Synthesis and Antimicrobial Evaluation of Some New Thiophene Derivatives

2-(2-Cyano-acetylamino)-4,5,6,7-tetrahydro-benzo[b]thiophene-3-carboxamide(3) was used as starting material for synthesis of 4-thiazolidinone, thiazolidine, and thiophene derivatives 6, 7a, b, and 8a, b, respectively. Thiocarbomyl derivative 5, 4-thizolidinone 9, and thioxothiazolidine 10 were obtained from reaction of 3 with thioglycolic acid and phenyl isothiocyanate/sulfur, respectively. Condensation of 3 with selected cyclic ketones and aromatic aldehydes yielded the arylidine derivatives 11a, b and 13, respectively. Refluxing of 11a, b with sulfur and morpholine yielded the thiophene derivatives 12a, b, respectively. Diazocoupling of compound 3 withp-tolyl diazonium chloride yielded the hydrazone derivative 14. The newly synthesized compounds were characterized by infrared, ¹H NMR, and mass spectral studies. Representative compounds of the synthesized product were tested and evaluated as antimicrobial agents. Compound 12b gives very high antimicrobial activity against Ampicillin.     

Amphiphilic calixarenes: Probing monolayer stability by selective modification of the hydrophobic-hydrophilic balance

Abstract

The synthesis of calix[4]arenes permuting 1 or 4 C12 acyl chains at the upper rim and 1 or 4 methylene ethyl ester groups at the lower rim is described. The Langmuir compression isotherms of the compounds show that in the case of 1 acyl + 1 ester, there is probably orientation parallel to the air-water interface. For the other systems, orientation is orthogonal to the interface, and for the 4 +4 compound a pseudo collapse with reorientation of the hydrophilic ester groups is observed.     

Synthesis and Antioxidant Evaluation of Some Nicotinonitriles

One‐pot condensation of malononitrile 1 , furan‐2‐carbaldehyde 2 , butan‐2‐one 3 , and ammonium acetate in ethanol, followed by cyanoacetylation of the formed nicotinonitrile 4 with 3‐(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)‐3‐oxopropanenitrile 5 afforded the cyanoacetamide 6 . Compound 6 was used as a key intermediate for synthesis of nicotinonitriles via reaction with different reagents.     

New flavonol glycosides from the leaves of Caragana brachyantha

Two new flavonol glycosides, brachysides C and D, together with three known flavonol glycosides, were isolated from the leaves of Caragana brachyantha. The structures of brachysides C and D were elucidated on the basis of detailed spectroscopic analysis as quercetin 5-O-[α-l-rhamnopyranosyl-(1 → 6)-β-d-glucopyranoside]-7-O-[α-l-rhamnopyranoside] and quercetin 5-O-[α-l-rhamnopyranosyl-(1 → 6)-β-d-glucopyranoside]-7-O-[α-l-rhamnopyranoside]-4′-O-[α-l-rhamnopyranoside], respectively. The presence of flavonol tetra- and triglycosides bearing a sugar moiety at position 5 was the first report from this genus Caragana.     

Determination of glucosamine and carisoprodol in pharmaceutical formulations by LC with pre-column derivatization and UV detection

A simple and reliable precolumn derivatization liquid chromatography method with ultraviolet detection has been developed and validated for the analysis of glucosamine (GS) in various dietary supplement formulations and raw materials. Additionally, the proposed method was used for analysis of carisoprodol (CR) found in ternary mixture with paracetamol (PR) and caffeine (CF). The linearity ranges were 1-100 μg/mL for GS, 1-150 μg/mL for CR, PR and CF. Derivatization was used with 1,2-naphthoquinone-4-sulphonic acid sodium salt in the presence of borate buffer. Chromatographic separation of GS-naphthoquinone derivative was achieved by using a mixture of acetonitrile and water (pH 7.3 adjusted with 0.1 M NaOH) in the ratio 10:90, v/v and flow-rate of 1.0 mL/min. UV detection was carried out at 280 nm. For PR, CF, and CR-naphthoquinone derivative, the chromatographic separation was achieved by using mixture of acetonitrile and 20 mM KH(2)PO(4) (pH 3.0 adjusted with phosphoric acid) in the ratio 20:80, v/v and flow-rate of 1.0 mL/min. UV detection was carried out at 275 nm. The limits of detection were 37.2, 35.9, 30.4 and 40.0 ng/mL for GS, CR, PR and CF, respectively.     

Reliability analysis of a consecutive r-out-of-n: F system based on neural networks

In this paper, we present a generalized Markov reliability and fault-tolerant model, which includes the effects of permanent fault and intermittent fault for reliability evaluations based on neural network techniques. The reliability of a consecutive r-out-of-n: F system was obtained with a three-layer connected neural network represents a discrete time state reliability Markov model of the system. Such that we fed the neural network with the desired reliability of the system under design. Then we extracted the parameters of the system from the neural weights at the convergence of the neural network to the desired reliability. Finally, we obtain simulation results.     

Synthesis and Antioxidant Activity of Some Novel Nicotinonitrile Derivatives Bearing a Furan Moiety

As a part of ongoing studies in developing new potent antioxidant agents, 2‐amino‐4‐(furan‐2‐yl)‐5,6‐dimethylnicotinonitrile 4 was utilized as a key intermediate for the synthesis of some new pyrimidines 5 and 11 , form (acet)amide 6 , 7 , urea and thiourea 9 , 10 , 1,8‐naphthyridines 12 , 13 , and 14 . Moreover, condensation of 4 with 5,5‐dimethyl‐1,3‐cyclohexanedione and cyclohexanone in ethanol furnished the pyridine derivatives 16 and 17 , respectively. Furthermore, refluxing of 4 with ethylenediamine in carbon disulfide afforded the 4,5‐dihydro‐1H‐imidazol‐2‐yl pyridine derivative 19 . In addition, refluxing of 4 with carbon disulfide and concentrated sulfuric acid furnished the pyridine derivatives 20 and 21 , respectively. The reaction of 4 with phenacyl chloride and ethyl chloroacetate in dimethylformamide in the presence of catalytic amount of triethylamine afforded the pyridine derivatives 22 and 23 , respectively. Finally, heating of 4 with 1‐phenyl‐3‐(piperidin‐1‐yl)propan‐1‐one hydrochloride in glacial acetic acid afforded phenylpropylamino pyridine derivative 24 . The structures of the newly synthesized compounds were confirmed by elemental analysis, IR, ¹H‐NMR, and mass spectral data. Representative compounds of the synthesized products were evaluated as antioxidant agents. Compounds 8 , 19 , and 22 are promising compounds.     

Synthesis, structural characterization, and computational studies of novel diiodine adducts with the heterocyclic thioamides N-methylbenzothiazole-2-thione and benzimidazole-2-thione: implications with the mechanism of action of antithyroid drugs

Reaction of N-methylbenzothiazole-2-thione (C8H7NS2 or NMBZT) with diiodine produced the charge-transfer (ct) complex [(NMBZT).I2] (1). NMBZT reacts with diiodine in the presence of FeCl3 in a molar ratio of 3:6:1 and forms the ionic complex [[(NMBZT)2I+].[FeCl4]-] (2) together with [[(NMBZT)2I+].[I7]-] (2a) iodonium salt. The reaction of benzimidazole-2-thione (C7H6N2S or MBZIM) with diiodine on the other hand results in the formation of the ct [[(MBZIM)2I]+[I3]-].[(MBZIM).I2] (3) compound. The compounds have been characterized by elemental analyses, DTA-TG, FT-Raman, FT-IR, UV-vis, and 1H NMR spectroscopies, and X-ray crystal structure determinations. Compound 1, C8H7I2NS2, is orthorhombic with a space group Pna2(1) and a = 12.5147(13) angstroms, b = 22.536(3) angstroms, c = 4.2994(5) angstroms, and Z = 4. Compound 2, C16H14Cl4FeIN2S4, is monoclinic, space group C2/c, a = 35.781(2) angstroms, b = 7.4761(5) angstroms, c = 18.4677(12) angstroms, beta = 107.219(1) degrees, and Z = 8. Compound 3, C21H18I6N6S3, monoclinic, space group P2(1)/n, a = 14.0652(11) angstroms, b = 22.536(3) angstroms, c = 4.2994(5) angstroms, beta = 99.635(7) degrees, and Z = 4, consists of two component moieties cocrystallized, one neutral which contains the benzimidazole-2-thione (MBIZM) ligand bonded with an iodine atom through sulfur, forming a compound with a "spoke" structure [(MBZIM)I2] 3a, while the other is the ionic complex [[(MBZII)2I+].[I3]-] (3b). The X-ray crystal structure of 1 shows a bond between the thione-sulfur atom and one of the iodine atoms in an essentially planar arrangement. In the cation of 2, an iodine is coordinated by two thione-sulfur atoms in a linear arrangement but the molecule is not planar. For the first time in the solid state a spoke-ionic mixed complex has been characterized in 3. One component of the structure is a molecular diiodine adduct, i.e., [(MBZIM)I2] (3a), with a linear coordination geometry in a decidedly planar arrangement, and the other component is an ionic adduct [[(MBZIM)2I]+.[I3]-] (3b) with the cation having an arrangement similar to that found for 1. Theoretical calculations using density functional (DFT) and ab initio Hartree-Fock theory have been carried out for 1 and 3a,b. The results are consistent with the experimental data. Conclusions on the behavior of a thioamide, when used as an antithyroid drug, have also been made.     

Optimization and Validation of an HPLC-UV Method for Determination of Tranexamic Acid in a Dosage Form and in Human Urine

A simple and reliable high-performance liquid chromatographic method with UV detection at 245 nm has been developed and validated for determination of tranexamic acid (TA) in a dosage form and in human urine. Before injection samples were derivatized with phenyl isothiocyanate (PITC). The reaction temperature, reaction time, and concentration of PITC used for derivatization were optimized. Chromatographic separation was on a C₁₈ column with a 65:35 (v/v) mixture of 10 mM phosphate buffer, pH 3.6, and acetonitrile as mobile phase. Heptaminol hydrochloride was used as internal standard.     

Performance improvement of a PGNAA setup due to change in moderator design: A Monte Carlo study

Effect of neutron source-moderator geometry has been studied on the performance of a thermal neutron capture-based prompt gamma neutron activation analysis (PGNAA) setup. In the study prompt gamma-ray and thermal neutron yield was calculated for various positions of the neutron source inside 3–10 cm long high density polyethylene moderators. The study has been carried out for a Portland cement sample using Monte Carlo calculations. The maximum yields of the thermal neutrons and prompt gamma-rays have been observed for a neutron source at a distance of 1 cm from the sample. The maximum yield of the 1.94 and 6.42 MeV prompt gamma-ray from a Portland cement sample has been observed for moderators having length equal to or greater than 7 cm. The yield of both gamma rays is 2.57 times higher than the previously reported value for a PGNAA setup with the source placed outside a 5 cm thick moderator. The higher yield of gamma rays will result in higher sensitivity of the PGNAA setup.