Antibacterial Efficacy of Dihydroxylated Chalcones in Binary and Ternary Combinations with Nalidixic Acid and Nalidix Acid-Rutin Against Escherichia coli ATCC 25 922

In order to determine the existence of synergism, the bacteriostatic action of flavonoids against Escherichia coli ATCC 25 922 between dihydroxylated chalcones and a clinically interesting conventional antibiotic, binary combinations of 2′,3-dihydroxychalcone, 2′,4-dihydroxychalcone and 2′,4′-dihydroxychalcone with nalidixic acid and its ternary combinations with rutin (inactive flavonoid) were assayed against this Gram negative bacterium. Using a kinetic-turbidimetric method, growth kinetics were monitored in broths containing variable amounts of dihydroxychalcone alone, combinations of dihydroxychalcone variable concentration-nalidixic acid constant concentration and dihydroxychalcone variable concentration-nalidixic acid constant concentration-rutin constant concentration, respectively. The minimum inhibitory concentrations of dihydroxychalcones alone and its binary and ternary combinations were evaluated. All chalcones, and their binary and ternary combinations showed antibacterial activity, being rutin an excellent synergizing for the dihydroxychalcone-nalidixic acid binary combination against E. coli ATCC 25 922. Thus, this synergistic effect is an important way that could lead to the development of new combination antibiotics against infections caused by E. coli.Fil: Talia, Juan Manuel. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis; ArgentinaFil: Tonn, Carlos Eugenio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; ArgentinaFil: Debattista, Nora Beatriz. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia; ArgentinaFil: Pappano, Nora Beatriz. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia; Argentin

Experiencia de laboratorio para el estudio de reacciones que involucran radicales libres

Los radicales libres y su efecto sobre la salud humana son de importancia creciente, debido a que diversas especies oxidantes reactivas, que contribuyen al fenómeno conocido como estrés oxidativo en el organismo, están involucradas en muchos procesos patológicos como por ejemplo inflamación, aterosclerosis, cáncer, envejecimiento prematura, etc.Free radicals and their effect on human health have a high importance. There are diverse reactive oxygen species that contribute to oxidative stress on human organism. These species are involved in many pathological processes such as inflammation, atherosclerosis, cancer, agung, etc. In the present work an experience of laboratory is proposed, in wich superoxide anion radical is generated and detected. This practice can be developed in subjects as Physical Chemistry of Chemistry, Biochemistry, Chemical Analyst careers.Fil: Montaña, Maria Paulina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Área de Química Física; ArgentinaFil: Debattista, Nora Beatriz. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Área de Química Física; ArgentinaFil: Pappano, Nora Beatriz. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Área de Química Física; Argentin

New antimicrobial combinations: substituted chalcones- oxacillin against methicillin resistant Staphylococcus aureus

Staphylococcus aureus, the most virulent Staphylococcus species, is also the prevalent pathogen isolated from hospitalized patients and the second most common from patients in outpatient settings. In general, bacteria have the genetic ability to transmit and acquire resistance to drugs, which are utilized as therapeutic agents. Related studies of antimicrobial activity indicate that crude extracts containing flavonoids, triterpenes and steroids have showed significative activity against several Staphylococcus aureus strains. Combination effects between flavonoids and antibiotics also have been reported. The aim of the present work was to investigate in vitro synergism between several chalcones substituted in combination with oxacillin, an antibiotic used conventionally against S. aureus ATCC 43 300 that is resistant to meticillin, using the kinetic turbidimetric method developed earlier. The results were satisfactory for all assayed combinations and in accordance with the mechanism of bacteriostatic inhibition previously proposed, except for 2´,4´-dihydroxy-3´-methoxychalcone - oxacillin. The best combination was 2´,3´-dihydroxychalcone - oxacillin (MIC: 11.2 μg/mL). Further investigations are needed to characterize the interaction mechanism with antibiotics. Thus, chalcones - oxacillin combination could lead to the development of new antibiotics against methicillin resistant S. aureus infection

Fenómenos de transporte aplicados a productos de interés farmacéutico

El diseño de fármacos de aplicación transdermal requiere el conocimiento previo de los fenómenos de difusión por los que se ve afectado el principio activo para alcanzar la circulación sanguínea. Estos conceptos se aplicaron al estudio de la permeación de compuestos de uso farmacéutico, quercetina y probenecid, de dosis terapéutica conocida en la administración por vía oral. Se diseñó un sistema in vitro que, simulando las condiciones in vivo, permitió determinar los parámetros fisicoquímicos de estas formulaciones transdermales. Se llevaron a cabo experiencias de permeación, utilizando, como membranas, piel de oreja y abdomen de cerdo dermatomizada, los principios activos se formularon en excipientes adecuados y a determinadas concentraciones. De acuerdo a los resultados obtenidos, se pudo concluir que, si bien, quercetina presenta valores de flujo y coeficientes de difusión más elevados que los de probenecid, ambos podrían ser administrados por vía transdermal.The transdermal application drug design requires the previous knowledge of the diffusion phenomena by which it is affected the active principle to reach the sanguineous circulation. These concepts were applied to the study of the permeación of composed of pharmaceutical use, quercetin and probenecid, of well-known therapeutic dose in the administration by oral route. A system in vitro was designed that, simulating the in vivo conditions, it allowed to determine physical chemistry parameters of these transdermals formulations. Permeation experiences were carried out, using, like membranes ear and abdomen pig skin, the active principles in suitable excipients and at determined concentrations were formulated. According to the obtained results, it was possible to be concluded that, although, quercetin presents flow and diffusion coefficient values more elevated that those of probenecid, both could be administered by transdermal route.Fil: Olivella, Mónica Susana. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Área de Química Física; ArgentinaFil: Lhez, Lucia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Área de Química Física; ArgentinaFil: Pappano, Nora Beatriz. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Área de Química Física; ArgentinaFil: Debattista, Nora Beatriz. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Área de Química Física; Argentin

Effects of dimethylformamide and l-menthol permeation enhancers on transdermal delivery of quercetin

In this work a feasibility study of transdermal delivery system for quercertin (Q) in carbopol gel through abdominal hairless pig skin in vitro was performed. Dimethylformamide (DMF) and L-menthol (M) were selected as enhancers. Permeation experiences were carried out by using Franz-type diffusion cells. Phosphate saline buffer (pH 7.4) was used in the receptor compartments. All the system was maintained at 32 ± 0.5°C with a circulating water jacket and magnetic stirring (180 rpm). Samples were analysed by UV-VIS spectrophotometer at 255 nm. Flux (Jm) values, permeation (P) and diffusion (D) coefficients were obtained. Results of Q in CG permeation experiences with different percentages of DMF and M showed that 16.7% DMF and 1.95% L-menthol enhancers were the best quantities for the system tested. Enhancer effect can be attributed to direct action on membrane structure by promoting its distension. Therefore, enhancer substitutes for water in pores, improving active principal permeation through pig skin. M significantly increases Q permeation about 17 times higher than control. The results of permeation experiments with M and DMF using the same enhancer concentration (1.42%) conclude that M action is 9 times higher than DMF, approximately, indicating that M is an effective enhancer for a transdermal therapeutic system of Q in CG as vehicle.Fil: Olivella, Mónica Susana. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Área de Química Física; ArgentinaFil: Lhez, Lucia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Área de Química Física; ArgentinaFil: Pappano, Nora Beatriz. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Área de Química Física; ArgentinaFil: Debattista, Nora Beatriz. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Área de Química Física; Argentin

Potentiometric and spectrophotometric study of 3-hydroxyflavone-La(III) complexes

Flavonoids are a large family of natural compounds that includes flavones, flavonols, and chalcones, among others. These compounds are investigated due to their varied biological properties and their capacity to complex metal ions. In this work, the complexation of four 3-hydroxyflavones with the lanthanum(III) ion was studied. A series of novel complexes of La(III) with the selected 3-hydroxyflavones, 3,7-dihydroxyflavone (L1), 3,7,3′- trihydroxyflavone (L2), 3,5,7,3′,4′-pentahydroxyflavone (quercetin) (L3), and 3,5,7,2′,4′-pentahydroxyflavone (morin) (L4), were studied by means of Potentiometric and spectrophotometric methods at 26.3 °C and 0.1 M ionic strength in a water-dioxan (1:1, v/v) medium. Their formation constants were evaluated by the Calvin-Bjerrum and Irving-Rossotti methods. Complex 1:1 was found for all four ligands, whereas the 2:1 ligand-metal stoichiometry was found for only three of the four ligands. The obtained protonation constants of the ligands were: L 1, log K1H = 9.128 ±0.664; L 2, log K1H = 11.091 ± 0.134, log K 2H = 8.822 ± 5·10-4; L 3, log K2H = 9.310 ±0.119, log K 2H = 8.382 ± 0.109; L4, log K 1H = 10.021 ± 0.355, log K2H = 7.173 ± 0.576. The determined stability constants were: L 1-La(III), log K1 = 7.269 ± 0.387; L 2-La(III), log K1 = 9.164 ± 0.020, log K 2 = 5.200 ± 0.185; L3-La(III), log K1 = 8.143 ± 0.284, log K2 = 5.632 ± 0.585; L 4-La(III), log K1 = 7.407 ± 0.596, log K 2 = 4.830 ± 0.165.Fil: Ferrari, Gabriela Verónica. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Área de Química Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; ArgentinaFil: Pappano, Nora Beatriz. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Área de Química Física; ArgentinaFil: Debattista, Nora Beatriz. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Área de Química Física; ArgentinaFil: Montaña, Maria Paulina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Área de Química Física; Argentin

High-performance liquid chromatography of chalcones: Quantitative structure-retention relationships using partial least-squares (PLS) modeling

In this study, the multivariate partial least squares projections to latent structures (PLS) technique was used for modeling the RP-HPLC retention data of 17 chalcones, which were determined with methanol-water mobile phases of different compositions. The PLS model was based on molecular descriptors which can be calculated for any compound utilizing only the knowledge of its molecular structure. The PLS analysis resulted in a model with the following statistics: r = 0.976, Q = 0.933, s = 0.076, and F = 43.63. The adequacy of the developed model was assessed by means of cross-validation and also, by PLS modeling of the retention data of several chalcones reported by Walczak et al. [J. Chromatogr. 353, 123, (1986)], which were obtained using stationary phases of different polarity (-NH2, DIOL, -CN, ODS, C8). The structural interpretation of the developed PLS model was accomplished by means of comparative correlations between the nonempirical descriptors used in the model and the solvation parameters developed by Abraham. The results obtained in this work provides evidence for the great potential of the topological approach for the development of quantitative structure-retention relationship (QSRR) models.Fil: Montaña, Maria Paulina. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Área de Química Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; ArgentinaFil: Pappano, Nora Beatriz. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Área de Química Física; ArgentinaFil: Debattista, Nora Beatriz. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Área de Química Física; ArgentinaFil: Raba, Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Área de Química Física; ArgentinaFil: Luco, Juan Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Laboratorio de Alimentos; Argentin

Novel synthesis of 3,3′-dihydroxyflavone and apparent formation constants of flavonoid-Ga(III) Complexes

Flavonoids are a wide variety of polyphenolic compounds. They have many biological properties. They also exhibit a metallic ion complexation capacity, which is important since it has been found that biological properties these ligands present can be enhanced when complexation occurs. In this work four flavonoid-Ga(III) complexes were studied: 2′,4′,3- trihydroxychalcone-Ga(III), 2′,3-dihydroxychalcone-Ga(III), 3,7,3′-trihydroxyflavone-Ga(III), and 3,3′-dihydroxyflavone-Ga(III). All ligands were synthesized by our working group, contributing a novel, cheaper, and more simple way to obtain 3,3′-dihydroxyflavone. The stoichiometry of the complexes was determined using the Yoe-Jones method. Both chalcone-Ga(III) complexes presented 1:1 L:M stoichiometry; meanwhile flavone-Ga(III) complexes presented 2:1 L:M stoichiometry. The pK values were determined by means of a spectrophotometric method. Values obtained were: 2′,4′,3-trihydroxychalcone-Ga(III), pK = 4.35 ± 0.38; 2′,3-dihydroxychalcone-Ga(III), pK = 3.40 ± 0.17; 3,7,3′-trihydroxyflavone-Ga(III), pK = 7.74 ± 0.19; and 3,3′-dihydroxyflavone-Ga(III), pK = 8.46 ± 0.27. © 2010 American Chemical Society.Fil: Ferrari, Gabriela Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; ArgentinaFil: Pappano, Nora Beatriz. Universidad Nacional de San Luis; ArgentinaFil: Montaña, Maria Paulina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; ArgentinaFil: Garcia, Norman Andino. Universidad Nacional de Río Cuarto; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Debattista, Nora Beatriz. Universidad Nacional de San Luis; Argentin

Chalcones as analytical reagents of aluminum: Stability, thermodynamic and kinetic study

Chalcones, a group of polyphenolic compounds, has been studied for a long time due to their biological properties and their ability as analytical reagents. In this work the stability and thermodynamic parameters concerning the fotmation in ethanolic medium of two chalcone-aluminium complexes (2′,3- dihydroxychalcone-Al(III) and 2′,4′,3-trihydroxychalcone-Al(III)) were studied and a kinetic study of the formation reaction was aslo performed. Both systems showed 1 : 1 L :M stoichiometry and stability constants at four temperatures were determined. Thermodynamic parameters indicate that both formation reactions are endothermic and driving force is entropic. Kinetic study revealed that 2′,4′,3-trihydroxychalcone-Al(III) formation is faster than 2′,3-dihydroxyclacone- Al(III), a factorwhich can be interestingwhen proposingnewanalytical reagents.Fil: Muñoz, Vanesa Alejandra. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Area de Química Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; ArgentinaFil: Kretek, Carolina G.. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Area de Química Física; ArgentinaFil: Montaña, Maria Paulina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Area de Química Física; ArgentinaFil: Pappano, Nora Beatriz. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Area de Química Física; ArgentinaFil: Debattista, Nora Beatriz. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Area de Química Física; ArgentinaFil: Ferrari, Gabriela Verónica. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Area de Química Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; Argentin

A comparative photochemical study on the behavior of 3,30 -dihydroxyflavone and its complex with La(III) as generators and quenchers of reactive oxygen species

A 1:1 complex between 3,30-dihydroxyflavone (DHF) and La(III) (DHF?La(III)) is formed in methanolic solution with the relatively high apparent stability constant value of 2.3e6 and a calculated standard entropy change of 88.2 J mol-1 K-1, both at 25 C. The photophysical properties of the complex and the free flavonoid are discussed in comparison to the well known related compound 3-hydroxyflavone. The ligand photogenerates O2(1Dg) by energy transfer from its excited triplet state (3DHF) to dissolved ground state oxygen, with a quantum yield of 0.13. 3DHF is quenched by La(III) with a rate constant close to the diffusion-controlled value. The respective abilities of the free flavonoid and DHF?La(III) as quenchers of the riboflavin-photogenerated reactive oxygen species singlet molecular oxygen (O2(1Dg)) and superoxide radical anion (O 2 ) have been investigated. Both individual compounds were photoirradiated with visible light in the presence of the flavin as the only light-absorbing compound. A detailed kinetics and mechanistic study employing polarographic monitoring of oxygen uptake and time resolved detection of O2(1Dg) phosphorescence indicates that DHF and the complex react with O2(1Dg) and O 2 by a non simple mechanism. The former deactivates O2(1Dg) in a predominant physical fashion, a fact that constitutes a desirable property for antioxidants. It was found that metal chelation greatly enhances the ability of DHF as an overall O2(1Dg) quencher.Fil: Ferrari, Gabriela Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Química de San Luis; ArgentinaFil: Montaña, Maria Paulina. Universidad Nacional de San Luis. Facultad de Quimica, Bioquimica y Farmacia. Departamento de Quimica. Area de Quimica Fisica; ArgentinaFil: Dimarco Palencia, Frida Claudia Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Química de San Luis; ArgentinaFil: Debattista, Nora Beatriz. Universidad Nacional de San Luis. Facultad de Quimica, Bioquimica y Farmacia. Departamento de Quimica. Area de Quimica Fisica; ArgentinaFil: Pappano, Nora Beatriz. Universidad Nacional de San Luis. Facultad de Quimica, Bioquimica y Farmacia. Departamento de Quimica. Area de Quimica Fisica; ArgentinaFil: Massad, Walter Alfredo. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Garcia, Norman Andino. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentin