Preparation and properties of nitrogen-substituted thiosulfinyl compounds and related new heterocycles

The reaction of dilithiated N,N′-dimethyl-1,2-diphenylethylenediamine with disulfur dichloride (S₂Cl₂) gave a thiosulfinyl compound (R₂N)₂SS, 2,5-dimethyl-3,4-diphenyl-1,2,5-thiadiazolidine 1-sulfide, whereas the treatment of dilithiated N,N′-bis(p-toluenesulfonyl)-1,2-diphenylethylenediamine with S₂Cl₂ furnished a new heterocycle, 3,6-bis(p-toluenesulfonyl)-4,5-diphenyl-4H,5H-1,2,3,6-dithiadiazine.     

Human D-amino acid oxidase: an update and review

The flavoprotein D-amino acid oxidase (DAO) degrades the gliotransmitter D-Ser, a potent activator of N-methyl-D-aspartate-type glutamate receptors. A body of evidence suggests that DAO, together with its activator, G72 protein, may play a key role in the pathophysiology of schizophrenia. It has also been suggested that 3,4-dihydroxy-D-phenylalanine (D-DOPA), the stereoisomer of 3,4-dihydroxy-L-phenylalanine (L-DOPA), is oxidized by DAO and converted to dopamine via an alternative biosynthetic pathway. We determined the crystal structures of human DAO in complex with the reaction products of two clinically important substrates, D-Ser and D-DOPA. Kinetic data show that the maximum velocity is much greater for D-DOPA than that for D-Ser, which strongly supports the proposed alternative pathway for dopamine biosynthesis in the treatment of Parkinson's disease. In addition, biochemical characterization of human DAO indicates that it binds FAD more weakly than does porcine D-amino acid oxidase (pDAO) and exists as a stable homodimer, even in the apoprotein form. Determination of the structures of human DAO in various states reveals that, in contrast to pDAO, the hydrophobic-Val-Ala-Ala-Gly-Leu (VAAGL) stretch (residues 47-51, structurally ambivalent peptide) located at the si-face of the flavin ring assumes a uniquely stable conformation, which provides a structural basis for the unique kinetic features of human DAO.     

Some fractional differintegral equations

Recently, Nishimoto [J. College. Engrg. Nihon Univ. Ser. B24 (1983), 7–13] studied a certain fractional integral equation and a system of simultaneous differintegral equations, each of order $\text{1}\text{2}$. Motivated by Nishimoto's work, Owa and Nishimoto [J. College Engrg. Nihon Univ. Ser. B24 (1983), 67–72] considered a general fractional differintegral equation. The object of the present paper is to investigate some interesting properties of functions which satisfy the general fractional differintegral equation solved by Owa and Nishimoto.     

Structures and properties of two diastereomeric cyclic sulfites derived from cis‐3,4‐di‐tert‐butylthiolane‐3,4‐diol and thionyl chloride

cis‐3,4‐Di‐tert‐butylthiolane‐3,4‐diol ( 1 ) was treated with an equimolar amount of thionyl chloride in the presence of triethylamine or pyridine in several solvents of different polarity to furnish two diastereomeric sulfites 2a and 2b generally in excellent combined yields. Although 2a was consistently formed as the major diastereomer when pyridine was used as the base, 2a and 2b were formed in approximately equal amounts when triethylamine was used as the base in polar solvents. X‐ray crystallographic analyses revealed that the S O group of 2a is anti to the thiolane ring and that of 2b syn to the thiolane ring. Density functional theory calculations (B3LYP/6‐31G* level) revealed that 2a is less stable than 2b by 1.28 kcal mol⁻¹, although 2a was formed generally as the predominant diastereomer. Spectroscopic data of 2a and 2b are discussed with emphasis on comparison with those obtained by calculations. Treatment of 2a and 2b with m‐chloroperbenzoic acid resulted in the oxidation of the divalent sulfur atom of the thiolane ring and not the sulfite sulfur atom. The above oxidations took place exclusively at the syn‐side with respect to the tert‐butyl groups.© 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:587–595, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10192     

Risk Assessment of Passive Smoking Based on Analysis of Hair Nicotine and Cotinine as Exposure Biomarkers by In-Tube Solid-Phase Microextraction Coupled On-Line to LC-MS/MS

Passive smoking due to environmental tobacco smoke is a serious public health concern because it increases the risk of lung cancer and cardiovascular disease. However, the current status and effect of passive smoking in various lifestyles are not fully understood. In this study, we measured hair nicotine and cotinine levels as exposure biomarkers in non-smokers and assessed the risk from the actual situation of passive smoking in different lifestyle environments. Nicotine and cotinine contents in hair samples of 110 non-smoker subjects were measured by in-tube solid-phase microextraction with on-line coupling to liquid chromatography-tandem mass spectrometry, and self-reported lifestyle questionnaires were completed by the subjects. Nicotine and cotinine were detected at concentrations of 1.38 ng mg⁻¹ and 12.8 pg mg⁻¹ respectively in the hair of non-smokers, with levels significantly higher in subjects who reported being sensitive to tobacco smoke exposure. These levels were also affected by type of food intake and cooking method. Nicotine and cotinine in hair are useful biomarkers for assessing the effects of passive smoking on long-term exposure to environmental tobacco smoke, and our analytical methods can measure these exposure levels in people who are unaware of passive smoking. The results of this study suggest that the environment and places of tobacco smoke exposure and the lifestyle behaviors therein are important for the health effects of passive smoking.     

Synthesis,structural elucidation,and antioxidant activity of new phenolic derivatives containing piperidine moiety: Experimental and theoretical investigations

The incorporation of the piperidine ring into drugs may play an interesting role to fulfill significant tasks and act as an active ingredient in various treatments. Herein, three novel derivatives of 3-acetyl-2-hydroxybenzoic acid ( 3-5 ) containing a piperidine ring were synthesized through the rearrangement of triacetic acid lactone in the presence of piperidine. Their molecular structures were characterized by ¹H and ¹³C NMR and single crystal X-ray diffraction techniques. The experimental data were compared with the predicted ones obtained in the polarizable continuum model at the B3LYP/6-311++G(d,p) level of theory. Relatively good correlations were obtained between the experimental data (spectral and Z-matrix coordinates) and the predicted ones, with correlation coefficients higher than 97%. The intercontacts between the closest units of 3-5 were identified through the analysis of the Hirshfeld surface and electrostatic potentials (ESP) maps. Hirshfeld surface and ESPs analyses reveal that the closest interactions between the units of the compounds are between hydrogen atoms (59%-67%). The antioxidant activity of 3-5 was evaluated using DPPH free radical scavenging and ABTS assays. They exhibit moderate antioxidant activity, which probably is attributable to the presence of a phenolic moiety in their basic skeleton. Molecular docking calculations suggest that 3-5 may mainly bind to the active binding site of peroxiredoxin 5 through strong and weak intermolecular hydrogen bonds.     

Synthesis and characterization of photosensitive cinnamate-modified cellulose acetate butyrate spin-coated or network derivatives

The photochemical behavior of photosensitive materials obtained by spin-coating or network synthesis of a cellulosic polymer bearing photo-cross-linkable cinnamate groups was investigated. First, cinnamate groups were grafted on a cellulose acetate butyrate polymer, with different grafting densities. The photochemical properties of the polymers were studied in solution by UV–visible and ¹H NMR spectroscopy. Then spin-coated films and networks were prepared and characterized as a function of the number of cinnamate groups per cellulosic unit. The water-wetting properties of both surfaces were studied by dynamic contact angle measurements, before and after photoirradiation, and subsequent heating. The surfaces obtained by the two methods have significantly different behaviors that can be assigned to the distinct photochemical pathways of the cinnamate groups upon irradiation depending on the sample preparation. Indeed, dimerization reaction is evidenced as the main process in the spin-coated films while the expected isomerization is predominant at the surface of the polymer networks.     

A simplified analytical approach for pricing discretely-sampled variance swaps with stochastic volatility

Pricing variance swaps under stochastic volatility with discretely-sampled realized variance has been a hot subject pursued recently; quite a few papers have already been published (Zhu and Lian (2009, 2011, [11], [4]); Swishchuk and Li (2011) [5]). In this paper, we present a simplified approach to price discretely-sampled variance swaps. Compared with the approach presented by Zhu and Lian (2011) [4], an important feature of our approach is that there is no need for the introduction of a new state variable and the utilization of the generalized Fourier transform. This has significantly simplified the solution procedure and will thus enable researchers to view this type of problems from a different angle.