References of "Wathelet, Jean-Paul"
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See detailStructure, properties and obtention routes of flaxseed lignan secoisolariciresinol
Sainvitu, Pauline ULg; Nott, Katherine ULg; Richard, Gaetan ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2012), 16(1), 115-124

Following a brief description of the structure and nomenclature of the lignan family, this review focuses on the flaxseed lignan secoisolariciresinol (SECO). The main properties, the analysis methods and ... [more ▼]

Following a brief description of the structure and nomenclature of the lignan family, this review focuses on the flaxseed lignan secoisolariciresinol (SECO). The main properties, the analysis methods and two routes for the preparation of SECO, i.e. extraction from renewable raw material and (hemi)-synthesis, are reviewed. Green methods recently developed for the first route and chemical syntheses inspired from biosyntheses for the second one are the main subjects of this paper. [less ▲]

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See detailRole of long-chain hydrocarbons in the aggregation behaviour of Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae)
Durieux, Delphine ULg; Fischer, Christophe ULg; Brostaux, Yves ULg et al

in Journal of Insect Physiology (2012)

The multicoloured Asian ladybeetles, Harmonia axyridis (Pallas), form large aggregations inside dwellings to survive cold winters, causing annoyances to householders from their number and sometimes the ... [more ▼]

The multicoloured Asian ladybeetles, Harmonia axyridis (Pallas), form large aggregations inside dwellings to survive cold winters, causing annoyances to householders from their number and sometimes the induction of allergic reactions. Migratory flight and macrosite choice of this species is well documented. H. axyridis shows a hypsotactic behaviour and a clear preference for contrasting visual elements. However, how the microsite is selected remains undocumented, although a better understanding of the implicated factors could lead to the development of new control methods for this pest. In this work, we have hypothesized that non-volatile compounds are involved in the microsite choice and the aggregation process of this beetle. Long chain hydrocarbons were identified inside aggregation sites, comprising saturated and unsaturated homologues. An aggregation bioassay was then conducted on overwintering individuals, highlighting the retention capacity of the previously cited compounds on the tested ladybeetles. Additional investigations have shown that H. axyridis males and females, originating from overwintering sites, deposit a similar blend of molecules while walking. A Y-shaped tube assay revealed that this blend is used by male and female congeners as cue, allowing individuals to orientate towards the treated side of the olfactometer. These results suggest the use of two different blends of long chain hydrocarbons by H. axyridis during its aggregative period, the first one to lead conspecifics towards aggregation sites (microsites) and the second to ensure the cohesion of the aggregation. These findings support the potential use of these blends, in association with volatiles, in the design of traps in order to control infestations of this species in dwellings. [less ▲]

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See detailEfficient microwave-promoted synthesis of glucuronic and galacturonic acid derivatives using sulfuric acid impregnated on silica
Richel, Aurore ULg; Nicks, Francois ULg; Laurent, Pascal ULg et al

in Green Chemistry Letters & Reviews (2012), 5(2), 179-186

Monomode microwave-assisted syntheses of D-glucuronic and D-galacturonic acid derivatives are reported in the presence of a solid acid catalyst, consisting of sulfuric acid loaded onto silica. This ... [more ▼]

Monomode microwave-assisted syntheses of D-glucuronic and D-galacturonic acid derivatives are reported in the presence of a solid acid catalyst, consisting of sulfuric acid loaded onto silica. This approach affords a variety of surface-active monoglycosylated glucofuranosidurono-6,3-lactones and disubstituted galacturonic adducts in excellent yields in less than 10 min at 85 °C. This study illustrates the application of microwave heating mode, in combination with a cost-effective solid catalyst, as an efficient, selective and eco-friendly methodology in carbohydrate chemistry. [less ▲]

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See detailChemical composition and physicochemical characteristics of fixed oils from Algerian Nigella sativa seeds
Benkaci, Ali; Wathelet, Jean-Paul ULg

in Chemistry of Natural Compounds (2012), 47(6), 925-931

The fatty acids, sterols, and polyphenols from the fixed oils of Nigella sativa seeds originating from four locations were determined. The seeds contained respectively 30.63–34.27% and 25.66–32.77% of ... [more ▼]

The fatty acids, sterols, and polyphenols from the fixed oils of Nigella sativa seeds originating from four locations were determined. The seeds contained respectively 30.63–34.27% and 25.66–32.77% of fixed oils using hexane and isopropyl alcohol in solvent extraction. Linoleic, oleic, and palmitic acids formed the main proportion using the two solvents, respectively: hexane 54.47–61.28%, isopropanol 56.98–67.30%; hexane 19.62–22.94%, isopropanol 18.85–21.96%, and hexane 11.17–13.60%, isopropanol 9.20–14.18%. Other minor unsaturated fatty acids were identified. Eight phytosterols were isolated and identified in the fixed oils by GC and GC/MS analysis, wherein -sitosterol was the dominating compound that inhibits the absorption of dietary cholesterol, followed by stigmasterol, campesterol, and 5-avenasterol. [less ▲]

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See detailComposition of the Essential Oil of Leaves and Berries of Algerian Myrtle (Myrtus comunis L.)
Brada, M.; Tabli, N.; Boutopumi, H. et al

in Journal of Essential Oil Research (2012)

Myrtus communis L. essential oils were obtained by hydrodistillation, and the yields were 0.3% (w/w) and 0.1% for leaves and berries, respectively. Using GC and GC/ MS techniques, twenty five components ... [more ▼]

Myrtus communis L. essential oils were obtained by hydrodistillation, and the yields were 0.3% (w/w) and 0.1% for leaves and berries, respectively. Using GC and GC/ MS techniques, twenty five components were identified in berry oil representing 89.5% of the oil composition. Linalool was the major compound in berry oil (36.2%) followed by estragole (18.4%) and 1,8-cineole (11.4%). Leaf oil was composed of 28 compounds representing 95.4% of the total composition of the oil. α-pinene was the major constituent of leaf oil at concentration of (46.9%), followed by 1,8-cineole (25.2%). The two Algerian oils were characterized by the lack of myrtenyl acetate. [less ▲]

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See detailCaractérisation des coposés volatils des huiles d'olive produites dans des coopératives de la région orientale du Maroc
Tanouti, K.; Serghini-Caid, H.; Sindic, Marianne ULg et al

in 5èmes Journées Internationales d'Etude sur les Lipides - JIEL 2011 : Graisses alimentaires, Lipides marins, Nutrition et Santé (2011, December 08)

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See detailInsecticidal activity of Boscia senegalensis (Pers.) Lam ex Poir. on Caryedon serratus (Ol.) pest of stored groundnuts
Gueye, Momar Talla; Seck, Dogo; Ba, Seynabou et al

in African Journal of Agricultural Research (2011), 6(30), 6348-6353

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See detailStratégies de production de 6-amyl-α-pyrone produit par Trichoderma spp. par culture en milieu semi-solide aspergé
Musoni, Michel ULg; Delvigne, Frank ULg; Destain, Jacqueline ULg et al

Conference (2011, November 29)

La biosynthèse de la 6-amyl-α-pyrone (arôme de noix de coco) à partir de l'espèce de Trichoderma a été étudiée dans différents bioréacteurs. L’étude compare la production du volatile dans un réacteur ... [more ▼]

La biosynthèse de la 6-amyl-α-pyrone (arôme de noix de coco) à partir de l'espèce de Trichoderma a été étudiée dans différents bioréacteurs. L’étude compare la production du volatile dans un réacteur classique submergé et un réacteur adapté avec plateau aspergé. La source de carbone était le glucose et l’huile de ricin, ce dernier et reconnu être le précurseur de la formation des lactones dans la biotransformation. Les milieux seront submergé et semi-solide, le volume de travail de 6, 12 et 16 litres. Il ressort des résultats obtenus au cours de l’étude que le composé aromatique est produit par la souche utilisé à partir du deuxième (133.8 mg/l) jour dans l’espace de tête et dans le milieu quand la culture est réalisé avec du glucose jusqu’au quatrième jour, alors qu’avec l’huile de ricin il est retrouvé dans le milieu uniquement (342,23 mg/l). La biomasse produite dans le réacteur de 6 l avec l’huile de ricin est de 279,6 g/l alors que pour le glucose est de 139,75, dans celui de 12 l il de 61,71 g/l avec l’huile de ricin et de 6,37 g/l avec le glucose, et celui de 16 l, 115,66 g/l et le glucose 7,4 g/l, ainsi, plus le volume est petit plus la production est meilleure. Il en va de même pour la concentration du volatile qui était de 2,42 g/l avec l’huile de ricin sur plateau et de 0,28 g/l avec le glucose. Dès lors, Il convient de noter que le système de production du volatile par le réacteur adapté avec plateau aspergé permet l’augmentation de la production de celui-ci, il présente la facilité d’aménagement, avec les contours possible, il offre la possibilité d’être extrapolable. En se référant à la possibilité de renouveler le milieu de culture en faisant circuler le milieu frais, compte tenue du fait que la biomasse est déposée sur les plateaux et qu’à la fin de culture la solution est translucide, retirable après un certain temps, il y découlerait l’amélioration de la productivité. [less ▲]

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See detailBINDING INTERACTIONS OF URONIC ACID DERIVATIVES TO LIPID VESICLES INVESTIGATED BY ISOTHERMAL TITRATION CALORIMETRY
Razafindralambo, Hary ULg; Laurent, Pascal ULg; Wathelet, Jean-Paul ULg et al

Poster (2011, November 12)

Uronic acid derivatives (UAD) constitute a particular class of carbohydrate-based small compounds, which are receiving growing interests today for many reasons. Beyond their excellent environmental ... [more ▼]

Uronic acid derivatives (UAD) constitute a particular class of carbohydrate-based small compounds, which are receiving growing interests today for many reasons. Beyond their excellent environmental compatibility, their potentiality mainly arises from the large abundance of their precursors from renewable resources, and the quasi-unlimited availability of their molecular structure and geometry [1]. Such a structural diversity allows them to be a typical compound class for the structure-activity relationship investigation using simplest models. This approach is very important for predicting their functionalities and activities. Among others, searching specific and potent biological activities against target molecules, cells, and micro-organisms is a big challenge today. In this context, binding interactions of three UAD having different hydrophobic residues (allyl, benzyl, and cyclohexyl) to 1-palmitoyl-2-oleyl-sn-glycerol-3-phosphatidylcholine (POPC) vesicles have been investigated using Isothermal Titration Calorimetry (ITC) technique [2]. The binding affinity (Ka) to the membrane model at 25°C has been determined and compared for the three compounds. Based on thermograms resulting from UAD aqueous solution titration experiments, with and without POPC vesicles, it clearly appears that both derivatives with a cyclic residue interact stronger with the lipid membrane model than their linear derivative counter-part, which exhibits almost no interaction. Moreover, the derivative compound with a cyclohexyl residue saturates faster POPC vesicles than that with a benzyl residue. We conclude that: (a) UAD having a cyclic hydrophobic residue, either saturated or unsaturated, bind more easily to the lipid membrane model than a linear one ending with a double bond; (b) the greater the number of hydrogen in the UAD residue chemical structure (saturated bonds), the stronger their binding affinity to POPC vesicles, suggesting the importance of H-bonding to such a lipid membrane model. The Ka mean value of the best tested UAD, i.e. with a cyclohexyl residue, is about 5.103 M-1. [1] Razafindralambo, H.; Blecker, C; and M. Paquot., Screening of basic properties of amphiphilic molecular the structures for colloidal system formation and stability: the case of carbohydrate-based surfactants in: Amphiphiles: Molecular Assembly and Applilcations, ed. R. Nagarajan, ACS, Washignton, 2011, (In press). [2] Razafindralambo, H.; Dufour, S.; Paquot, M.; Deleu, M., Thermodynamic studies of the binding interactions of surfactin analogues to lipid vesicles: application of isothermal titration calorimetry. J. Therm. Anal. Calorim., 2009, 9 (3), 817-821. Acknowledgment: This work was supported by Belgian Walloon Region with DG06 research project of excellence (TECHNOSE). [less ▲]

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See detailLes volatils racinaires de l’orge : un langage souterrain ?
Barsics, Fanny ULg; Gfeller, Aurélie ULg; Fauconnier, Marie-Laure ULg et al

Scientific conference (2011, October 13)

Cette présentation résume les avancées du projet Rhizovol après une année de travaux de recherche.

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See detailThe use of semiochemical slow-release devices in integrated pest management strategies
Heuskin, Stéphanie ULg; Verheggen, François ULg; Haubruge, Eric ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2011), 15(3), 459-470

The development of integrated pest management (IPM) strategies is increasing since many problems appeared with the use of synthetic pesticides. Semiochemicals – informative molecules used in insect-insect ... [more ▼]

The development of integrated pest management (IPM) strategies is increasing since many problems appeared with the use of synthetic pesticides. Semiochemicals – informative molecules used in insect-insect or plant-insect interaction – are more and more considered within IPM strategies as alternative or complementary approach to insecticide treatments. Indeed, these species-specific compounds do not present any related adversely affectation of beneficial organisms and do not generate any risk of pest insect resistance as observed with insecticides. Because of their complex biological activity, their dispersion in the environment to be protected or monitored needs the elaboration of slow-release devices ensuring a controlled release of the biologically active volatile compounds. These sensitive molecules also need to be protected from degradation by UV light and oxygen. Many studies were conducted on estimation of release-rate from commercialized or experimental slow-release devices. The influence of climatic parameters and dispenser type were estimated by previous authors in order to provide indications about the on-field longevity of lures. The present review outlines a list of slow-release studies conducted by many authors followed by a critical analysis of these studies. [less ▲]

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See detailMonolayer Properties of Uronic Acid Bicatenary Derivatives at the Air-Water Interface: Effect of Hydroxyl Group Stereochemistry Evidenced by Experimental and Computational Approaches
Razafindralambo, Hary ULg; Richel, Aurore ULg; Wathelet, Bernard ULg et al

in Physical Chemistry Chemical Physics [=PCCP] (2011), 13(33), 1529115298

By screening uronic acid-based surfactant interfacial properties, the effect of the hydroxyl group stereochemistry (OH-4) on the conformation of bicatenary (disubstituted) derivatives at the air–water ... [more ▼]

By screening uronic acid-based surfactant interfacial properties, the effect of the hydroxyl group stereochemistry (OH-4) on the conformation of bicatenary (disubstituted) derivatives at the air–water interface has been evidenced by experimental and computational approaches. Physical and optical properties of a monolayer characterized by Langmuirfilmbalance, Brewster angle microscopy, and ellipsometry at 20°C reveal that the derivative of glucuronate (C14/14–GlcA) forms a more expanded monolayer, and shows a transition state under compression, in the opposite to that of galacturonate (C14/14–GalA). Both films are very mechanically resistant (compression modulus > 300m Nm-1) and stable (collapse pressure exceeding 60mNm-1), while that of C14/14–GalA exhibits a very high compression modulus up to 600mNm-1 like films in the solid state. Computational approaches provide single and assembly molecular models that corroborate the molecule expansion degree and interactions data from experimental results. Differences in the molecular conformation and film behaviours of uronic acid bicatenary derivatives at the air–water interface are attributed to the intra-H-bonding formation, which is more favourable with an OH-4 in the axial (C14/14–GalA) than in the equatorial position (C14/14–GlcA). [less ▲]

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See detailEarthworms use odor cues to locate and feed on microorganisms in soil
Zirbes, Lara ULg; Mark, Mescher; Vrancken, Véronique ULg et al

in PLoS ONE (2011), 6(7), 21927

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See detailOptimisation of a semiochemical slow-release alginate formulation attractive towards Aphidius ervi Haliday parasitoids
Heuskin, Stéphanie ULg; Lorge, Stéphanie; Godin, Bruno et al

in Pest Management Science (2011)

BACKGROUND: Optimisation of alginate formulations is described in order to develop semiochemical (E-β-farnesene and E-β-caryophyllene) slow-release devices in biological control approaches by attracting ... [more ▼]

BACKGROUND: Optimisation of alginate formulations is described in order to develop semiochemical (E-β-farnesene and E-β-caryophyllene) slow-release devices in biological control approaches by attracting predators and parasitoids of aphids. Various formulation criteria were optimised with respect to semiochemical encapsulation capacity. Moreover, the optimised formulation was characterised by texturometry and confocal microscopy. The slow-release rates of semiochemicals were calculated in laboratory controlled conditions. The attractiveness of semiochemical formulations towards Aphidius ervi was demonstrated by olfactometry. RESULTS: Two major parameters were highlighted in encapsulation optimisation: the type of alginate (Sigma L) and the type of crosslinker ion (Ca2+). Other formulation parameters were optimised: ionic strength (0.5M), Ca2+ (0.2 M) and alginate (1.5%) concentrations and the maturation time of beads in CaCl2 solution (48 h). After physical characterisation of beads, semiochemical slow-release measurements showed that alginate formulations were efficient sesquiterpene releasers, with 503 μg of E-β-farnesene and 1791 μg of E-β-caryophyllene totally released in 35 days. The efficiency of semiochemical alginate beads as attractants for female parasitoids was demonstrated, with high percentages of attraction for semiochemical odours (88 and 90% for E-β-farnesene and E-β-caryophyllene respectively) and significant statistical results. CONCLUSION: Semiochemical alginate beads can be considered as efficient slow-release systems in biological control. These formulations could be very useful to attract aphid parasitoids on crop fields. [less ▲]

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See detailDevelopment of natural semiochemical slow-release formulations as biological control devices
Heuskin, Stéphanie ULg; Lorge, Stéphanie ULg; Leroy, Pascal ULg et al

in Ioannou, Efstathia; Roussis, Vassilios (Eds.) Trends in natural products research : a PSE young scientists' meeting, June 12-15, 2011, Kolymvari - Crete. Book of abstracts (2011, June 12)

Semiochemicals – informative molecules used in insect-insect or plant-insect interactions – have been widely considered within various integrated pest management (IPM) strategies. In the present work, two ... [more ▼]

Semiochemicals – informative molecules used in insect-insect or plant-insect interactions – have been widely considered within various integrated pest management (IPM) strategies. In the present work, two sesquiterpenoids, E-β-farnesene and E-β-caryophyllene, were formulated for their properties as aphid enemy attractants. E-β-farnesene, the alarm pheromone of many aphid species, was also identified as a kairomone by attracting aphid predators and parasitoids. E-β-caryophyllene was identified as a potential component of the aggregation pheromone of the Asian ladybird, Harmonia axyridis Pallas, another aphid predator. The two products were purified from essential oils of Matricaria chamomilla L. (Asteraceae) and Nepeta cataria L. (Lamiaceae), respectively. Natural and biodegradable formulations were then investigated in order to deliver these molecules on crop fields for a long period of time as biological control devices. Due to their sensitivity to oxidation, both sesquiterpenes needed to be protected from oxygen degradation. For this purpose, alginate – hydrophilic matrix with low oxygen permeability – was used as polymer for the formulations: the main objective was to deliver semiochemicals in the air in a controlled way. Consequently, a careful selection of alginates was realised. Formulated beads showed different structural and encapsulation properties depending on various formulation factors. Alginate formulations were characterised by texturometry and by confocal microscopy in order to observe the distribution of semiochemicals in alginate network. The last step of alginate bead characterisation consisted in studying release rate of semiochemicals in laboratory-controlled conditions by optimised volatile collection system and validated fast GC analytical procedures Finally, the efficiency of formulations as aphid predator (Syrphidae species) and parasitoid (Aphidius ervi) attractants was demonstrated by field trapping and olfactometry experiments. [less ▲]

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