Scielo RSS <![CDATA[Journal of the Chilean Chemical Society]]> https://scielo.conicyt.cl/rss.php?pid=0717-970720110004&lang=es vol. 56 num. 4 lang. es <![CDATA[SciELO Logo]]> https://scielo.conicyt.cl/img/en/fbpelogp.gif https://scielo.conicyt.cl <![CDATA[<b>FLAVONOL PROFILES FOR VARIETAL DIFFERENTIATION BETWEEN CARMÉNÈRE AND MERLOT WINES PRODUCED IN CHILE</b>: <b>HPLC AND CHEMOMETRIC ANALYSIS</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400001&lng=es&nrm=iso&tlng=es Wine differentiation is an important issue for the Chilean winemaking industry, especially for the Carménère variety, which was rediscovered in this country around 20 years ago. Authentication parameters are required for this wine due to its frequent confusion with Merlot. The concentration of anthocyanins, shikimic acid, and the principal flavonols found in wine allowed some varietal differentiation between Carménère and Merlot wines. Myricetin and quercetin are the most concentrated flavonols in wine in which they are present in free and conjugated forms. These compounds are responsible for important wine antioxidant properties. In the present work, using only the concentrations of free and conjugated quercetin and myricetin, differentiation between Carménère and Merlot varieties was better achieved. Flavonol profiles of wine produced in Chile were studied with HPLC-DAD-ESI-MSn. An overview of the concentration range of flavonols present in 248 Chilean red wines is presented, finding that the mean concentration of the sum of total myricetin and total quercetin were higher in Carménère (81.5 mgL-1) and Merlot (78.9 mgL¹) than in Cabernet Sauvignon (53.9 mgL¹) wines. These mean levels were higher than the majority of the concentrations reported in the literature. The chemometric analysis shows that the ratio of total quercetin/total myricetin combined with the concentration of free myricetin allowed the varietal differentiation between Carménère and Merlot wines. <![CDATA[<b>A NEW METHOD FOR ONE-POT SYNTHESIS OF ARYLOXYPHENOXYPROPIONATE HERBICIDES USING 2,4,6-TRICHLORO-1,3,5-TRIAZINE AND (<em><sup>n-</sup></em>BU)<sub>4</sub>NI AS A HOMOGENEOUS CATALYST</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400002&lng=es&nrm=iso&tlng=es The one-pot reaction of halo-heterocycle, (R)-4-hydroxyphenoxy propionic acid and an alcohol, amine or sulfonamide is described as an efficient method for the synthesis of aryloxyphenoxy propionate hrerbicides by using 2,4,6-trichloro-1,3,5-triazine in the presence of (n-BU)4NI, as a homogeneous catalyst under mild conditions. The present procedure offers several advantages, such as good yields, short reaction times and easy workup. <![CDATA[<b>ELECTROCHEMICAL INVESTIGATION OF CYSTEAMINE AT CARBON FIBER MICRODISK ELECTRODE</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400003&lng=es&nrm=iso&tlng=es The electrooxidation of cysteamine compound was carried out using convolutive cyclic voltammetry, linear sweep voltammetry and chronoamperomtry techniques at a carbon fiber microdisk electrode in 0. 1 M perchloric acid. The electrooxidation potential (E0'' ) of cysteamine occurs at + 0.921 V. The mechanistic pathway of electrooxidation process at carbon fiber microelectrode is loss of 1 electron per molecule. The electrode process is controlled mainly by diffusion. The chemical and electrochemical parameters of the investigated system were determined experimentally and verified theoretically via digital simulation method. <![CDATA[<b>PROTONATION EQUILIBRIA OF L-DOPA AND 1,10 PHENONTHROLINE IN PROPYLENE GLYCOL-WATER MIXTURES</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400004&lng=es&nrm=iso&tlng=es Protonation equilibria of L-Dopa and 1,10 phenonthroline have been studied in varying concentrations (0-60% v/v) of propylene glycol-water mixtures maintaining an ionic strength of 0.16 mol dm-3 at 303 K using pH metric method. The protonation constants have been calculated with the computer program MINIQUAD75 and the best fit models are arrived at based on statistical grounds employing crystallographic R factor, χ2 , skewness and kurtosis. Dopa has three dissociable protons and one amino group which associate with proton. It exists as LH4+ at low pH and gets deprotonated with the formation of LH3, LH2- and LH2- successively with increase in pH. Phen forms LH2(2+) at low pH and gets deprotonated with the formation of LH+ and L with increase in pH. Secondary formation functions confirm the existence of 3 and 2 protonation equilibria for dopa and phen, respectively. The linear increase of log values of protonation constants of Dopa with decreasing dielectric constant of PG-water mixtures indicates the dominance of electrostatic forces in the protonation-deprotonation equilibria. Phen exhibits non-linear trend indicating the dominance of non-electrostatic forces. <![CDATA[<b><i>iN</i></b><b><i>-VITRO</i> INTERACTION STUDIES OF VERAPAMIL WITH FLUOROQUINOLONES USING FIRST ORDER</b> <b>DERIVATIVE UV SPECTROPHOTOMETRY AND RP-HPLC</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400005&lng=es&nrm=iso&tlng=es Verapamil, a calcium channel blocker, is classified as a class IV anti-arrhythmic agent. It is used in the treatment of hypertension, as an important therapeutic agent for angina pectoris, ischemic heart disease, hypertension and hypertrophic cardiomyopathy. Many in-vivo studies have been carried out to find out the effects on concurrent use of calcium channel blocker with various groups of drugs. In the present paper an in-vitro approach was adapted to study the interaction of verapamil with commonly administered fluoroquinolones i.e. ciprofloxacin, levofloxacin, norfloxacin and sparfloxacin. The interaction studies were carried out in different simulated body fluids pH ranges from 1-9 at 37 ºC. To perform these studies first-derivative UV spectrophotometric (using zero-crossing technique) and simultaneous RP-HPLC methods were developed and validated. HPLC analysis was conducted on Shim-pack CLC-ODS (6.0 X 150 mm) column. The mobile phase constituted of acetonitrile: water (45:55), whose pH was adjusted to 2.8 and pumped at a flow rate of 1.2 mL min-1 at 230 nm. The results obtained from both methodologies indicated that the availability of verapamil was not affected by simultaneous administration of fluoroquinolones. Hence the two drugs could be safely administered concomitantly. <![CDATA[<b>SYNTHESIS, CHARACTERIZATION AND ANTIHYPERTENSIVE ACTIVITY OF SOME NEW SUBSTITUTED PYRIDAZINE DERIVATIVES</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400006&lng=es&nrm=iso&tlng=es Some new 6-(substituted phenyl)-2-(4-substituted phenyl-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-3-yl)-4,5-dihydropyridazin-3(2H)-one derivatives were synthesized by a sequence of reactions starting from respective aryl hydrocarbons. The final compounds (4a-i) were screened for antihypertensive activities by non-invasive method using Tail Cuff method. The compounds 4e and 4i showed appreciable antihypertensive activity. <![CDATA[<b>BIOMIMETIC CALCIUM CARBONATE IN THE CARBOXYMETHYL CHITOSAN /BOVINE</b> <b>SERUM ALBUMIN SYSTEM</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400007&lng=es&nrm=iso&tlng=es Being a biocompatible, biodegradable and bioactive material, chitosan in the form of membranes offers a great potential as a substrate in mineralization processes in vitro. In the present work, chitosan with (without) bovine serum albumin used as templates induced the formation of calcium carbonate. The unusual morphology of calcium carbonate was get from the chitosan /bovine serum albumin system. The CaCO3 crystals obtained in system were characterized by scanning electron microscopy, Fourier transform infrared spectrography and powder X-ray diffractometry. The possible formation mechanism of CaCO3 was discussed. <![CDATA[<b>REGIOSELECTIVE AND HIGH-YIELDING BROMINATION OF PHENOLS AND ANILINS USING</b> <em><b>N</b></em><b>-BROMOSACCHARIN AND AMBERLYST-15</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400008&lng=es&nrm=iso&tlng=es A regioselective and facile conversion method for bromination of anilines and phenols using N-bromosaccharine in the presence of a catalytic amount of Amberlyst-15 lead to enhancement of the reaction rate and yielded brominated products in good to excellent yields and short reaction times. <![CDATA[<b>SYNTHESIS OF 1-BENZYL-3-[4-(ARYL-1-PIPERAZINYL) CARBONYL]-1H-INDOLES</b>: <b>NOVEL LIGANDS WITH</b> <b>POTENTIAL D4 DOPAMINERGIC ACTIVITY</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400009&lng=es&nrm=iso&tlng=es The synthesis of a series of functionalized 1-Benzyl-3-[4-Aryl-1-piperazingl]carbonyl-1H-Indoles 6(a-f), as a potential new class of bioactive ligands at D4 receptors is reported. The synthetic strategy took place through a five steps sequence to provide indole amides 6(a-f) in 75-92% yield. <![CDATA[<b>INVESTIGATION INTO THE REGIOCHEMISTRY OF SOME PYRAZOLES DERIVED FROM 1, 3-DIPOLAR CYCLOADDITION OF ACRYLONITRILE WITH SOME NITRILIMINES</b>: <b>THEORETICAL AND</b> <b>EXPERIMENTAL STUDIES</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400010&lng=es&nrm=iso&tlng=es 1,3-dipolar cycloaddition between acrylonitrile and two N-(4-substituted)phenyl-C-(4-chlorophenyl)nitrilimines which were generated in situ afforded the new pyrazoles. The regiochemistry and reactivity of these reactions has been investigated on the basis of density functional theory (DFT) -based reactivity indexes and activation energy calculations. The theoretical 13C NMR chemical shifts of the cycloadducts which were obtained by GIAO method were comparable with the observed values. <![CDATA[<b>CERIMETRIC DETERMINATION OF FOUR ANTIHYPERTENSIVE DRUGS IN PHARMACEUTICAL</b> <b>PREPARATIONS</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400011&lng=es&nrm=iso&tlng=es A sensitive spectrophotometric method is described for the determination of atenolol (ATE), timolol maleate (TIM), captopril (CPL) and diltiazem hydrochloride (DIL.HCl) in bulk drugs and in pharmaceutical preparations. The method is based on the oxidation of the studied drugs by a known excess of cerric (IV) in acid medium followed by determination of unreacted oxidant by adding a fixed amount of methyl orange dye (MO) and the increasing in absorbance is measured at 510 nm. In this method the amount of cerium (IV) reacted corresponds to drugs concentration. The experimental conditions were optimized. Regression analysis of a Beer's plot showed good correlation in the concentration ranges of 3.2-6.4, 8.0-18, 3.4-5.2 and 3.6-5.2 µg/ml for ATE, TIM, CPL and DIL.HCl, respectively. The calculated molar absorptivity values are 5.28x10(4), 3.27x10(4), 6.43x10(4) and 1.12x10(5) L /mol cm, respectively and the corresponding Sandell's sensitivity values are 5.043, 13.2, 3.381 and 4.024 ng/cm², respectively. The limit of detection (LOD) and quantification (LOQ) are reported. No interference was observed from the additives and the applicability of the method was tested by analyzing the pharmaceutical preparations containing the investigated drugs. Statistical comparison of the results with those of official methods shows excellent agreement and indicates no significant difference in precision. <![CDATA[<b>HPLC DETERMINATION OF ETOPOSIDE IN INJECTABLE DOSAGE FORMS</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400012&lng=es&nrm=iso&tlng=es 1. The present study describes a direct and an alternative HPLC method for the determination of etoposide in injectable dosage forms. Etoposide, an antineoplastic drug, was eluted through C18 ODS Hypersil column of 250 ÷ 4.6 mm id with 5 ìçé particle size using simple mobile phase of methanol: water (1:1, v/v) at a flow rate of 1.0 mL min¹ and detected at 204 nm. The limit of detection of etoposide was 0.03 µg mL-1. The proposed method was found linear in the range of 0.25 µg mL¹ to 62.5 µg mL¹ and CV was 1.3% at 0.25 µg mL¹ , 0.48% at 3.90 µg mL¹ and 0.13% at 62.5 µg mL¹. The accuracy of the developed method for two injectable dosage forms was 99.4 and 99.7% with RSD of 0.3%. The validation results and statistical data demonstrate that the method is simple, cost effective, reproducible and suitable in quality analysis of the active ingredient and dosage form. <![CDATA[<b>HIGHLY EFFICIENT AND VERSATILE ACETYLATION OF ALCOHOLS, PHENOLS AND AMINES CATALYZED BY METHYLENEDIPHOSPHONIC ACID (MDP) UNDER SOLVENT-FREE CONDITIONS</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400013&lng=es&nrm=iso&tlng=es Methylenediphosphonic Acid (MDP) was found to be a simple, cheap and reusable heterogeneous catalyst for the acetylation of structurally diverse alcohols, phenols and amines with acetic anhydride under solvent-free conditions at room temperature. This method showed preferential selectivity for the acetylation of the amino group in the presence of hydroxyl group. The method is very mild and the yields were in excellent. <![CDATA[<b>SYNTHESIS OF β</b><b>-DIKETIMINATE DERIVATIVES OF ZINC ALKOXIDES</b>: <b>CATALYTIC PROPERTIES FOR RING OPENING POLYMERIZATION</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400014&lng=es&nrm=iso&tlng=es A series of zinc (II) complexes has been prepared based on a β-diketiminate ligand framework and exhibits the highest rate of polymerization with better stereoselectivity in the formation of polylactic from the rac-lactide with aggregation and narrow polydisperties. Degree of aggregation and their reactivity's depends on the nature of alkoxy groups, the role of metal ion, solvent and their structural properties. The nature of substituent group on β-diketiminate ligand exerts a significant change affecting both the degree of selectivity and the rate of polymerization. The polymerizations are living, as evidenced by the narrow polydisperties and with their linear nature and average molecular weight. <![CDATA[<b>PREPARATION AND PHYSICOCHEMICAL EVALUATION OF BIODEGRADABLE MAGNETIC</b> <em><b>Κ</b></em><b>-CARRAGEENAN</b> <b>BEADS AND APPLICATION FOR CHROMIUM IONS PRE-CONCENTRATION</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400015&lng=es&nrm=iso&tlng=es This study aims to examine the ability of magnetic K-carrageenan beads as an adsorbent in solid phase extraction towards chromium ions from aqueous solution. In this study, K-carrageenan magnetic gel-beads were obtained via interphase technique. The beads were kept in 0.3 M KCl to maintain gel strength. Physicochemical of the resulting materials were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and magnetometer. FTIR results have confirmed the presence of functional groups such as sulphate esters groups. The diameter of carrageenan beads was about ~764 µm where SEM micrographs showed the spherical formed shape of carrageenan beads and a rough surface with pores. The saturation magnetization value, M, of carrageenan beads in this study was 18.78 EMU/g. The magnetic function of carrageenan beads is to facilitate bead collection and to get the Cr6+ ion that adsorbed onto the beads. The adsorption of chromium ions by magnetic carrageenan beads are through an ion exchange mechanism and formation of metal-ligand complex. Optimal timing for adsorption of chromium ions was at 60th minute. The optimal operation conditions can be achieved on pH value~1 and concentration of 100 ppm. Langmuir adsorption isotherm curve for Cr6+ is similar to Langmuir adsorption isotherm types III (unfavorable). <![CDATA[<b>REACTION KINETICS OF METHANE COMBUSTION OVER La<sub>1-x</sub> Ca FeO<sub>3</sub> PEROVSKITES</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400016&lng=es&nrm=iso&tlng=es The reaction kinetics of methane combustion over La1-xCa xFeO3 perovskites (x=0.0, 0.2, 0.4) was studied. The results show that the catalytic activity is higher in the calcium-doped perovskites. It is found that this higher catalytic activity is related to a lower activation energy. The value of the activation energy is not affected by the level of Ca-doping. The observed difference in the catalytic activity between the doped perovskites is interpreted as a consequence of the so-called compensatory effect, i.e., a larger pre-exponential factor which results from the higher number of active sites promoted by defect reactions triggered by the substitution of lanthanum by calcium. The substitution of lanthanum by a lower valence cation, as calcium, entails both the formation of oxygen vacancies and oxidation of some iron ions from Fe3+ to Fe4+, in order to preserve the electroneutrality. The oxygen vacancies account for the increasing participation of lattice oxygen in the combustion kinetics as the calcium doping increases. The experimental results were satisfactorily fitted to the Rideal-Elay mechanism. <![CDATA[<b>DILUTED ACID PRETREATMENT OF <i>PINUS RADIATA</i> FOR BIOETHANOL PRODUCTION USING IMMOBILIZED <i>SACCHAROMYCES CEREVISIAE</i> IR2-9 IN A SIMULTANEOUS SACCHARIFICATION AND</b> <b>FERMENTATION PROCESS</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400017&lng=es&nrm=iso&tlng=es The production of bioethanol from pretreated lignocellulosic materials requires the utilization of microorganisms adapted to ferment the materials in conditions were high consistency, temperatures and inhibitors concentrations were commonly found. The yeast immobilization in calcium alginate capsules has been reported to enhance the yeast protection and increase the efficiency in the fermentation process. In this work, it was investigated the use Saccharomyces cerevisiae immobilized in calcium alginate and its performance in simultaneous saccharification and fermentation (SSF) of diluted-acid-pretreated Pinus radiata. Results showed that when immobilized yeast was used, the bioethanol yield from pretreated wood was higher than with free yeast cells during a SSF process. Maximum ethanol yield obtained from the acid pretreated and milled wood chips was 153 L/ton wood, while from the hydrolysate fraction it was 18 L/ton wood. The sum of ethanol produced from dilute acid pretreated P. radiata for both solid and liquid fractions was 171 L ethanol/ton wood from a maximum theoretical of 236 L/ ton pretretated wood (or 72% of conversion). <![CDATA[<b>INFLUENCE OF SILICA NANOPARTICLES ON THE THERMOMECHANICAL PROPERTIES OF RECYCLED</b> <b>POLYSTYRENE</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400018&lng=es&nrm=iso&tlng=es Polystyrene from packing materials (rPS) was reinforced with 1, 3 and 5 % of silica prepared by the sol-gel method, through a blending process . The thermal, morphological and mechanical properties were compared with those of the virgin polystyrene (PS). The results show that the glass transition temperature (Tg), storage modulus (E') and impact strength of the pure rPS and silica-rPS composites were higher than those of virgin PS. Thermogravimetric analysis revealed that the thermal stability of virgin PS was slightly greater than that of the rPS. The addition of silica to rPS increased their thermal stability to similar values of the virgin PS. SEM studies showed that the silica nanoparticles had an uniform size but its dispersion into the polymer matrix was not homogeneous. These results suggest that postconsumer PS can be used to obtain composite materials with good mechanical and thermal properties. <![CDATA[<b>SYNTHESIS, CHARACTERIZATION AND ANTIOXIDANT ACTIVITY OF SOME TRANSITION METAL</b> <b>COMPLEXES WITH TERPENOID DERIVATIVES</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400019&lng=es&nrm=iso&tlng=es A series of transition metal complexes of Fe(III), Co(II) and Cu(II) containing the bidentate N,O and N,S donor ligand, camphor semicarbazone (1,7,7-trimethylbicyclo [2,2,1]heptanesemicarbazone, TBHSC) and camphor thiosemicarbazone (1,7,7- trimethylbicyclo [2,2,1]heptanethiosemicarbazone, TBHTSC) have been synthesized and characterized by elemental analysis, molar conductance measurement and various spectral studies (IR, electronic and FAB Mass) and thermogravimetric analysis (TGA). All the metal complexes (1-8) are [M(LH)Cl2] and [M(LH)2Cl2] type, where M = Fe(III), Co(II) and Cu(II); LH = TBHSC and TBHTSC. TBHSC and TBHTSC act as neutral bidentate ligands in all the complexes. FAB mass spectroscopic studies of the three representative complexes (1), (2), (4), (5) and (8) suggest their monomeric nature. The proposed geometries of the complexes were octahedral geometry for 1:2 complexes, square planar for 1:1 complexes and distorted octahedral for Cu(II) complexes (1:2). The free radical scavenging activity of newly synthesized ligands (TBHSC, TBHTSC) and their metal complexes have been determined at the concentration range of 50-1000 μg/ml by means of their interaction with the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH). All the compounds have shown encouraging antioxidant activities. The least IC50 value (111.0 μg/ml) for compound (5) showed the potent scavenging property compared to other test compounds. <![CDATA[<b>MORPHOLOGY AND THERMAL BEHAVIOUR OF POLY(METHYL METHACRYLATE)/POLY(ETHYLENE GLYCOL) SEMI-INTERPENETRATING POLYMER NETWORKS</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400020&lng=es&nrm=iso&tlng=es Poly(methyl methacrylate) (PMMA) networks and linear poly(ethylene glycol) (PEG) can form semi-interpenetrating polymer networks (semi-IPNs), i.e. PMMA/PEG semi-IPNs. The morphology and thermal behaviors of PMMA/PEG semi-IPNs was studied by DSC, TEM, Optical Microscopy, and SEM. The results indicated that the content of PEG and the cross-linking density of PMMA networks have an important influence on the phase separation in the PMMA/PEG semi-IPNs. When the content of PEG and cross-linking density is more than 35 and 3.5 wt%, respectively, PMMA/PEG semi-IPNs are a mixture of PEG in the crystalline state with PMMA networks in the amorphous state. <![CDATA[<b>STUDY OF THERMODYNAMIC AND NMR PROPERTIES OF SOME CYCLOHEXANE DERIVATIVES</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400021&lng=es&nrm=iso&tlng=es The preferential conformations of a series of six-membered saturated heterocycles containing oxygen and sulfur atoms, 4-alkyl-6-methyl-1,3-dithiane, with alkyl=methyl, ethyl, propyl, isobuthyl, terbuthyl have been studied by means of ab-initio theoretical methods. The chair conformation is the most stable structure found for all compounds studied here, likewise in its counterparts: cyclohexane, dithiane, and dioxane. The structures show anomalous effects of the chemical shifts, in C2 and C5, due to a σ C-S → σ* C-Hec hyperconjugative interaction. They are also affected by normal Perlin effect in C2, where C2-Hec coupling constants are larger than C2-Hax. <![CDATA[<b>EXTRACTIVE SPECTROPHOTOMETRY METHODS FOR DETERMINATION OF RASAGILINE MESYLATE IN PHARMACEUTICAL FORMULATIONS USING ACIDIC TRIPHENYLMETHANE DYES</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400022&lng=es&nrm=iso&tlng=es Three simple and sensitive extractive spectrophotometric methods have been described for the assay of Rasagiline mesylate either in pure form or in pharmaceutical formulations. The developed methods involve formation of coloured chloroform extractable ion-pair complexes of the drug with bromothymol blue (BTB), bromophenol blue (BPB) and bromocresol green (BCG) in acidic medium. The extracted complexes showed absorbance maxima at 414 nm for all three methods. Beer's law is obeyed in the concentration ranges 3.0-30, 3.0.0-30 and 2.0-25µg/ml with BTB, BPB and BCG respectively. The effect of concentration of dye, pH, and interference of excipients have been studied and optimized. The limits of detection and quantification have been determined for three methods. All the three methods have been validated as per the guidelines of ICH. The methods have been applied to the determination of drug in commercial tablets and results of analysis were validated statistically through recovery studies. <![CDATA[<b>SYNTHESIS AND EVALUATION OF 5-(6-METHOXYNAPHTHALEN-2-YL)-1-ARYL-1-(4-(TRIFLUOROMETHYL)PHENYLAMINO)PENTAN-3-ONE AS POTENTIAL ANTIDIABETIC AGENTS</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400023&lng=es&nrm=iso&tlng=es We wish to report a set of seventeen ketones bearing nabumetone and trifluoro- methylaniline(TFMA) moieties. Synthesized via direct Mannich reaction in a solution of ethanol- chloroform catalyzed by concentrated hydrochloric acid, the chemical structures of these compounds were characterized by IR, ¹H NMR, 13C NMR, ESI MS and HR MS. Studies on their antidiabetic activities revealed that all title compounds possessed moderate α-glucosidase inhibitory activities and protein tyrosine phosphatase 1B (PTP 1B) inhibitory activities. Among them, a few compounds also exhibit considerable peroxisome proliferator-activated receptor response element (PPRE) agonist activity, in particular the relative PPRE agonist activity of compounds 1r and 1l reached 54.02% and 57.60%, respectively. These results represent significant examples of new molecular type for antidiabetic agents that merit further evaluation. <![CDATA[<b>ISOFLAVANS DERIVATIVES AS INHIBITORS OF SOYBEAN LIPOXYGENASE</b>: <b><i>IN-VITRO</i> AND DOCKING STUDIES</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400024&lng=es&nrm=iso&tlng=es The lipoxygenases (LOX) are a family of non-heme iron-containing dioxygenases which catalyze the stereospecific insertion of molecular oxygen into arachidonic acid, leading to hydroxy derivatives as end products. In this work, we studied the behavior of seven isoflavans on 15-soybean lipoxygenases (15-sLOX), comparing them with the known inhibitors quercetin and 3, 4-dihydroxybenzoic acid. Four of the seven investigated isoflavans showed IC50 values smaller than 50 µM , being more potent than quercetin or 3, 4-dihydroxybenzoic acid. Besides a catecholic pattern, the presence of an aromatic ring B seems to confer additional activity to these compounds, a result which was rationalized by docking studies of these isoflavanss into the enzyme binding site. <![CDATA[<b>AN AUTOMATED METHOD FOR DETERMINATION OF ASCORBIC ACID IN URINE BY FLOW INJECTION CHEMILUMINESCENCE COUPLING WITH ON-LINE REMOVAL OF INTERFERENCE</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400025&lng=es&nrm=iso&tlng=es A simple and automated method for determination of ascorbic acid (AA) in complex samples by flow injection chemiluminescence (FI-CL) was presented. It is based on the inhibitory effect of ascorbic acid on the chemiluminescence reaction between luminol and hydrogen peroxide in the flow system. A home-made micro column of cation exchange resin was adapted to the FI manifold to achieve on-line removal of interference. This method was used to determine the AA content in urine samples with a detection limit of 6.03 x10(9) mol/L AA and recovery of 93.1-111.0%. This proposed method allows high - throughput determination of AA in urine samples without chromatographic separation, demonstrating that the FI-CL method has significant potential in determination of species in complex samples by adapting a micro column filled with various functionalized materials to the FI manifold. <![CDATA[<b>PROGRESS OF TOTAL PETROLEUM HYDROCARBONS (TPH<sub>s</sub>) TREATED WITH BIOSOLVENT IN A SIMULATED OIL SPILL ON SANDY BEACH MICROCOSMS</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400026&lng=es&nrm=iso&tlng=es Experiments with microcosms of sand corresponding to high, mid and low intertidal area were contaminated with crude oil and treated with biosolvent. Two treatments were done. The first (treatment 1) treating the sand 5 days before the event of contamination and the second (treatment 2) treated immediately after the contamination. The degradation of total TPH after 90 days ranged from 44 to 78%. However, the first 10 days were very important in terms of degradation and it slowed down significantly until 90 days. The degradation rate for light fractions in treatment 1 was slightly slower than treatment 2. On the other hand, for heavier fractions the degradation rate of heavier fractions in treatment 1 was at least twice as faster than treatment 2. Implicating that pre-treating the samples with biosolvent some days before the event of contamination may accelerate the degradation process of heavier fraction that are more difficult to degrade. The biosolvent used was degraded in a range from 55 to 100% showing that the biosolvent employed was biodegradable. <![CDATA[<b>SYNTHESIS, CHARACTERIZATION AND THERMAL STUDIES OF WHOLLY AROMATIC POLY(IMIDE-AMIDES) CONTAINING SI AND/OR GE IN THE MAIN CHAIN</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400027&lng=es&nrm=iso&tlng=es Poly(imide-amides) (PIAs) containing the heteroatoms Si and/or Ge in the main chain were obtained from diacids, which were synthesized from trimellitic anhydride and the diamines bis(4-aminophenyl)diphenylsilane or bis(4-aminophenyl)diphenylgermane. With the same diamines the polymers containing the heteroatoms Si and Ge in the main chain were obtained. Polymers were soluble in aprotic polar solvents and characterized by IR and ¹H, 13C and 29Si NMR spectroscopy, and the results were in agreement with the proposed structures. Low inherent viscosity values (ηinh) (0.04 - 0.12 dL/g) were obtained, indicating the presence of oligomeric species. The Tg values were obtained by differential scanning calorimetry (DSC), and the results did not show a relation with the nature of the heteroatoms, in the sense that the polymers with Si should have higher Tg values than those with Ge due to the lower volume of the former atom. Also, the low values of ηinh associated to low molecular weight species, have important influence on Tg values. The thermal decomposition temperatures were obtained by dynamic thermogravimetry. These analyses showed that the highest thermal decomposition temperature (TDT) values were obtained for PIA-II and PIA-III with Si and Ge in the repeating unit, and the lowest TDT values with two Si atoms in the unit. <![CDATA[<b>KINETICS OF P - NITROPHENYL ACETATE HYDROLYSIS CATALYZED BY </b><b>α</b><b>- CHYMOTRYPSIN IN PRESENCE OF POLYETHYLENE GLYCOL</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400028&lng=es&nrm=iso&tlng=es The effect of poly (ethyleneglycol) (PEG) addition on the rate of p-nitrophenyl acetate (PNPA) catalyzed by a- chymotrypsin has been measured in TRIS buffer at pH = 7.4. The presence of PEG (up to 30 % p/v) leads to an increase in the rate of the process. The effect of PEG is evident both, in the pre-steady state and steady state stages of the process. The reaction follows a Michaelis-Menten mechanism under all the conditions employed. The Michaelis constant slightly decreases and the catalytic rate constant slightly increases with PEG concentration over all the polymer concentration range employed (up to 30%). The decrease in the Michaelis constant suggests that the effect of the polymer is due to crowding. <![CDATA[<b>PREPARATION AND CHARACTERIZATION OF THE EMAMECTIN BENZOATE/HYDROXYPROPYL-B-CYCLODEXTRIN INCLUSION COMPLEX</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072011000400029&lng=es&nrm=iso&tlng=es The objective of this study was to prepare an inclusion complex of the insecticide emamectin benzoate (EB) with hydroxypropyl-β-cyclodextrin (HO-β-CD) by co-evaporation and spray drying methods. The complexation of both compounds was evaluated on the aqueous and solid state using phase solubility diagrams, differential scanning calorimetry (DSC), X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The aqueous solubility of the inclusion complexes at pH 8 had a 2-fold increase respect to the drug alone and dissolution profiles showed a rise in the dissolution rate. These results suggest that the use of HO-β-CD could be an interesting alternative to enhance the bioavailability of EB in salmons.