Propiedades de fusión de algunos lípidos estructurados procedentes del aceite de soja con alto contenido en ácido esteárico

A number of structured lipids native to high stearic acid soybean oil were synthesized and their physical properties were determined by pulsed nuclear magnetic resonance (NMR), Mettler dropping point and differential scanning calorimetry (DSC). 1,3 Distearo-2-olein (SOS), 1,3 distearo-2-linolein (SLS) and1,3 distearo-2-linolenin (SlnS) were synthesized from pure 1,3 diacylglycerols and the appropriate fatty acid. Pulsed NMR determinations over the temperature range 10-50 ºC showed that the symmetrical triacylglycerols (SUS: where S = stearic, U = oleic, linoleic or linolenic) are high and sharply melting materials, all showing substantial amounts of solids at temperatures up to 33.3 ºC, yet are completely melted at only a few degrees higher. Mettler dropping points for SOS, SLS and SlnS were 44.1, 37.9 and 36.5 ºC respectively. The heats of fusion for the structured triacylglycerols were determined by DSC and shown to be of the order 29-32 cal/gm compared to 45 cal/gm for SSS. The heats of fusion were also calculated from Mettler dropping point determinations as admixtures with soybean oil and showed consistent agreement with the DSC data.Se sintetizaron algunos lípidos estructurados procedentes del aceite de soja con alto contenido en ácido esteárico y sus propiedades físicas se determinaron por resonancia magnética nuclear pulsada (NMR), punto de goteo Mettler y calorimetría diferencial de barrido (DSC). Se sintetizaron 1,3 diestearo-2-oleina (SOS), 1,3 diestearo-2-linoleina (SLS) y 1,3 diestearo-2-linolenina (SlnS) a partir de 1,3 diacilgliceroles y de los ácidos grasos adecuados puros. Las determinaciones de NMR pulsada en el rango de temperaturas 10- 50 ºC mostraron que los triacilgliceroles simétricos (SUS: donde S = esteárico, U = oleico, linoleico o linolénico) funden a mayor temperatura y más bruscamente, todos presentan altos contenidos en sólidos a todas las temperaturas hasta los 33.3 ºC, estando completamente fundidos a sólo unos pocos grados por encima. Los puntos fusión Mettler de SOS, SLS y SlnS fueron 44.1, 37.9 y 36.5 ºC respectivamente. Los calores de fusión de los triacilgliceroles estructurados determinados por DSC resultaron del orden de 29-32 cal/gm frente a 45 cal/gm del SSS. Se calcularon los calores de fusión también mediante las determinaciones de los puntos de goteo Mettler como mezclas con aceite de soja y mostraron una buena concordancia con los datos DSC

Sex pheromone biosynthesis in the pine caterpillar moth, Dendrolimus punctatus (Lepidoptera : Lasiocampidae): pathways leading to Z5-monoene and 5,7-conjugated diene components

Biosynthesis of the sex pheromone components (Z)-5-dodecenol and (Z,E)-5,7-dodecadienol in Dendrolimus punctatus was studied by topical application of deuterium-labeled fatty acids to pheromone glands and subsequent analysis of fatty acyl groups and pheromone components by gas chromatography-mass spectrometry. Our studies suggest that both (Z)-5-dodecenol and (Z,E)-5,7-dodecadienol can be biosynthetically derived from chain elongation of palmitate to stearate in the gland, and its subsequent All desaturation to produce (Z)-11-octadecenoate. After three cycles of 2-carbon chain-shortening, the pheromone glands produce (Z)-5-dodecenoate, which is then converted to (Z)-5-dodecenol by reduction. A second Delta11 desaturation of (Z)-9-hexadecenoate produces (Z, E)-9,11-hexadecadienoate, which is then chain shortened in two cycles of beta-oxidation and finally converted to (ZE)-5,7-dodecadienol by reduction