LC‐MS/MS method for the determination of haemanthamine in rat plasma,bile and urine and its application to a pilot pharmacokinetic study

Evidence gathered in various studies points to the fact that haemanthamine, an isoquinoline alkaloid, has multiple medicinally interesting characteristics, including antitumor, antileukemic, antioxidant, antiviral, anticonvulsant and antimalarial activity. This work presents, for the first time, a universal LC‐MS/MS method for analysis of haemanthamine in plasma, bile and urine which has been verified in a pilot pharmacokinetic experiment on rats. Chromatographic separation was performed on a pentafluorophenyl core–shell column in gradient elution mode with a mobile phase consisting of acetonitrile–methanol–ammonium formate buffer. A sample preparation based on liquid–liquid extraction with methyl tert‐butyl ether was employed with ambelline used as an internal standard. Quantification was performed using LC‐MS‐ESI(+) in Selected Reaction Monitoring mode. The method was validated according to the European Medicines Agency guideline in a concentration range of 0.1–10 μmol/L in plasma, bile and urine. The concentration–time profiles of haemanthamine in plasma, bile and urine after a single i.v. bolus of 10 mg/kg have been described for the first time. The presented study addresses the lack of information on haemanthamine pharmacokinetics and also introduces a new universal method of haemanthamine analysis in complex biological matrices. Copyright © 2015 John Wiley & Sons, Ltd.     

AHP model for performance evaluation of employees in a Czech management consulting company

Central European Journal of Operations Research - The article is focused on an application of the analytic hierarchy process (AHP) to the performance evaluation of employees of a management...     

[2+2+2] Cycloisomerisation of Aromatic Cyanodiynes in the Synthesis of Pyridohelicenes and Their Analogues

We have developed a methodology for the synthesis of pyridohelicenes and their analogues based on the Ni⁰‐, Co^I‐ or Rh^I‐mediated intramolecular [2+2+2] cycloisomerisation of cyanodiynes. It allows for folding the linear precursors into the corresponding helical backbones comprising the newly formed pyridine unit in their central part. Along with racemic pyrido[n]helicenes (n=5,6,7) and their derivatives, both enantio‐ and diastereomerically pure pyrido[n]helicene‐like molecules (n=5,6) were prepared by employing the chiral substrate‐controlled cyclisation of the corresponding enantiopure cyanodiynes.     

Oxidation of small unsaturated methyl and ethyl esters

The ignition delay times were measured behind reflected shock waves for temperatures from 1280 to 1930 K, pressures from of 7–9.65 atm, fuel concentrations of 0.4, 0.5, and 1%, and equivalence ratios equal to 0.25, 1.0, and 2.0 in the cases of four unsaturated esters: methyl crotonate, methyl acrylate, ethyl crotonate, and ethyl acrylate. Ignition delay times were measured using chemiluminescence emission from OH at 306 nm and piezoelectric pressure measurements made at the shock tube sidewall. No important difference of reactivity was observed between methyl and ethyl unsaturated esters, methyl and ethyl crotonate having the same reactivity as methyl butanoate. The reactivity of acrylates is greater than that of crotonates especially at the lowest investigated temperatures. Detailed mechanisms for the combustion of the four studied unsaturated esters have been automatically generated using the version of EXGAS software recently improved to take into account this class of oxygenated reactants. These mechanisms have been validated through satisfactory comparison of simulated and experimental results. The main reaction pathways have been derived from flow rate and sensitivity analyses. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 204–218, 2011     

Determination of steroid hormones in biological and environmental samples using green microextraction techniques: an overview

Residues of steroid hormones have become a cause for concern because they can affect the biological activity of non-target organisms. Steroid hormones are a potential risk for wildlife and humans through the consumption of contaminated food or water. Their determination requires extraction and clean-up steps, prior to detection, to reach low concentration levels. In recent years, a great effort has been made to develop new analytical methodologies, such as microextraction techniques, that reduce environmental pollution. Researchers have modified old methods to incorporate procedures that use less-hazardous chemicals or that use smaller amounts of them. They are able to do direct analysis using miniaturised equipment and reduced amounts of solvents and wastes. These accomplishments are the main objectives of green analytical chemistry. In this overview, we focus on microextraction techniques for the determination of steroid hormones in biological (e.g., human urine, human serum, fish, shrimp and prawn tissue and milk) and environmental (e.g., wastewaters, surface waters, tap waters, river waters, sewage sludges, marine sediments and river sediments) samples. We comment on the most recent applications in sorptive-microextraction modes, such as solid phase microextraction (SPME) with molecularly imprinted polymers (MIPs), in-tube solid-phase microextraction (IT-SPME), stir-bar sorptive extraction (SBSE) and microextraction in packed sorbent (MEPS). We also describe liquid-phase microextraction (LPME) approaches reported in the literature that are applied to the determination of steroid hormones.     

Skin Constituents as Cosmetic Ingredients. Part I: A Study of Bio‐mimetic Monoglycerides Behavior at the Squalene‐Water Interface by the “Pendant Drop” Method in a Static Mode

This work presents the behavior of bio‐mimetic monoglycerides at the squalene/water interface. The study was done in the so‐called “static” mode using the “pendant drop method”, enabling us to characterize these molecules according to the value of their critical efficiency concentration (CEC), their maximum surface excess concentration (Γ_∞), the efficiency of the surface tension reduction parameter (pC20), and the minimum value of their interfacial tension (γ_min). It also permitted the study of the influence of the structure of the carbon chain of those monoglycerides on their interfacial behavior.

The analysis of the different parameters shows that monoglycerides with small hydrocarbon chains, monoglycerides with one or more double bonds, and monoglycerides possessing a hydroxyl function grafted in the middle of the chain constitute excellent surfactants. Two different groups can be found: one group composed of short saturated hydrocarbon chain monoglycerides (C12∶0 to C16∶0) and long hydrocarbon chain monoglycerides (C18∶0 to C22∶0); the second group, composed of unsaturated hydrocarbon chain monoglycerides, also includes hydroxystearate and isostearate monoglycerides. The first group could be used for the formulation of “hydrating” cosmetic products having secondary droplets, the second group for W/O emulsions.