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See detailProbiotics as a Sources of Aromas in Functionnal Food: Selected Examples and Analytical Methodology (chap.5)
Kenne Kemene, Thierry ULiege; Lognay, Georges ULiege; Fauconnier, Marie-Laure ULiege

in Razafindralambo, Hary (Ed.) Trends in Probiotic Applications (in press)

Probiotics play an important role in functional foods by generating natural aromas that are fundamental for the acceptability of such products by consumers. Selected strains are added to conventional ... [more ▼]

Probiotics play an important role in functional foods by generating natural aromas that are fundamental for the acceptability of such products by consumers. Selected strains are added to conventional functional foods, not just for health properties but also for their capability to improve flavor and overall taste. Beyond their applications to functional dairy products, the use of microorganisms for the aroma in-situ generation is now expanded to meat and plant-based products. However, aromas produced by probiotics are often complex and all odor compounds are not always suitable to all foodstuff types. Therefore, it is also valuable to overview, in the present chapter, the specific analytical methodology currently used for characterizing and selecting interesting aroma compounds. [less ▲]

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See detailCharacterization of Essential oils and hydrosols from senegalese Eucalyptus camaldulensis (Dehnh.)
Ndiaye, El Hadji B.; Diop, Michel B.; Gueye, Momar T. et al

in Journal of Essential Oil Research (in press)

The volatile oils of Eucalyptus camaldulensis leaves harvested in three agro-ecological areas in Senegal were analyzed by GC-FID and GC-MS. Yields ranged from 0.5 to 1.0%. Qualitative and quantitative ... [more ▼]

The volatile oils of Eucalyptus camaldulensis leaves harvested in three agro-ecological areas in Senegal were analyzed by GC-FID and GC-MS. Yields ranged from 0.5 to 1.0%. Qualitative and quantitative différences were determined in the composition according to leave sources. The main compounds of Saint-Louis oils were= 18.-cineole (69.3-73.0%) and limonene (12.4-13.5%) whereas those from Kaolack were charaterized by p-cymene (28.4-32.6%), 1.8-cineole (16.8-20.0%), alpha-pinene (8.7-11.6%) and limonene (7.8-8.3%). Those from Dakar revealed high content of béta-pinene (25.3-34.4%) and alpha-eudesmol (12.3-20.6%). During drying of leaves, the proportions of all major compounds (except limonene) increased and were optimal after 2 hours extraction duration. [less ▲]

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See detailCould saponins be used to enhance bioremediation of polycyclic aromatic hydrocarbons in aged-contaminated soils ?
Davin, Marie ULiege; Starren, Amandine; Deleu, Magali ULiege et al

in Chemosphere (2018), 194

Polycyclic aromatic hydrocarbons (PAH) are persistent organic compounds of major concern that tend to accumulate in the environment, threatening ecosystems and health. Brownfields represent an important ... [more ▼]

Polycyclic aromatic hydrocarbons (PAH) are persistent organic compounds of major concern that tend to accumulate in the environment, threatening ecosystems and health. Brownfields represent an important tank for PAHs and require remediation. Researches to develop bioremediation and phytoremediation techniques are being conducted as alternatives to environmentally aggressive, expensive and often disruptive soil remediation strategies. The objectives of the present study were to investigate the potential of saponins (natural surfactants) as extracting agents and as bioremediation enhancers on an aged-contaminated soil. Two experiments were conducted on a brownfield soil containing 15 PAHs. In a first experiment, soil samples were extracted with saponins solutions (0; 1; 2; 4 and 8 g.L-1). In a second experiment conducted in microcosms (28°C), soil samples were incubated for 14 or 28 days in presence of saponins (0; 2.5 and 5 mg.g- 1). CO2 emissions were monitored throughout the experiment. After the incubation, dehydrogenase activity was measured as an indicator of microbiological activity and residual PAHs were determined. In both experiments PAHs were determined using High-Performance Liquid Chromatography and Fluorimetric Detection. The 4 g.L-1 saponins solution extracted significantly more acenaphtene, fluorene, phenanthrene, anthracene, and pyrene than water. PAHs remediation was not enhanced in presence of saponins compared to control samples after 28 days. However CO2 emissions and dehydrogenase activities were significantly more important in presence of saponins, suggesting no toxic effect of these surfactants towards soil microbiota. [less ▲]

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See detailOviposition deterrent activity of basil plants and their essentials oils against Tuta absoluta (Lepidoptera: Gelechiidae)
Yarou, Boni Barthélémy ULiege; Bawin, Thomas; Boullis, Antoine ULiege et al

in Environmental Science and Pollution Research (2017)

The leafminer Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) is one of the most important pests of tomato, reducing crop yields by up to 100% in greenhouses and fields, in several countries globally ... [more ▼]

The leafminer Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) is one of the most important pests of tomato, reducing crop yields by up to 100% in greenhouses and fields, in several countries globally. Because synthetic insecticides lead to resistance and have adverse effects on natural enemies and the health of producers, alternative control methods are needed. In this study, we assessed the oviposition-deterring effect of basil plants, Ocimum gratissimum L. and O. basilicum L. (Lamiaceae), using dual-choice behavioural assays performed in flight tunnels. We found that both plants significantly reduced T. absoluta oviposition behaviour on a tomato plant located nearby. To evaluate the potential effect of basil volatile organic compounds, we formulated essential oils of both plant species in paraffin oil, and observed a similar oviposition-deterring effect. Gas chromatography analyses detected 18 constituents in these essential oils which the major constituents included thymol (33.3%), p-cymene (20.4%), γ-terpinene (16.9%), myrcene (3.9%) in O. gratissimum and estragol (73.8%), linalool (8.6%), β-elemene (2.9%) and E-β-ocimene (2.6%) in O. basilicum. Twenty and 33 compounds were identified of the volatiles collected on O. gratissimum and O. basilicum plants, respectively. The main components include the following: p-cymene (33.5%), γ-terpinene (23.6%), α-terpinene (7.2%), α-thujene (6.7%) and E-α-bergamotene (38.9%) in O. gratissimum, and methyl eugenol (26.1%), E-β-ocimene (17.7%), and linalool (9.4%) in O. basilicum. Four compounds (α-pinene, β-pinene, Myrcene, Limonene) were common in essential oils and plants. Our results suggest the valuable potential of basil and associated essential oils as a component of integrated management strategies against the tomato leafminer. [less ▲]

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See detailUHPLC-ESI-MS/MS quantitation of natural estrogens in aqueous matrices as pyridine-3-sulfonyl derivatives
Glineur, Alex ULiege; Ronkart, Sébastien; Nott, Kathérine et al

Conference (2017, June 22)

Natural estrogens (estrone: E1, 17-β-estradiol : E2, estriol : E3) and synthetic estrogen (17-α-ethinylestradiol: EE2) are powerful endocrine disruptors. They may have deleterious effects on aquatic ... [more ▼]

Natural estrogens (estrone: E1, 17-β-estradiol : E2, estriol : E3) and synthetic estrogen (17-α-ethinylestradiol: EE2) are powerful endocrine disruptors. They may have deleterious effects on aquatic wildlife and also humans even at extremely low concentrations. For this reason, these molecules have been included in a watch list from the European Commission regarding emerging aquatic pollutants. The maximum detection limits are set at 0.035 and 0.40 ng/L for EE2 and E1, E2 respectively. Reaching such low levels of concentration of estrogenic compounds is a challenge, even using state-of-the-art analytical methods. In this study, we developed a UHPLC-ESI-MS/MS method allowing the quantification of E1, E2, E3 and EE2 residues in aqueous matrices. Studies commonly used ESI in negative mode albeit the poor ionization efficiency of native estrogenic compounds in this mode. In this study, the molecules were derivatised using a sulfonyl chloride reagent (pyridine-3-sulfonyl, P-3-S). The resulting response in the positive mode was significantly enhanced. Similarly to other dansyl derivatives, the product ion spectra of the P-3-S derivatives indicate ions originating from the derivatization reagent moiety. Moreover, several other ions were included in the product ion spectra of the P-3-S derivatives. Their specificity was assessed by a qualitative approach implying the analysis of different types of water samples (groundwater, surface water). Some product ions were found to be noticeably better for quantification and confirmation of the analytes. The developed analytical method was validated according to the NF T90-210 norm which is suitable to assess the performances of a method in the water quality field. The limits of quantification were 0.04, 0.05, 0.10 and 0.02 ng/L in groundwater and 0.89, 0.79,4.42 and 0.29 ng/L in surface water for E1, E2, E3 and EE2 respectively. [less ▲]

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See detailInsect fatty acids: A comparison of lipids from three Orthopterans and Tenebrio molitor L. larvae
Paul, Aman ULiege; Frederich, Michel ULiege; Caparros Megido, Rudy ULiege et al

in Journal of Asia-Pacific Entomology (2017), 20(2), 337-340

In order to explore some potential insect sources of food lipids, the lipid compositions of three Orthopterans (Acheta domesticus, Conocephalus discolor and Chorthippus parallelus) were analyzed and ... [more ▼]

In order to explore some potential insect sources of food lipids, the lipid compositions of three Orthopterans (Acheta domesticus, Conocephalus discolor and Chorthippus parallelus) were analyzed and compared with those of Tenebrio molitor larvae. A. domesticus, Co. discolor, Ch. parallelus and T. molitor larvae were found to contain approximately 15%, 13%, 10% and 32% lipids on dry weight, respectively. The lipids from three Orthopterans contain much higher amounts of essential fatty acids than those of T. molitor larvae. The two Orthopterans of the suborder Ensifera i.e., A. domesticus and Co. discolor contain linoleic acid in major quantities, while Ch. parallelus of the suborder Caelifera, contain α-linolenic acid in major quantities. The consumption of linoleic and α-linolenic fatty acid is linked with numerous health promoting effects. The factors that contribute to differences in fatty acid profiles of these insects are being discussed. At last the nutritional parameters including polyunsaturated to saturated and omega 6 to omega 3 fatty acid ratios of these insect lipids are also being discussed to understand the potential role of these lipids in human nutrition. [less ▲]

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See detailThe importance of pollen chemistry in evolutionary host shifts of bees
Vanderplanck, Maryse ULiege; Vereecken, Nicolas; Grumiau, Laurent et al

in Scientific Reports (2017)

Although bee-plant associations are generally maintained through speciation processes, host shifts have occurred during evolution. Understanding shifts between both phylogenetically and morphologically ... [more ▼]

Although bee-plant associations are generally maintained through speciation processes, host shifts have occurred during evolution. Understanding shifts between both phylogenetically and morphologically unrelated plants (i.e., host-saltation) is especially important since they could have been key processes in the origin and radiation of bees. Probably far from being a random process, such host-saltation might be driven by hidden constraints associated with plant traits. We selected two clades of oligolectic bees (i.e., Colletes succinctus group and Melitta leporina group) foraging on co-flowering but unrelated host-plants to test this hypothesis. We analyzed floral scent, floral color and chemical composition of pollen from host and non-host plants of these two clades. We did not find evidence for host-plant evolution in the Melitta leporina group driven by one of the assayed floral traits. On the contrary, hosts of the C. succinctus group display similar primary nutritive content of pollen (i.e., amino acids and sterols) but not similar floral scent or color, suggesting that shared pollen chemistry probably mediates saltation in this clade. Our study revealed that constraints shaping floral associations are diverse and clearly depend on species life-history traits, but evidence suggests that pollen chemistry may act as a major floral filter and guide evolutionary host-shifts. [less ▲]

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See detailQuantification of natural estrogens in aqueous matrices as pyridine-3-sulfonyl derivatives by UHPLC-ESI-MS/MS
Glineur, Alex ULiege; Ronkart, Sébastien; Nott, Kathérine et al

Conference (2017, February 07)

Natural estrogens (estrone: E1, 17-β-estradiol : E2, estriol : E3) and synthetic estrogen (17-α-ethinylestradiol: EE2) are powerful endocrine disruptors. They may have deleterious effects on aquatic ... [more ▼]

Natural estrogens (estrone: E1, 17-β-estradiol : E2, estriol : E3) and synthetic estrogen (17-α-ethinylestradiol: EE2) are powerful endocrine disruptors. They may have deleterious effects on aquatic wildlife and also humans even at extremely low concentrations. For this reason, these molecules have been included in a watch list from the European Commission regarding emerging aquatic pollutants. The maximum detection limits are set at 0.035 and 0.40 ng/L for EE2 and E1, E2 respectively. Reaching such low levels of concentration of estrogenic compounds is a challenge, even using state-of-the-art analytical methods. In this study, we developed a UHPLC-ESI-MS/MS method allowing the quantification of E1, E2, E3 and EE2 residues in aqueous matrices. Studies commonly used ESI in negative mode albeit the poor ionization efficiency of native estrogenic compounds in this mode. In this study, the molecules were derivatised using a sulfonyl chloride reagent (pyridine-3-sulfonyl, P-3-S). The resulting response in the positive mode was significantly enhanced. Similarly to other dansyl derivatives, the product ion spectra of the P-3-S derivatives indicate ions originating from the derivatization reagent moiety. Moreover, several other ions were included in the product ion spectra of the P-3-S derivatives. Their specificity was assessed by a qualitative approach implying the analysis of different types of water samples (groundwater, surface water). Some product ions were found to be noticeably better for quantification and confirmation of the analytes. The developed analytical method was validated according to the NF T90-210 norm which is suitable to assess the performances of a method in the water quality field. The limits of quantification were 0.04, 0.05, 0.10 and 0.02 ng/L in groundwater and 0.89, 0.79,4.42 and 0.29 ng/L in surface water for E1, E2, E3 and EE2 respectively. [less ▲]

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See detailElevated carbon dioxide concentration reduces alarm signaling in aphids
Boullis, Antoine ULiege; Fassotte, Bérénice ULiege; Sarles, Landry ULiege et al

in Journal of Chemical Ecology (2017), 43

Insects often rely on olfaction to communicate with surrounding conspecifics. While the chemical language of insects has been deciphered in recent decades, few studies have assessed how changes in ... [more ▼]

Insects often rely on olfaction to communicate with surrounding conspecifics. While the chemical language of insects has been deciphered in recent decades, few studies have assessed how changes in atmospheric greenhouse gas concentrations will impact pheromonal communication by insects. Here, we hypothesize that changes in the concentration of atmospheric carbon dioxide (CO2) affect the whole dynamics of alarm signaling in aphids, including: (1) the production of the active compound (E)-β-farnesene (Eβf), (2) emission behavior when under attack, (3) perception by the olfactory apparatus, and (4) the escape response. We reared two strains of the pea aphid Acyrthosiphon pisum under ambient and elevated CO2 concentrations for several generations. We found that an increase in CO2 concentration reduced the production (i.e., individual content) and emission of Eβf (released under predation events). While no difference in Eβf neuronal perception was observed, we found that an increase in CO2 strongly reduces the escape behavior expressed by an aphid colony following exposure to natural doses of the alarm pheromone. In conclusion, our results confirm that changes to greenhouse gases do impact chemical communication in insects, and could potentially have a cascade effect on interactions with higher trophic levels. [less ▲]

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See detailLooking for phosphate-accumulating bacteria in activated sludge processes : a multidisciplinary approach
Tarayre, Cédric ULiege; Charlier, Raphaëlle; Delepierre, Anissa ULiege et al

in Environmental Science and Pollution Research (2017)

Over the past decades, an increasing need in renewable resources has progressively appeared. This trend concerns not only fossil fuels but also mineral resources. Wastewater and sewage sludge contain ... [more ▼]

Over the past decades, an increasing need in renewable resources has progressively appeared. This trend concerns not only fossil fuels but also mineral resources. Wastewater and sewage sludge contain significant concentrations in phosphate and can be considered as a fertilizer source of the utmost importance. In wastewater treatment plants, the biological uptake of phosphate is performed by a specific microbiota: the phosphate-accumulating organisms. These microorganisms are recovered in sewage sludge. Here, we aimed to investigate the occurrence of phosphate accumulators in four wastewater treatment plants. A 16S metagenetic analysis identified the main bacterial phyla extracted from the aerobic treatment: α-Proteobacteria, β-Proteobacteria, and Sphingobacteria. An enrichment stage was performed to stimulate the specific growth of phosphate-accumulating bacteria in an acetate medium. An analysis of metabolic activities of sulfur and phosphorus highlighted strong modifications related to phosphorus and much less distinguishable effects with sulfur. A solid acetate medium containing 5-Br-4-Cl-3-indolyl phosphate was used to select potential phosphate-accumulating bacteria from the enriched consortia. The positive strains have been found to belong in the genera Acinetobacter, Corynebacterium, and Pseudomonas. Finally, electron microscopy was applied to the strains and allowed to confirm the presence of polyphosphate granules. Some of these bacteria contained granules the size of which exceeded 100 nm. [less ▲]

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See detailIdentification of walnut husk (Juglans regia L.) volatiles and the behavioural response of the invasiveWalnut Husk Fly, Rhagoletis completa Cresson
Sarles, Landry ULiege; Boullis, Antoine ULiege; Fassotte, Bérénice ULiege et al

in Pest Management Science (2017)

Abstract BACKGROUND: Several European countries are important walnut (Juglans regia L.) producers. However, these countries must contendwith the recent introduction of theWalnut Husk Fly,Rhagoletis ... [more ▼]

Abstract BACKGROUND: Several European countries are important walnut (Juglans regia L.) producers. However, these countries must contendwith the recent introduction of theWalnut Husk Fly,Rhagoletis completa Cresson (Diptera, Tephritidae),which is causing severe economic losses, especially in organic production. Because most Tephritid fruit flies use kairomones in their search for host plants, we hypothesise that this highly specialist species orients toward the volatile blend released by walnut husks. RESULTS:We collected, identified, and quantified the volatile organic chemicals (VOCs) released by walnut husks from themost commonly cultivated variety in France (Franquette). Then, the behavioural response of R. completa toward synthetic odour blends was recorded in dual choice assays conducted in net cages. A total of 26 VOCs were identified, with 𝜶-pinene, 𝜷-pinene, trans-linalool, eugenol, and tetradecane representing the major constituents. In the dual choice assay, male and female R. completa were strongly attracted to synthetic blend that includedmost of the identified husk VOCs. CONCLUSION:When searching for a host plant, R. completa use host fruit kairomones. The potential of these semiochemicals in monitoring andmanagement of this quarantine pest is discussed. [less ▲]

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See detailStudy of the chemical composition of essential oils and floral waters of Cymbopogon citratus (DC.) Stapf (Poaceae) from Senegal
Diop, Serigne Mbacké; Guèye, Momar Talla; Ndiaye, Ibrahima et al

in International Journal of Biological and Chemical Sciences (2017), 11(4), 1884-1892

This work aimed to study the chemical composition of essential oils and floral waters of Cymbopogon citratus (DC.) Stapf (Poaceae) from Senegal. The plants were collected in two different localities ... [more ▼]

This work aimed to study the chemical composition of essential oils and floral waters of Cymbopogon citratus (DC.) Stapf (Poaceae) from Senegal. The plants were collected in two different localities, Dakar and Kaolack. The extracts were obtained by steam distillation from both fresh and dried plants and analyses carried out by GC/FID and GC/MS. Oils from Dakar were dominated by geranial which represented 46.0-43.9%, neral 31.8-31.0%, myrcene 10.8-11.7% and geraniol 2.7-4.2% in the fresh and dried plants, respectively. Their floral waters contained mainly 44.6-41.4% geranial, 39.7-35.6% neral and 8.8-13.2% geraniol. The oils from Kaolack were characterized by geranial which constituted 49.5-44.5%, neral 33.3-31.2%, myrcene 7.2-9.6% and geraniol 4.3-6.1% in the fresh and dried plants, respectively. In their floral waters, it is identified 42.8-33.6% geranial, 38.4-27.6% neral and 12.5-24.5% geraniol. This original study revealed that both oils and floral waters of C. citratus from Senegal are characterized by geranial and neral whose repellent properties against mosquitoes are known. [less ▲]

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See detailChemical Composition of Distilled Essential Oils and Hydrosols of Four Senegalese Citrus and Enantiomeric Characterization of Chiral Compounds
Ndiaye, El Hadji Barka; Gueye, Momar Talla; Ndiaye, Ibrahima et al

in Journal of Essential Oil-Bearing Plants [=JEOBP] (2017), 20(3), 820-834

Peels of four local Citrus species (Citrus sinensis L. Obsbeck, Citrus reticulata Blanco, Citrus maxima Burm. and Citrus aurantifolia christm.) grown in a same locality under the same climatic conditions ... [more ▼]

Peels of four local Citrus species (Citrus sinensis L. Obsbeck, Citrus reticulata Blanco, Citrus maxima Burm. and Citrus aurantifolia christm.) grown in a same locality under the same climatic conditions were subjected to steam distillation. The essential oils and floral waters obtained were analyzed by gas chromatography coupled with a flame ionization detector (CPG-FID) and by gas chromatography coupled to a mass spectrometer (CPG-MS). The essential oils yields were ranged between 0.2 and 0.7 %. The qualitative and quantitative analyses show 74 compounds in all oils samples. The oils were largely dominated by hydrocarbon monoterpenes with limonene as major compound (91.5-94.0 %; 90.4-93.4 %; 77.7-93.7 % and 34.8-51.2 %) in oils from Citrus sinensis, Citrus reticulata, Citrus maxima and Citrus aurantifolia, respectively. In addition to limonene, oils of Citrus aurantifolia contained high amounts of β-pinene (6.8-14.4 %), pcymene (5.8-12.2 %), γ-terpinene (0.3 -7.4 %), neral (1.5-9.4 %), geraniol (1.9-12.7 %). Although presenting the same major compound (limonene), the oils had compositions that were qualitatively and quantitatively different. The enantiomeric analyses showed that the chiral major compounds were (R) - (+) - limonene, (S) - (-) – limonene, (1S) - (-) -β-pinene, (1R)-(+)-β-pinene and (S) - (+) - carvone. The hydrosols analyzed were composed of oxygenated compounds and did not have the same major compound. A qualitative and quantitative difference in chemical composition was noted between the Hydrosols. [less ▲]

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See detailChemical composition, acute toxicity, antimicrobial and anti-inflammatory activities of Thymus fontanesii essential oil from Algeria
Sidali, Lamia; Brada, Mousa; Fauconnier, Marie-Laure ULiege et al

in PhytoChem & BioSub Journal (2017), 11(1), 11

The aim of the present study was to determine the chemical composition and to evaluate the acute toxicity, antimicrobial and anti-inflammatory activities of Thymus fontanesii essential oils (TFEO). The ... [more ▼]

The aim of the present study was to determine the chemical composition and to evaluate the acute toxicity, antimicrobial and anti-inflammatory activities of Thymus fontanesii essential oils (TFEO). The oils were obtained by hydrodistillation from the aerial parts of T. fontanesii at yield of 2.4±0.2%. Using GC and GC/MS techniques, 24 compounds were identified representing more than 98% of the oil composition. The main constituents were carvacrol (54.7±1.2%), p-cymene (17.5±0.3%) and ɣ-terpinene (8.8±0.6%). Using the disc diffusion and broth microdilution methods against six microbial strains, the antimicrobial evaluation showed that TFEO exhibited good antibacterial activity against all the strains tested except Pseudomonas aeruginosa. The acute toxicity test of TFEO was conducted in mice by gavage in single doses of 100-3000 mg/kg. However, the mortality rate as well as the acute toxicity of the oral administered oil increased progressively with increasing dose (LD50=875mg/kg). Anti-inflammatory activity of TFEO was evaluated using carrageenaninduced paw edema in mice. The paw edema was reduced by the TFEO at doses of 50 mg/kg (22.8%) and 100 mg/kg (62.2%). The TFEO was found to possess potent anti-inflammatory activity.Results of the present study indicate that TFEO has a noteworthy potential for the use in pharmaceutical formulations. [less ▲]

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See detailChemical composition of essential oils and hydrosols of three Eucalyptus species from Senegal: Eucalyptus alba Renv, Eucalyptus camaldulensis Dehnh and Eucalyptus tereticornis Hook
Barka Ndiaye, El Hadji; Talla Gueye, Momar; Ndiaye, Ibrahima et al

in American Journal of Essential Oils and Natural Products (2017), 5(1), 1-7

The leaves of three eucalyptus species Eucalyptus Alba, Eucalyptus camaldulensis and ucalyptus tereticornis were collected in Kaolack (Senegal) and were extracted by steam distillation after 3, 7, 14 and ... [more ▼]

The leaves of three eucalyptus species Eucalyptus Alba, Eucalyptus camaldulensis and ucalyptus tereticornis were collected in Kaolack (Senegal) and were extracted by steam distillation after 3, 7, 14 and 21 days of drying. The volatile components of aqueous distillates (hydrosols) were obtained by liquid–liquid extraction using n-hexane. The different extracts were analyzed by gas chromatography coupled to a flame ionization detector (GC-FID) and by gas chromatography coupled to a mass spectrometer (GC-MS). Essential oils yields obtained range from 0.3 to 1.6%. E. camaldulensis had the higher yield. Forty four compounds were characterized in E. camaldulensis essential oils. These lasts were dominated by 1.8-cineole (47.54 to 52.47%), limonene (16.5 to 19.1%), α-pinene (7.3 to 11.2%) and p-cymene (6.0 to 8.8%). Fifty compounds were identified in E. Alba oils with 1.8-cineole (36.0-38.3%) α-pinene (19.0-26.4%), limonene (5.7- 8.3%), trans-pinocarveol (3.5 -5.0%) β-pinene (1.9 to 4.6%) as major compounds. In E. tereticornis oils, fifty two compounds were identified. Their composition were dominated by p-cymene (42.49 to 48.51%) followed by 1.8-cineole (21.3- 24.5%), limonene (4.8- 5.9%) and α-pinene (1.9 to 6.7%). The analyzed hydrosols were composed by oxygenated molecules whose major part was found in oils. As essential oils, all corresponding hydrosols hade high rate of 1.8-cineole. E. alba hydrosol contains mainly 1.8-cineole (39.1%), trans-pinocarveol (19.3%), pinocarvone (6.8%). E. camaldulensis hydrosol was dominated by 1.8-cineole (52.6%), α-terpineol (6.6%), cis-p-mentha-1-(7)-8-dien-2ol (5.1%). The major compounds of E. tereticornis hydrolat were: 1.8-cineole (30.7%), α-terpineol (8.8%), trans-pinocarveol (7.6%), carvacrol (7.0%). The results showed that although 1.8-cineole was the main component of the hydrosols of all eucalyptus species, but its relative content was higher in E. camaldulensis. [less ▲]

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See detailChemical Composition and Acaricidal Activity of Thymus algeriensis Essential Oil against Varroa destructor
Kouache, Benmoussa; Brada, Moussa; Saadi, Abdelkader et al

in Natural Product Communications (2017), 12(0), 1-4

The aim of the present study was to determine the chemical composition and evaluate the acaricidal activity of Thymus algeriensis essential oil (TAEO) against Varroa destructor. This ectoparasitic mite is ... [more ▼]

The aim of the present study was to determine the chemical composition and evaluate the acaricidal activity of Thymus algeriensis essential oil (TAEO) against Varroa destructor. This ectoparasitic mite is a pest of the honey bee Apis mellifera. The essential oil from the aerial parts of T. algeriensis, obtained by hydrodistillation, was obtained in a yield of 2.8± 0.2%, w/w. The TAEO was analyzed by GC and GC/MS. Thirty-four compounds were identified, representing 99.3% of the oil. The main constituents were carvacrol (48.4%), γ-terpinene (14.9%), p-cymene (14.7%), and thymol (5.6%). Four lots were constituted at the level of an apiary in order to study the dynamics of the Varroa destructor and its host, Apis mellifera. After diagnosis by the biological method "install of diapers", the lots were treated at different doses of TAEO (0.1, 0.3 and 0.5%). TAEO was sprayed on top of the hives. The results show that TAEO at 0.5% resulted in a decrease in the rate of infestation of Varroa destructor, causing a mortality rate of 32.6% without negative effect on the nesting of the queen. The essential oil of T. algeriensis could be used as a bioacaricidal agent. [less ▲]

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See detailImpact of pollen resources drift on common bumblebees in NW Europe
Roger, N.; Moerman, R.; Carvalheiro, L. G. et al

in Global Change Biology (2017), 23(1), 68-76

Several bee species are experiencing significant population declines. As bees exclusively rely on pollen for development and survival, such declines could be partly related to changes in their host plant ... [more ▼]

Several bee species are experiencing significant population declines. As bees exclusively rely on pollen for development and survival, such declines could be partly related to changes in their host plant abundance and quality. Here, we investigate whether generalist bumblebee species, with stable population trends over the past years, adapted their diets in response to changes in the distribution and chemical quality of their pollen resources. We selected five common species of bumblebee in NW Europe for which we had a precise description of their pollen diet through two time periods (‘prior to 1950’ and ‘2004–2005’). For each species, we assessed whether the shift in their pollen diet was related with the changes in the suitable area of their pollen resources. Concurrently, we evaluated whether the chemical composition of pollen resources changed over time and experimentally tested the impact of new major pollen species on the development of B. terrestris microcolonies. Only one species (i.e. B. lapidarius) significantly included more pollen from resources whose suitable area expanded. This opportunist pattern could partly explain the expansion of B. lapidarius in Europe. Regarding the temporal variation in the chemical composition of the pollen diet, total and essential amino acid contents did not differ significantly between the two time periods while we found significant differences among plant species. This result is driven by the great diversity of resources used by bumblebee species in both periods. Our bioassay revealed that the shift to new major pollen resources allowed microcolonies to develop, bringing new evidence on the opportunist feature of bumblebee in their diets. Overall, this study shows that the response to pollen resource drift varies among closely related pollinators, and a species-rich plant community ensures generalist species to select a nutrient-rich pollen diet. © 2016 John Wiley & Sons Ltd [less ▲]

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