Identification of coumarins in DCM bark, leaf and fruit extracts from Mammea neurophylla (Calophyllaceae) by LC-PDA-MSn

4-phenyl and 4-propylcoumarins display a wide variety of biological activities including anti-oxidant and anti-inflammatory effects, antiparasitical activities against Leishmania or Plasmodium as well as antibacterial, antiviral (HIV) and cytotoxic activities. Using LC-PDA-MSn we have developed a specific protocol allowing the simultaneous and qualitative detection of 4-phenyl and 4-propylcoumarins in DCM bark, fruit and leaf extracts obtained from Mammea neurophylla. By comparison of their retention times, MS and UV data with that of authentic samples, nine, seven and five 4-phenylcoumarins could be directly identified in bark, leaf and fruit extracts respectively. On the other hand, interlocking UV spectra and ESI-MSn data analysis allowed us to deduce plausible structures of five, eight and four other coumarins in bark, leaf and fruit respectively by comparison with their reported spectral data. During this study new Mammea A/AA 9-hydroxy-cyclo F and Mammea A/AB 9-hydroxy-cyclo F were identified. We believe that this protocol will be useful in case of dereplicative studies of Mammea and related species

Chemical composition and antiglycoxidant activities of French organic propolis extracts

International audienc

Polyphenolic content and pharmacological potential of french BFA propolis extracts

Propolis, or bee glue, is a natural resinous hive product collected by honeybees from buds and exudates of various trees and plants. Mixed with beewax and salivary enzymes, it is employed to fill cracks and embalm dead invaders in the hive. Propolis has been used in folk medecine since ancien times due to its pharmacological potential associated with antioxidant, antifungal, antibacterial as well as antitumoral properties. A batch of various French propolis extracts, supplied by “Ballot-Flurin Apiculteurs” (BFA), a company located in the South-West of France and specialized in apitherapy products, was fractionated and analysed by HPLC/MS. Its qualitative chemical composition highlights the presence of polyphenols such as hydroxycinnamic acid derivatives and flavonoids. Total polyphenol content and antioxidant activities were evaluated on six BFA propolis extracts, using respectively Folin-Ciocalteu, DPPH and ORAC assays. Preliminary antifungal (Candida albicans) and antibacterial (Staphylococcus aureus) evaluations will also be given

NICMOS Imaging of a Damped Lyman-alpha Absorber at z=1.89 toward LBQS 1210+1731 : Constraints on Size and Star Formation Rate

We report results of a high-resolution imaging search (in rest frame H-$\alpha$ and optical continuum) for the galaxy associated with the damped Lyman-$\alpha$ (DLA) absorber at $z=1.892$ toward the $z_{em}=2.543$ quasar LBQS 1210+1731, using HST/NICMOS. After PSF subtraction, a feature is seen in both the broad-band and narrow-band images, at a projected separation of 0.25\arcsec from the quasar. If associated with the DLA, the object would be $\approx 2-3$ $h_{70}^{-1}$ kpc in size with a flux of $9.8 \pm 2.4$ $\mu$Jy in the F160W filter, implying a luminosity at $\lambda_{central}=5500$ {\AA} in the rest frame of $1.5 \times 10^{10}$ $h_{70}^{-2}$ L$_{\odot}$ at $z=1.89$, for $q_{0}=0.5$. However, no significant H-$\alpha$ emission is seen, suggesting a low star formation rate (SFR) (3 $\sigma$ upper limit of 4.0 $h_{70}^{-2}$ M$_{\odot}$ yr$^{-1}$), or very high dust obscuration. Alternatively, the object may be associated with the host galaxy of the quasar. H-band images obtained with the NICMOS camera 2 coronagraph show a much fainter structure $\approx 4-5$ $h_{70}^{-1}$ kpc in size and containing four knots of continuum emission, located 0.7\arcsec away from the quasar. We have probed regions far closer to the quasar sight-line than in most previous studies of high-redshift intervening DLAs. The two objects we report mark the closest detected high-redshift DLA candidates yet to any quasar sight line. If the features in our images are associated with the DLA, they suggest faint, compact, somewhat clumpy objects rather than large, well-formed proto-galactic disks or spheroids.Comment: 52 pages of text, 19 figures, To be published in Astrophysical Journal (accepted Dec. 8, 1999

Momentum Spectra of Electrons Rescattered from Rare-Gas Targets Following Their Extraction by One- and Two-Color Femtosecond Laser Pulses

We have used velocity-map imaging to measure the three-dimensional momenta of electrons rescattered from Xe and Ar following the liberation of the electrons from these atoms by 45 fs, 800 nm intense laser pulses. Strong structure in the rescattering region is observed in both angle and energy, and is interpreted in terms of quantitative rescattering (QRS) theory. Momentum images have also been taken with two-color (800 nm + 400 nm) pulses on Xe targets. A strong dependence of the spectra on the relative phase of the two colors is observed in the rescattering region. Interpretation of the phase dependence using both QRS theory and a full solution to the time-dependent Schrödinger equation shows that the rescattered electrons provide a much more robust method for determining the relative phase of the two colors than do the direct electrons

Orientation Dependence of the Ionization of CO and NO in an Intense Femtosecond Two-Color Laser Field

Two-color (800- and 400-nm) short (45-fs) linearly polarized pulses are used to ionize and dissociate CO and NO. The emission of Cq+, Nq+, and O⁺ fragments indicates that the higher ionization rate occurs when the peak electric field points from C to O in CO and from N to O in NO. This preferred direction is in agreement with that predicted by Stark-corrected strong-field-approximation calculations

Chemical Composition and Antioxidant Activity of French BFA Propolis extracts

Introduction: Propolis is a resinous natural substance collected by honeybees from buds and exudates of various trees and plants, mixed with beewax and salivary enzymes. Bees generally use it as a sealer, to smooth out the internal walls of the hive as well as a protective barrier against intruders. Several pharmacological activities have been attributed to propolis extracts, mainly antibacterial, antiviral, antifungal, antitumoral but also antioxidant properties we will focus on here. Research methods: A mixture of 24 batches of French propolis, supplied by “Ballot-Flurin Apiculteurs” (BFA), a company located in the South-West of France, was extracted with five different solvents: water, 70% ethanol, methanol, methylene chloride and a mixture of solvents (methylene chloride/methanol/water). Their chemical composition was determined by High Performance Liquid Chromatography coupled with Diode Array Detector (HPLC/DAD) and with Mass Spectrometry (HPLC/MS) profilings followed, when necessary, by Nuclear Magnetic Resonance (NMR) 1D and 2D studies. Total polyphenol content and antioxidant activities were evaluated for these five BFA propolis extracts using respectively Folin-Ciocalteu, 2,2-diPhenyl-1-PicrylHydrazyl (DPPH) and Oxygen Radical Absorbance Capacity (ORAC) assays. Results and discussion: All extracts of BFA French propolis exhibited phenolic acids and esters as well as flavonoids, except for the aqueous one which predominantly contained phenolic acids. They also showed high antioxidant activities, about 2-5 times higher than an ethanolic rosemary extract which was recently approved as a food additive in Europe (E392). Therefore, among these extracts, the aqueous one offers the advantage of a strong antioxidant activity combined with a “green extraction”, when toxic residual solvents are a real issue in pharmaceutical, cosmetic and food additive products

Large-Angle Electron Diffraction Structure in Laser-Induced Rescattering from Rare Gases

We have measured full momentum images of electrons rescattered from Xe, Kr, and Ar following the liberation of the electrons from these atoms by short, intense laser pulses. At high momenta the spectra show angular structure (diffraction) which is very target dependent and in good agreement with calculated differential cross sections for the scattering of free electrons from the corresponding ionic cores

On Virtual Displacement and Virtual Work in Lagrangian Dynamics

The confusion and ambiguity encountered by students, in understanding virtual displacement and virtual work, is discussed in this article. A definition of virtual displacement is presented that allows one to express them explicitly for holonomic (velocity independent), non-holonomic (velocity dependent), scleronomous (time independent) and rheonomous (time dependent) constraints. It is observed that for holonomic, scleronomous constraints, the virtual displacements are the displacements allowed by the constraints. However, this is not so for a general class of constraints. For simple physical systems, it is shown that, the work done by the constraint forces on virtual displacements is zero. This motivates Lagrange's extension of d'Alembert's principle to system of particles in constrained motion. However a similar zero work principle does not hold for the allowed displacements. It is also demonstrated that d'Alembert's principle of zero virtual work is necessary for the solvability of a constrained mechanical problem. We identify this special class of constraints, physically realized and solvable, as {\it the ideal constraints}. The concept of virtual displacement and the principle of zero virtual work by constraint forces are central to both Lagrange's method of undetermined multipliers, and Lagrange's equations in generalized coordinates.Comment: 12 pages, 10 figures. This article is based on an earlier article physics/0410123. It includes new figures, equations and logical conten