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Pesticides commonly used in the Republic of Serbia (tebuconazole, pendimethalin, pyraclostrobin, propiconazole and famoxadone) have high stability, so their potential toxicity to humans needs to be investigated. These pesticides are in use in the Republic of Serbia in various formulations. Their toxicity and interactions with acetylcholinesterase were thoroughly investigated in this study using computational tools. The ADMET (adsorption, distribution, metabolism, excretion, toxicity) study showed that all of them are efficient oral compounds, and that pendimethalin was a mutagenic compound. Glide scores ranged from -18.41 (pendimethalin) to -27.61 kJ mol-1 (famoxadone) in Mus musculus, and from -19.58 (pendimethalin) to -24.31 kJ mol-1 (propiconazole) in Homo sapiens. In addition, the experimental stability of the pesticides solutions in methanol was studied using the fast gas chromatography-mass spectrometry (GC-MS, retention times of the studied pesticides ranged from 14.47 (pendimethalin) to 22 min (famoxadone)). They showed good stability over time, apart from pyraclostrobin which decomposed mainly into its desmethoxy derivative after 20 months. Based on the promising modelling results, pyraclostrobin and famoxadone emerge as potential candidates for further investigation in the treatment of Alzheimer's disease, taking care to increase their stability. [ABSTRACT FROM AUTHOR]

Some of simple carbohydrates and their derivatives are used for the clinical treatment of various diseases. Epoxide derivatives, which can be obtained by the intramolecular elimination of water from two vicinal hydroxyl groups, are stable, but sufficiently reactive compounds very often used as intermediaries in various syntheses. Synthesis of epoxide derivative, methyl 3,4-anhydro--6-bromo-2-O-tert-butyldimethylsilyl-6-deoxy-α-D-allopyranoside from α-D-glucose was achieved in high yields in the minimal number of synthetic steps. Anhydrous glucose was used as a starting material which was transformed into methyl α-D-glucopyranoside using dry, gaseous hydrogen chloride. Thus obtained derivative was treated with benzaldehyde in the presence of zinc chloride as Lewis acid giving methyl (R)-4,6-O-benzylidene-α-D-glucopyranoside. The obtained compound was treated with N-bromosuccinimide (NBS) in dichloromethane in the presence of barium carbonate giving methyl 4-O-benzoyl-6--bromo-6-deoxy-α-D-glucopyranoside. In the next step, the obtained compound was treated with tert-butyldimethylsilyl chloride (TBDMSCl) in pyridine, and methyl 4-O-benzoyl-6-bromo-2-O-tert-butyldimethylsilyl-6-deoxy-α-D-glucopyranoside was further mesylated, and the obtained methyl 4-O-benzoyl-6--bromo-2-O-tert-butyldimethylsilyl-6-deoxy-3-O-mesyl-α-D-glucopyranoside was treated at the end with KOH to give methyl 3,4-anhydro-6-bromo-2-O-tert--butyldimethylsilyl-6-deoxy-α-D-allopyranoside (yield 78 %). [ABSTRACT FROM AUTHOR]

The influence of temperature, reaction time, and type of the catalyst on the yield of the 2,3,5-trimethylpyridine (collidine) from 3-amino-2-methylpropenal and methylethylketone was investigated. 3-Amino-2-methylpropenal was synthesized from 3-ethoxy-2-methylacrolein previously synthesized from methylmalondialdehyde tetraethyl acetal, obtained from triethyl orthoformate and propenyl ether. The optimal conditions for the investigated synthesis were temperature of 150 °C, reaction time 24 h, and the CH3COOH/pTsOH catalyst. This synthesis is the first successful attempt to synthesize 2,3,5-trimethylpyridine in an acid medium. [ABSTRACT FROM AUTHOR]

The aim of this work was to develop a new kinetic spectrophotometric method for the determination of ibuprofen in pharmaceutical formulations. Ibuprofen was determined in an acidic ethanolic medium by monitoring the rate of appearance of 1-nitroso-2-naphthol, resulting from the displacement by ibuprofen of Co(III) from the tris(1-nitroso-2-naptholato)cobalt(III) complex. The optimum operating conditions regarding reagent concentrations and temperature were established. The tangent method was adopted for constructing the calibration curve, which was found to be linear over the concentration range 0.21-1.44 and 1.44-2.06 μg ml-1. The optimized conditions yielded a theoretical detection limit of 0.03 μg ml-1 based on the 3.3 S0 criterion. The interference effects of the usual excipients of powdery drugs, foreign ions and amino acids on the reaction rate were studied in order to assess the selectivity of the method. The developed procedure was successfully applied for the rapid determination of ibuprofen in commercial pharmaceutical formulations and human control serum. The unique features of this procedure are that the determination can be performed at room temperature and the analysis time is short. The newly developed method is simple, inexpensive and efficient for use in the analysis of a large number of samples. [ABSTRACT FROM AUTHOR]

An accurate, sensitive and reproducible high performance liquid chromatographic (HPLC) method for the quantification of doxycycline hyclate in pharmaceutical samples has been developed and validated. The drug and the standard were eluted from a Lichrosorb RP-8 (250 mm×4.6 mm, 10 μm particle size) at 20 °C with a mobile phase consisting of methanol, acetonitrile and 0.010 M aqueous solution of oxalic acid (2:3:5, v/v/v). The flow rate was 1.25 ml min-1. A UV detector set at 350 nm was used to monitor the effluent. Each analysis required no longer than 4 min. The limits of detection and quantification were 1.15 and 3.84 μg ml-1, respectively. Recoveries for different concentrations ranged from 99.58 to 101.93 %. [ABSTRACT FROM AUTHOR]