Kinetics of oxidation of phenylhydrazine by a μ-oxo diiron(III,III) complex in acidic aqueous media

Phenylhydrazine (R) quantitatively reduces [Fe₂(μ-O)(phen)₄(H₂O)₂]⁴⁺ (1) (phen?=?1,10-phenanthroline) and its conjugate base [Fe₂(μ-O)(phen)₄(H₂O)(OH)]³⁺ (2) to [Fe(phen)₃]²⁺ in presence of excess 1,10-phenanthroline in the pH range 4.12–5.55. Oxidation products of phenylhydrazine are dinitrogen and phenol. The reaction proceeds through two parallel paths: 1?+?R?→?products (k ₁), 2?+?R?→?products (k ₂); neither RH⁺ nor the doubly deprotonated conjugate base of the oxidant, [Fe₂(μ-O)(phen)₄(OH)₂]²⁺ (3) is kinetically reactive though both are present in the reaction media. At 25.0°C, I?=?1.0?M (NaNO₃), the rate constants are k ₁?=?425?±?10?M^?1?s^?1 and k ₂?=?103?±?5?M^?1?s^?1. An inner-sphere, one-electron, rate-limiting step is proposed.     

Characterisation and quantification of liposome-type nanoparticles in a beverage matrix using hydrodynamic chromatography and MALDI–TOF mass spectrometry

This paper describes the characterisation of liposome-type nanoparticles (NPs) dispersed in a beverage matrix. Characterisation is based on a two-step procedure: first, liposomes are separated on the basis of size in the nanometre range by use of hydrodynamic chromatography (HDC); second, chemical characterisation is performed by use of MALDI–TOF mass spectrometry (MS). Characterisation of three types of Coatsome liposome, a commercially available type of empty liposome, was investigated. All three liposome types, Coatsome A?=?anionic, N?=?neutral, and C?=?cationic, gave single peaks in HDC, reflecting diameters of 153, 187, and 205 nm, respectively. Subsequent MALDI–TOF MS in positive mode furnished major signals at m/z?=?734.5 ([M?+?H]⁺ adduct) and m/z?=?756.6 ([M?+?Na]⁺ adduct) of l-(α)-dipalmitoylphosphatidylcholine (DPPC) monomer and dimeric adducts at m/z?=?1468.1 and m/z?=?1490.1, respectively. MALDI–TOF MS in negative mode gave a signal at m/z?=?721.3 ([M???H]^? adduct) of l-(α)-dipalmitoylphosphatidylglycerol (DPPG), except for Coatsome C which lacks this phospholipid. After HDC separation of Coatsome A NPs the major DPPC and DPPG signals can be detected in the expected fractions by use of MALDI–TOF MS in positive and negative modes, respectively. Validation of the analytical strategy revealed linearity (R ²?>?0.99), repeatability (relative standard deviation <10 %), and reproducibility (relative standard deviation between days <10 %) were good, recovery was 61?±?5 %, and the limit of quantification was 1 mg?mL^?1 in this matrix. With 4 mg Coatsome A mL^?1 20 out of 20 samples furnished the 734.5 and 756.6 signals typical of DPPC in MALDI–TOF MS characterisation.     

Anti-glycating and anti-oxidant compounds from traditionally used anti-diabetic plant Geigeria alata(DC) Oliv. & Hiern.

Abstract

A new sesquiterpene lactone geigerianoloide (1) and four known flavonoids axillarin (2), quercetin (3), 3-methoxy-5,7,3',4'-tetrahydroxy-flavone (4) and hispidulin (5) were isolated from Geigeria alata (DC) Oliv. & Hiern. (Asteraceae). Structures were deduced using ¹H- and ¹³C- NMR spectroscopy, mass spectrometry, while the structure of compound 1 was also deduced using X-ray crystallography technique.

Geigeria alata is traditionally used for diabetes, therefore compounds were tested for anti-glycation activity, in which compounds 2 and 3 showed potent activities (IC₅₀ values of 246.97?±?0.83 and 262.37?±?0.22 µM, respectively) compared to IC₅₀ value 294.50?±?1.5 µM of rutin. Moreover, compound 4 exhibited a comparable activity to rutin (IC₅₀?=?293.28?±?1.34 µM). Compound 5 showed a weak activity.

Compounds 2, 3, and 4 exhibited potent DPPH radical scavenging activity (IC₅₀?=?0.1?±?0.00, 0.13?±?0.00 and 0.15?±?0.01 µM, respectively). Compounds 2, 3, and 4 demonstrated significant superoxide anion scavenging activity with IC₅₀ values of 0.14?±?0.001, 0.17?±?0.00, and 0.11?±?0.006 µM, respectively.     

Synthesis of new bicarbazole-linked triazoles as non-cytotoxic reactive oxygen species (ROS) inhibitors

Abstract

Carbazole analogs 3 and 4 and a new library of bicarbazole-linked triazoles 6–11 were prepared via new synthetic methodology. Metal-catalyzed oxidative coupling reaction was utilized for the synthesis of bicarbazole acetylene 4 and different metals (Zn⁺², Co⁺², Fe⁺³, Ni⁺², Cu⁺², Mn⁺²) as catalyst were screened. Only Fe-catalyzed reaction was found to be excellent and gave homocoupled product 4. Cu-catalyzed 1,3-dipolar cycloaddition was also utilized to install triazole moiety for the synthesis of hybrid molecules 6–11. Based on reported anti-inflammatory activity of carbazole and triazole scaffolds, all compounds were screened for their reactive oxygen species (ROS) inhibitory potential. Results from these studies revealed triazole 9 as most active compound (IC₅₀ value of 7.6?±?0.1?µg/mL on human whole blood and 2.7?±?0.09?µg/mL on isolated neutrophils) using ibuprofen as a standard. Therefore, class described herein can serve as attractive structural element for further studies on ROS inhibition.     

1,2-Benzisoxazole-3-acetamide derivatives as dual agents for DPP-IV inhibition and anticancer activity

Abstract

Herein, we have designed various benzisoxazole acetamide derivatives with and without glycine spacer as DPP-IV inhibitors. Compounds 9a–d and 11a–e were synthesized and screened for their in vitro DPP-IV inhibition. Compounds 11a and 11c showed moderate activity for DPP-IV inhibition, whereas other remained inactive at 25–200?µM concentrations. DPP-IV inhibition can be a good strategy for modulating diabetes and cancer; hence, we have screened compounds 9a–d and 11a–e for their anticancer activity using MTT assay against A549 and MCF7 cell lines. Compounds 9a–d without glycine spacer have shown good anticancer activity compared to compounds 11a–e with glycine spacer. Compound 9b has shown moderate activity with IC₅₀ values 4.72?±?0.72 and 4.39?±?0.809?µM against A549 and MCF7 cell lines, respectively. Interestingly, compound 9c with cyano group has shown very good anticancer activity with IC₅₀ 2.36?±?0.34?µM against MCF7 cell line as compared to fluorouracil with IC₅₀ 45.04?±?1.02?µM.     

Synthesis of spirooxindoles promoted by the deep eutectic solvent,ZnCl2+urea via the pseudo four-component reaction: anticancer,antioxidant, and molecular docking studies

Abstract

Various spirooxindoles (7a–c, 8a–c, 9a–c, and 10a–c) were efficiently synthesized using deep eutectic solvent ZnCl₂+urea and well characterized using IR, ¹H NMR, and ¹³C NMR spectroscopic techniques. The biological screening results showed that the compound 9a exhibited potent anticancer activity against MCF7 and HeLa cell lines with IC₅₀ values 6.47?±?0.01 and 9.14?±?0.32?µM, respectively. The compound 7c exhibited potent activity against the HeLa cell line with IC₅₀ value 6.81?±?0.01?µM. The compound 9a exhibited a potent antioxidant activity with IC₅₀ value 7.34?±?0.17?µM. The comparative molecular docking study against the cancer proteins EGFR and HER2 revealed that the EGFR was the best target protein receptor for the target compounds. Among all the compounds, the compound 9a exhibited the least binding energy ?10.72?kcal/mol against the protein EGFR (PDB ID: 4HJO).     

Combustion-synthesized sodium manganese (cobalt) oxides as cathodes for sodium ion batteries

We report on the electrochemical properties of layered manganese oxides, with and without cobalt substituents, as cathodes in sodium ion batteries. We fabricated sub-micrometre-sized particles of Na_0.7MnO_2?+?z and Na_0.7Co_0.11Mn_0.89O_2?+?z via combustion synthesis. X-ray diffraction revealed the same layered hexagonal P2-type bronze structure with high crystallinity for both materials. Potentiostatic and galvanostatic charge/discharge cycles in the range 1.5–3.8 V vs. Na | Na⁺ were performed to identify potential-dependent phase transitions, capacity, and capacity retention. After charging to 3.8 V, both materials had an initial discharge capacity of 138 mA?h?g^?1 at a rate of 0.3 C. For the 20th cycle, those values reduced to 75 and 92 mA?h?g^?1 for Co-free and Co-doped samples, respectively. Our findings indicate that earlier works probably underestimated the potential of (doped) P2-type Na_0.7MnO_2?+?z as cathode material for sodium ion batteries in terms of capacity and cycle stability. Apart from doping, a simple optimization parameter seems to be the particle size of the active material.     

Cuprous complexes and dioxygen,VII. Competition between one- and two-electron reduction of O2 in the autoxidation of Cu(1-methyl-2-hydroxymethyl-imidazole)2+

The complexation of 1-methyl-2-hydroxymethyl-imidazole (L) with Cu(I) and Cu(II) has been studied in aqueous acetonitrile (AN). Cu(I) forms three complexes, Cu(AN)L⁺, CuL₂⁺, and Cu(AN)H_?1L, with stability constants logK(Cu(AN)⁺ + L ? Cu(AN)L⁺) = 4.60 ± 0.02, logβ₂ = 11.31 ± 0.04, and logK(Cu(AN)H_?1L+H⁺ ? Cu(AN)L⁺) = 10.43 ± 0.08 in 0.15M AN. The main species for Cu(II) are CuL²⁺, CuH_?1L⁺, CuH_?1L₂⁺, and CuH_?2L₂. The autoxidation of CuL₂⁺ was followed with an oxygen sensor and spectrophotometrically. Competition between the formation of superoxide in a one-electron reduction of O₂ and a path leading to H₂O₂ via binuclear (CuL₂)₂O was inferred from the rate law with k_a = (2.31 ± 0.12) · 10⁴M ^?2S ^?1, k_b = (1.0 ± 0.2) · 10³M ^?1, k_c = (2.85 ± 0.07) · 10²M ^?2S ^?1, k_d = 3.89 ± 0.14M ^?1S ^?1, k_e = 0.112 ± 0.004, k_f = (2.06 ± 0.24) · 10^?10M S ^?1, k_g = (1.35 ± 0.07) · 10^?7 S ^?1, and k_h = (6.8 ± 1.4) · 10^?7M ^?1 S ^?1.     

Synthesis and monoamine oxidase A/B inhibitory evaluation of new benzothiazole-thiazolylhydrazine derivatives

Abstract

In this study, a novel series of benzothiazole-thiazolylhydrazine (3a–3i) was synthesized and their structures were characterized by ¹H-NMR, ¹³C-NMR spectrometry, and mass spectroscopy. These compounds were evaluated as inhibitors of type A and type B monoamine oxidase (MAO) enzymes. The most active compound 3b (2-((2-(2-(4-(4-Nitrophenyl)thiazol-2-yl)hydrazineylidene)-2-phenylethyl)thio)benzothiazole) showed strong inhibitory activity at hMAO-A (IC₅₀ of 0.095?±?0.004?µM). Furthermore, compound 3i (2-((2-(2-(4-(2,4-dichlorophenyl)thiazol-2-yl)hydrazineylidene)-2-phenylethyl)thio)benzothiazole) showed significant inhibition profile on hMAO-A with the IC₅₀ values 0.141?±?0.006?µM.     

Acute kidney injury caused by the intraperitoneal injection of Bothrops jararaca venom in rats

Abstract

We examined the ability of Bothrops jararaca venom (12.5?mg/kg) injected intraperitoneally (i.p.) to cause acute kidney injury (AKI) in rats. Blood urea and creatinine (AKI biomarkers, in g dL^?1) were elevated after 2?h in venom-treated rats (urea: from 0.41?±?0.1 to 0.7?±?0.03; creatinine from 46.7?±?3.1 to 85?±?6.7; p?<?0.05; n?=?3 each), with no change in circulating reduced glutathione. Venom-treated rats survived for ～6?h, at which point platelets were reduced (×10³ µL^?1; from 763.8?±?30.2 to 52.5?±?18.2) whereas leukocytes and erythrocytes were slightly increased (from 4.7?±?0.3 to 6.6?±?0.1?×?10³?µL^?1 and from 8.38?±?0.1 to 9.2?±?0.09?×?10⁶?µL^?1, respectively; p?<?0.05); blood protein (5.2?±?0.4?g dL^?1) and albumin (2.7?±?0.1?g dL^?1) were normal, whereas blood and urinary urea and creatinine were increased. All parameters returned to normal with antivenom given 2?h post-envenomation. The i.p. injection of venom caused AKI similar to that seen with other routes of administration.     

Synthesis,EGFR-TK inhibition and anticancer activity of new quinoxaline derivatives

Abstract

Ethyl 4-substituted-3-oxo-quinoxaline-2-carboxylates 3–5 were obtained via alkylation of ethyl 3-oxo-3,4-dihydroquinoxaline-2-carboxylate (1). Compound 1 was heterocyclized using hydrazines, ethylenediamine, and ethanolamine to give pyrazoloquinoxalines 6, 7, diazepinoquinoxaline 8, and oxazepinoquinoxaline 10. The quinoxaline-2-carboxamides 9, 11, 12 were prepared via condensation of compound 1 with different amines. Compound 1 was thiated using Lawesson’s reagent affording quinoxaline-3-thione 13, in fair yield. In addition, the reaction of 4-methyl-3-oxoquinoxaline 3 with some binucleophiles led to a series of new oxoquinoxaline derivatives 14–18. The molecular structure of compounds 1, 3, and 9 was confirmed by X-ray crystallography.

The anti-proliferative activity showed that among all the tested compounds, compounds 3, (IC₅₀ 2.51?±?3.0, 4.22?±?1.6 and 2.27?±?1.9?µM), 11 (IC₅₀ 1.32?±?2.61, 1.41?±?1.23 and 1.18?±?1.91?µM) and 17 (IC₅₀ 1.72?±?1.32, 1.85?±?0.94 and 1.92?±?4.83?µM) showed noteworthy anti-proliferative effects against the three cancer cell lines, HCT116, HePG2 and MCF7, respectively, compared to the reference drugs doxorubicin (IC₅₀ 1.41?±?0.58, 0.90?±?0.62 and 1.01?±?3.02?µM) and erlotinib (IC₅₀ 1.63?±?0.81, 1.57?±?0.62 and 1.49?±?0.54?µM). Compounds 3 (0.899?nM), 11 (0.508?nM) and 17 (0.807) showed strong EGFR inhibitory activity compared to Erlotinib (0.439?nM) and these results are in agreement with the docking study. These results suggest that compounds could probably be promising anticancer agents with EGFR inhibitory activity.     

12α-hydroxy-N-demethyl-sauroxine,a lycodane type alkaloid from Phlegmariurus saururus

Abstract

12α-hydroxy-N-demethyl-sauroxine (1), another new Lycopodium alkaloid from the Lycodane group, was isolated from Phlegmariurus saururus (Lam.) B. Øllg. (Lycopodiaceae). Elucidation of the chemical structure and relative stereochemistry were stated by spectroscopic data and chemical correlation. In addition, the inhibitory activity on acetylcholinesterase for 1 was determined as well as for N-methyllycodine (2), a derivative with the same nucleus, previously identified in P. saururus (IC₅₀ = 33.8?±?0.8?μM and 547.5?±?0.5?μM, respectively) and N-demethylsauroxine (3) whose inhibition in the actual conditions was better than the previously informed.     

Design and synthesis of fluorescent symmetric bis-triazolylated-1,4-dihydropyridines as potent antibreast cancer agents

Herein, we report the synthesis of fluorescent 1,4-dihydropyridine-linked bis-triazoles (2a–2n) through Hantzsch synthesis by the condensation of o/m-chloro-substituted benzaldehyde, ethyl 3-oxo-4(prop-2-yn-1-yloxy)butanoate, and ammonium acetate in the presence of Ba(NO₃)₂ as a catalyst followed by the click reaction of resultant Hantzsch product (1) with various aromatic as well as aliphatic azides. All the synthesized compounds were well characterized by ¹H-NMR, ¹³C-NMR, FTIR, and HRMS spectral techniques. Antibreast cancer evaluation of all the synthesized derivatives revealed that the compounds 2f (IC₅₀?=?7?±?0.02?µM) and 2g (IC₅₀?=?5?±?0.03?µM) showed better anticancer activity (lower IC₅₀) than the standard drug tamoxifen (IC₅₀?=?11.2?±?0.01?µM) against breast carcinoma (MDA-MB-231) cell line. The synthesized compounds were also screened against normal human embryonic kidney (HEK-293) cell line and found to be nontoxic. The fluorescent nature and cytotoxicity assay of these newly synthesized hybrids recommend their utility in tumor cell imaging.     

Kinetics and mechanism of the reduction of monochloramine by hydroxylamine and hydroxylammonium ion

The kinetics and mechanism by which monochloramine is reduced by hydroxylamine in aqueous solution over the pH range of 5–8 are reported. The reaction proceeds via two different mechanisms depending upon whether the hydroxylamine is protonated or unprotonated. When the hydroxylamine is protonated, the reaction stoichiometry is 1:1. The reaction stoichiometry becomes 3:1 (hydroxylamine:monochloramine) when the hydroxylamine is unprotonated. The principle products under both conditions are Cl^–, NH⁺₄, and N₂O. The rate law is given by ?[d[NH₂Cl]/dt] = k₊[NH₃OH⁺][NH₂Cl] + k₀[NH₂OH][NH₂Cl]. At an ionic strength of 1.2 M, at 25°C, and under pseudo‐first‐order conditions, k₊= (1.03 ± 0.06) ×10³ L · mol^?1 · s^?1 and k₀=91 ± 15 L · mol^?1 · s^?1. Isotopic studies demonstrate that both nitrogen atoms in the N₂O come from the NH₂OH/NH₃OH⁺. Activation parameters for the reaction determined at pH 5.1 and 8.0 at an ionic strength of 1.2 M were found to be ΔH? = 36 ± 3 kJ · mol^–1 and Δ S? = ?66 ± 9 J · K^?1 · mol^?1, and Δ H? = 12 ± 2 kJ · mol^?1 and Δ S? = ?168 ± 6 J · K^?1 · mol^?1, respectively, and confirm that the transition states are significantly different for the two reaction pathways. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 38: 124–135, 2006     

Monooxovanadium(V) 2-phenylphenoxides: synthesis,characterization, and antimicrobial potential

Monooxovanadium(V) complexes of the composition VOCl_{3? n} (L) _n (where L = 2-phenylphenoxide ion; n = 1–3) (1–3) have been synthesized in quantitative yields by the reaction of VOCl₃ with 2-phenylphenol in toluene. The characterization of the complexes has been accomplished by elemental analysis, molar conductance measurements, IR, ¹H-NMR, electronic, mass spectral, and thermal studies. The ligands as well as the complexes have been screened for their in vitro antimicrobial activity against the pathogenic bacteria Escherichia coli and Staphylococcus aureus and fungi Candida albicans, Aspergillus niger, and Fusarium oxysporum by a twofold serial dilution. An increase in the biocidal activity was observed for the vanadium complexes. The minimum inhibitory concentration (MIC) values were 6.25–25 µg mL^?1 for complexes, relative to that of the free ligand of 25–50 µg mL^?1.     

Ionophores in Rubidium Ion‐Selective Membrane Electrodes

Binaphthyl‐based crown ethers incorporating anthraquinone, benzoquinone, and 1,4‐dimethoxybezene have been synthesized and tested for Rb⁺ selective ionophores in the poly(vinyl chloride) (PVC) membrane. The membrane containing NPOE gave a better Rb⁺ selectivity than those containing either DOA or BPPA as a plasticizer. The response was linear within the concentration range of 1.0×10^?5–1.0×10^?1 M and the slope was 54.7±0.5 mV/dec. The detection limit was determined to be 9.0×10^?6 M and the optimum pH range of the membrane was 6.0–9.0. The ISE membrane exhibits good selectivity for Rb⁺ over ammonium, alkali metal, and alkaline earth metal ions. Selectivity coefficients for the other metal ions, log K^Pot were ?2.5 for Li⁺, ?2.4 for Na⁺, ?2.0 for H⁺, ?1.0 for K⁺, ?1.2 for Cs⁺, ?1.6 for NH₄⁺, ?4.5 for Mg²⁺, ?5.0 for Ca²⁺,?4.9 for Ba²⁺. The lifetime of the membrane was about one month.     

Simultaneous Determination Baicalin and Forsythin in Shuanghuanglian Oral Liquid by HPLC/DAD and LC‐ESI‐MS

Rapid, simple and reliable HPLC/DAD and LC‐ESI‐MS methods for the simultaneous determination of baicalin and forsythin in the traditional Chinese medicinal preparation Shuanghuanglian oral liquid were described and validated. The separation condition for HPLC/DAD was optimized using a BDS hypersil C18 column (Thermo, 2.1 × 150 mm, particle size 5 μm) by gradient elution using methanol‐0.2 % ammonium acetate as the mobile phase. The suitable detection wavelength was set at 277 nm for the quantitative analysis of baicalin and forsythin in this method. Some operational parameters of the ESI interface were optimized, negative m/z 445[M?H]^? for baicalin and negative m/z 593[M+CH₃COO]^? for forsythin, positive m/z 447[M+H]⁺ for baicalin and positive m/z 552[M+NH 4]⁺ for forsythin, respectively. These HPLC/DAD and LC‐ESI‐MS methods were validated in terms of recovery, linearity, accuracy and precision (intra‐ and inter‐day validation). These methods can be used as a complementary method for the commercial quality control of Shuanghuanglian oral liquid and its pharmaceutical preparations.     

THE EPR SPECTRA OF TETRADENTATE SCHIFF BASE COMPLEXES OF COPPER (II) II. N,N'-bis(salicylidene)ethylenediimine and 7-methyl-N,N'-bis (salicylidene)ethylenediimine

Abstract

The EPR spectra of single crystals of ⁶³Cu(II) doped N, N'-bis(salicylidene)ethylenediimine Ni(II), [Ni(sal)₂en] and 7-methyl-N, N'-bis(salicylidene)ethylenediimine Ni(II), [Ni(7-me sal)₂en] have been studied. The usual doublet spin-Hamiltonian parameters for the complexes have been found to be: Cu(II)[(sal)₂en]; g _z =2.192 ± 0.002; g _x =2.046 ± 0.004; g _y =2.049 ± 0.004; A _z =201.0 × 10^?4 cm^?1; A _x =29.3 × 10^?4 cm^?1; A _y =31.3 × 10^?4 cm^?1; A^N _z =12.6 × 10^?4 cm^?1; A ^N _x =14.5 × 10^?4 cm^?1; A ^N _y =15.7 × 10^?4 cm^?1; A ^H _z =6.3 × 10^?4 cm^?1; A ^H _x =7.3 × 10^?4 cm^?1; A ^H _y =7.9 × 10^?4 cm^?1; Cu(II)[(7-me sal)₂en]; g _z =2.189 ± 0.002; g _x =2.037 ± 0.004; g _y =2.046 ± 0.004; A _z =203.0 × 10^?4 cm^?1; A _x =36.9 × 10^?4 cm^?1; A _y =22.7 × 10^?4 cm^?1; A ^N _z =12.6 × 10^?4 cm^?1; A ^N _x =13.3 × 10^?4 cm^?1; A ^N _y =14.0 × 10^?4 cm^?1. Values of molecular orbital coefficients calculated for these complexes show that their bonding properties are similar to those of other compounds of this type. There is considerable covalency in the metal-ligand [sgrave]-bonds, and significant in-plane pi-bonding is present.     

Preparation and structural characterization of oxovanadium(V) complexes with Schiff bases and their inhibition studies on Helicobacter pylori urease

A series of structurally similar dinuclear oxovanadium(V) complexes, [VO₂L]₂ (L?=?L¹?=?2-[(2-methylaminoethylimino)methyl]phenolate (1); L?=?L²?=?2-[(2-ethylaminoethylimino)methyl]phenolate (2); L?=?L³?=?2-[(2-isopropylaminoethylimino)methyl]phenolate (3)), has been synthesized and characterized by physico-chemical methods and single-crystal X-ray diffraction. The V in each complex is octahedral, with three donors of L and one oxo defining the equatorial plane, and with two oxos occupying the axial positions. The complexes were tested for their urease inhibitory activities. The inhibition rate (%) of 1, 2, and 3 at 100?µmol?L^?1 on urease are 67?±?1, 53.5?±?0.9, and 44?±?1. The relationship between structures of the complexes and the urease inhibitory activities indicates that shorter terminal groups of the complexes have stronger activities against urease. Molecular docking study of the complexes with the Helicobacter pylori urease was performed.     

The ortho effect in the mass spectra of ortho/para isomers of bisphenol a derivatives and related compounds

New examples of the ortho effect in bisphenol A derivatives including interaction of the hydrogen of the ortho-hydroxy group with the neighbouring aromatic ring have been observed. The characteristic ions [M ? PhOH]^+middot; (m/z = 134) and [M ? CH₃ ? PhOH]⁺ (m/z = 119) were shown to form through the hydrogen transfer from hydroxy and isopropyl groups, respectively. The spectra of cyclic derivatives having ortho-hydroxy functions show [M ? 43]⁺, [M ? C₈H₉O]⁺, m/z = 147, m/z = 135 and [M ? C₉H₁₀O]⁺ ions. The proposed mechanims of the corresponding transformations were supported by mass spectra of deuterated analogues, methyl and trimethyl silyl ethers.