In vitro evaluation of cytotoxic and mutagenic activity of avarol

The cytotoxicity of avarol, a main secondary metabolite of the Mediterranean sponge Dysidea avara, was in vitro screened by MTT assay against four human tumour cell lines. The colon HT-29 tumour cells practically showed to be the only sensitive ones towards this organic compound. No toxicity was found against the fetal lung fibroblast MRC-5 cells at the concentrations tested. In comparison with doxorubicin, used as a positive control, avarol actually exhibited at least 588-fold less toxicity towards normal MRC-5 cells. Finally, comet assay indicated that DNA fragmentation was almost fivefold higher upon the treatment with doxorubicin, compared to avarol. The obtained results have actually confirmed that avarol scaffold may contribute to development of new cytostatics inspired by nature.     

Determination of residues of azaperone in the kidneys by liquid chromatography with fluorescence detection

An analytical method has been developed for the quantitative determination of residues of the tranquillizer azaperone (AZN) in the kidneys of slaughtered animals. Samples were extracted with acetonitrile, extracts were acidified and further purified with solid-phase extraction (SPE) on a polymeric mixed-mode cation-exchange sorbent, Oasis. AZN and its main metabolite azaperol (AZL) were eluted by alkaline methanol (MeOH), the eluate was evaporated, re-dissolved and analysed by gradient high performance liquid chromatography (LC) on reversed and deactivated phase LiChrospher 60-RP select B at excitation and emission wavelengths of 245 and 345 nm, respectively. The method was validated according to the requirements of European Commission Decision 2002/657/EC, using fortified porcine kidneys. The method proved to be selective, specific against carazolol (CAR) and linear over a concentration range 10-150 microg kg(-1) (r2>0.99). Over a concentration range 50-150 microg kg(-1), mean recovery of AZN and AZL was 88.2 and 91.2%, respectively, with intra-laboratory reproducibility of <11.0 and <9.0%, respectively. The decision limit (CCalpha) of AZN and AZL was 112 and 111 microg kg(-1), respectively, and the limit of quantification (LOQ) was 10 and 5 microg kg(-1), respectively. The procedure was also applied to bovine, poultry and horse kidneys, giving similar results, and has been successfully implemented in statutory residue monitoring control in food of animal origin in Slovenia.     

Combinatorial synthesis, reversed-phase and normal-phase high-performance liquid chromatography elution data and liquid chromatography/positive atmospheric pressure chemical ionization tandem mass spectra of methoxylated and glycosylated resveratrol analogues

Analyses of methoxylated and glycosylated stilbenes remain scarce in the literature because of the commercial unavailability of these compounds. Here a library of 22 compounds was synthesized by combinatorial chemistry. Their elution profiles were compared on three different columns (C18, C8, and silica) with those of seven commercial resveratrol analogues and two viniferins. The spectra recorded by liquid chromatography/positive atmospheric pressure chemical ionization tandem mass spectrometry (LC-APCI(+)-MS/MS) are discussed and recommendations made for easier identification of new stilbenes.     

Growth and electronic properties of ultra-thin Ag films on Ni(1 1 1)

We studied the growth mode and electronic properties of ultra-thin silver films deposited on Ni(1 1 1) surface by means of scanning tunnelling microscopy (STM) and angle resolved photoemission spectroscopy (ARPES). The formation of the 4d-quantum well states (QWS) was analysed within the phase accumulation model (PAM). The electronic structure of the 1 ML film is consistent with the silver layer which very weakly interacts with the supporting surface. The line-shape analysis of Ag-4d_xz,yz QWS spectrum support the notion of strong localization of these states within the silver layer. The asymmetry of the photoemission peaks implies that the decay of the photo-hole appears to be influenced by the dynamics of the electrons in the supporting surface.     

Densitometric determination of (+)-catechin and (−)-epicatechin by 4-dimethylaminocinnamaldehyde reagent

We report the optimization of a sensitive, selective and robust derivatization method using 4-dimethylaminocinnamaldehyde (DMACA) for densitometric determination of (+)-catechin and (−)-epicatechin. The separation of these compounds was achieved by thin-layer chromatography (TLC) on cellulose plates developed with water. With DMACA in HCl, both compounds gave blue bands, while under the same conditions, vanillin produced a fast fading red coloration of bands. Quantitation at 655 nm showed that for both compounds the calibration curve was linear from 2 to 12 ng and polynomial from 2 to 30 ng, and the repeatability of chromatography of 20 ng was 3.5% (RSD, n = 6). The visible limit of detection of both standards was 1 ng, but the densitometric limit of detection was lower (0.2 ng). The optimized DMACA reagent is superior to the more frequently used vanillin reagent and is applicable also for determination of mixtures containing other catechins ((−)-catechin, (−)-epicatechin gallate, (−)-epigallocatechin gallate, procyanidin A2, procyanidin B1 and procyanidin B2).     

Simultaneous Determination of Hydrochlorothiazide, Cilazapril and Its Active Metabolite Cilazaprilat in Urine by Gradient RP-LC

A rapid and simple liquid chromatographic method with UV detection has been developed for the determination of hydrochlorothiazide (HCTZ), cilazapril (CL) and its active metabolite cilazaprilat (CLT) in urine. Sample preparation for urine consisted of solid-phase extraction using styrene-divinylbenzene (SDB-2) cartridges. The chromatographic system was a Zorbax Eclipse XDB-C₁₈ column with a mixture of methanol and 10 mM phosphate buffer, pH 2.3 with gradient (20 to 60% of methanol) as mobile phase at a flow rate of 1.0 mL min^?1. The detection was performed at the wavelength of 206 nm. Enalapril maleat was used as an internal standard. The detector response was linear in the range of 2.4–30.0, 1.6–15.0 and 1.8–20.0 μg mL^?1 for HCTZ, CL and CLT, respectively. LOQ was determined to be 2.4, 1.6 and 1.8 μg mL^?1 for HCTZ, CL and CLT, respectively. Both intra- and inter-day precision were within acceptable limits. The method has been applied to urine samples obtained from three hypertensive patients after intake of HCTZ and CL therapeutic dose.     

Raman Analysis of Polymerization of APST Molecule

In this work we investigated the solidification of aminopropylsilanetriol dissolved in water (∼25%) under different conditions by Raman spectroscopy. The solidification was carried out at three different temperatures 8 °C, 23 °C and 60 °C. The influence of electromagnetic radiation on the polymerization process was also studied. Samples were held to solidify in dark and at UV (254 nm and 356nm) spectral range. In order to investigate the influence of the substrate on the resulting polymer structure, teflon, PVC, glass, brass and silica were used. Best ordered polymerized structure was achieved for samples deposited on plastics and solidified in dark, at room temperature.     

Microbubble-enhanced hemorrhage control using high intensity focused ultrasound

Our objective was to investigate whether hemorrhage control can be achieved faster when high-intensity focused ultrasound (HIFU) is applied in the presence of ultrasound contrast agents (UCA) as compared to HIFU only application. Incisions (3 cm long and 0.5 cm deep) were produced in the livers of anesthetized rabbits. UCA Optison (0.18 ml/kg) was injected into the mesenteric vein. A HIFU applicator (5.5 MHz, 6800 W/cm² in situ) was scanned at a rate of 1–2 mm/s in one direction over the incision (with multiple passes if needed), until hemostasis was achieved. Hemostasis times were 59 ± 23 s (n = 21) in the presence of Optison and 70 ± 23 s (n = 29) without Optison. The presence of Optison produced on average 37% reduction in hemostasis times normalized to initial bleeding rates (p < 0.05), as well as 60% faster formation of the coagulum seal over the incision (p < 0.05). Gross and histological observations showed similar appearance of HIFU lesions produced in the presence of Optison and HIFU lesions produced without Optison. Our results suggest potential utility of UCA for increasing efficiency of HIFU-induced hemostasis of solid organ injuries.     

Search for P-ODD asymmetry in the radiative cross-section of the interaction of neutrons with lead nuclei

The P-odd effect in the radiation cross section of capture of longitudinally polarized neutrons in a sample of natural lead is measured. The experiment was performed at PF1B facility at the Institut Max von Laue-Paul Langevin. The neutron polarization P _n was 92%, the total flux of polarized neutrons was ～3 × 10¹⁰ n/s, and the mean neutron wavelength was λ = 4.7 Å. Taking into account “0-test” we estimated the asymmetry: a _γ(^natPb) = (2.3 ± 3.5) × 10^?7, i.e., α _γ ≤ 8.1 × 10^?7 at 90% confidence level.     

Nature of the water/aromatic parallel alignment interactions

The water/aromatic parallel alignment interactions are interactions where the water molecule or one of its O? H bonds is parallel to the aromatic ring plane. The calculated energies of the interactions are significant, up to ΔE_{CCSD(T)(limit)} = ?2.45 kcal mol^?1 at large horizontal displacement, out of benzene ring and CH bond region. These interactions are stronger than CH···O water/benzene interactions, but weaker than OH···π interactions. To investigate the nature of water/aromatic parallel alignment interactions, energy decomposition methods, symmetry‐adapted perturbation theory, and extended transition state‐natural orbitals for chemical valence (NOCV), were used. The calculations have shown that, for the complexes at large horizontal displacements, major contribution to interaction energy comes from electrostatic interactions between monomers, and for the complexes at small horizontal displacements, dispersion interactions are dominant binding force. The NOCV‐based analysis has shown that in structures with strong interaction energies charge transfer of the type π → σ*(O? H) between the monomers also exists. © 2014 Wiley Periodicals, Inc.