Elena E. Stashenko

GC-MS Analysis of Volatile Plant Secondary Metabolites

Knowledge of the identity and relative amounts of the volatile substances released by plants is of great importance to several fields of basic and applied research in biology, chemistry and may other disciplines. Obtaining this knowledge requires overcoming many analytical challenges posed by these complex mixtures, because they normally present large variations in component amounts, chemical structures and functionalities. Gas chromatography (GC) is recognized as the most suitable technique to find out how many components and in what proportion there are in a complex mixture of volatile compounds. When it is coupled to mass spectrometry (GC-MS), additional information arises about each separated compound molecular mass, elemental composition (when high resolution mass spectrometry is used), functional groups, and in certain cases, molecular geometry and spatial isomerism. This chapter covers the most determinant factors which affect biogenic volatile compound (BVOC) GC-MS analysis. Sample preparation, chromatographic separation and mass spectrometry are the main parts explained within the framework of BVOC analysis and practical examples of their application to flower scent and essential oil analysis are presented.

Caracterización de los metabolitos secundarios de dos especies de ocimum (fam. labiatae), en función del método de extracción

Secondary metabolites of two Ocimum species (Labiatae) were obtained by microwave-assisted hydrodistillation (MWHD), simultaneous distillation-solvent extraction (SDE), supercritical fluid extraction (SFE) , static headspace (S-HS) and headspace solid-phase microextraction (HS-SPME). Identification was performed using chromatographic (GC-IK and tR ) and spectroscopic (MS, EI 70 eV) criteria. The main components of Ocimum sp.1 (sigueme blanco) were trans-methyl cinnamate, linalo ol, eucaliptol and cis-methyl cinnamate; and of Ocimum sp.2 (sigueme morado) were estragole, linalool and eucaliptol.

COMPOSICIÓN QUÍMICA DE EXTRACTOS OBTENIDOS POR DESTILACIÓN- EXTRACCIÓN SIMULTÁNEA CON SOLVENTE DE HOJAS E INFLORESCENCIAS DE NUEVE ESPECIES Y/O VARIEDADES DE ALBAHACAS (OCIMUM spp.)

RESUMEN Se determino la composicion quimica de extractos obtenidos por destilacionextraccion simultanea con solvente (SDE) de nueve especies y/o variedades de Ocimum spp. (albahacas moradas, reina, hibrida, citrica y americana; siguemes morado y blanco). La identificacion de los compuestos se realizo por GC-MS y por comparacion de sus espectros de masas con los de las bases de datos QuadLib, NIST02 y Wiley138 e indices de retencion de Kovats . Los siguientes fueron los compuestos mayoritarios identificados en los extractos: eucaliptol, linalol, nerol, geraniol, neral, geranial, estragol, eugenol y transcinamato de metilo. PALABRAS CLAVES : Ocimum spp., albahaca, SDE.

Estudio comparativo por gc-ms de metabolitos secundarios volátiles de dos quimiotipos de lippia origanoides h.b.k., obtenidos por diferentes técnicas de extracción.

Microwave-assisted hydrodistillation, simultaneous distillation-solvent extraction, and supercritical fluid extraction, were used to isolate secondary metabolitos from two Lippia origanoides chemotypes cultivated in an experimental garden. Compound identification was based on chromatographic and mass-spectral criteria. The main components identified in the chemotype I extracts were p-cymene (13%) and 1,8-cineole (9%). The main components found in the chemotype II extracts were thymol (56%) and p-cymene (10%).

ESTUDIO COMPARATIVO DE LA COMPOSICIÓN QUÍMICA DE LOS ACEITES ESENCIALES DE Aloysia triphylla LHER BRITTON CULTIVADA EN DIFERENTES REGIONES DE COLOMBIA

Se compararon las composiciones quimicas de aceites esenciales (AEs) de plantas de Aloysia triphylla, recolectadas en tres regiones de Colombia, en tres estados de madurez. Los AEs fueron obtenidos por hidrodestilacion asistida por la radiacion de microondas (MWHD) y analizados por GC-MS. El componente mayoritario presente en los AEs evaluados fue el citral (32-41 por ciento). El mayor rendimiento ( por cientop/p) se obtuvo para las plantas recolectadas en Bolivar, Santander (0.88 por ciento). La mayor acumulacion de metabolitos de interes se logro para las plantas con dos meses de edad y antes de floracion.

Determinación de la actividad antioxidante in vitro de los aceites volátiles de cuatro plantas de uso tradicional mediante la medición de la peroxidación lipídica de aceite

In this work, we tested several essential oils for their effect to retard oxidative degradation, accelerated by UV- exposure. The antioxidant activity of essential oils was evaluated by measuring the change in the hexanal content found in the lipid matrix during lipid peroxidation. The decreases in hexanal concentration caused by the addition of essential oils at 1 and 2 %(w/w) to sunflower oil were as follows: 48 and 50% for cilantro (Coriander sativum L.), 31 and 50% for rosemary (Rosmarinus officinalis L .), 60 and 68% for Lippia alba (MilI.) and 23 and 46% for ylang-ylang (Cananga odorata), respectively.

Determinación del rendimiento cuántico de la fotoisomerización del trans-anetol

trans-Anethole is a photosensitive molecule of interest to the food industry and it is a component of many essential oils. However, trans-anethole can easily isomerize to the cis- isomer, which is recognized as toxic. A solution of transanethole in toluene was irradiated with a UV lamp. The products of the photoreaction were analyzed by gas chromatography and mass spectrometry. The quantum yields of the trans- cis- anethole isomerization reaction at 4 and 15 oC were 0.67 and 0.17, respectively.

ANÁLISIS POR HRGC DE LA COMPOSICIÓN DE EXTRACTOS Y FRACCIONES VOLÁTILES DE FLORES DE Hedychium coronarium Köeng (FAM. ZINGIBERACEA)

Headspace-solid phase microextraction (HS-SPME) and simultaneous distillation extraction (SDE) were used to isolate volatile secondary metabolites from flowers of Hedychium coronarium, which were analyzed using GC-MS. The main compounds obtained by SDE were a-pinene (6.2%), s-pinene (16.7%), 1,8cyneole (5.7%), E-s-ocimene (4.2%), linalol (3.6%), s-caryophyllene (9.6%), sfarnesene (5.6%) and caryophyllene oxide (7.5%), while those isolated by HSSPME were 1,8-cineole (9.3%), trans-s-ocimene (24.2%), methyl benzoate (20.0%) and linalool (27.3%).

COMPARACIÓN DE LA COMPOSICIÓN QUÍMICA Y DE LA ACTIVIDAD BIOLÓGICA DE LOS ACEITES ESENCIALES DE Lippia alba (Mill.) N.E.Br., OBTENIDOS VARIANDO LAS CONDICIONES DE EXTRACCIÓN Y SECADO

A comparison was made between the chemical composition and biological activity of Lippia alba essential oils, obtained by microwave-assisted hydrodistillation, MWHD under different extraction times and plant drying (in the shade) levels. The essential oils were analyzed by GC -MS. Although the oils were qualitatively similar, quantitative differences in the composition and significant oil yield differences were observed. The oil with the highest yield (2.2 % w/w) and limonene and carvone content was obtained after 45 min extraction from plant material dried for 4 days . The highest toxicity against Artemia franciscana was shown by the oil obtained after 60 min extraction from plant material dried for 3 days.

Composición química del aceite esencial de hojas y tallos de bursera graveolens (burseraceae) de colombia.

The essential oils of leaves and stems of Bursera graveolens (Burseraceae family), were obtained using microwave-assisted hydrodistillation (MWHD) and analyzed by gas chromatography-mass spectrometry (EI, 70 eV ). The main components found in the oil of leaves were: limonene (48.3%), caryophyllene oxide (13.6%) and trans-caryophyllene (8.1%). The essential oil of stem s showed a higher content of limonene (42.1%), myrcene (19.8%) and menthofuran (14.7). The components Z-β-ocymene (14.3%) and menthofuran present in the oil of stems, were not found in the essential oil of leaves.