Synthesis of the complete carbocyclic skeleton of vinigrol

[reaction: see text] An efficient entry to the fully elaborated skeleton of vinigrol is described. The installation of the desired stereochemistry at C(12) and the construction of the eight-membered ring were achieved in one operation by a remarkably facile anionic oxy-Cope rearrangement of Z-isopropenyl isomer 24.     

Quadratic kernel-free non-linear support vector machine

A new quadratic kernel-free non-linear support vector machine (which is called QSVM) is introduced. The SVM optimization problem can be stated as follows: Maximize the geometrical margin subject to all the training data with a functional margin greater than a constant. The functional margin is equal to W ^T X + b which is the equation of the hyper-plane used for linear separation. The geometrical margin is equal to . And the constant in this case is equal to one. To separate the data non-linearly, a dual optimization form and the Kernel trick must be used. In this paper, a quadratic decision function that is capable of separating non-linearly the data is used. The geometrical margin is proved to be equal to the inverse of the norm of the gradient of the decision function. The functional margin is the equation of the quadratic function. QSVM is proved to be put in a quadratic optimization setting. This setting does not require the use of a dual form or the use of the Kernel trick. Comparisons between the QSVM and the SVM using the Gaussian and the polynomial kernels on databases from the UCI repository are shown.     

Diet variability of Mediterranean insular populations of Rattus rattus studied by stable isotope analysis

The black rat Rattus rattus is a successful colonizer that threatens native species on numerous islands. Stable isotopes of carbon and nitrogen were used to quantify the rat diet on islands off the southern French coast. Samples of rat hair and faeces and their potential food were collected on each island. The nitrogen isotopic values of invertebrates and vegetation on Riou (near Marseille) differed from the other two islands (Hyères archipelago). This was attributed to a large colony of gulls on Riou, of which rats take great advantage. A part of the observed variability was due to methodological skews: two kinds of hair gave different results and there was an effect of the season and year of sampling but inter-island differences were noticeable. In certain cases, the food source value from plants and invertebrates could supply the total food needs of rats as there was no evidence of consumption of eggs, chicks or birds.     

Cellulose based pH-sensitive hydrogel for highly efficient dye removal in water treatment: kinetic,thermodynamic, theoretical and computational studies

In this paper, a new green pH-sensitive EDTA crosslinked HEC (cellulose-based hydrogel (swelling rate?~?1005%)) adsorbent was successfully elaborated. The synthesis of HEC-EDTA at the high advanced crosslinking degree (up to 92%), was carried out using DAEDT and DMAP as acyl transfer agent, where the lamellar morphology (2D-microstructure) was highly suggested based on the average functionality of the reaction system. The crosslinking degree was confirmed using structural analyzes (FTIR and 13C CP/MAS-NMR) and elemental profile analysis. The new EDTA crosslinked HEC demonstrated a high uptake capacity (~?2000 mg g^?1) to aquatic micropollutants, especially methylene blue as cationic dyes model. The kinetic study showed that the adsorption process was well described by the pseudo-second-order kinetic, while the thermodynamic parameters exhibited a negative effect of temperature indicating a physical adsorption process. In addition, the adsorption capacity was studied varying to the experimental conditions (pH, contact time, concentration, etc.), and the Freundlich model revealed a strong correlation to the experimental data indicating an energetic heterogeneity of the surface active sites. Furthermore, using COMPASS II, the molecular dynamics (MD) simulations were conducted to optimize the chemical system, where the results showed the predominance of non-covalent molecular adsorbent-adsorbate interactions, which governs cluster design and configurations.

     

Improving the high variable bioavailability of griseofulvin by SEDDS

To enhance the dissolution and oral absorption of poorly water-soluble griseofulvin (GF), self-emulsifying drug delivery system (SEDDS) composed of oil, surfactant and cosurfactant for oral administration of griseofulvin was formulated, and its physicochemical properties and pharmacokinetic parameters were evaluated. The solubility of griseofulvin was further improved by the addition of hydrochloric acid. Droplet size of griseofulvin emulsion was kept constant both in simulated gastric fluid without pepsin and simulated intestinal fluid throughout 12 weeks incubation period. Griseofulvin in the SEDDS rapidly dissolved in different dissolution media. This was not the case for the commercial GRIS-PEG tablets. In different fed diet groups, AUC 0-->24 h, Cp max, and T max of griseofulvin after oral administration of SEDDS in rats were comparable to those after oral dose of GRIS-PEG tablet. Although, in fed lipidic diet group, the mean AUC and Cp max after oral administration of GRIS-PEG in rats were 1.28 and 1.15 fold higher, respectively, compared with those of SEDDS, these have not shown to be significantly different. These results demonstrate that the SEDDS of griseofulvin composed of Capmul GMO-50, Poloxamer and Myvacet 9-45 greatly enhanced the dissolution of griseofulvin (without ultramicronisation). However, food intake effect on the bioavailability of griseofulvin has remained. Thus, this system may provide a useful dosage form for oral water-insoluble drugs which have problems in their dissolution.     

Synthesis of allocolchicines using sequential ring-closing enyne metathesis-Diels-Alder reactions

New allocolchinoids having functionality in the C ring at position C10 or C11 have been synthesized using the enyne ring-closing metathesis (RCM) reaction for construction of the seven-membered ring and a Diels-Alder-aromatization sequence for the elaboration of the aromatic ring C. [reaction: see text].     

The Production and Evaluation of an Electrochemical Sensors for Strychnine and Its Main Metabolite Strychnine N-Oxide for Their Use in Biological Samples

Strychnine (STN) and its major metabolite Strychnine N-Oxide (SNO) were examined electrochemically. Both parent compounds and its major metabolite showed electroactivity on glassy carbon electrodes using CV and DPV techniques. One oxidation peak at 1008 mV was observed for STN with the optimum peak intensity at pH 7. SNO produced two oxidation peaks, at 617 mV and 797 mV, at pH 5. The peaks demonstrated irreversible behaviour and the irreversibility of the system was confirmed at different scan rates. A calibration curve was produced for both CV and DPV measurements and the sensitivity of the proposed EC method was good compared with previous electrochemical and non-electrochemical methods. The precision of oxidation peak of STN using the STN-MIP method produced a maximum value of 11.5% and 2.32% for inter-day and intraday %RSD, respectively. The average% recovery was around 92%. The electrochemical method has been successfully applied to the determination of STN in spiked plasma and urine samples. For SNO, both anodic peaks of SNO demonstrated irreversible behaviour. A different sweep rate was used for calculating the number of ‘transfer electrons’ in the system; based on this, the mechanism of oxidation reaction was proposed. Calibration curves for both oxidative peaks were produced using DPV measurements. The second anodic peak demonstrated high linearity and precision with %RSD < 1.96%.     

Synthesis,characterization and anticancer activity of 3-aminopyrazine-2-carboxylic acid transition metal complexes

Synthetic procedures are described that allow access to the new complexes cis-[Mo₂O₅(apc)₂], cis-[WO₂(apc)₂], trans-[UO₂(apc)₂], [Ru(apc)₂(H₂O)₂], [Ru(PPh₃)₂(apc)₂], [Rh(apc)₃], [Rh(PPh₃)₂(apc)₂]ClO₄, [M(apc)₂], [M(PPh₃)₂(apc)]Cl, [M(bpy)(apc)]Cl (M(II) = Pd, Pt), [Pd(bpy)(apc)Cl], [Ag(apc)(H₂O)₂] and [Ir(bpy)(Hapc)₂]Cl₃, where Hapc, is 3-aminopyrazine-2-carboxylic acid. These complexes were characterized by physico-chemical and spectroscopic techniques. Both Hapc and several of its complexes display significant anticancer activity against Ehrlich ascites tumour cells (EAC) in albino mice.     

New Kernel-type estimator of Shanonnʼs entropy

In the present Note, we propose an estimator of Shanonn?s entropy based on smooth estimators of quantile density. The consistency and asymptotic normality of the proposed estimates are obtained.