate the antioxidant, antibacterial, cytotoxic, and DNA damage protective effects of SL21 neuropeptide. SL21 neuropeptide generated from the C‐terminus of chromogranin A (CgA) was synthesized by solid‐phase method. Synthetic peptide was subjected to various in vitro antioxidant assays including the scavenging of 1,1‐diphenyl‐2‐pycryl‐hydrazyl (DPPH), 2,2‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) (ABTS·+), and hydroxyl free radicals, metal ion chelation, inhibition of lipid peroxidation, and reducing power. Moreover, protective effect of SL21 on H2O2‐induced DNA damage was analyzed using pTZ57/RT plasmid. Methylthiazoltetrazolium assay was also performed to study the cytotoxic effect of SL21 neuropeptide on human peripheral blood mononuclear cells. Furthermore, antibacterial and hemolysis assays were conducted. The results demonstrated high activities of SL21 in scavenging free radicals (DPPH, ABTS·+, and hydroxyl), chelating of Cu2+/Fe2+ metal ions, reducing power, and inhibition of lipid peroxidation in a concentration‐dependent manner. SL21 neuropeptide revealed a protective effect on DNA damage caused by hydroxyl radicals. Interestingly, the peptide exhibited no significant cytotoxicity towards peripheral blood mononuclear cells. Furthermore, SL21 peptide displayed antimicrobial activity against Staphylococcus aureus and Pseudomonas aeruginosa without any hemolytic activity on human red blood cells. Conclusively, the present study established SL21 (catestatin) as a novel antioxidative peptide that could further be investigated for its potential use as a pharmaceutical agent. Copyright © 2014 European Peptide Society and John Wiley & Sons, Ltd. 相似文献
14.
Lukas K. Filak Gerhard Mühlgassner Michael A. Jakupec Petra Heffeter Walter Berger Vladimir B. Arion Bernhard K. Keppler 《Journal of biological inorganic chemistry》2010,15(6):903-918
The synthesis of ruthenium(II) and osmium(II) arene complexes with the closely related indolo[3,2-c]quinolines N-(11H-indolo[3,2-c]quinolin-6-yl)-ethane-1,2-diamine (L
1
) and N′-(11H-indolo[3,2-c]quinolin-6-yl)-N,N-dimethylethane-1,2-diamine (L
2
) and indolo[3,2-d]benzazepines N-(7,12-dihydroindolo-[3,2-d][1]benzazepin-6-yl)-ethane-1,2-diamine (L
3
) and N′-(7,12-dihydroindolo-[3,2-d][1]benzazepin-6-yl)-N,N-dimethylethane-1,2-diamine (L
4
) of the general formulas [(η6-p-cymene)MII(L
1
)Cl]Cl, where M is Ru (4) and Os (6), [(η6-p-cymene)MII(L
2
)Cl]Cl, where M is Ru (5) and Os (7), [(η6-p-cymene)MII(L
3
)Cl]Cl, where M is Ru (8) and Os (10), and [(η6-p-cymene)MII(L
4
)Cl]Cl, where M is Ru (9) and Os (11), is reported. The compounds have been comprehensively characterized by elemental analysis, electrospray ionization mass
spectrometry, spectroscopy (IR, UV–vis, and NMR), and X-ray crystallography (L
1
·HCl, 4·H2O, 5, and 9·2.5H2O). Structure–activity relationships with regard to cytotoxicity and cell cycle effects in human cancer cells as well as cyclin-dependent
kinase (cdk) inhibition and DNA intercalation in cell-free settings have been established. The metal-free indolo[3,2-c]quinolines inhibit cancer cell growth in vitro, with IC50 values in the high nanomolar range, whereas those of the related indolo[3,2-d]benzazepines are in the low micromolar range. In cell-free experiments, these classes of compounds inhibit the activity of
cdk2/cyclin E, but the much higher cytotoxicity and stronger cell cycle effects of indoloquinolines L
1
and 7 are not paralleled by a substantially higher kinase inhibition compared with indolobenzazepines L
4
and 11, arguing for additional targets and molecular effects, such as intercalation into DNA. 相似文献
15.
《Cytotherapy》2014,16(3):406-411
Background aimsThe increasing scarcity of young related donors has led to the use of older donors for related allogeneic hematopoietic stem cell transplantation (HSCT). This study analyzed the influence of age on the results of mobilization of peripheral blood stem cells (PBSCs) in healthy donors as well as on the engraftment and outcome of HSCT.MethodsA retrospective analysis from a single center was performed comparing the results of PBSC mobilization from related healthy donors according to their age.ResultsThe study included 133 consecutive related donors. The median age was 50 years (range, 4–77 years); 70 (53%) donors were males, and 44 (33%) were >55 years old. All donors were mobilized with granulocyte colony-stimulating factor for 5 days. The peak CD34+ cell count in peripheral blood was higher in younger than in older donors (median, 90.5 CD34+ cells/μL [range, 18–240 CD34+ cells/μL] versus 72 CD34+ cells/μL [range, 20–172.5 CD34+ cells/μL], P = 0.008). The volume processed was lower in younger than in older donors (16,131 mL [range, 4424–36,906 mL] versus 18,653 mL [range, 10,003–26,261 mL], P = 0.002) with similar CD34+ cells collected (579.3 × 106 cells [range, 135.14 × 106–1557.24 × 106 cells] versus 513.69 × 106 cells [range, 149.81 × 106–1290 × 106 cells], P = 0.844). There were no differences in time to recovery of neutrophils and platelets or in the incidences of acute and chronic graft-versus-host disease, overall survival, non-relapse mortality and relapse incidence.ConclusionsDonors >55 years old mobilized fewer CD34+ cells and required a greater volume to collect a similar number of CD34+ cells. The outcome of HSCT was not influenced by donor age. Donor age should not be a limitation for related allogeneic HSCT. 相似文献
16.
Marek Doskocz Agnieszka Strupińska Szczepan Roszak Monika Prokopowicz Leo H. Koole Paweł Kafarski 《Journal of molecular modeling》2009,15(6):651-658
The study of spin-spin coupling constants across hydrogen bond provides useful information about configuration of complexes.
The interesting case of such interactions was observed as a coupling across an intramolecular hydrogen bond in 8-bromo-2′,3′-O-isopropylideneadenosine between the -CH2OH (at 5″ proton) group and the nitrogen atom of adenine. In this paper we report theoretical investigations on the 4h
J
NH coupling across the H″-C-O-H···N hydrogen bond in adenosine derivatives in various solvent models.
Figure Coupling constants in 8-bromo-2′,3′-O-isopropylideneadenosine
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
17.
The inclusion complex of β-cyclodextrin (β-CD) and 4-methylbenzyl-4′-[trans-4- (guanidinomethyl)cylohexylcarbonyloxy]-biphenyl-4-carboxlylate monohydrochloride (TG44) had been investigated by using densify functional theory (DFT) and PM3 semiempirical method. The results indicate that
the β-CD includes predominantly the biphenyl moiety of TG44, and the inclusion complex formed by TG44 entering into the cavity of β-CD from its narrow side (the primary hydroxyl group side) is more stable than that formed by TG44 entering into the cavity of β-CD from its wide side (the secondary hydroxyl group side). The negative enthalpy changes calculated from the statistical
thermodynamic calculations at 1 atm and 298.15 K suggest that the inclusion complexes are favored enthalpy-driven processes.
The molecular modeling results are in good agreement with the experiment for 2D 1H–13C H HETCOR spectroscopic and H-NMR spectroscopic observations. 相似文献
18.
Caixia Yuan Liping Lu Xiaoli Gao Yanbo Wu Maolin Guo Ying Li Xueqi Fu Miaoli Zhu 《Journal of biological inorganic chemistry》2009,14(6):841-851
Abstract A series of oxovanadium complexes with mixed ligands, a tridentate ONO-donor Schiff base ligand [viz., salicylidene anthranilic
acid (SAA)], and a bidentate NN ligand [viz., 2,2′-bipyridine (bpy), 1,10-phenanthroline (phen), dipyrido[3,2-d:2′,3′-f]quinoxaline (dpq), dipyrido[3,2-a:2′,3′-c]phenazine (dppz), or 7-methyldipyrido[3,2-a:2′,3′-c]phenazine (dppm)], have been synthesized and characterized by elemental analysis, electrospray ionization mass spectrometry,
UV–vis spectroscopy, Fourier transform IR spectroscopy, EPR spectroscopy, and X-ray crystallography. Crystal structures of
both complexes, [VIVO(SAA)(bpy)]·0.25bpy and [VIVO(SAA)(phen)]·0.33H2O, reveal that oxovanadium(IV) is coordinated with one nitrogen and two oxygen atoms from the Schiff base and two nitrogen
atoms from the bidentate planar ligands, in a distorted octahedral geometry (VO3N3). The oxidation state of V(IV) with d
1 configuration was confirmed by EPR spectroscopy. The speciation of VO–SAA–bpy in aqueous solution was investigated by potentiomtreic
pH titrations, and the results revealed that the main species are two ternary complexes at a pH range of 7.0–7.4, and one
is the isolated crystalline complex. The complexes have been found to be potent inhibitors against human protein tyrosine
phosphatase 1B (PTP1B) (IC50 approximately 30–61 nM), T-cell protein tyrosine phosphatase (TCPTP), and Src homology phosphatase 1 (SHP-1) in vitro. Interestingly,
the [VIVO(SAA)(bpy)] complex selectively inhibits PTP1B over the other two phosphatases (approximate ninefold selectivity against
SHP-1 and about twofold selectivity against TCPTP). Kinetics assays suggest that the complexes inhibit PTP1B in a competitive
and reversible manner. These suggest that the complexes may be promising candidates as novel antidiabetic agents.
Graphical Abstract
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
19.
A. A. Tulub 《Biophysics》2011,56(2):200-205
The Car-Parrinello Molecular Dynamics (CPMD) has been used to study the ion-radical (IR) polymerization (triplet (T) and singlet
(S/T0) states) of adenine mononucleotides upon interaction with Mg2+(H2O)2-ATP4−. It has been found that the IR polymerization occurs only upon Mg2+(H2O)2-ATP4− excitation into a T state (the Franck-Condon or femtosecond laser excitation); it naturally occurs in the dark with DNA polymerase
or another Mg-holoenzyme upon interaction of Mg with two Asp residues. The IR path affects only the HO-C3′ group of ribose, leaving the HO-C2′ group inactive. The IR polymerization starts with the homolytic removal of the hydrogen atom from the HO-C3′ group and its transfer onto the hydroxyl radical ·OH, a product of the ATP cleavage, which yields a water molecule. A further
progress of the reaction involves interaction between two ion-radicals ·ATP. The reaction is sensitive to the recombination
of ·OH and ·ATP. It is mostly suppressed by the appearance of identically directed electron spins on both radicals (the radical
pair in the T0 state) in the vicinity of the HO-C3′ group and not suppressed in the vicinity of the HO-C2′ group (the spins in the radical pair are oppositely directed, the radical pair in the T0 state), making the latter inert on the IR polymerization, but allowing it to be active in the ionic (hydrolytic) polymerization. 相似文献
20.
Deshmukh SS 《Current microbiology》2007,54(3):186-189
Nuclease Stn α from Streptomyces thermonitrificans hydrolyses DNA and RNA at the rate of approximately 10:l. The optimum pH and temperature for RNA hydrolysis were 7.0 and
45°C. The RNase activity of nuclease Stn α had neither an obligate requirement of metal ions nor was it activated in the presence
of metal ions. The enzyme was inhibited by Zn2+, Mg2+, Co2+, and Ca2+; inorganic phosphate; pyrophosphate; NaCl; KCl; and metal chelators. It was stable at high concentrations of urea but susceptible
to low concentrations of Sodium dodecyl sulfate and guanidine hydrochloride. The rates by which nuclease Stn α hydrolysed
polyribonucleotides occurs in the order of poly A >> RNA >> poly U > poly G > poly C. The enzyme cleaved RNA to 3′ mononucleotides
with preferential liberation of 3′AMP, indicating it to be an adenylic acid preferential endonuclease. 相似文献