Toward the synthesis of macrolide aspergillide D

Stereoselective synthesis of 16-membered macrocyclic core of marine natural product, Aspergillide D is described using linear strategy. The salient features of this synthetic study include the Sharpless asymmetric kinetic resolution followed by regioselective ring-opening reaction of corresponding epoxide to establish the stereo centers and ring-closing metathesis (RCM) by Grubbs'-II catalyst for the construction of macrocyclic ring.     

Structural and ionic conductivity studies of solid polymer electrolytes based on poly (vinylchloride) and poly (methylmethacrylate) blends

Thin film of poly (vinylchloride) and poly (methylmethacrylate) blend polymer electrolytes plasticized with a combination of DBP and Li₂SO₄ salts have been prepared by solution casting technique. The prepared films were subjected to a.c. impedance measurements as a function of temperature ranging from 304–373 K. The maximum conductivity at 304 K was found to be 1.24 × 10⁻⁸ S·cm⁻¹ for PVC-PMMA-Li₂SO₄-DBP (7.5-17.5-5-70 mole-%). Temperature dependence studies on the ionic conductivity in the PVC-PMMA-Li₂SO₄-DBP system suggest that the ion conduction follows the Williams-Landel-Ferry (WLF) mechanism, which is further confirmed by Vogel-Tamman-Fulcher (VTF) plots. XRD, FTIR, SEM and thermal studies revealed complex formation in.     

Investigations on poly(methyl methacrylate)-poly(ethylene oxide) hybrid polymer electrolytes with dioctyl phthalate, dimethyl phthalate and diethyl phthalate as plasticizers

Plasticizers can be used to change the mechanical and electrical properties of polymer electrolytes by reducing the degree of crystallinity and lowering the glass transition temperature. The transport properties of gel-type ionic conducting membranes consisting of poly(ethylene oxide) (PEO), poly(methyl methacrylate) (PMMA), LiClO₄ and dioctyl phthalate, diethyl phthalate or dimethyl phthalate (DMP) are studied. The polymer films are characterized by X-ray diffraction, Fourier transform infrared and impedance spectroscopic studies. It is found that the addition of DMP as the plasticizer in the PEO-PMMA-LiClO₄ polymer complex favours an enhancement in ionic conductivity. The maximum conductivity value obtained for the solid polymer electrolyte film at 305 K is 3.529×10^{– 4} S cm^–1. Electronic Publication     

Ionic conductivity studies in composite solid polymer electrolytes based on methylmethacrylate

The preparation and characterization of composite polymer electrolytes of PMMA-LiClO₄-DMP for different concentrations of CeO₂ have been investigated. FTIR studies indicate complex formation between the polymer, salt and plasticizer. The electrical conductivity values measured by a.c. impedance spectroscopy are found to depend upon the CeO₂ concentration. The temperature dependence of the conductivity of the polymer films seems to obey the VTF relation. The conductivity values are presented and the results are discussed.     

In vivo metabolic investigation of silodosin using UHPLC–QTOF–MS/MS and in silico toxicological screening of its metabolites

Silodosin (SLD) is a novel α1‐adrenoceptor antagonist which has shown promising clinical efficacy and safety in patients with benign prostatic hyperplasia (BPH). However, lack of information about metabolism of SLD prompted us to investigate metabolic fate of SLD in rats. To identify in vivo metabolites of SLD, urine, feces and plasma were collected from Sprague–Dawley rats after its oral administration. The samples were prepared using an optimized sample preparation approach involving protein precipitation followed by solid‐phase extraction and then subjected to LC/HR‐MS/MS analysis. A total of 13 phase I and six phase II metabolites of SLD have been identified in rat urine which includes hydroxylated, N‐dealkylated, dehydrogenated, oxidative, glucosylated, glucuronide and N‐sulphated metabolites, which are also observed in feces. In plasma, only dehydrogenated, N‐dealkylated and unchanged SLD are observed. The structure elucidation of metabolites was done by fragmentation in MS/MS in combination with HRMS data. The potential toxicity profile of SLD and its metabolites were predicted using TOPKAT software and most of the metabolites were proposed to show a certain degree of skin sensitization and occular irritancy. Copyright © 2016 John Wiley & Sons, Ltd.     

Effect of mangiferin on benzo(a)pyrene induced lung carcinogenesis in experimental Swiss albino mice

The present study is an effort to identify a potent chemopreventive agent against cancer, in which oxidative stress plays an important causative role. The modulatory effect of mangiferin on mitochondrial lipid peroxidation (LPO), tricarboxylic acid (TCA) cycle key enzymes and electron transport chain complexes was investigated against lung carcinogenesis induced by benzo(a)pyrene (50 mg kg(-1) b/w orally) in Swiss albino mice. Decreased activities of electron transport chain complexes and TCA cycle key enzymes such as isocitrate dehydrogenase (ICDH), succinate dehydrogenase (SDH), malate dehydrogenase (MDH) and alpha-ketoglutarate dehydrogenase (alpha-KGDH), in lung cancer bearing animals were observed. Pre- and post-treatment with mangiferin (100 mg kg(-1) b/w orally) for 18 weeks, prevented the above biochemical changes, which were inclined towards normal control animal values. This study further confirms the chemopreventive and chemotherapeutic effect of mangiferin and these results are consistent with our hypothesis that mangiferin is a promising chemopreventive agent.     

Combination therapeutic effect of cisplatin along with Solanum trilobatum on benzo(a)pyrene induced experimental lung carcinogenesis

Lung cancer is one of the leading causes of cancer death in the world and is notoriously difficult to treat effectively. In the present study, male Swiss albino mice were divided into five groups of six animals each: group I animals received corn oil orally and served as a control; group II cancer-induced animals received benzo(a)pyrene (B[a]P) (50 mg kg(-1) bodyweight dissolved in corn oil, orally) twice weekly for four successive weeks; group III cancer-bearing animals (after 12 weeks of induction) were treated with cisplatin (6 mg kg(-1) bodyweight, i.p.) once weekly for 4 weeks; group IV cancer-bearing animals were treated with cisplatin along with Solanum trilobatum (300 mg kg(-1) bodyweight) orally once weekly for 4 weeks; and group V animals constituted the drug control treated with cisplatin along with S. trilobatum. The serum, lung and liver were investigated biochemically for aryl hydrocarbon hydroxylase, gamma-glutamyl transpeptidase, 5'-nucleotidase, lactate dehydrogenase (LDH) and protein-bound carbohydrate components (hexose, hexosamine and sialic acid). These enzyme activities were increased significantly in cancer-bearing animals compared with control animals. The elevation of these in cancer-bearing animals was indicative of the persistent deteriorating effect of B[a]P in cancer-bearing animals. Our data suggest that cisplatin, administered with S. trilobatum, may extend its chemotherapeutic effect through modulating protein-bound carbohydrate levels and marker enzymes, as they are indicators of cancer. The combination of cisplatin with S. trilobatum could effectively treat the B[a]P-induced lung cancer in mice by offering protection from reactive oxygen species damage and also by suppressing cell proliferation.     

Coordinatively Unsaturated Lanthanide(III) Helicates: Luminescence Sensors for Adenosine Monophosphate in Aqueous Media

Coordinatively unsaturated double‐stranded helicates [(H₂L)₂Eu₂(NO₃)₂(H₂O)₄](NO₃)₄, [(H₂L)₂Tb₂(H₂O)₆](NO₃)₆, and [(H₂L)₂Tb₂(H₂O)₆]Cl₆ (H₂L=butanedioicacid‐1,4‐bis[2‐(2‐pyridinylmethylene)hydrazide]) are easily obtained by self‐assembly from the ligand and the corresponding lanthanide(III) salts. The complexes are characterized by X‐ray crystallography showing the helical arrangement of the ligands. Co‐ligands at the metal ions can be easily substituted by appropriate anions. A specific luminescence response of AMP in presence of ADP, ATP, and other anions is observed. Specificity is assigned to the perfect size match of AMP to bridge the two metal centers and to replace quenching co‐ligands in the coordination sphere.     

Chemical bath deposition synthesis of sub-micron ZnS-coated polystyrene

The synthesis of ZnS-coated polystyrene composite colloids by the decomposition of thioacetamide in the presence of polystyrene seed particles and metal salt is presented. The chemical bath deposition technique incorporates poly(vinyl pyrrolidone) to inhibit particle aggregation during the synthesis so that core-shell particles with sizes in the low sub-micron range were achieved. The shell thickness was well controlled through the reaction time and core size. ZnS shells were composed of primary crystallites, approximately 5 nm in diameter, which had the zinc blend crystal structure. The porosity of the shells was between 12 and 19%. Accordingly, the effective refractive index of the particles varied between 1.73 and 1.98 at wavelengths above the optical absorption edge of ZnS. Ordered colloidal crystals were produced by convective assembly of the poly(sodium 4-styrenesulfonate) stabilized core-shell particles. Assemblies of ZnS shell-polystyrene core particles are photonic crystal materials which may have applications in optical computing and communications environments.     

Indium triflate and ionic liquid-mediated Friedländer synthesis of 2-acylquinolines

Friedländer synthesis of 2-acylquinolines from the reaction of symmetrical and unsymmetrical 1,2-diketones with 2-aminoarylketones in the presence of indium triflate (In(OTf)₃) and ionic liquid gives quantitative yields. Once the reaction was completed, the catalysts can be recovered and subsequently run for next cycles. Results obtained from theoretical studies have been more strengthened by FT-IR, FT-NMR chemical shifts, and structural parameters which were attained with B3LYP/6-31G(d,p) level of theory and the related results were demonstrated with the experimental interpretations.