Hydrolytic efficiency and isomerization during de-esterification of natural astaxanthin esters by saponification and enzymolysis

Background: Astaxanthin from natural sources is typically esterified with fatty acids; hence, it must be hydrolyzed to remove esters before identification and quantification by conventional HPLC. Alkaline-catalyzed saponification and enzyme-catalyzed enzymolysis are the most commonly used de-esterification methods. However, information on the efficiency and isomerization during de-esterification of natural astaxanthin esters by these two methods remains scarce. Therefore, we conducted two HPLC-based experiments to determine which method is better for hydrolyzing astaxanthin esters. Results: To assess the effect of enzymolysis (0.67 U/mL cholesterol esterase, at 37°C) and saponification (0.021 M NaOH, at 5°C) conditions on free astaxanthin recovery and destruction or structural transformation of astaxanthin, we varied the total treatment time across a range of 195 min. The results showed that enzymolysis and saponification were complete in 60 min and 90 min, respectively. After complete hydrolysis, the maximum free astaxanthin recovery obtained by enzymolysis was 42.6% more than that obtained by saponification. The identification of by-products, semi-astacene and astacene, during the process of saponification also indicated that a more severe degradation of astaxanthin occurred during saponification. Moreover, the composition of astaxanthin isomers during saponification was similar to that of the isomers during enzymolysis between 30 min and 75 min (all-trans:9-cis:13-cis = 21:3:1, approximately) but dramatically changed after 90 min, whereas the composition in the enzymolysis treatment remained relatively stable throughout. Conclusion: Compared with saponification, enzymolysis with cholesterol esterase was recommended as a more accurate method for de-esterification of natural astaxanthin esters for further qualitative and quantitative HPLC analysis.

Asymmetric bioreduction of ketoesters derivatives by Kluyveromyces marxianus: influence of molecular structure on the conversion and enantiomeric excess

ABSTRACT This study presents the bioreduction of six β-ketoesters by whole cells of Kluyveromyces marxianus and molecular investigation of a series of 13 β-ketoesters by hologram quantitative structure-activity relationship (HQSAR) in order to relate with conversion and enantiomeric excess of β-stereogenic-hydroxyesters obtained by the same methodology. Four of these were obtained as (R)-configuration and two (S)-configuration, among them four compounds exhibited >99% enantiomeric excess. The β-ketoesters series LUMO maps showed that the β-carbon of the ketoester scaffold are exposed to undergo nucleophilic attack, suggesting a more favorable β-carbon side to enzymatic reduction based on adopted molecular conformation at the reaction moment. The HQSAR method was performed on the β-ketoesters derivatives separating them into those provided predominantly (R)- or (S)-β-hydroxyesters. The HQSAR models for both (R)- and (S)-configuration showed high predictive capacity. The HQSAR contribution maps suggest the importance of β-ketoesters scaffold as well as the substituents attached therein to asymmetric reduction, showing a possible influence of the ester group carbonyl position on the molecular conformation in the enzyme catalytic site, exposing a β-carbon side to the bioconversion to (S)- and (R)-enantiomers.

Nivel de autoconcepto en niños con secuelas de quemaduras: estudio comparativo / Self-concept level in children with burns sequelae: A comparative study

Introducción: Autoconcepto es el conjunto de ideas y actitudes que se tiene acerca de sí mismo. Nuestro objetivo fue evaluar si existen diferencias en el nivel de autoconcepto de niños de 8-12 años con y sin secuelas de quemaduras, e identificar variables predictoras del autoconcepto en los niños con secuelas. Pacientes y método: Estudio comparativo, transversal de 109 niños con secuelas de quemaduras de 8 a 12 años de edad, con 109 niños sin secuelas de quemaduras, del mismo grupo de edad y nivel socioeconómico. Se utilizó la escala de autoconcepto de Piers-Harris, que entrega medida de autoconcepto general y dimensiones: conductual, estatus intelectual y escolar, apariencia y atributos físicos, ansiedad, popularidad, felicidad y satisfacción. Resultados: No hubo diferencias significativas en el nivel de autoconcepto general ni en sus dimensiones al comparar ambos grupos (p > 0,05). Dentro del grupo con secuelas de quemaduras la variable número de secuelas resultó ser un factor protector para las dimensiones ansiedad, popularidad, felicidad-satisfacción y autoconcepto general. La variable localización surgió como factor de riesgo para la dimensión conductual. Discusión: La ausencia de diferencias en autoconcepto entre niños con secuelas de quemaduras y sin ellas es similar a lo reportado por la literatura. El hallazgo en factores de riesgo y protectores motiva a continuar investigando, incorporando antecedentes premórbidos y familiares.

Introduction: Self-concept is the set of ideas and attitudes that a person has about him/herself. Objective: To evaluate whether there are differences in the level of self-concept in children 8-12 years old with and without burns sequelae. To identify predictive variables of self-concept in children with sequelae. Patients and method: A comparative cross-sectional study of self-concept in 109 children with burns sequelae, from 8 to 12 years old, with 109 children without burns sequelae, and of the same age and socioeconomic status. The Piers-Harris self-concept scale is used, which provides a general measurement of self-concept and behavioural, intellectual and school status, appearance, and physical attributes, anxiety, popularity, happiness and satisfaction dimensions. Results: There were no significant differences in the level of general self-concept or their dimensions (P > .05). In the group with burns sequelae, the protective factor was the variable number of sequels was associated with the dimensions of anxiety, popularity, happiness-satisfaction and general self-concept. The location variable emerged as a risk factor for the behavioural dimension. Discussion: The absence of differences in self-concept between children with burns sequelae and children without them is similar to that reported in the literature. The finding in the risk and protective factors encourages to further research, and perhaps incorporating pre-morbidity and family background.

Variación secular de los nacimientos, peso y longitud al nacer: perspectiva local / Secular variation of births, weight and length at birth: Local perspective

Objetivo: Analizar la evolución de los nacimientos y medidas antropométricas al nacer entre 1974-2011 en el Hospital de Limache, Región de Valparaíso, Chile. Pacientes y métodos: Se construyeron series de tiempo de nacimientos, peso y longitud al nacer, peso y talla baja al nacer. Se modelaron las tendencias con regresiones multivariadas usándose splines para representar los cambios de tendencia por década. Resultados: La serie comprende 17.574 nacimientos. Hubo un aumento de los nacimientos/año en los 70 (30/año) y disminución de 17 y 22 nacimientos/año en los 80 y 90 (p < 0,001); después, sin tendencia significativa. Los recién nacidos entre 2000-2011 registran 266 g más que los de la década de los 70 (p < 0,001), alcanzando actualmente en promedio 3.530 g. El bajo peso al nacer disminuyó de 8% en los 70 a 1,1% después de 2000. La longitud al nacer incrementó 1 cm en 37 años, con disminución de la talla baja de 7,6% a 2,1% en el periodo estudiado. Conclusión: Los nacimientos en el Hospital de Limache disminuyeron y las medidas antropométricas al nacer mejoraron; sin embargo, hay que considerar los posibles sesgos que distorsionan estas estimaciones.

Objective: To analyse the outcomes of births and anthropometric measurements at birth of children born between 1974 and 2011 at Limache Hospital (Valparaíso, Chile). Patients and method: Times series were constructed of births, weight and length at birth, and low weight and length at birth. The trend was modelled with linear and logistical regressions using splines to represent breaks in the trend by decade. Results: The series includes 17,574 births. There was an increase in births per year in the 1970s (30/year) and declines in them to 17 and 22 births/year in the 1980s and 1990s, respectively (P < .001), with no significant trend thereafter. Newborns from 2000 to 2011 weighed 266 grams more than those in the 1970s (P < .001), and have now reached a mean weight of 3,530 g. Low birthweight fell from 8% in the 1970s to 1.1% after 2000. Birth length increased by 1 cm in the 37 years studied, with a reduction of low birth length from 7.6% to 2.1% during the period. Conclusion: Live births in the Limache Hospital declined, and anthropometric measurements at birth improved in the years analysed. This information is useful in developing interventions, taking into account the possible selection biases that could distort these estimates and their interpretation.

Biodiesel production from marine cyanobacteria cultured in plate and tubular photobioreactors.

Carbon (neutral) based renewable liquid biofuels are alternative to petroleum derived transport fuels that contribute to global warming and are of a limited availability. Microalgae based biofuels are considered as promising source of energy. Lyngbya sp. and Synechococcus sp. were studied for the possibility of biodiesel production in different media such as ASNIII, sea water enrichment medium and BG11. The sea water enrichment medium was found superior in enhancing the growth rate of these microalgae. Nitrogen depletion has less effect in total chlorophyll a content, at the same time the lipid content was increased in both Lyngbya sp. and Synechococcus sp. by 1.4 and 1.2 % respectively. Increase in salinity from 0.5-1.0 M also showed an increase in the lipid content to 2.0 and 0.8 % in these strains; but a salinity of 1.5 M has a total inhibitory effect in the growth. The total biomass yield was comparatively higher in tubular LED photobioreactor than the fluorescent flat plated photobioreactor. Lipid extraction was obtained maximum at 60 ºC in 1:10 sample: solvent ratio. GC-MS analysis of biodiesel showed high content of polyunsaturated fatty acids (PUFA; 4.86 %) than saturated fatty acid (SFA; 4.10 %). Biodiesel production was found maximum in Synechococcus sp. than Lyngbya sp. The viscosity of the biodiesel was closely related to conventional diesel. The results strongly suggest that marine microalgae could be used as a renewable energy source for biodiesel production.

Antimicrobial effect of para-alkoxyphenylcarbamic acid esters containing substituted N-phenylpiperazine moiety

In current research, nine basic esters of para-alkoxyphenylcarbamic acid with incorporated 4-(4fluoro-/3-trifluoromethylphenyl)piperazin-1-yl fragment, 6i-6m and 8f-8i, were screened for their in vitro antimicrobial activity against Candida albicans, Staphylococcus aureus and Escherichia coli, respectively. Taking into account the minimum inhibitory concentration assay (MIC), as the most active against given yeast was evaluated 8i (MIC = 0.20 mg/mL), the most lipophilic structure containing para-butoxy and trifluoromethyl substituents. Investigating the efficiency of the compounds bearing only a single atom of fluorine and appropriate para-alkoxy side chain against Candida albicans, the cut-off effect was observed. From evaluated homological series, the maximum of the effectiveness was noticed for the stucture 6 k (MIC = 0.39 mg/mL), containing para-propoxy group attached to phenylcarbamoyloxy fragment, beyond which the compounds ceased to be active. On the contrary, all the tested molecules were against Staphylococcus aureus and Escherichia coli (MICs > 1.00 mg/mL) practically inactive.

Reactions of uridine and 4-thiouridine derivatives with some-halo esters

Uridine and 4-thiouridine were converted into the corresponding 2,3-o-isopropylidene-5-thiocyanato derivatives. Then, each resulted derivative was reacted individually with both of ethyl alpha- chloroacetoacetate, ethyl alpha-bromobenzoylacetate and ethyl bromo pyruvate. Furthermore, these 5-thiocyanato products were transformed into the corresponding 5-mercapto analogues. The produced analogues were undergo ring formation to give the corresponding 4,5-cyclized pyrimidine derivatives