Absolute Configuration of Falcarinol (9Z-heptadeca-1,9-diene-4,6- diyn-3-ol) from Pastinaca sativa

Falcarinol (9Z-heptadeca-1,9-diene-4,6-diyn-3-ol; 1) is a polyacetylene commonly found in several plant families. The absolute configuration of naturally occurring 1 is not clear and contradictory results have been reported in the literature. Determination of the absolute configuration of 1 from Pastinaca sativa L. was carried out. Isolation of 95% pure 1 was performed via successive fractionation and preparative-HPLC. A racemic mixture comprised of 3R-1 and 3S-1 was synthesized in order to confirm the absolute configuration of the isolated natural product using chiral HPLC. Based on a combination of chiral HPLC and specific rotation, 1 present in P. sativa was found to have a 3R absolute configuration (i.e. (3R, 9Z)-heptadeca-1,9-diene-4,6-diyn-3-ol)

The abundances of polyacetylenes towards CRL618

We present a mid-infrared high spectral resolution spectrum of CRL618 in the frequency ranges 778-784 and 1227-1249 cm^-1 (8.01-8.15 and 12.75-12.85 um) taken with the Texas Echelon-cross-Echelle Spectrograph (TEXES) and the Infrared Telescope Facility (IRTF). We have identified more than 170 ro-vibrational lines arising from C2H2, HCN, C4H2, and C6H2. We have found no unmistakable trace of C8H2. The line profiles display a complex structure suggesting the presence of polyacetylenes in several components of the circumstellar envelope (CSE). We derive total column densities of 2.5 10^17, 3.1 10^17, 2.1 10^17, 9.3 10^16 cm^-2, and < 5 10^16 cm^-2 for HCN, C2H2, C4H2, C6H2, and C8H2, respectively. The observations indicate that both the rotational and vibrational temperatures in the innermost CSE depend on the molecule, varying from 100 to 350 K for the rotational temperatures and 100 to 500 K for the vibrational temperatures. Our results support a chemistry in the innermost CSE based on radical-neutral reactions triggered by the intense UV radiation field.Comment: 9 pages, 4 figures, 1 table; accepted for publication in The Astrophysical Journa

The Abundances Of Polyacetylenes Toward CRL618

We present a mid-infrared high spectral resolution spectrum of CRL618 in the frequency ranges 778-784 and 1227-1249 cm(-1) (8.01-8.15 and 12.75-12.85 mu m) taken with the Texas Echelon-cross-Echelle Spectrograph (TEXES) and the Infrared Telescope Facility (IRTF). We have identified more than 170 rovibrational lines arising from C2H2, HCN, C4H2, and C6H2. We have found no unmistakable trace of C8H2. The line profiles display a complex structure suggesting the presence of polyacetylenes in several components of the circumstellar envelope (CSE). We derive total column densities of 2.5x10(17), 3.1x10(17), 2.1x10(17), 9.3x10(16) cm(-2), and less than or similar to 5x10(16) cm(-2) for HCN, C2H2, C4H2, C6H2, and C8H2, respectively. The observations indicate that both the rotational and vibrational temperatures in the innermost CSE depend on the molecule, varying from 100 to 350 K for the rotational temperatures and 100 to 500 K for the vibrational temperatures. Our results support a chemistry in the innermost CSE based on radical-neutral reactions triggered by the intense UV radiation field.Spanish Ministerio de Educacion y Ciencia ESP2004-665, AYA2003-2785"Comunidad de Madrid" government S-0505/ESP-0237European Community MCRTN-CT-2004-51230CSICCONACyT SEP-2004-C01-47090UNAMNSF AST-0708074Astronom

OrgTrace – No Difference in Levels of Bioactive Compounds found in Crops from Selected Organic and Conventional Cultivation Systems

The objective of the present study was to compare the content of selected bioactive compounds in organically and conventionally grown crops, and to evaluate if the ability of the crops to synthesize selected secondary metabolites was systematically affected by growth systems across different growth years as well as soil types. The results showed that contents of neither polyacetylenes and carotenoids in carrots, flavonoids in onions, nor phenolic acids in carrots and potatoes were significantly influenced by growth system. Thus it could not be concluded that the organically grown crops had higher contents of bioactive compounds than the conventionally grown. This indicates that giving preference to organic products because they contain more bioactive components is doubtfull. However, there are many other reasons for the consumer to choose organic food products, including: no pesticide residues in foods, animal welfare, and environmental protection

Subgap Two-Photon States in Polycyclic Aromatic Hydrocarbons: Evidence for Strong Electron Correlations

Strong electron correlation effects in the photophysics of quasi-one-dimensional $\pi$-conjugated organic systems such as polyenes, polyacetylenes, polydiacetylenes, etc., have been extensively studied. Far less is known on correlation effects in two-dimensional $\pi$-conjugated systems. Here we present theoretical and experimental evidence for moderate repulsive electron-electron interactions in a number of finite polycyclic aromatic hydrocarbon molecules with $D_{6h}$ symmetry. We show that the excited state orderings in these molecules are reversed relative to that expected within one-electron and mean-field theories. Our results reflect similarities as well as differences in the role and magnitude of electron correlation effects in these two-dimensional molecules compared to those in polyenes.Comment: 11 pages, 5 figures, 2 table

Organic Food and Health: A new project to study the effects of plant cultivation methods (organic and conventional) on nutritional value, health and reproduction in an animal experiment

Many consumers believe that food from plants grown under certain conditions, such as organic agriculture, will benefit health more than conventional food. This cannot be determined simply by analysing the material, since our understanding of the connections between food components and health is still to imprecise for such a purpose. Rather than waiting until basic research provides the knowledge needed for this approach, in the spring of 2001 we have initiated a project to study physiological effects of plant quality directly, in an animal experiment. The following cultivation treatments are used to grow plants that are typical ingredients for a human diet (potato, mature peas, kale, spring wheat, oilseed rape, carrots and apples): 1. A model of a distinct conventional cultivation system, with high input of mineral nutrients and use of as much pesticides as is allowed. 2. A model of a distinct organic cultivation system, with low input of organic plant nutrients and no use of pesticides. 3. A combination of model 1 and 2, with low input of nutrients and use of pesticides. The materials from each cultivation treatment will be thoroughly characterised, by measuring contents of nutrients (protein, minerals, energy content, vitamins), the biological value of major protein sources of feed plants will be assessed, selected secondary metabolites including known anti-nutrients will be measured and other quality indicators will be assessed including biocrystallization. Based on these results, 3 feed mixtures will be prepared, either based on defined weight percentages of each material from each treatment, or, if large variation in biological value is found, one or two feed mixtures can be adjusted to provide the same availability of protein and energy as the reference treatment (model 1). Potato, mature peas and kale will be cooked and freeze-dried, wheat is ground and baked to biscuits, oil is produced from the rapeseed, and raw carrots and apples are shredded and freeze dried, before feed pellets with the desired composition are prepared from the material. Three groups of rats are each provided one of the dietary treatments during 2.5 generation, and reproductive characteristics and performance are recorded. Subgroups of the last generation are selected for an intensive study in which uptake and excretion of energy and protein and selected micronutrients are determined. Respiration trials are performed to assess the energy metabolism, and simultaneous measurements of the activity levels of the rats are performed. In addition, blood and tissue samples of the rats will be obtained to study the effect of the dietary treatments on the immunological and antioxidant status of the rats. Data from the experiments are assembled and analysed using relevant statistical models, and the relationship to the nutritional characteristics of the plant material is described. Funding for the core project for a 4-year period is secured from the Danish Research Centre for Organic Farming (DARCOF). However, the intention is to provide a platform for international collaboration, since the well-documented material of plants and animals can provide multiple opportunities for associated projects. To investigate other aspects of plant composition or health than what is foreseen in the present project, or to follow up on it with additional experiments

Titan: Aerosol photochemistry and variations related to the sunspot cycle

A photochemical theory is proposed for producing complex polymers in a methane atmosphere. It is argued that the polyacetylenes (C_(2n)H_2) are the most likely precursor molecules for the formation of the stratospheric haze layer on Titan. The production of polyacetylenes involves a strong positive feedback, leading to more production of polyactylenes. The thermosphere of Titan may undergo substantial expansion and contraction over a solar cycle, with important consequences for the chemistry of the upper atmosphere