Determination of quinine and quinidine by continuous-flow chemiluminescence

A rapid and precise continuous-flow method is described for the determination of quinine and quinidine (5.00–500 μg ml^?1) which is based on the sensitizing effect of the compounds on the chemiluminescent oxidation of sulphite by cerium(IV). When applied to tablets, the procedure is relatively free from interferences from common excipients. The results obtained for the assay of commercial formulations compared well with those obtained by an official method and demonstrated good accuracy and precision.     

Reactions of indole derivatives with cardioprotective activity with reactive oxygen species. Comparison with melatonin

We have previously reported on the synthesis of novel indole derivatives containing an amine-triazole moiety (1a-d, 2a-c), and their antioxidant activity on in vitro non-enzymatic rat hepatic microsomal lipid peroxidation. Some of the compounds showed protective activity against oxidative injury of ischemic myocardium. In the present paper we investigated the interactions of these derivatives with reactive oxygen species, in order to find a mechanism of their antioxidant capacity and to identify structural characteristics responsible for these properties. These interactions were compared with melatonin, which is also an indole derivative. The antioxidant profiles of the compounds were established by different in vitro protocols as follows: 1) by the interaction of the compounds with the 1,1-diphenyl-2-picrylhydrazyl (DPPH) stable free radical, 2) their scavenging effects on superoxide anions using an enzymic system of xanthine-xanthine oxidase, 3) their inhibitory effects on xanthine oxidase and 4) their ability to scavenge hydroxyl radicals by comparison with dimethyl sulfoxide (DMSO) for *OH. All compounds were found to interact with DPPH, most of them to be superoxide anion scavengers and to be strong hydroxyl radical scavengers. Derivatives 1a and 1d substituted on the nitrogen of the indolic nucleus were found to have better antioxidant properties than the reference compounds used and melatonin.     

Sources and transport of hydrocarbons in the Rhone delta sediments (Northwestern Mediterranean)

Summary To assess sources and transport processes of hydrocarbons in the Rhone delta, superficial sediments were collected near the river mouth and at the limit of the continental shelf in February 85 and September 86. After spiking with perdeuterated standards and isolation of lipids, a normal-phase HPLC step permitted the separation of hydrocarbons in non-aromatics (NAH) and aromatics (PAH), and the fractionation of the latter into sub-groups as a function of the number of aromatic cycles. Analysis of fractions and quantitation of individual compounds were performed by GC and GC/MS. Hydrocarbon concentrations varied from 21.2 to 166.7 g/g for the NAH, and from 1070 to 6363 ng/g for the PAH. Relevant seasonal variations were observed, reflecting quantitative and qualitative fluctuations of inputs. Petrogenic, pyrolytic and natural derived imprints, as well as their respective contributions were evidenced by distribution patterns, values of ratios of characteristic compounds and occurrence of specific components. Pyrolytic inputs were considerably higher in winter, reflecting intense inputs from combustion processes and/or run-off. On the contrary, fossil as well as natural inputs were significantly higher in summer.     

Corrole and Porphyrin Amino Acid Conjugates: Synthesis and Physicochemical Properties

A series of conjugates of amino acids with porphyrins and corroles was synthesized. Their self‐assembling ability under defined conditions was investigated by scanning electron microscopy. The morphology and photophysical properties of these molecules were studied by absorption and fluorescence spectroscopy in solid, liquid, and self‐assembled forms. We observed that both corrole and porphyrin conjugated with the l ‐phenylalanine–l ‐phenylalanine peptide to form spherical nanostructures with bathochromic shifts in the emission spectra, indicating the formation of aggregates. These aggregates are characterized by the impressive absorption of light over nearly the whole visible range. The broadening of all bands was particularly strong in the case of corroles. The fluorescence lifetimes of self‐assembled species were longer as compared to the solid‐state form.     

Preparation of Reinforced Anisometric Patchy Supraparticles for Self-Propulsion

The preparation of fumed silica-based anisometric supraparticles with well-defined catalytically active patches suitable for self-propulsion is presented here. These sub-millimeter-sized particles can self-propel as they contain Pt-covered magnetite (Fe₃O₄) nanoparticles, where the Pt can decompose catalytically a “fuel” like H₂O₂ and thereby propel the supraparticles. By their magnetic properties, the catalytically active nanoparticles can be concentrated in patches on the supraparticle surface. The goal is to obtain robust supraparticles with well-defined patchiness and long-time stability during self-propulsion through evaporation-induced self-assembly (EISA) on a superhydrophobic surface. The latter is a major issue as oxygen evolution can lead to the disintegration of the supraparticles. Therefore, enhanced mechanical stability is sought using a number of different additives, where the best results are obtained by incorporating polystyrene microspheres followed by heat treatment or reinforcement with microfibrillated cellulose (MFC) and sodium trisilicate (Na₂SiO₃). The detailed internal structure of the different types of particles is investigated by confocal micro-X-ray fluorescence spectroscopy (CMXRF), which allows for precisely locating the catalytic Fe₃O₄@Pt nanoparticles within the supraparticles with a resolution in the µm range. The insights on the supraparticle structure, together with their long-time stability, allow fabricating optimized patchy supraparticles for potential applications in propulsion-enhanced catalysis.     

Preparation and characterization of polymer layer systems for validation of 3D Micro X-ray fluorescence spectroscopy

For the validation of the quantification of the newly-developed method of 3D Micro X-ray fluorescence spectroscopy (3D Micro-XRF) samples with a low average Z matrix and minor high Z elements are best suited. In a light matrix the interferences by matrix effects are minimized so that organic polymers are appropriate as basis for analytes which are more easily detected by X-ray fluorescence spectroscopy.     

Determination of antimicrobial activity and resistance to oxidation of moringa peregrina seed oil

The antimicrobial activity of the oil extracted with n-hexane from the seeds of Moringa peregrina was tested against Staphylococcus aureus, S. epidermidis, Pseudomonas aeruginosa, Escherichia coli, Enterobacter cloacae, Klebsiella pneumoniae, Candida albicans, C. tropicalis and C. glabrata. The oil proved effective against all of the tested microorganisms. Standard antibiotics (netilmycin, 5-flucytocine, intraconazole and 7-amino-4-methylcoumarin-3-acetic acid) were used for comparison. The resistance to oxidation of the extracted seed oil was also determined.