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1.
A series of (hetero)arylethenesulfonyl fluorides (1–58) were synthesized and screened for their in vitro antioxidant (DPPH, ABTS and DMPD methods) and anti-inflammatory activities. The results revealed that compounds 4, 15, 16, 24, 25, 26, 38, 39, 40, and 54 exhibited excellent antioxidant activity using all the three performed antioxidant methods, which were superior to the standard antioxidants ascorbic acid and gallic acid. Compounds 6–9, 11, 18, 19, 21, 22, 30, 39, 40, 44, 45, 48–50, 54, 55 and 57 displayed promising anti-inflammatory activity, which were better than the reference drug indomethacin. Preliminary structure–activity relationship (SAR) revealed that compounds containing electron donating (OH and OCH3) groups on the phenyl ring possessed excellent antioxidant properties while compounds containing electron-withdrawing (Cl, NO2, F and Br) groups on the phenyl ring were found to be most potent anti-inflammatory agents. The presence of SO2F group played a crucial role in increases both antioxidant and anti-inflammatory activities. 相似文献
2.
《Inorganica chimica acta》1988,144(1):81-87
A new series of sterically bulky tripodal tetradentate ligands have been synthesized. The ligands were found to react readily with MoO 2(acac) 2 in absolute methanol to yield the corresponding cis- dioxoMo(VI) complexes. These complexes were characterized by IR, 1H and 13C NMR, UV-Vis spectroscopy, elemental analysis and cyclic voltammetry (CV). Cyclic voltammetry was performed in DMF and CH 2Cl 2. In CH 2Cl 2 the ease of reduction was found to decrease in the order MoO 2[LNO 2 (SCH 3)]> MoO 2[LNO 2(OCH 3)]> MoO 2 [LNO 2 (N(CH 3) 2)]. The CV results are consistent with that expected for a S,O,N substitution pattern. 相似文献
3.
《Inorganica chimica acta》1988,148(1):71-84
Os3(CO)10(MeCN)2 reacts at room temperature in MeCN or toluene with R-Pyca2 to yield two isomers of Os3(CO)10(R-Pyca) that differ in the bonding of the R-Pyca ligand to the Os3(CO)10 unit. In all cases Os3(CO)10(R-Pyca(4e)) (isomer A; 4a: R = c-Pr, 4b: R = i-Pr, 4c: R = neo-Pent, 4d: R = t-Bu), containing a chelating 4e donating R-Pyca ligand and three OsS bonds, could be isolated. In the case of R = c-Pr and R = i-Pr Os3(CO)10(R-Pyca(6e)) (isomer B; 5a: R = c-Pr, 5b: R = i-Pr), in which only two OsS bonds are present and the R-Pyca ligand is bonded as a 6e donating ligand bridging two non-bonded Os atoms, could be isolated as a minor product.At 70 °C Os3(CO)10(R-Pyca(4e)) (4b and 4d) loses one carbonyl and the pyridine moiety of the R-Pyca ligand is ortho-metallated to form HOs3(C5H3N-2-C(H)NR)(CO)9 (6b: R = i-Pr and 6d: R = t-Bu). Under the same conditions Os3(CO)10(i-Pr-Pyca(6e)) (5b) reacts to Os2(CO)6(6e)) (7b) containing a bridging 6e donating ligands. The latter two reactions were followed with FT-IR spectroscopy in a high temperature IR cell.The structure of the complexes in solution have been studied by 1H and 1C NMR and IR spectroscopy. The stoichiometries of 4a and 5a were determined by FAB-mass spectrometry while an exact mass determination was carried out for 4a.The crystal structure of 6b has been determined. Crystal of 6b are monoclinic, space group P21/n, with a = 7.808(2),b = 17.613(3),c = 16.400(8)Å, β = 94.09(3)° and Z = 4. The structure was refined to R = 0.039. The molecule contains a triangular array of osmium atoms [Os(1)Os(2) = 2.898(2)Å, Os(1)Os(3) = 2.886(2)Åand Os(2)O(3) = 2.911(2)Å] and nine terminally bonded carbonyl ligands. The C5H3N-2-C(H)N-i-Pr ligand is chelate bonded to Os(2) with the pyridine and imine nitrogens atoms axially and equatorially coordinated respectively [Os(2)N(1) = 2.00(2)Åand Os(2)N(2) = 2.11(2)Å]. The i-Pr-Pyca ligand is ortho-metallated at C(1) and forms a four membered ring containing Os(2), Os(3), C(1) and N(1), the Os(3)C(1) distance being 2.12(2)Å. The hydride, which could not be located unequivocally from a difference Fourier map is proposed to bridge the Os(2)(3) bond on the basis of stereochemical considerations. 相似文献
4.
Nguyen Tien An Do Truong Thien Nguyen Thi Dong Pham Le Dung 《Carbohydrate polymers》2009,75(3):489-497
In this work, only N-substituted chitosan derivatives (water-soluble N-carboxymethylchitosan derivatives: N-CMC) with different degrees of substitution were obtained by reaction of a fully deacetylated chitosan (derived from deacetylation of chitosan using decrystallized method) with monochloroacetic acid at pH 8 and temperature of 90 °C. The structure of N-carboxymethylchitosan and chitosan was characterized by IR, 1H, 13C and 1H–13C NMR-HSQC spectra. In the IR spectrum of the N-carboxymethylchitosan, the appearance of peak at 1742 cm?1 was assigned for CO group of NHCH2COOH of substituted chitosan. In the 1H NMR spectra, the peaks at about 3.81÷4.06 ppm, assigned for CH2 groups of NHCH2 and N(CH2)2, were the major feature, while in the 1H–13C NMR-HSQC spectra, signals of CH2 confirmed the presence of these two different substituted CH2 groups. The degree of substitution (DS) of N-monosubstitution (DSN-mono) decreased from 0.47 to 0.03 meanwhile that of N,N-disubstitution (DSN,N-di) increased from 0.52 to 0.96 since the mass ratio of chitosan/monochloroacetic acid changing from 1/1 to 1/4. The N-carboxymethylchitosan derivatives have been used for adsorption Cu(II) ion from aqueous solution. The results shown that the optimum conditions for adsorption Cu(II) ion in nitrate solution were pH 6.5, temperature of 30 °C, for 60–90 min and the substituted chitosan derivative having DSN-mono of 0.16 and DSN,N-di of 0.81 had maximum adsorption capacity of 192 mg Cu(II) per gram of N-CMC. 相似文献
5.
6.
《Bioorganic & medicinal chemistry》2014,22(20):5697-5704
The direct conversion of aliphatic CH bonds into CN bonds provides an attractive approach to the introduction of nitrogen-containing functionalities in organic molecules. Following the recent discovery that cytochrome P450 enzymes can catalyze the cyclization of arylsulfonyl azide compounds via an intramolecular C(sp3)H amination reaction, we have explored here the CH amination reactivity of other hemoproteins. Various heme-containing proteins, and in particular myoglobin and horseradish peroxidase, were found to be capable of catalyzing this transformation. Based on this finding, a series of engineered and artificial myoglobin variants containing active site mutations and non-native Mn- and Co-protoporphyrin IX cofactors, respectively, were prepared to investigate the effect of these structural changes on the catalytic activity and selectivity of these catalysts. Our studies showed that metallo-substituted myoglobins constitute viable CH amination catalysts, revealing a distinctive reactivity trend as compared to synthetic metalloporphyrin counterparts. On the other hand, amino acid substitutions at the level of the heme pocket were found to be beneficial toward improving the stereo- and enantioselectivity of these Mb-catalyzed reactions. Mechanistic studies involving kinetic isotope effect experiments indicate that CH bond cleavage is implicated in the rate-limiting step of myoglobin-catalyzed amination of arylsulfonyl azides. Altogether, these studies indicate that myoglobin constitutes a promising scaffold for the design and development of CH amination catalysts. 相似文献
7.
The impacts of the regulation of sulfur (S) metabolism in vivo on arsenic (As) and S species and on As accumulation by Pteris vittata L. were investigated using a synchrotron-based X-ray-absorption fine structure method. The S assimilation inhibitor l-buthionine-sulfoximine (BSO) markedly inhibited As reduction, doubling arsenate (As(V)) content in P. vittata rhizoids. The resulting As transport blockage in rhizoids, decreased As movement to aboveground tissues by 47%. The significant impact of BSO demonstrated the vital role of sulfhydryl groups (SH) as reductants in As(V) reduction and confirmed the importance of As(V) reduction in As accumulation in this fern. The S metabolism accelerant O-acetyl-l-serine resulted in the appearance of large amounts of As–SH in rhizoids and had no obvious impact on As accumulation, but with As stress conditions, effectively increased plant biomass, possibly through chelation of excess As with SH. Thus, SH appeared able to act as both a reductant and a chelator of As in P. vittata, and the ratio of SH to As may have been a factor that determined the specific role of SH in P. vittata under these conditions. 相似文献
8.
Reactive oxygen species and antioxidant machinery in abiotic stress tolerance in crop plants 总被引:24,自引:0,他引:24
Various abiotic stresses lead to the overproduction of reactive oxygen species (ROS) in plants which are highly reactive and toxic and cause damage to proteins, lipids, carbohydrates and DNA which ultimately results in oxidative stress. The ROS comprises both free radical (O2?, superoxide radicals; OH, hydroxyl radical; HO2, perhydroxy radical and RO, alkoxy radicals) and non-radical (molecular) forms (H2O2, hydrogen peroxide and 1O2, singlet oxygen). In chloroplasts, photosystem I and II (PSI and PSII) are the major sites for the production of 1O2 and O2?. In mitochondria, complex I, ubiquinone and complex III of electron transport chain (ETC) are the major sites for the generation of O2?. The antioxidant defense machinery protects plants against oxidative stress damages. Plants possess very efficient enzymatic (superoxide dismutase, SOD; catalase, CAT; ascorbate peroxidase, APX; glutathione reductase, GR; monodehydroascorbate reductase, MDHAR; dehydroascorbate reductase, DHAR; glutathione peroxidase, GPX; guaicol peroxidase, GOPX and glutathione-S- transferase, GST) and non-enzymatic (ascorbic acid, ASH; glutathione, GSH; phenolic compounds, alkaloids, non-protein amino acids and α-tocopherols) antioxidant defense systems which work in concert to control the cascades of uncontrolled oxidation and protect plant cells from oxidative damage by scavenging of ROS. ROS also influence the expression of a number of genes and therefore control the many processes like growth, cell cycle, programmed cell death (PCD), abiotic stress responses, pathogen defense, systemic signaling and development. In this review, we describe the biochemistry of ROS and their production sites, and ROS scavenging antioxidant defense machinery. 相似文献
9.
《Peptides》2013
Peptide de13a was previously purified from the venom of the worm-hunting cone snail Conus delessertii from the Yucatán Channel, México. This peptide has eight cysteine (Cys) residues in the unique arrangement CCCCCCCC, which defines the cysteine framework XIII (“” represents one or more non-Cys residues). Remarkably, δ-hydroxy-lysine residues have been found only in conotoxin de13a, which also contains an unusually high proportion of hydroxylated amino acid residues. Here, we report the cDNA cloning of the complete precursor De13.1 of a related peptide, de13b, which has the same Cys framework and inter-Cys spacings as peptide de13a, and shares high protein/nucleic acid sequence identity (87%/90%) with de13a, suggesting that both peptides belong to the same conotoxin gene superfamily. Analysis of the signal peptide of precursor De13.1 reveals that this precursor belongs to a novel conotoxin gene superfamily that we chose to name gene superfamily G. Thus far superfamily G only includes two peptides, each of which contains the same, distinctive Cys framework and a high proportion of amino acid residues with hydroxylated side chains. 相似文献
10.
《生物化学与生物物理学报:生物膜》2015,1848(5):1234-1247
The trans isomers of fatty acids are found in human adipose tissue. These isomers have been linked with deleterious health effects (e.g., coronary artery disease). In this study, we performed molecular dynamics simulations to investigate the structures and dynamic properties of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) and 1-palmitoyl-2-elaidoyl sn-glycero-3-phosphatidylcholine (PEPC) lipid bilayers. The geometry of the olefinic bond and membrane packing effects significantly influenced the conformations and dynamics of the two CC single bonds adjacent to the olefinic bond. For the PEPC lipid, the two CC single bonds adjacent to the olefinic bond adopted mainly nonplanar skew–trans and planar cis–trans motifs; although the cis conformation featured relatively strong steric repulsion, it was stabilized through membrane packing because its planar structure is more suitable for membrane packing. Moreover, membrane packing effects stabilized the planar transition state for conformational conversion to a greater extent than they did with the nonplanar transition state, thereby affecting the dynamics of conformational conversion. The rotational motions of the first neighboring CC single bonds were much faster than those of typical saturated CC single bonds; in contrast, the rotational motions of the second neighboring CC single bonds were significantly slower than those of typical saturated torsion angles. The packing of PEPC lipids is superior to that of POPC lipids, leading to a smaller area per lipid, a higher order parameter and a smaller diffusion coefficient. The distinct properties of POPC and PEPC lipids result in PEPC lipids forming microdomains within a POPC matrix. 相似文献
11.
《Inorganica chimica acta》1988,144(1):57-61
The complex [PtCIMe(i-PrNCHCHNi-Pr)] and its unstable five-coordinate ethylene adduct have been prepared and characterized by 1H NMR. The crystal and molecular structure of the former has been determined. The complex crystallizes in the orthorhombic space group Pca2 1, with a = 12.138(6), b = 9.601(6), c = 10.586(6)Å, Z = 4. Refinement converged to a final R index of 0.059. The geometrical parameters of the structure are compared with those of a related complex and discussed in relation to the stability of the five-coordinate olefin adducts. 相似文献
12.
The human cholesteryl ester transfer protein (CETP) transfers cholesteryl ester from high-density lipoprotein (HDL) to other lipoproteins and has been established as an attractive target for reducing the risk of atherosclerosis. Here, an amphipathic α-helix peptide, namely SBH-peptide (465EHLLVDFLQSLS476), was derived from the C-terminal tail of CETP. The peptide exhibits self-binding capability towards the CETP. Crystal structure analysis, molecular dynamics (MD) simulations and ab initio electron correlation characterizations of CETP–SBH-peptide complex system revealed that the Phe471 residue plays a key role in SBH-peptide binding, which can form a π-π stacking with the Phe197 residue of CETP. In addition, substitution of the hydrogen atom H4 of Phe471 with halogen atoms, in particular the bromine atom Br4, can constitute a geometrically satisfactory halogen bonding with the oxygen atom O of CETP Ile193 residue. Fluorescence polarization assays substantiated that (i) mutation of the aromatic Phe471 to small Ala residue would impair the SBH-peptide affinity with Kd change from 10.5 to 26.4 μM, indicating that the π-π stacking should exist in Phe471⋯Phe197 adduct, and (ii) substitution with Br4 can considerably improve SBH-peptide affinity by ∼3-fold, but the SBH-peptide binding does not change essentially upon substitution with Br3 (a negative control that is theoretically unable to form the halogen bonding), indicating that the rationally designed halogen bonding should form between the Phe471(Br4) residue of SBH-peptide and the Ile193 residue of CETP protein. 相似文献
13.
《Bio Systems》2008,91(3):792-801
We have investigated the roles played by CH⋯OC interactions in RNA binding proteins. There was an average of 78 CH⋯OC interactions per protein and also there was an average of one significant CH⋯OC interaction for every 6 residues in the 59 RNA binding proteins studied. Main chain–Main chain (MM) CH⋯OC interactions are the predominant type of interactions in RNA binding proteins. The donor atom contribution to CH⋯OC interactions was mainly from aliphatic residues. The acceptor atom contribution for MM CH⋯OC interactions was mainly from Val, Phe, Leu, Ile, Arg and Ala. The secondary structure preference analysis of CH⋯OC interacting residues showed that, Arg, Gln, Glu and Tyr preferred to be in helix, while Ala, Asp, Cys, Gly, Ile, Leu, Lys, Met, Phe, Trp and Val preferred to be in strand conformation. Most of the CH⋯OC interacting polar amino acid residues were solvent exposed while, majority of the CH⋯OC interacting non polar residues were excluded from the solvent. Long and medium-range CH⋯OC interactions are the predominant type of interactions in RNA binding proteins. More than 50% of CH⋯OC interacting residues had a higher conservation score. Significant percentage of CH⋯OC interacting residues had one or more stabilization centers. Sixty-six percent of the theoretically predicted stabilizing residues were also involved in CH⋯OC interactions and hence these residues may also contribute additional stability to RNA binding proteins. 相似文献
14.
Selenium (Se) hyperaccumulator plants can accumulate and tolerate Se up to 1% of their dry weight. Since little is known about below-ground processes of Se uptake and metabolism in hyperaccumulators, X-ray absorption spectromicroscopy was used to characterize the chemical composition and spatial distribution of Se in roots of Astragalus and Stanleya hyperaccumulators. Selenium was present throughout the roots, with the highest levels in the cortex. The main form of Se (48–95%) in both species collected from naturally seleniferous soil was an organic CSeC compound, likely methyl-selenocysteine. In addition, surprisingly high fractions (up to 35%) of elemental Se (Se0) were found, a form so far not reported in plants but commonly produced by Se-tolerant bacteria and fungi. Four fungi collected from hyperaccumulator roots were characterized with respect to their Se tolerance and ability to produce Se0, and then used to inoculate hyperaccumulators in a controlled greenhouse study. The roots of the greenhouse-grown Astragalus and Stanleya contained mainly CSeC; in most plants no Se0 was detected, with the exception of Astragalus nodules and roots of Astragalus inoculated with Alternaria astragali, an Se0-producing fungus. Apparently, Se0-producing endosymbionts including nitrogen-fixing bacteria and endophytic fungi or bacteria in the root can affect Se speciation in hyperaccumulator roots. Microbes that affect plant Se speciation may be applicable in phytoremediation and biofortification, especially if they are promiscuous and affect Se tolerance in crop species. 相似文献
15.
In the present study, 7-subsituted coumarin derivatives were synthesized using various aromatic and heterocyclic amines, and evaluated in vivo for anti-inflammatory and analgesic activity, and for ulcerogenic risk. The most active compounds were evaluated in vitro for 5-lipoxygenase (5-LOX) inhibition. Docking study was performed to predict the binding affinity, and orientation at the active site of the enzyme. In vivo anti-inflammatory and analgesic activity, and in vitro 5-LOX enzyme inhibition study revealed that compound 33 and 35 are the most potent compounds in all the screening methods. In vitro kinetic study of 35 showed mixed or non-competitive type of inhibition with 5-LOX enzyme. Presence of OCH3 group in 35 and Cl in 33 at C6-position of benzothiazole ring were found very important substitutions for potent activity. 相似文献
16.
17.
《Biochimica et Biophysica Acta - Proteins and Proteomics》2018,1866(7):783-788
Recently, non-enzymatic stereoinversions of aspartic acid (Asp) residues in proteins and peptides have been reported. Here, we performed replica exchange molecular dynamics (REMD) simulations of model peptides (exon 6, 26A-1, and 26A-2) extracted from elastin to investigate their structural features, thereby revealing the factor that influences stereoinversions. For REMD trajectories, we calculated distances between carboxyl carbon in Asp and amide nitrogen in the (n + 1) residue (CN distances). Because bond formation between carbon and nitrogen is indispensable to the formation of a succinimide intermediate the distance between them seems to play an important role in stereoinversion. Moreover, we calculated polar surface areas (PSAs) for the trajectories, finding that CN distances and PSA were different for each peptide, with the longest CN distance and smallest PSA observed for exon 6 peptide, where stereoinversion of Asp is the slowest. Although the average CN distance was shorter for exon 26A-1 peptide than for exon 26A-2 peptide, the number of conformations with CN distances <3.0 Å was greater for exon 26A-2 peptide than for exon 26A-1 peptide. Furthermore, PSA for amide nitrogen of the (n + 1) residue was larger for exon 26A-2 peptide than for exon 26A-1 peptide. These results indicated that the flexibility of Asp and (n + 1) residues and hydrophilicity of peptides, especially in the (n + 1) residue, play important roles in the stereoinversion of Asp. This article is part of a Special Issue entitled: D-Amino acids: biology in the mirror, edited by Dr. Loredano Pollegioni, Dr. Jean-Pierre Mothet and Dr. Molla Gianluca. 相似文献
18.
The crystal and molecular structure of the fluorescent probe 8-anilino-1-naphthalenesulfonic acid (ANS) has been determined as the ammonium monohydrate with two conformationally distinct molecules in the triclinic lattice. The angles between the aromatic rings and the CNC plane are ?9/22° and 112/22° respectively. There is an NH...O intramolecular hydrogen bond in each molecule indicating that hydrogen bond formation is not dependent on the anilino geometry. There are also short intramolecular H...H contacts involving the hydrogens which have anomalous proton shifts shown in a recent NMR study. 相似文献
19.
《Inorganica chimica acta》1988,144(1):143-146
Spectrochemical properties of LnI 2 (Ln = Sm, Eu, Yb) prepared with lanthanoid metal and diiodoethane in THF were characterized by means of UV—Vis, fluorescence and ESR spectroscopy. A comparative investigation has also been made concerning LnI 3 (Ln= LaLu) and the Grignard-type compounds RLnI (R = Et, Ph; Ln = Eu, Yb). LnI 2 (Ln = Sm, Eu, Yb) was also prepared from reaction of lanthanoid metal and iodine in THF. 相似文献
20.
A simple and rapid technique which permits the separation of cyclic AMP, adenine, adenosine, hypoxanthine, inosine, 5′-AMP, IMP, ADP, and ATP by the use of unidirectional high-voltage paper electrophoresis has been described. The separation of these compounds based on their charge difference utilizes the following properties: (1) the protonation of the NH2 group of the adenine, (2) the primary and secondary ionization of the phosphate group of the nucleotides, and (3) the formation of the chelated oxyderivative of boron with the two cis (OH) groups of the ribose moieties of nucleosides and nucleotides. 相似文献