The application of multiplex fluorimetric sensor for the analysis of flavonoids content in the medicinal herbs family Asteraceae, Lamiaceae, Rosaceae

BACKGROUND: The aim of our research work was to quantify total flavonoid contents in the leaves of 13 plant species family Asteraceae, 8 representatives of family Lamiaceae and 9 plant species belonging to familyRosaceae, using the multiplex fluorimetric sensor. Fluorescence was measured using optical fluorescence apparatus Multiplex(R) 3 (Force-A, France) for non-destructive flavonoids estimation. The content of total flavonoids was estimated by FLAV index (expressed in relative units), that is deduced from flavonoids UV absorbing properties. RESULTS: Among observed plant species, the highest amount of total flavonoids has been found in leaves ofHelianthus multiflorus (1.65 RU) and Echinops ritro (1.27 RU), Rudbeckia fulgida (1.13 RU) belonging to the family Asteraceae. Lowest flavonoid content has been observed in the leaves of marigold (Calendula officinalis) (0.14 RU) also belonging to family Asteraceae. The highest content of flavonoids among experimental plants of family Rosaceae has been estimated in the leaves of Rosa canina (1.18 RU) and among plant species of family Lamiaceae in the leaves of Coleus blumei (0.90 RU). CONCLUSIONS: This research work was done as pre-screening of flavonoids content in the leaves of plant species belonging to family Asteraceae, Lamiaceae and Rosaceae. Results indicated that statistically significant differences (P > 0.05) in flavonoids content were observed not only between families, but also among individual plant species within one family

A discursive review of the textual use of ‘trapped’ in environmental migration studies: The conceptual birth and troubled teenage years of trapped populations

First mooted in 2011, the concept of Trapped Populations referring to people unable to move from environmentally high-risk areas broadened the study of human responses to environmental change. While a seemingly straightforward concept, the underlying discourses around the reasons for being ‘trapped’, and the language describing the concept have profound influences on the way in which policy and practice approaches the needs of populations at risk from environmental stresses and shocks. In this article, we apply a Critical Discourse Analysis to the academic literature on the subject to reveal some of the assumptions implicit within discussing ‘trapped’ populations. The analysis reveals a dominant school of thought that assisted migration, relocation, and resettlement in the face of climate change are potentially effective adaptation strategies along a gradient of migrant agency and governance

A people-centred perspective on climate change, environmental stress, and livelihood resilience in Bangladesh

The Ganges–Brahmaputra delta enables Bangladesh to sustain a dense population, but it also exposes people to natural hazards. This article presents findings from the Gibika project, which researches livelihood resilience in seven study sites across Bangladesh. This study aims to understand how people in the study sites build resilience against environmental stresses, such as cyclones, floods, riverbank erosion, and drought, and in what ways their strategies sometimes fail. The article applies a new methodology for studying people’s decision making in risk-prone environments: the personal Livelihood History interviews (N = 28). The findings show how environmental stress, shocks, and disturbances affect people’s livelihood resilience and why adaptation measures can be unsuccessful. Floods, riverbank erosion, and droughts cause damage to agricultural lands, crops, houses, and properties. People manage to adapt by modifying their agricultural practices, switching to alternative livelihoods, or using migration as an adaptive strategy. In the coastal study sites, cyclones are a severe hazard. The study reveals that when a cyclone approaches, people sometimes choose not to evacuate: they put their lives at risk to protect their livelihoods and properties. Future policy and adaptation planning must use lessons learned from people currently facing environmental stress and shocks

Preferring Diagnoses by Abduction

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Chemical Composition and Allelopathic Potential of Essential Oils from Citharexylum spinosum L. grown in Tunisia

Citharexylum spinosum L. (Verbenaceae) also known as C. quadrangulare Jacq. or C. fruticosum L. is an exotic tree introduced many years ago in Tunisia, specially used as a street and park ornamental tree. Essential oils were obtained by hydrodistillation of the different parts (roots, stems, leaves, flowers and fruits; drupes) collected from trees grown in the area of Monastir (Tunisia). In total, 84 compounds, representing 90.1-98.4% of the whole oil composition, were identified by GC-FID and GC/MS analyses. The root essential oil was distinguished by its high content in monoterpene hydrocarbons (α-phellandrene; 30.8%) whereas that obtained from stems was dominated by sesquiterpene hydrocarbons (cuparene; 16.4%). The leaf oil was rich in an apocarotenoid derivative (hexahydrofarnesyl acetone; 26%) and an aliphatic hydrocarbon (n-nonadecane; 14.5%). Flowers oil was rich in esters (2-phenylethyl benzoate; 33.5%). Finally, drupes oil was rich in oxygenated sesquiterpenes (β-eudesmol; 33.1%). Flowers oil showed a significant phytotoxic effect against lettuce seeds germination, it induces a total inhibition when tested at 1 mg/ml. The highest inhibition of 100% was detected for flower oil tested at 1 mg/ml. Our in vitro studies suggest a possible and new alternative use of C. spinosum essential oils in herbicidal formulations, further experiments involving field conditions are necessary to confirm its herbicidal potential. This article is protected by copyright. All rights reserved

Effet des venins de Macrovipera Lebetina et de Cerastes sur l'adhérence aux intégrines des cellules cancéreuse (IGR39, HT29-D4 et IGROV1)

International audienceIn this work, we provide experimental arguments in favor of the fact that components from Macrovipera lebetina and Cerastes cerastes venoms bind to IGR39 melanoma cells but not to HT29D4 cells that derive from carcinoma adenome. Furthermore, Macrovipera lebetina and Cerastes cerastes venoms inhibit the adherence of IGR39 and HT 29-D4 to various extracellular matrix proteins. Macrovipera lebetina and Cerastes cerastes venoms did not inhibit the non specific adherence of IGR 39 cells to polylysine. In addition, binding of components from Cerastes cerastes venom to IGR39 cells is inhibited by GRGDS peptide and by monoclonal antibidy anti-av, while these two components have no effect on the adherence of IGR39 to Macrovipera lebetina venom.Dans ce travail nous apportons des preuves expérimentales en faveur du fait que des composants du venin de Macrovipera lebetina et Cerastes ceraste sont capables de se fixer spécifiquement sur les cellules mélanomateuse IGR39 mais pas aux cellules HT29D4 dérivant d'un adénocarcinome

Purification and characterization of a fibrinogenase from Vipera lebetina (desert adder) venom

International audienceA fibrinogenase from Vipera lebetina venom was isolated by gel filtration in a Superose 12 column prep grade HR 16/50 and by ion-exchange in a Mono Q HR 5/5 column. The purified enzyme, which was obtained with a yield of 8 mg from 60 mg of crude venom, is a glycoprotein having an isoelectric point of 5.9±0.1 and a mol. wt of 26,000±1000 as estimated by SDS-PAGE. The biochemical characterization of the enzyme revealed that it hydrolyzes readily the Bβ chain of fibrinogen and the Aα chain as well as fibrin and casein. Over a pH range from 4 to 11 the enzyme was not inactivated by a 20 min treatment at 90°C. The isolated fibrinogenase is inhibited by ethylenediamine tetraacetic acid, dithiothreitol and l-cysteine but not by phenylmethylsulfonyl fluoride. On the other hand, it is activated by Ca2+ and Mg2+. Purified fibrinogenase up to a dose of 100 μg/mouse shows no toxicity and has no hemorrhagic activity

Direct vs. mediated effects of scorpion venom: an experimental study of the effects of a second challenge with scorpion venom

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Cerastotin, a serine protease from Cerastes cerastes venom, with platelet-aggregating and agglutinating properties.

International audienceCerastotin, a thrombin-like enzyme from the venom of the desert viper Cerastes cerastes, has been purified by gel filtration on Sephadex G-75 and two ion-exchange chromatographies on Mono S columns. It is a neutral glycoprotein (pI = 6.6), present as a single polypeptide chain of 40 kDa. Its N-terminal sequence shows strong similarity with those of other thrombin-like enzymes from snake venoms. Cerastotin possesses esterase and amidolytic activities measured with N(alpha)-tosyl-L-arginine methyl ester and the thrombin chromogenic substrate D-phenylalanyl-L-pipecolyl-L-arginine p-nitroanilide, respectively. The amidolytic activity is inhibited by phenylmethylsulfonyl fluoride, N(alpha)-tosyl-L-lysine chloromethane, N(alpha)-tosyl-L-phenylalanyl chloromethane, D-phenylalanyl-L-prolyl-L-arginyl chloromethane and benzamidine, suggesting that cerastotin is a serine protease. Cerastotin efficiently clots human plasma and cleaves preferentially the alpha chain of fibrinogen. Cerastotin did not induce aggregation of washed normal platelets, but did aggregate platelets in the presence of exogenous fibrinogen. A monoclonal antibody directed against glycoprotein (GPIb), which specifically inhibits induced agglutination by ristocetin also completely blocks platelet aggregation induced by cerastotin. However, another anti-GPIb monoclonal antibody, which specifically inhibits alpha-thrombin binding to GPIb, did not prevent this aggregation. Furthermore, platelets which were desensitised by alpha-thrombin still aggregate in the presence of cerastotin, but not alpha-thrombin. Similarly a monoclonal antibody, anti-GPIIb-IIIa, which blocks fibrinogen binding, did not inhibit cerastotin-induced platelet aggregation. This activity is abolished in the presence of 1 mM phenylmethylsulfonyl fluoride and/or 10 mM EDTA. Cerastotin also agglutinates formalin-fixed and washed platelets, only in the simultaneous presence of fibrinogen and of Von Willebrand factor