Targeted carotenoid metabolite profiling in transgenic cereals and correlations with carotenoid gene expression

El meu treball de recerca va consistir en la millora, desenvolupament i aplicació de tècniques analítiques per a l'anàlisi qualitatiu i quantitatiu de carotenoides en cereals, principalment en blat de moro i arròs. Inicialment vaig treballar en l'optimització del mètode d'extracció d'aquests pigments. Es compararen diferents combinacions de solvents per determinar el millor solvent extractant que permetés alliberar tots els carotenoides de la llavor de blat de moro, malgrat les seves diferents polaritats. Addicionalment, vaig millorar i desenvolupar dos mètodes cromatogràfics per HPLC i UHPLC per realitzar la separació d'aquests pigments. Es compararen diverses fases estacionàries i mòbils amb la finalitat de trobar el millor sistema que permetés la separació de la majoria d'aquests compostos. La identificació dels analits es va realitzar mitjançant l'ús detectors de fotodíodes en sèrie i de masses. Es compararen tècniques d'ionització com ara ESI, APCI i APPI per ionitzar aquests pigments.Mi trabajo de investigación consistió en la mejora, desarrollo y aplicación de técnicas analíticas para el análisis cualitativo y cuantitativo de carotenoides en cereales, principalmente en maíz y arroz. Inicialmente trabajé en la optimización del método de extracción de estos pigmentos. Diferentes combinaciones de solventes fueron comparadas para determinar el mejor solvente de extracción, que permitiera liberar de la semilla de maíz, todos los carotenoides a pesar de sus distintas polaridades. Adicionalmente, mejoré y desarrollé dos métodos cromatográficos por HPLC y UHPLC para conseguir realizar la separación de estos pigmentos. Varias fases estacionarias y móviles fueron comparadas con el fin de encontrar el mejor sistema que permitirá la separación de la mayoría de estos compuestos. La identificación de los analitos se realizó mediante el uso detectores de fotodiodos en serie y de masas. Técnicas de ionización tales como ESI, APCI y APPI fueron comparadas para ionizar los pigmentos.My research program focused on the development and optimization of qualitative and quantitative analytical methodology for carotenoid determination in cereal crops. Initially, I improved the protocol to extract carotenoids from maize and rice tissues. I compared different combinations of solvents in order to identify the most suitable mixture that allowed me to extract, in spite of its different polarities, all the carotenoids present in the samples. I also improved and developed two chromatographic methods by high performance liquid chromatography (HPLC) and ultra high performance liquid chromatography (UHPLC) to separate these pigments. Various stationary and mobile phases were evaluated in order to obtain the most optimal resolution among the different pigments found in the samples. The identification of these molecules was carried out using photo diode array (PDA) and mass (MS) detectors. I investigated the effect of ionizing carotenoids using electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) techniques

Estudio fitoquímico preliminar de la especie Solanum Stellatiglandulasum bitter y evaluación preliminar de la actividad biológica frente a Artemia salina leach

Desde la constitución de la sociedad humana hace diez mil millones de años, el ser humano utiliza especies vegetales como medio nutricional y medicinal, siendo los vegetales terrestres o acuáticos elementos básicos en las cadenas tróficas de la vida. El ochenta por ciento (80%) de la humanidad depende de remedios caseros y herbarios que han sido base farmacoquímica de medicamentos universales, y de otros tratamientos tradicionales como la acupuntura y la homeopatía para curar sus dolencias y patologías.1PregradoQuímicoArmenia Quindí

Influence of sample processing on the analysis of carotenoids in maize

We performed a number of tests with the aim to develop an effective extraction method for the analysis of carotenoid content in maize seed. Mixtures of methanol–ethyl acetate (6:4, v/v) and methanol–tetrahydrofuran (1:1, v/v) were the most effective solvent systems for carotenoid extraction from maize endosperm under the conditions assayed. In addition, we also addressed sample preparation prior to the analysis of carotenoids by liquid chromatography (LC). The LC response of extracted carotenoids and standards in several solvents was evaluated and results were related to the degree of solubility of these pigments. Three key factors were found to be important when selecting a suitable injection solvent: compatibility between the mobile phase and injection solvent, carotenoid polarity and content in the matrix

Analytical tools for the analysis of carotenoids in diverse materials

High-performance liquid chromatography (HPLC) has become the method of choice for carotenoid analysis. Although a number of normal-phase columns have been reported, reverse-phase columns are the most widely used stationary phases for the analysis of these molecules. C18 and C30 stationary phases have provided good resolution for the separation of geometrical isomers and carotenoids with similar polarity. More recently ultra high-performance liquid chromatography (UHPLC) has been used. UHPLC has a number of distinct advantages over conventional HPLC. These include: faster analyses (due to shorter retention times), narrower peaks (giving increased signal-to-noise ratio) and higher sensitivity. High strength silica (HSS) T3 and C18 and ethylene bridged hybrid (BEH) C18 stationary phases, with sub-2 μm particles have been used successfully for UHPLC analysis and separation of carotenoids. A number of spectroscopic and mass spectrometric techniques have also been used for carotenoid qualitative and quantitative analysis. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI/TOF-MS), atmospheric-pressure solids-analysis probe (ASAP) and Raman spectroscopy are used to profile rapidly and qualitative carotenoids present in different crude extracts. Such detection methods can be used directly for the analysis of samples without the need for sample preparation or chromatographic separation. Consequently, they allow for a fast screen for the detection of multiple analytes. Quantitative carotenoid analysis can be carried out using absorbance or mass detectors. Liquid chromatography–tandem mass spectrometry (LC–MS/MS) is efficient for carotenoid identification through the use of transitions for the detection of analytes through precursor and daughter ions. This approach is suitable for the identification of carotenoids with the same molecular mass but different fragmentation patterns. Here we review critically the latest improvements for carotenoid resolution and detection and we discuss a number of analytical techniques for qualitative and quantitative analysis of carotenoids