Synthesis,spectral characterization and bioactivity evaluation of novel α-aminophosphonates

A facile synthesis of novel α-aminophosphonates 5a-j was accomplished by condensation of imines (3a-j) with diethyl phosphite (4) in ethanol at 50–60°C using easily recoverable and reusable catalyst, tetramethyl guanidine (TMG) via pudovik reaction in high yields. All the title compounds were characterized by spectral and elemental analysis. They were further screened for their abilities towards in vitro antibacterial, antifungal and antioxidant activities. The compounds 5g, 5d, 5f exhibited good antibacterial and antifungal activities compared to the standard bactericide, Penicillin and fungicide, Griseofulvin, respectively. The compounds 5h, 5i, 5g, and 5c exhibited good antioxidant activity compared to the standard ascorbic acid.     

Interaction of flavonoids,the naturally occurring antioxidants with different media: A UV–visible spectroscopic study

Quantitative parameters for interaction of flavonoids—the naturally occurring antioxidants, with solvents and surfactants are determined using UV–visible absorption spectroscopy. The availability of flavonoids; kaempferol, apigenin, kaempferide and rhamnetin in micelles of sodium dodecyl sulfate (SDS) is reflected in terms of partition coefficient, K_c. Thermodynamic calculations show that the process of transfer of flavonoid molecules to anionic micelles of SDS is energy efficient. A distortion in flavonoid's morphology occurs in case of kaempferol and apigenin in surfactant and water, exhibited in terms of a new band in the UV region of electronic spectra of these flavonoids. The partition coefficients of structurally related flavonoids are correlated with their antioxidant activities.     

Synthesis,anti-platelet aggregation activity evaluation and structure–activity relationships of a series of novel purine derivatives

This article described how further extensive variation of the substituents on the purine scaffold of adenosine triphosphate (ATP), and the human anti-platelet aggregation activities were modified in order to find exploitation of the structure–activity relationships (SAR). A series of novel designed 6-alkylamino-2-alkylthio-9-hydroxyalkyl(carbalkoxy) purine derivatives were synthesized via a modification procedure, and the human anti-platelet aggregation activities were evaluated. The SAR of these compounds were analyzed in detail, and the results of the structural requirements of the substituents to improve potency may provide a basis for the development of potent P2Y₁₂ antagonists.     

Statistical analysis of the impact of spectral correlation on observed formation constants from UV–visible spectroscopic measurements

Information retrieved from UV–visible spectroscopic data by application of a self-modelling factor analysis algorithm showed apparently systematically shifted thermodynamic properties for the same chemical system as a function of spectral slit widths. This empirical observation triggered a systematic investigation into the likely effects of residual and spectral correlation on the numerical results from quantitative spectroscopic investigations. If slit width was a nuisance factor it would reduce the comparability of information evaluated from spectroscopic data. The influence of spectral slit width was investigated by simulation, i.e. by generating and evaluating synthetic spectra with known properties. The simulations showed that increasing spectral correlation may introduce bias into factor analysis evaluations. By evaluation of the complete measurement uncertainty budget using threshold bootstrap target factor (TB CAT) analysis, the apparent shifts are insignificant relative to the total width of the quantitys measurement uncertainty. Increasing the slit widths causes some systematic effects, for example broadening of the registered spectral bands and reduction of spectral noise, because of higher light intensity passing to the detector. Hence, the observed systematic shifts in mean values might be caused by some latent correlation. As a general conclusion, slit width does not affect bias. However, the simulations show that spectral correlation and residual correlation may cause bias. Residual correlation can be taken into account by computer-intensive statistical methods, for example moving block or threshold bootstrap analysis. Spectral correlation is a property of the chemical system under study and cannot be manipulated. As a major result, evidence is given showing that stronger spectral correlation (r<–0.7) causes non-negligible bias in the evaluated thermodynamic information from such a system.     

Synthesis and evaluation of antibacterial and anti-oxidant activity of small molecular chitosan–fucoidan conjugate nanoparticles

Research on Chemical Intermediates - Low-molecular weight chitosan (LMWC) and low-molecular weight fucoidan (LMWF) have been reported to possess diverse biological activity. In this study, LMWC and...     

GC–MS characterisation and antibacterial activity evaluation of Nigella sativa oil against diverse strains of Salmonella

Salmonella resistance is becoming a worldwide serious health issue in these days; therefore, it is an urgent need to develop some alternative approaches to overcome this problem. Twenty bacterial strains were isolated and purified from different environmental sources and confirmed as Salmonella by morphological and biochemical analyses. Further confirmation was done by 16s rRNA sequencing. Antibiotic susceptibility test was performed by well diffusion assay against different concentrations of Ceftriaxone and Ciprofloxacin. The behaviour of both antibiotics was different against diverse strains of Salmonella. Salmonella strains resistant to both antibiotics were analysed for antibacterial activity of natural extracts of Nigella sativa (black seeds). N. sativa oil was found to be more effective against Salmonella species for which even Ceftriaxone and Ciprofloxacin were ineffective. Gas chromatography and mass spectrometry analysis of N. sativa oil was also accomplished, exhibiting 10 compounds including thymoquinone, p-cymene, cis-carveol, thymol, α-phellandrene, α-pinene, β-pinene, trans-anethole, α-longipinene and longifolene.     

Simultaneous determination of DTPA,EDTA, and NTA by UV–visible spectrometry and HPLC

In this study, UV–visible spectrophotometry (UV–Vis) and high-performance liquid chromatography (HPLC) were used for simultaneous analysis of chelating agents diethylenetriamine pentaacetic acid (DTPA), ethylenediamine tetraacetic acid (EDTA), and nitrilotriacetic acid (NTA), as their metal chelates in dishwashing detergents, natural waters, and pulp mill water. The total amounts of the chelating agents in dishwashing detergents were verified by potentiometric titration with Fe(III) solution. Nickel(II) chelates were determined by UV–Vis and iron(III)chelates by HPLC and titration. Recoveries of DTPA, EDTA, and NTA from a standard mixture of analytes by UV–Vis were 107±7, 101±12 and 94±13%, respectively, and the recovery of the total amount of complexing agents was 99±4%. The limits of detection for DTPA, EDTA, and NTA were 667, 324, and 739 mol L^–1, respectively. In HPLC measurements the optimized mobile phase contained 0.03 mol L^–1 sodium acetate, 0.002 mol L^–1 tetrabutylammonium bromide, and 5% methanol at pH 3.15 and the detection was by UV–Vis detection at 254 nm. All three complexing agents could be separated from each other in a simultaneous analysis in less than 5 min. The limits of detection were 0.34, 0.27, and 0.62 mol L^–1 for DTPA, EDTA, and NTA, respectively. The total amounts of the analytes measured in the dishwashing detergents by the three techniques were found to be highly comparable (ANOVA: F=0.04, P=0.96). R² values were 0.99 for EDTA, 0.99 for NTA, and 0.99 for all the results when UV–Vis and HPLC determinations were compared using regression lines. The UV–Vis and HPLC methods were proved to be viable also for analyses of natural and pulp mill waters. The absence of matrix interferences was verified by the standard addition technique.     

Synthesis, bioactivity and DFT structure–activity relationship study of novel 1,2,3-thiadiazole derivatives

A series of novel 1,2,3-thiadiazole derivatives were designed and synthesized. Their structures were characterized by ¹H NMR, MS and HRMS. The bioactivity tests indicated that compound 9b exhibits a favorable KARI inhibition rate, and some of these novel compounds also showed moderate herbicidal activity against Brassica campestris.     

Synthesis,characterization, and visible light–induced photocatalytic evaluation of WO3/NaNbO3 composites for the degradation of 2,4-D herbicide

In this research study, WO₃/NaNbO₃-coupled photocatalysts were synthesized at three WO₃ mass ratios (15, 85, and 95 wt%) and characterized. These composites were characterized via X-ray powder diffraction, N₂ physisorption, UV–Vis diffuse reflectance spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy, and photoluminescence techniques. For comparison, bare WO₃ and NaNbO₃ were also synthesized and characterized. 2,4-Dichlorophenoxyacetic acid (2,4-D) was degraded under visible light to evaluate its photocatalytic performance. The WO₃ (95 wt%)/NaNbO₃ composite showed higher photocatalytic activity than pure WO₃ and NaNbO₃ and even than the 15 and 85 wt% coupled materials; thus, the combination with the highest ratio of WO₃ with respect to NaNbO₃ showed increased photocatalytic activity compared with the bare materials.     

A study of photodegradation of sulforhodamine B on Au–TiO2/bentonite under UV and visible light irradiation

Au–TiO₂/bentonite samples were prepared via deposition–precipitation method and calcined at different temperatures. These samples were characterized by X-ray diffraction (XRD), UV–vis diffusion reflectance spectroscopy (DRS), BET method, X-ray photoelectron spectroscopy (XPS) and TEM. The photocatalytic activities of the samples were tested by photodegradation of sulforhodamine B (SRB) under ultraviolet (UV) and visible light irradiation. The result showed that Au–TiO₂/bentonite catalysts exhibited higher efficiency for mineralizing SRB than the well-known commercial TiO₂ photocatalyst P25 in terms of COD changes. The most important advantage of Au–TiO₂/bentonite over P25 was that it could be readily separated from aqueous suspensions by sedimentation after the reaction. It can maintain almost the same activity after being repeatedly used for 12 times. Possible mechanisms for SRB photoreaction in the presence of Au–TiO₂/bentonite were proposed in this paper.     

Synthesis,antiproliferative evaluation,and structure–activity relationships of novel triazole–isoindoline hybrids bearing 3,4,5-trimethoxyphenyl moiety

As an aspect of our ongoing research on developing novel antiproliferative agents, 31 new triazole–isoindoline hybrids bearing 3,4,5-trimethoxyphenyl moiety were synthesized and evaluated for their antiproliferative activity against four cancer cell lines (HepG2, HeLa, PC-3, and HCT116). Some compounds showed excellent potency, and compared to fluorouracil, the most promising compound 6s exhibited 5.8-, 4.3-, and 1.3- fold increase in activities against HeLa, HepG2, and PC-3 cell lines with IC₅₀ values of 9.7, 10.7, and 16.8 μM, respectively. Moreover, structure–activity relationship studies indicated that a much shorter amide linkage and electron-withdrawing groups at phenyl ring of the acetamide fragment contribute to the antitumour activity.     

Synthesis,structure and characterisation of rac and meso–ansa-bridged permethylindenyl cobalt complexes

Disodium ethylene-bis-hexamethylindenyl, {(C₉Me₆)₂C₂H₄}Na₂ (EBI1Na₂), has been prepared in good yield by the reaction of lithium heptamethylindenyl with cyanogen bromide followed by treatment with sodium naphthalenide. EBI1Na₂ reacts with anhydrous Co(acac)₂ to give a mixture of rac and meso-ethylene-bis-hexamethylindenyl cobalt(II) (EBI1Co). The isomers can be separated by fractional crystallisation and the rac-isomer has been structurally characterised. Oxidation of the reaction mixture yields both rac and meso-ethylene-bis-hexamethylindenyl cobalt(III) which have both been structurally characterised.     

Synthesis and herbicidal activity evaluation of novel β-carboline derivatives

Based on the original structure of harmine, several novel 1,2,3,4-tetrahydro-β-carboline, β-carboline and 1-substituted-β-carboline derivatives bearing a substituted carbohydrazide group at C-3 were designed and synthesized to investigate the structure-activity relationship of their analogues. All of the compounds were characterized by infrared (IR), proton and carbon nuclear magnetic resonance (1H-NMR, 13C-NMR), and mass spectroscopy (MS). The bioassay tests showed that N'-benzylidene-1-phenyl-β-carboline-3-carbohydrazide (C(25)H(18)N(4)O, m.w. 390.4) (c2) and N'-(4-trifluoromethyl-benzylidene)-1-phenyl-β-carboline-3-carbohydrazide (C(26)H(17)N(4)OF(3), m.w. 458) (d2) exhibited good inhibitory activity against dicotyledonous and monocotyledonous weeds, with EC(50) values of 4.83 μM and 14.25 μM, respectively.     

Synthesis of immobilized nanopalladium on polymer-supported Schiff base, and study of its catalytic activity in the Suzuki–Miyaura reaction

Abstract  

Nanopalladium particles immobilized on a matrix of poly(vinyl chloride) (PVC)-supported Schiff base were prepared from PVC with sequential attachment of ethylenediamine and salicylaldehyde, followed by treatment with an ethanolic solution of palladium chloride. The as-prepared catalyst was found to be air and moisture-stable and to have significant catalytic activity in Suzuki–Miyaura reactions under mild operating conditions. Various phenyl halides were coupled with phenylboronic acid in aqueous ethanol, under air, to afford the corresponding cross-coupled products in good yields. Furthermore, the catalyst can be easily recovered by simple filtration and reused for up to five cycles without losing its activity.     

Application of multi-way analysis to UV–visible spectroscopy,gas chromatography and electronic nose data for wine ageing evaluation

In this study, a multi-way method (Tucker3) was applied to evaluate the performance of an electronic nose for following the ageing of red wines. The odour evaluation carried out with the electronic nose was combined with the quantitative analysis of volatile composition performed by GC–MS, and colour characterisation by UV–visible spectroscopy. Thanks to Tucker3, it was possible to understand connections among data obtained from these three different systems and to estimate the effect of different sources of variability on wine evaluation. In particular, the application of Tucker3 supplied a global visualisation of data structure, which was very informative to understand relationships between sensors responses and chemical composition of wines. The results obtained indicate that the analytical methods employed are useful tools to follow the wine ageing process, to differentiate wine samples according to ageing type (either in barrel or in stainless steel tanks with the addition of small oak wood pieces) and to the origin (French or American) of the oak wood. Finally, it was possible to designate the volatile compounds which play a major role in such a characterisation.     

Synthesis,antifungal activity and 3D-QSAR study of novel nopol-based 1,3,4-thiadiazole–thioether compounds

Research on Chemical Intermediates - A series of novel nopol derivatives containing 1,3,4-thiadiazole–thioether moiety were synthesized from β-pinene, which is a natural, abundant and...     

Synthesis and evaluation of antiviral activity of 2′-deoxyuridines with 5-methylene-2-thiohydantoin substituents in the 5-position

Summary 1-(2-Deoxy-3,5-bis-O-(4-methylbenzoyl)-D-erythro-pentofuranosyl)-5-formyluracil (4) was synthesized from 5-formyluracil and an appropriate methyl glycoside and condensed with 2-thiohydantoin (5a) and its corresponding 3-phenyl derivative5b to give 5-[1-(2-deoxy-3,5-bis-O-(4-methylbenzoyl)-D-erythro-pentofuranosyl)uracil-5-ylmethylene]-2-thiohydantoins7a and7b, respectively, in 65–70% yield. They were deprotected with sodium methoxide in methanol to give both anomers of the free nucleosides. In a different route 5-formyluracil (1) was condensed with5b and subsequently with an appropriate methyl glycoside to give7b.On leave from Chemistry Department, Faculties of Science and Education, Tanta University, Tanta, Egypt     

Synthesis and anti-α-glucosidase activity evaluation of betulinic acid derivatives

In this article, a series of betulinic acid derivatives (3a ～ 3u, 4a ～ 4e) were synthesized through a stepwise structure optimization and evaluated for their anti-α-glucosidase activities. All synthesized derivatives exhibited stronger anti-α-glucosidase activities (IC₅₀: 0.56 ± 0.05 ～ 3.99 ± 0.23 μM) than betulinic acid (IC₅₀: 7.21 ± 0.58 μM) and acarbose (IC₅₀: 611.45 ± 15.51 μM). Compound 3q presented the outstanding inhibitory activity (IC₅₀: 0.56 ± 0.05 μM), which was ～ 1100 time stronger than that of acarbose. Compound 3q was revealed as a reversible and noncompetitive α-glucosidase inhibitor by inhibitory mechanism assay. Fluorescence spectra, 3D fluorescence and CD spectra results showed that the interaction of compound 3q with α-glucosidase caused the conformational and secondary structure content change of α-glucosidase. Finally, the molecular docking simulated the interaction between compound 3q with α-glucosidase and the physicochemical parameter was assessed using SwissADME software.     

Synthesis, spectral and structural characterisation of ditelluroxanes: μ-oxo-bis[nitrato-; 2,4,6-trinitrophenolato-dialkyl tellurium (IV)]

The synthesis of ditelluroxanes: μ-oxo-bis[nitrato dimethyl tellurium (IV)] [(CH₃)₂TeNO₃]₂O (1), μ-oxo-bis[(2,4,6-trinitro)phenolato dimethyl tellurium (IV)] [(CH₃)₂TeOC₆H₂(NO₂)₃]₂O (2) and μ-oxo-bis[1-(2,4,6-trinitro)phenolato-1,1,2,3,4,5-hexahydrotellurophene] [C₄H₈TeOC₆H₂(NO₂)₃]₂O (3) was achieved. 1 was synthesised by the reaction of (CH₃)₂TeI₂ with fuming HNO₃ while 2 and 3 were synthesised by the reactions of R₂Te(OH)₂ [R₂ = (CH₃)₂, (C₄H₈)] (in situ) with 2,4,6-trinitrophenol [ 2,4,6-(NO₂)₃C₆H₂OH] (picric acid). 1-3 have been investigated through UV/Vis; FT-IR, (¹H, ¹³C) NMR spectroscopy and single crystal X-ray diffraction studies. In 1-3 the immediate coordination geometry about the central tellurium atom can be described as pseudo trigonal bipyramidal and the stereochemically active electron lone pair occupying equatorial position. The supramolecular self-organisations of these tetraorgano ditelluroxanes (1-3) are explained through cooperative participation of Te?O secondary bonds, C-H?O hydrogen bonds and π-stacking of the organic substituents.