Oral malodor,assessed by closed-loop,gas chromatography,and ion-trap technology

A method is described for the analysis of volatile organic compounds in saliva and tongue coating samples. The techniue is based on an off-line preconcentration step by means of a closed-loop trapping system followed by gas chromatography-ion trap detection. With the closed-loop technique, the volatile organic compounds(VOCs) are released from the matrix and trapped on an adsorbent without interference of water. The VOCs are released from the adsorbent into the gas chromatograph by thermdesorption. After separation, identification of the compounds is performed by ion trap technology. By this technique 82 compounds could be demonstrated in saliva and tongue coating samples. The technique is also used to demonstrate the formation of volatile bacterial fermentation compounds when a protein substrate is added to tongue coating samples. It is considered a very promising tool in further research on oral malodor.     

Synthesis, optical, and thermal properties of conjugated, bispyridyl and tetrapyridyl compounds by Knoevenagel reaction

A series of conjugated, bispyridyl and tetrapyridyl compounds were synthesized from either terephthalaldehyde or isophthalaldehyde and activated pyridyl compounds by Knoevenagel reaction on heating in acetic anhydride in presence of acetic acid and their optical and thermal properties were examined. All of them exhibited photoluminescence in chloroform, tetrahydrofuran, and dimethyl sulfoxide as well as in solid state. In solid state, their emission spectra exhibited bathochromic shifts when compared with those in less or more polar solvents. Some compounds emitted UV light both in polar solvents and in the solid state; other compounds emitted UV light in polar solvents, but emitted visible light in the solid state.     

Improving the accuracy of carbon-to-hydrogen ratio determination for P,N, S,O, Cl,and Br-containing organic compounds using atomic emission detection

The objective of this work was to investigate the dependence of atomic emission detector C and H response on microwave-induced plasma conditions and to improve the accuracy of carbon-to-hydrogen ratio determination for trialkylphosphates, herbicides, chlorophenols, and sulfur-containing organic compounds. Compounds which differed structurally from the analytes were used as reference compounds. It was found that when the oxygen concentration in the helium was the maximum for the instrument (9%) relative errors in carbon-to-hydrogen ratio determination were 3–8%, irrespective of analyte and reference compound structure, whereas when working in the mode of operation recommended by the manufacturer of the instrument (1.5% oxygen in helium) the respective errors were 10–20% or higher. This improvement in the accuracy of carbon-to-hydrogen ratio determination was accompanied by a factor of ten decrease in sensitivity.     

Cytotoxicity,tyrosine kinase inhibition of novel pyran,pyridine, thiophene,and imidazole derivatives

In this work, we are interested to use multicomponent reactions of cyclohexan-1,3-dione with different reagents for synthesizing new derivatives of pyran, pyridine, thiophene, and imidazole with antitumor activities. Twenty-two newly synthesized derivatives were selected and tested for their anticancer potency. Several of these compounds exhibited quite interesting potencies toward three human tumor cell lines, namely NCI-H460 (non-small cell lung cancer), SF-268 (CNS cancer), and MCF-7 (breast adenocarcinoma), especially when compared to that of reference drugs, doxorubicin and 5-Fu.Compounds 5b , 5c , 7b , 9b , 14a , 16c , 18a , 19c , 20b , and 22b , were found to be the most cytotoxic compounds toward the selected cell lines. On the other hand, 7b , 14a , 16c , 19c , and 22b revealed high inhibitions toward the tyrosine kinases. Active compounds against VEGFR-2, 14a , 16c , and 19c, were docked inside VEGFR-2enzyme to show the interaction between the tested compounds and the amino acids of the active site.     

Design,synthesis, and characterization of novel pyrimidines bearing indole as antimicrobial agents

Pyrimidines and pyrimidine bearing indole derivatives are very important species in organic chemistry due to their wide use as bioactive compounds with a broad range of good biological activities. Due to the wide spread of different species of bacteria and fungi nowadays, in the present work, a novel series of indolyl‐pyrimidines (2–13) were synthesized starting from 3‐chloro‐1H‐indole‐2‐carbaldehyde (1) . Elemental analysis, IR, 1H‐NMR, 13C‐NMR, and mass spectral data elucidated the structure of newly synthesized compounds. All compounds were screened for their in vitro antibacterial and antifungal activity, and they demonstrated promising results; all the new compounds synthesized from compound (1) , which allowed reactions with thiourea and ethyl cyanoacetate, gave the target compound (2) , which was used as a precursor for the synthesis of indolylthiazolopyrimidine derivatives (3–8) by reactions with halocarbonyl compounds such as chloroacetone, phancyl bromide, and chloroacetic acid through alkylation of the mercapto group followed by cyclization through a nucleophilic attack. When compound (2) subjected to react with hydrazine hydrate gave 4‐indolyl‐2‐hydrazinopyrimidine (5) , the latter compound, when allowed to react with ethyl chloroacetate or diethyloxalate, gave indolylpyrimidotriazine derivatives (10 , 11) ; in contrast, when the compound reacted with acetic anhydride or formic acid, it gave triazolopyrimidine derivatives (12, 13) .     

Synthesis and mesophase behaviour of mesogens bearing omega, alpha, alpha-trihydroperfluoroalkoxy end tails

One series of two-ring and two series of three-ring liquid crystal compounds, all containing omega, alpha, alpha-trihydroperfluoroalkoxy terminal tails, were prepared and characterized by IR, NMR, MS and elemental analysis. Their phase transition behaviour was investigated by DSC and polarizing optical microscopy. Biphenylene derivatives with the omega, alpha, alpha-trihydroperfluoroalkoxy end group form a stable smectic A phase. In the three-ring system, biphenylene ester compounds exhibit a smectic phase without a nematic phase. The compounds exhibit smectic A and smectic C phases when the terminal groups are intermediate length alkyl and fluorinated alkyl chains. Mesogens with fluorinated tails have a broader smectic C phase than the non-fluorinated mesogens.     

Synthesis,structures and properties ofN-(trihalogermylmethyl)-substituted amides,lactams and imides,the derivatives of the five-coordinate germanium

The formation of trichlorogermyl-substituted amides, lactams, and imides occurs when 2Et₂O·HGeCl₃ is condensed with compounds possessing the -NCH₂Cl fragment and equally well when HGeCl₃ interacts with compounds containing -NCH₂OH and-NCH₂OSiMe₃ groups. In some cases, the use of the latter is more advantageous from the preparative point of view. In compounds thus obtained, the germanium is five-coordinate due to the coordination . Deceased August 13, 1993. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1793–1799, October, 1993.     

Self-assembly of rings, catenanes, and a doubly braided catenane containing gold(I): the hinge-group effect in diacetylide ligands

Reaction of the flexible dialkynyldigold(I) precursors X(4-C6H4OCH2C-CAu)2 with 1,4-bis(diphenylphosphino)butane gave complexes of formula [[[mu-X(4-C6H4OCH2CCAu)2[mu-(Ph2PCH2CH2CH2CH2PPh2)]]n]. The complexes exist as 25-membered ring compounds with n = 1 when X = O or S, as [2]catenanes with n = 2 when X = CH2 or CMe2, and as a unique doubly braided [2]catenane, containing interlocked 50-membered rings with n = 4 when X = cyclohexylidene. These compounds form easily and selectively by self-assembly; reasons for the selectivity are also discussed.     

Simultaneous determination of protopseudohypericin, pseudohypericin, protohypericin, and hypericin without light exposure

St. John's wort products are commonly standardized to total naphthodianthrones and hyperforin. Determination of these marker compounds is complicated because of the photochemistry of the naphthodianthrones pseudohypericin and hypericin and the instability of hyperforin in solution. Protopseudohypericin and protohypericin have been identified as naturally occurring naphthodianthrones and, when exposed to light, they are converted into pseudohypericin and hypericin, respectively. However, exposure to light and the resulting naphthodianthrone free-radical reactions oxidize hyperforin. A mathematical relationship between the response of the proto compound and the resulting naphthodianthrone can be established by comparing the analytical response of the proto compound in a solution protected from light with the increase in the analytical response of naphthodianthrone in the same solution after exposure to light. By mathematically converting the proto compounds to their respective products, exposure to light can be avoided while still including proto compounds in a single assay. The method presented here details the reporting of all significant naphthodianthrones, including protopseudohypericin and protohypericin, without exposure to light. This approach includes the benefits of improved naphthodianthrone precision and protection of hyperforin from oxidation.     

Bacteria and the Biodegradation of Chemicals Achieved Naturally,by Combination,or by Construction

The natural potential of bacteria for the biological degradation of synthetic compounds is greater than is commonly supposed and extends to many heteroarenes and even some chloroarenes. An increase in the number of substituents on the aromatic ring or a certain substitution pattern is what confers xenobiotic character to a compound. In addition, when enzymes with low substrate specificity encounter foreign compounds with random variations, products with very strong xenobiotic character often result. In this case, changing the conditions or introducing a cooperation between several different types of bacteria can be used to degrade these compounds. Finally, mineralization, the complete breakdown of organic substances into carbon dioxide and inorganic salts, of xenobiotics previously regarded as persistent can be achieved by taking advantage of natural or induced gene transfer to construct hybrid degradative pathways. After an introduction to the world of bacteria and their place in Nature, we will describe their natural potential for biodegradation with reference to aliphatic and aromatic hydrocarbons. The discussion will then turn to the types of the substituents that confer xenobiotic properties to compounds and how these compounds are degraded despite their xenobiotic character.     

Enrichment of high-throughput screening data with increasing levels of noise using support vector machines, recursive partitioning, and laplacian-modified naive bayesian classifiers

High-throughput screening (HTS) plays a pivotal role in lead discovery for the pharmaceutical industry. In tandem, cheminformatics approaches are employed to increase the probability of the identification of novel biologically active compounds by mining the HTS data. HTS data is notoriously noisy, and therefore, the selection of the optimal data mining method is important for the success of such an analysis. Here, we describe a retrospective analysis of four HTS data sets using three mining approaches: Laplacian-modified naive Bayes, recursive partitioning, and support vector machine (SVM) classifiers with increasing stochastic noise in the form of false positives and false negatives. All three of the data mining methods at hand tolerated increasing levels of false positives even when the ratio of misclassified compounds to true active compounds was 5:1 in the training set. False negatives in the ratio of 1:1 were tolerated as well. SVM outperformed the other two methods in capturing active compounds and scaffolds in the top 1%. A Murcko scaffold analysis could explain the differences in enrichments among the four data sets. This study demonstrates that data mining methods can add a true value to the screen even when the data is contaminated with a high level of stochastic noise.     

Simultaneous analysis of cationic, anionic, and neutral compounds using monolithic CEC columns

A new capillary electrochromatography (CEC) column for the simultaneous analysis of cationic, neutral, and anionic compounds using CEC-ESI-MS is described. Three different silica monolith columns were prepared by changing the poly(ethylene glycol) (PEG) contents for comparison of the separation property of these columns. Different separation programs were used for the simultaneous separation of different charged compounds under the same conditions. The column prepared with 80 mg of PEG separated typical compounds within 15 min using 1 M formic acid as the electrolyte. The analytes migrated in the order of cationic, neutral, and anionic compounds, which means that the migration order was mainly determined by the electrophoresis. The hydrodynamic flow by pressure from the inlet side was significant for a stable analysis to be achieved. The effect of the composition of the sheath liquid was also examined. All analytes (14 amino acids, thiourea, urea, citric acid, and ATP) were detectable when 1% acetic acid in 50% (v/v) methanol was used as the sheath liquid.     

Synthesis,antibacterial activity and docking studies of substituted quinolone thiosemicarbazones

Abstract

Fifteen 2-quinolone thiosemicarbazone derivatives of which eleven were new, were synthesized at room temperature. The key intermediate was the quinolone carbaldehyde, from which thiosemicarbazones were formed by the reaction of thiosemicarbazides with the aldehyde moiety. The structures of the synthesized compounds were elucidated by 1D and 2D-NMR spectroscopy and mass spectrometry. The synthesized compounds showed antibacterial activity with MBCs in the range 0.80 to 36.49?mM against Staphylococcus aureus, Staphylococcus aureus Rosenbach (MRSA), Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli and Salmonella typhimurium. The best activity was seen when a larger halogen such as chlorine and bromine were substituted at C-6 on the quinolone scaffold and when a planar phenyl group was present on the thiosemicarbazone moiety. Activity was reduced when a smaller fluorine atom was present at C-6 or when a methyl group was attached to the thiosemicarbazone. This group of compounds showed a high negative binding affinity, which suggested promising antimcrobial activity. The 6-chloro derivative with a phenyl group on the thiosemicarbazone had the greatest negative binding affinity.     

Effect of methanol quality on the ionisation of herbicides,insecticides and fungicides using gradient elution liquid chromatography

This paper explores the changes in the electrospray signal response of 39 structurally different compounds caused by the quality of the methanol, when used as a component in a gradient elution mobile phase. When three batches of LC–MS grade methanol from one manufacturer were evaluated, the largest variation in the electrospray signal responses of the 39 compounds examined was 18%. However, significant enhancement of the electrospray signals of up to 106% were observed among different brands of LC–MS grade methanol from different manufacturers. The effect of methanol quality on signal response was found to be compound dependent. This study also demonstrated that the senescence of the methanol was important. Using an expired batch of LC–MS grade methanol, electrospray signals were suppressed by as much as 95% for all compounds measured using positive mode electrospray. Conversely, the negative mode electrospray signals of compounds such as 4-octyl benzoic acid showed an enhancement of up to 96% when using the same batch of methanol. Linuron was used as a model compound to examine the change in the electrospray response, during gradient elution, when the proportion of an expired batch of methanol was varied. An infusion experiment showed that the linuron signal intensity decreased as the proportion of expired methanol increased in the mobile phase, which was in direct contrast to the increase in linuron signal observed with a non-expired batch of methanol. A series of isocratic experiments also showed that the linuron signal decreased as the proportion of expired methanol increased in the mobile phase. The ion ratios of several of the compounds studied changed significantly when using the expired batch of LC–MS methanol. The change in the ion ratios accentuates the difficulty of identifying compounds from in-source spectral libraries. A protocol is recommended for assessing the quality of methanol for LC–MS applications.     

Electronic, linear, and nonlinear optical properties of III-V indium compound semiconductors

We have made an extensive theoretical study of the electronic, linear, and nonlinear optical properties of the III-V indium compound semiconductors InX (X=P, As, and Sb) with the use of full potential linear augmented plane wave method. The results for the band structure, density of states, and the frequency-dependent linear and nonlinear optical responses are presented here and compared with available experimental data. Good agreement is found. Our calculations show that these compounds have similar electronic structures. The valence band maximum and the conduction band minimum are located at Gamma resulting in a direct energy gap. The energy band gap of these compounds decreases when P is replaced by As and As by Sb. This can be attributed to the increase in bandwidth of the conduction bands. The linear and nonlinear optical spectra are analyzed and the origin of some of the peaks in the spectra is discussed in terms of the calculated electronic structure. The calculated linear optical properties show very good agreement with the available experimental data. We find that the intra-and interband contributions of the second-harmonic generation increase when moving from P to As to Sb. The smaller energy band gap compounds have larger values of chi(123) ((2))(0) in agreement with the experimental measurements and other theoretical calculations.     

Synthesis,spectral characterization,catalytic and antibacterial activity of macrocyclic Cu<Superscript>II</Superscript> compounds

Macrocyclic Cu^II compounds of the type Cu(L₄)Cl₂ (where L₄ = N₄ or N₂O₂ donor macrocyclic ligand) have been synthesized by treating the corresponding macrocycles with copper chloride in methanol. These compounds were characterized with the help of elemental analysis, i.r., mass, ESR, electronic spectra, conductance, magnetic and thermal studies. Distorted octahedral geometry has been proposed for all of these compounds. These compounds were found to be efficient in the catalytic oxidation of ascorbic acid and the percentage yields of oxidation products were determined spectrophotometrically. The biological activities of these compounds have been tested against gram +ve and gram −ve bacteria and found to be more active when compared with commercially available antibacterials like streptomycin and ampicillin.     

Synthesis,Characterization, and Antioxidant Activity of a New Class of Amido linked Azolyl Thiophenes

A new class of amido linked azolyl thiophenes was prepared from the synthetic intermediates azolyl amines and 5‐chlorothiophene‐2‐carbonyl chloride adopting conventional and ultrasonication methodologies. It was observed that the reaction took place in shorter reaction times with higher yields under ultrasonication. The structures of the synthesized compounds were characterized by spectral parameters and also tested for antioxidant activity. Among all the tested compounds, methoxy substituted oxazolyl thiophene carboxamide ( 8c ) displayed promising antioxidant activity. Besides, the electron donating groups on the phenyl ring enhanced the antioxidant activity when compared with the electron withdrawing groups.     

含吡啶亚甲基的S,N-烯酮缩醛的合成及生物活性

合成了含吡啶亚甲基的氰基、酯基或双氰基S,N-烯酮缩醛化合物．应用X射线衍射方法确定了目标化合物为E构型．生物活性测定表明,该类化合物具有很高的除草活性,并且对农作物表现出优良的选择性．