Studies on Cage Compounds. Synthesis of 8,11-Diazenediyl-4,4-Dimethoxy-2,3,5,6-Tetrachloropentacyclo[5.4.0.02,5.03,10.05,9]Undecane

The title compound ( 7 ) was synthesized in six steps from 1,8,9,10-tetrachloro-11,11-dimethoxy-endo-tricyclo[6.2.1.0^2,7]undeca-4,9-diene-3,6-dione ( 4 ) in an overall yield of 36%. The key intermediate, 1,8,9,10-tetrachloro-11,11-dimethoxy-endo-tricyclo-[6.2.1.0^2,7]undeca-3,5,9-triene ( 12 ), obtained from 4 by reduction, mesylation and then 1,4-elimination, was allowed to react with diethyl azodicarboxylate to afford the Diels-Alder adduct 16 . Photochemical closure of 16 , followed by hydrolysis and decarboxylation, gave the title compound. The title compound failed to give either the homopentaprismanone derivative 3 or the diene 9 by the photochemical or thermal elimination of molecular nitrogen.     

New Lignans from the Roots of Taiwania cryptomerioides Hayata

The five new lignans designated 3′,4′‐de‐O‐methylenehinokinin ( 1 ), taiwaninolide ( 2 ), 8′‐hydroxysavinin ( 3 ), isoguamarol ( 4 ), and 4′‐O‐methylsalicifolin ( 5 ), as well as the new 4‐(3,4‐dimethoxybenzyl)dihydro‐3‐(4‐hydroxybenzyl)furan‐2(3H)‐one ( 6 ) were isolated from the roots of Taiwania cryptomerioides, besides the three known compounds hinokinin ( 8 ), savinin ( 9 ), and 3,4‐de‐O‐methylenehinokinin ( 7 ). The structures of the new constituents were elucidated through chemical and spectral studies. A compound previously isolated from the heartwood of Chamaecyparis obtusa var. formosana was assigned structure 1 ; however, this structure has now been revised to be 3,4‐de‐O‐methylenehinokinin ( 7 ).     

Adsorption of Cr(III) from wastewater by wine processing waste sludge

Wine processing waste sludge has been shown to be an effective adsorbent for the adsorption of Cr(III) from aqueous solution. The sludge has been characterized by scanning electron microscopy (SEM) and energy dispersive X-rays (EDX). The effect of pH, initial concentration of Cr(III), sludge particle size, and temperature on the adsorption studied. The equilibrium data could be described well by the Langmuir and Freundlich isotherm equations. A separation factor was used to judge the favorable adsorption. The calculated thermodynamic parameters, deltaH0 and deltaS0, are 1.95 kJ/mol and 27.16 J/molK, respectively. The deltaG0 values range from -5.98 to -6.79 J/mol, which shows the physical adsorption properties of the sludge. Adsorption dynamics had been successfully studied by the Lagergren model and an intraparticle diffusion model.     

Studies of the triplet state of the proton-transfer tautomer in salicylaldehydes

The spectroscopy and dynamics of the low-lying triplet state of the proton-transfer tautomer in salicylaldehydes have been studied via internal heavy-atom effects coupled with a sensitive near-IR detecting system. For 3,5-diiodosalicylaldehyde a weak proton-transfer keto-tautomer phosphorescence was resolved with a maximum at 710 nm (τ_p1.8 μs, Φ_obs5.23×10⁻⁴) in a 77 K methylcyclohexane glass. The results, in combination with the time-resolved thermal lensing experiment, further deduced the triplet-state population yield and radiative decay rate to be 0.20 (298 K) and 3.12×10² s⁻¹, respectively. Consequently, the energetics and dynamics of the triplet states during a proton transfer cycle are discussed in detail.     

Clay-catalyzed reactions of coagulant polymers during water chlorination

The influence of suspended clay/solid particles on organic–coagulant reactions during water chlorination was investigated by analyses of total product formation potential (TPFP) and disinfection by-product (DBP) distribution as a function of exchanged clay cation, coagulant organic polymer, and reaction time. Montmorillonite clays appeared to act as a catalytic center where the reaction between adsorbed polymer and disinfectant (chlorine) was mediated closely by the exchanged clay cation. The transition-metal cations in clays catalyzed more effectively than other cations the reactions between a coagulant polymer and chlorine, forming a large number of volatile DBPs. The relative catalytic effects of clays/solids followed the order Ti-Mont > Fe-Mont > Cu-Mont > Mn-Mont > Ca-Mont > Na-Mont > quartz > talc. The effects of coagulant polymers on TPFP follow the order nonionic polymer > anionic polymer > cationic polymer. The catalytic role of the clay cation was further confirmed by the observed inhibition in DBP formation when strong chelating agents (o-phenanthroline and ethylenediamine) were added to the clay suspension. Moreover, in the presence of clays, total DBPs increased appreciably when either the reaction time or the amount of the added clay or coagulant polymer increased. For volatile DBPs, the formation of halogenated methanes was usually time-dependent, with chloroform and dichloromethane showing the greatest dependence.     

New Cadinane‐Type Sesquiterpenes from the Roots of Taiwania cryptomerioides Hayata

Six new cadinane‐type sesquiterpenes, (1β,4β,5α,10α)‐1,4‐epoxymuurolan‐5‐ol ( 1 ), (4α,10β)‐4,10‐dihydroxycadin‐1(6)‐en‐5‐one ( 2 ), (2β,3α,4β,6β)‐2,3‐dihydroxycadin‐1(10)‐en‐5‐one ( 3 ), (2β,3α)‐α‐corocalene‐2,3‐diol ( 4 ), (7S)‐α‐calacoren‐14‐ol ( 5 ), and (8β,9β,10β)‐8,9‐epoxycalamenene‐3,10‐diol ( 6 ) together with one known compound, (8β,9β,10β)‐8,9‐epoxycalamenen‐10‐ol ( 7 ), were isolated from the roots of Taiwania cryptomerioides. The structures of the new constituents were essentially elucidated by spectral evidence.     

Analysis of erythromycin in biological fluids by high-performance liquid chromatography with electrochemical detection

A simple and sensitive high-performance liquid chromatographic assay was developed for the quantitative determination of major erythromycin components and their potential metabolites or degradation products in plasma and urine. An ether extract of alkalized plasma sample was chromatographed on a reversed-phase column and the components in the column effluent were monitored by an electrochemical detector. The recovery of the drug from extraction was virtually 100%. The detection limits for erythromycin A in plasma were 5-10 ng/ml and 30 ng/ml using 1 and 0.2 ml of sample, respectively. For urine samples, a simple one-step deproteinization with two volumes of acetonitrile was satisfactory for analysis. The method has been evaluated in plasma and urine from dogs receiving oral or intravenous erythromycin A. The standard curves for potential metabolites or degradation products were not constructed due to the lack of sufficient samples.     

On-line stacking capillary electrophoresis for analysis of methotrexate and its eight metabolites in whole blood

Therapeutic drug monitoring of methotrexate (MTX) and its metabolites is significant for the evaluation of treatment response of acute lymphoblastic leukemia and the prevention of adverse effects. Those eight metabolites including 7-hydroxymethotrexate, MTX-polyglutamate derivatives (MTX-(Glu)(n), n=2-7), and 2,4-diamino-N(10)-methylpteroic acid, especially the MTX-(Glu)(n), only exist in blood cells and also present antifolate effects. Therefore, whole blood analysis has importance in clinical therapy. This study combined solid-phase extraction and on-line stacking capillary electrophoresis to examine the levels of MTX and its eight metabolites in whole blood. A higher conductivity buffer (HCB) was used to accumulate large amount of samples into a narrow zone, which resulted in effective stacking and sharp peaks. A fused-silica capillary was filled with phosphate buffer (80 mM, pH 2.5) containing 15% v/v tetrahydrofuran and 100 mM sodium dodecyl sulfate. Then HCB (100 mM phosphate, pH 2.5; 1 psi, 60 s) was injected for accumulating large volume of analytes (1 psi, 200 s). Owing to the pH difference between sample zone and HCB, dynamic pH junction was generated for focusing. Meanwhile, sweeping made further stacking by using sodium dodecyl sulfate in phosphate buffer. The limits of detection (S/N=3) were 0.1 microM for MTX, 0.2 microM for 7-hydroxymethotrexate and 2,4-diamino-N(10)-methylpteroic acid, 0.3 microM for MTX-(Glu)(n=2--5), and 0.5 microM for MTX-(Glu)(n=6--7). During validation, this method showed good linearity (r> / =0.9914) and reproducibility (relative standard deviation and relative error, both less than 13%). The applications were performed to monitor blood MTX and its metabolites in acute lymphoblastic leukemia patients. The blood concentrations could provide some information related to therapeutic response and adverse effects.     

Activation mechanisms of butyrylcholinesterase by 2,4,6-trinitrotoluene, 3,3-dimethylbutyl-N-n-butylcarbamate, and 2-trimethylsilyl-ethyl-N-n-butylcarbamate

The goal of this work was to propose a possible mechanism for the butyrylcholinesterase activation by 2,4,6-trinitrotoluene (TNT), 3,3-dimethylbutyl-N-n-butylcarbamate (1), and 2-trimethylsilyl-ethyl-N-n-butylcarbamate (2). Kinetically, TNT, and compounds 1 and 2 were characterized as the nonessential activators of butyrylcholinesterase. TNT, and compounds 1 and 2 were hydrophobic compounds and were proposed to bind to the hydrophobic activator binding site, which was located outside the active site gorge of the enzyme. The conformational change from a normal active site gorge to a more accessible active site gorge of the enzyme was proposed after binding of TNT, and compounds 1 and 2 to the activator binding site of the enzyme. Therefore, TNT, and compounds 1 and 2 may act as the excess of butyrylcholine in the substrate activator for the butyrylcholinesterase catalyzed reactions.