An Easy Synthetic Approach to Construct Some Ebselen Analogues and Benzo[b]selenophene Derivatives: Their Antioxidant and Cytotoxic Assessment

2‐(Chloroseleno)benzoyl chloride serves as a versatile building block for the synthesis of novel ebselen (2‐phenyl‐1,2‐benzisoselenazol‐3(2H)‐one) analogues and benzo[b]selenophen‐3(2H)‐one derivatives. The antioxidant activity and cytotoxic evaluation of the newly synthesized compounds were implemented. Among all the synthesized compounds, 1‐(3‐hydroxybenzo[b]selenophen‐2‐yl)ethanone oxime ( 9 ) was the most potent antioxidant and the most cytotoxic compound as well.     

Synthesis, characterization and antioxidant activity of naringenin Schiff base and its Cu(II), Ni(II), Zn(II) complexes

A new ligand, naringenin-2-hydroxy benzoyl hydrazone (H(5)L), was prepared by condensation of naringenin with 2-hydroxy benzoyl hydrazine. Its Cu(II), Ni(II), Zn(II) complexes have also been synthesized and characterized on the basis of (1)H-NMR, IR, UV-Vis spectra, elemental analyses, molar conductivity and thermal analyses. The general formula of these complexes was M(H(3)L) [M=Cu(II), Ni(II) and Zn(II)]. In addition, the antioxidant activities (superoxide and hydroxyl radical) of the free ligand and its complexes were determined in vitro. These compounds were found to possess potent antioxidant activity and be better than standard antioxidants like vitamin C and mannitol. In particular, the Cu(II) complex displayed excellent activity on the superoxide radical.     

Surface-enhanced Raman spectra study of metal complexes of N-D-glucosamine beta-naphthaldehyde and glycine and their interaction with DNA

Copper(II), zinc(II), cobalt(II) and cobalt(III) complexes of N-D-glucosamine beta-naphthaldehyde (C17H19O6N, NG) and glycine were synthesized. The four novel metal complexes, Cu(II)C19H28O11N2(CuGNG), Zn(II)C19H24O9N2 (ZnGNG), Co(II)C19H28O11N2(Co(II)GNG) and Co(III)C21H29O12N2(Co(III)GNG) were characterized by means of infrared (IR), electronic absorption spectroscopy and NMR etc. The surface-enhanced Raman spectra of the four complexes and their interaction with DNA were studied. By comparison of the surface-enhanced Raman spectra (SERS), the information of the four complexes' SER active sites and adsorption orientation were obtained. Combined with fluorescence spectra of Ethidium bromide (EthBr) DNA system, we concluded that none of the four complexes intercalate into DNA and that the presence of the glycine ligand lowered the anticancer activity of NG series complexes.     

Organoantimony(V) cyanoximates: synthesis,spectra and crystal structures

A series of 25 new organoantimony(V) cyanoximates has been synthesized and studied using IR, visible, and NMR spectroscopy and X-ray analysis. Crystal structures were determined for compounds (C6H5)4Sb[ONC(CN)C(O)NH2] (1) and (C6H5)4Sb[ONC(CN)C(O)N(CH3)2] (2). Both complexes crystallized in the monoclinic space group P2(1)/c (Z = 4) with unit cell parameters (A, grad) of a = 14.921(3), b = 10.165(2), c = 17.571(7), beta = 113.26(6) for compound 1, and a = 16.415(4), b = 10.406(3), c = 17.152(3), beta = 17.152(3), beta = 117.79(2) for compound 2. For 5438 and 5056 independent reflections the refinement yielded R-factors 0.022 and 0.037 for the structures of 1 and 2, respectively. Cyanoxime anions are bound to the antimony(V) atoms in a monodentate fashion via the oxygen atoms of the oxime groups. The ligands adopt trans-anti configuration in these compounds. The coordination polyhedron in both complexes is a distorted trigonal bipyramid with the axial location of the cyanoxime ligand. A similar binding mode of other anions in synthesized organoantimony(V) complexes has been offered on the basis of the similarity of their IR spectra to those of the compounds whose structures were determined crystallographically. The exact assignment of vibrations involving the oxime group was carried out using synthesized 15N(53%), isotopomers.     

Antioxidant activity assay based on the inhibition of oxidation and photobleaching of l-cysteine-capped CdTe quantum dots

Quantum dots (QDs) have recently been the focus of attention of many investigators for development of diagnostic tools in many research areas. In this work, we established a new QD-based assay to evaluate the antioxidant/polyphenolic activity. This assay is based on measurement of the inhibitory effect of the antioxidant/polyphenolic compounds on the UV-induced bleaching of CdTe QDs with l-cysteine capping. QDs exhibited excellent photostability without any UV exposure, while they bleached rapidly under UV irradiation. Generation of reactive oxygen species (ROS) under UV irradiation is probably the main cause of the photobleaching of QDs. By comparing the photostability of QDs in buffer solution in the absence and presence of sodium azide, as a known (1)O(2) quencher, the involvement of (1)O(2) in photobleaching of QDs was confirmed. The photobleaching effect induced by ROS could be reduced in the presence of antioxidant/polyphenolic compounds. We tested several antioxidant/polyphenolic compounds as well as known antioxidants such as trolox and 4 different types of tea. The results obtained by the QD-based assay revealed a very good correlation with the data acquired by Folin-Ciocalteu assay. Furthermore, a deeper understanding of the mechanism and the solution for photobleaching of QDs under UV irradiation might be very meaningful in promoting their clinical applications.     

Predicting how polyphenol antioxidants prevent DNA damage by binding to iron

Prevention of oxidative DNA damage due to hydroxyl radical is important for the prevention and treatment of disease. Because of their widely recognized antioxidant ability, 12 polyphenolic compounds were assayed by gel electrophoresis to directly quantify the inhibition of DNA damage by polyphenols with Fe(2+) and H2O2. All of the polyphenol compounds have IC50 values ranging from 1-59 microM and inhibit 100% of DNA damage at 50-500 microM concentrations. Gel electrophoresis results with iron(II)EDTA and UV-vis spectroscopy experiments confirm that binding of the polyphenol to iron is essential for antioxidant activity. Furthermore, antioxidant potency of polyphenol compounds correlates to the pKa of the first phenolic hydrogen, representing the first predictive model of antioxidant potency based on metal-binding. Understanding this iron-coordination mechanism for polyphenol antioxidant activity will aid in the design of more-potent antioxidants to treat and prevent diseases caused by oxidative stress, and help develop structure-activity relationships for these compounds.     

Trinuclear and Dinuclear Manganese Complexes of 2/4-Formylbenzoic Acid Oxime Ligands： Syntheses and Crystal Structures

Two manganese complexes, [Mn3（2-cba）6（phen）2] 1 （2-cba = 2-cyanobenzoic acid, phe11 = 1,10-phenanthroline） and [MnE（4-fbaO）E（phen）4]（PF6）E.EHEO 2 （4-fbao = 4-formylbenzoic acid oxime）, have been synthesized by the reaction of 2-formylbenzoic acid oxime （2-fbao, HELl） or 4-formylbenzoic acid oxime （4-fbao, HELE） with phen and manganese acetate in ethanol or methanol solution. A translation from the oximino （-CHN=OH） of HELl to cyano （-C-N） was found in the formation of complex 1 at room temperature. The complexes were structurally determined by single-crystal X-ray diffraction. The crystal of compound I belongs to monoclinic, space group C2/c, with a = 17.983（6）, b = 23.364（7）, c =14.589（5） A, β = 92.401（5）° V = 6124（3） A^3, Z = 4, C72H40Mn3N10O12, Mr= 1401.96, Dc = 1.521 g/cm^3, F（000） = 2852.0, Rint = 0.0372, T= 293（2） K,μ = 0.686 mm^-1, the final R = 0.0644 and wR = 0.1813 for 5803 observed reflections with I 〉 2δ（I）. The crystal of compound 2 is of monoclinic system, space group P21/n, with a = 13.050（4）, b = 20.577（5）, c = 13.323（4）A,β = 113.578（3）°, V = 3227.2（14）A3, Z = 2, C64H48F12Mn2N10O8P2, Mr = 1484.94, Dc = 1.528 g/cm^3, F（000） = 1508.0, Rint= 0.0295, T= 293（2） K,μ = 0.539 mm^-1, the final R = 0.0629 and wR = 0.1789 for 5298 observed reflections with I 〉 2σ（I）. Compounds 1 and 2 are linear trinuclear and dinuclear manganese complexes respectively, which are both bridged by carboxylate groups of the ligands.     

H_2O-DMSO体系中联吡啶甲基化及其钨硅酸盐的形成

以Keggin型钨硅酸H_4[SiW_(12)O_(40)]·24H_2O和MN~(2+)为原料,4,4′-联吡啶(4,4′-bipy)为有机前驱体,水和二甲基亚砜(DMSO)为混合溶剂,在水热条件下,4,4′-bipy发生N-甲基化,并与DMSO共同修饰[SiW_(12)O_(40)]~(4-)阴离子,形成了1个钨硅酸盐基无机-有机杂化化合物(CH_3)_2bipy)((CH_3)_2SOH)_2[SiW_(12)O_(40)].通过元素分析、红外光谱(IR)、热重(TG)及X-射线单晶衍射分析对该化合物进行了表征,初步探讨了该化合物的形成条件,并研究了其在水溶液中的电化学性质及其对H_2O_2还原的电催化活性.     

Is the Beckmann rearrangement a concerted or stepwise reaction? A computational study

[reaction: see text] RB3LYP calculations were performed on the Beckman rearrangement by the use of three substrates, acetone oxime (1), acetophenone oxime (2), and cyclohexanone oxime (3). Acidic solvents were modeled by H+ (CH3COOH)3 and H3O+ (H2O)6, and reaction paths were determined precisely. For 1, a two-step process involving a sigma-type cationic complex was obtained. For 2, a three-step process with pi- and sigma-type complexes was found in H+ (CH3COOH)3 and a two-step process involving a sigma-type cationic complex was obtained in H3O+ (H2O)6. However, for 3, a concerted process without pi and sigma complexes was calculated, which leads to the product, epsilon-caprolactam. Three different mechanisms were explained in terms of FMO theory.     

Anderson型多酸基无机一有机杂化化合物的合成及催化氧化性质研究

合成了一种新的基于Anderson结构镍钼酸盐的无机-有机杂化化合物(C3 H7 NO2)2[(H2O)5 (C3 H7 NO2) Ni]2[NiMo6 H6 O24]·2H2O(C3 H7 NO2=β-丙氨酸),通过单晶X射线衍射方法确定了其晶体结构,结构分析表明,该化合物结晶于单斜空间群P21/C,晶胞参数a=1.847 25(13) nm,b=1.059 32(7) nm,c=1.224 77(7) nm,β=104.177(6)°.并对该化合物进行了红外、紫外可见和热重测试,该化合物在苯甲硫醚的催化氧化反应中作为多相催化剂,表现出好的催化活性.     

Comparative Antioxidant Study of Stem and Stem Induced Callus of Phyllanthus fraternus Webster—An Important Antiviral and Hepatoprotective Plant

Phyllanthus fraternus is widely used in the cure of various liver diseases and possess antiviral properties especially against hepatitis virus. In the present study, evaluation of the antioxidant activity of stem and calli induced from stem has been done by different assays. Extraction was done by standard method in water and ethanol. Total antioxidant capacity was measured by 1, 1-diphenyl-2-picrylhydrazyl free radical scavenging method. Lipid peroxidation was measured in terms of thiobarbituric acid-reactive substances (TBARS) by using egg yolk homogenates as lipid-rich media, and superoxide radical scavenging activity was measured using riboflavin–light–nitro blue tetrazolium assay. Reducing power was determined on the basis of Fe³⁺–Fe²⁺ transformation in the presence of the extract. In addition to the antioxidant activity, polyphenolic compounds like total phenolics and flavonoids were also measured by spectroscopic method. Results showed that the ethanolic extract of stem is more potent in antioxidant activity than its aqueous extract and ethanolic extract of calli. A significant correlation between antioxidant capacity and polyphenolic content and reducing potential was observed, indicating that phenolic compounds and reducers present in extract are major contributors to the antioxidant potential. Thus, this plant extract could be used as a potent natural antioxidant.     

Design and Antioxidant Properties of Bifunctional 2H-Imidazole-Derived Phenolic Compounds—A New Family of Effective Inhibitors for Oxidative Stress-Associated Destructive Processes

The synthesis of inhibitors for oxidative stress-associated destructive processes based on 2H-imidazole-derived phenolic compounds affording the bifunctional 2H-imidazole-derived phenolic compounds in good-to-excellent yields was reported. In particular, a series of bifunctional organic molecules of the 5-aryl-2H-imidazole family of various architectures bearing both electron-donating and electron-withdrawing substituents in the aryl fragment along with the different arrangements of the hydroxy groups in the polyphenol moiety, namely derivatives of phloroglucinol, pyrogallol, hydroxyquinol, including previously unknown water-soluble molecules, were studied. The structural and antioxidant properties of these bifunctional 5-aryl-2H-imidazoles were comprehensively studied. The redox transformations of the synthesized compounds were carried out. The integrated approach based on single and mixed mechanisms of antioxidant action, namely the AOC, ARC, Folin, and DPPH assays, were applied to estimate antioxidant activities. The relationship “structure-antioxidant properties” was established for each of the antioxidant action mechanisms. The conjugation effect was shown to result in a decrease in the mobility of the hydrogen atom, thus complicating the process of electron transfer in nearly all cases. On the contrary, the conjugation in imidazolyl substituted phloroglucinols was found to enhance their activity through the hydrogen transfer mechanism. Imidazole-derived polyphenolic compounds bearing the most electron-withdrawing functionality, namely the nitro group, were established to possess the higher values for both antioxidant and antiradical capacities. It was demonstrated that in the case of phloroglucinol derivatives, the conjugation effect resulted in a significant increase in the antiradical capacity (ARC) for a whole family of the considered 2H-imidazole-derived phenolic compounds in comparison with the corresponding unsubstituted phenols. Particularly, conjugation of the polyphenolic subunit with 2,2-dimethyl-5-(4-nitrophenyl)-2H-imidazol-4-yl fragment was shown to increase ARC from 2.26 to 5.16 (10⁴ mol-eq/L). This means that the considered family of compounds is capable of exhibiting an antioxidant activity via transferring a hydrogen atom, exceeding the activity of known natural polyphenolic compounds.     

Antioxidant capacity of Ocimum basilicum L. and Origanum vulgare L. extracts

The antioxidant properties of five different extracts (Et?O, CHCl?, EtOAc, n-BuOH, and H?O) of Ocimum basilicum L. and Origanum vulgare L. were studied. Antioxidant activity was assessed in six different model systems. Free radical scavenging capacity (RSC) was evaluated by measuring the scavenging capacity of extracts on DPPH, NO, O??? and OH radical, as well as on hydrogen peroxide (H?O?). In addition, the protective effects on lipid peroxidation in liposomes (LPx) were evaluated by TBA-assay using the Fe2?/ascorbate induction system. The amount of total phenolic compounds and content of total flavonoids was also determined. EtOAc, n-BuOH and H?O extracts of O. basilicum and O. vulgare expressed very strong scavenger activity. Furthermore, the mentioned extracts showed notable inhibition of LPx. On the other hand, Et?O and CHCl? extracts showed much weaker effect in the neutralization of DPPH, NO and O??? radicals and the neutralization of H?O?. When examining the production of OH radicals and inhibition of LPx, the Et?O and CHCl? extracts showed weak prooxidative properties. The observed differences in antioxidant activity could be partially explained by the levels of phenolics and flavonoids in the investigated O. basilicum and O. vulgare extracts.     

新型苦参碱肟酯类化合物的合成

利用生物活性因子拼接法将活性基团肟酯引入植物源活性化合物苦参碱中对其结构进行修饰,以苦参碱为原料,与亚硝酸叔丁酯反应制得关键中间体肟（2）; 2与苯甲酰氯类化合物经酯化反应合成了8个新型的苦参碱肟酯类化合物,其结构经¹H NMR, ¹³C NMR和MS表征。     

4‐[N,N‐Bis(2‐hydroxy­imino‐2‐phenyl­ethyl)­amino]‐1,5‐di­methyl‐2‐phenyl‐2,3‐di­hydro‐1H‐pyrazol‐3‐one monohydrate

The title compound, C₂₇H₂₇N₅O₃·H₂O, is built up from pyrazolinone, phenyl and aceto­phenone oxime moieties. The 2‐­phenyl substituent is nearly perpendicular to the pyrazo­linone ring, with a dihedral angle of 87.66 (1)°. The aceto­phenone oxime moieties are twisted out of the pyrazolinone‐ring plane by 47.04 (1)°. The mol­ecules in the crystal pack in an antiparallel fashion and are held together by hydrogen‐bonded water mol­ecules and intermolecular O—H⋯O and O—H⋯N hydrogen bonds.     

Antioxidant, anti-lipoxygenase and cytotoxic activity of Leptadenia pyrotechnica (Forssk.) decne polyphenolic constituents

Leptadenia pyrotechnica Forssk is a traditional medicinal herb used for treatment of inflammatory diseases and cancer. In this research, the aqueous ethanolic crude extract of Leptadenia pyrotechnica aerial parts, along with its ethyl acetate, n-butanol and water partitioning fractions were evaluated for their antioxidant capacity, polyphenolic content, anti-inflammatory and anti-cancer properties. The total antioxidant capacity was estimated by the FRAP, DPPH, ABTS and β-carotene bleaching assays.The ethyl acetate fraction exhibited the highest polyphenolic content (252.27 mg gallic acid/g) and the best antioxidant activity (1.2, 0.57, 0.45 mmol ascorbic acid equivalent/g in the FRAP, ABTS and DPPH assays, respectively). Furthermore, the same extract showed appreciable anti-inflammatory via lipoxygenase (LOX) inhibitory activity (IC?? = 1.41 μg/mL). Moreover, the ethyl acetate fraction also showed the strongest cytotoxic effect (IC?? = 43.16 μg/mL) against MCF-7 human breast cancer cell line. These results suggest that this plant may be considered an interesting source of compounds with antioxidant, anti-inflammatory and anti-cancer properties for therapeutic, nutraceutical and functional food applications.     

Synthesis, Crystal Structure and Fungicidal Activity of （Z）-3,3-Dimethyl-1-（1H-1,2,4-triazol-1-yl）butan-2-one O-2-Chlorobenzyl Oxime Nitrate

The title compound has been synthesized by the reaction of 3,3-dimethyl-1-(1H-1,2,4-triazol-1-yl)butan-2-one oxime with 2-chlorobenzyl chloride, and then treated with 65～68% HNO3. Its crystal structure was determined by single-crystal X-ray diffraction. The crystal belongs to the monoclinic system, space group P21/c with a = 14.5481(8), b = 9.3351(5), c = 13.1911(7) , β = 98.9450(10)°, Z = 4, V = 1769.67(17) 3, Mr = 369.81, Dc = 1.388 g/cm3, S = 1.06, μ = 0.247 mm-1, F(000) = 776, the final R = 0.0352 and wR = 0.0960 for 3069 observed reflections (I > 2σ(I)). X-ray crystal structure presents the intramolecular N–H…O hydrogen bond. The packing is nearly parallel without π-π stacking interactions between two adjacent phenyl rings and stabilized by Van der Waals force. The preliminary bioassay shows that the title compound possesses fungicidal activity against Gibberella zeae at the dosage of 25 mg/L.     

Naringenin Schiff base: antioxidant activity,acid–base profile,and interactions with DNA

A Schiff base derived from naringenin (NTSC) and its complex with Cu(II) ([Cu(H₃L)(OAc)]·H₂O, Cu(II)–NTSC) have been synthesized and characterized by physicochemical and spectroscopic methods. EPR studies confirmed that nitrogen, oxygen, and sulfur are the donor atoms bound to Cu(II) in the complex. The geometry of the complex has been modelled using DFT methods. Furthermore, naringenin and NTSC were used for the formation of Cu(II) complexes in solution, for comparison of biological activities. Antioxidant studies confirmed better radical scavenging activity of both NTSC and its Cu(II) complex compared to naringenin. The interaction of these compounds with calf thymus DNA was monitored by UV–Vis spectroscopy.     

Polymeric Forms of Plant Flavonoids Obtained by Enzymatic Reactions

Naringenin is one of the flavonoids originating from citrus fruit. This polyphenol is mainly found in grapefruit, orange and lemon. The antioxidant and antimicrobial properties of flavonoids depend on their structure, including the polymeric form. The aim of this research was to achieve enzymatic polymerization of naringenin and to study the properties of poly(naringenin). The polymerization was performed by methods using two different enzymes, i.e., laccase and horseradish peroxidase (HRP). According to the literature data, naringenin had not been polymerized previously using the enzymatic polymerization method. Therefore, obtaining polymeric naringenin by reaction with enzymes is a scientific novelty. The research methodology included analysis of the structure of poly(naringenin) by NMR, GPC, FTIR and UV-Vis and its morphology by SEM, as well as analysis of its properties, i.e., thermal stability (DSC and TGA), antioxidant activity (ABTS, DPPH, FRAP and CUPRAC) and antimicrobial properties. Naringenin oligomers were obtained as a result of polymerization with two types of enzymes. The polymeric forms of naringenin were more resistant to thermo-oxidation; the final oxidation temperature T_o of naringenin catalyzed by laccase (poly(naringenin)-laccase) was 28.2 °C higher, and poly(naringenin)-HRP 23.6 °C higher than that of the basic flavonoid. Additionally, due to the higher molar mass and associated increase in OH groups in the structure, naringenin catalyzed by laccase (poly(naringenin)-laccase) showed better activity for scavenging ABTS^+• radicals than naringenin catalyzed by HRP (poly(naringenin)-HRP) and naringenin. In addition, poly(naringenin)-laccase at a concentration of 5 mg/mL exhibited better microbial activity against E. coli than monomeric naringenin.