Variability of polyphenolic extracts from different oil palm trees and evaluation of their effect on Coelaenomenodera lameensis (Coleoptera, Chrysomelidae) larvae

Coelaenomenodera lameensis is an insect and the major pest of the oil palm. In case of strong attack, it causes up to 50% loss of production. Larval development of C. lameensis is more pronounced on sensitive palm tree Elaeis guineensis originating from La Mé, Yocoboué and Deli compared to tolerant palm trees Elaeis oleifera originating from Central American. The objective of this work is to study the variability content of polyphenols from different palm trees and their effect on the larvae of C. lameensis. To do this, the extracts from the leaflets of these palms were analyzed by HPLC and tested on larvae of the leaf miner. Considering the results, HPLC analysis has revealed additional peaks polyphenols characterizing trees palm Elaeis oleifera tolerant, the retention time of 22.9, 26.4 and 30.4 min. Furthermore, bio-essays conducted on the larvae of Coelaenomenodera lameensis showed differential mortality of these larvae following the origin, the time and the concentration of applied chemical extracts. Indeed, this result indicates that the molecules in the three characteristic peaks are probably potential polyphenols and are in charge of tolerance to C. lameensis.Keywords: Elaeis guineensis, Elaeis oleifera, leaf miner, HPLC, polyphenols

P35 Comparaison de l’interaction moléculaire entre le Taxol@ et les nanoparticules à base de poly (alkyl méthylidène malonate) PMM 2.1.2 et à base de poly (alkylcynoacrylate)(PACA

L’administration et le ciblage contrôlés de médicaments représentent un défi passionnant pour améliorer l’efficacité thérapeutique et/ou prophylactique des molécules biologiquement actives tout en réduisant leurs effets secondaires. Ainsi, différents systèmes tels que les supports macromoléculaires solubles, les liposomes et les particules polymériques ont été intensivement décrits et testés cliniquement. Pour cette étude, le taxol@ (TX, paclitaxel) a été choisi comme médicament hôte modèle pour comparer son encapsulation dans des nanoparticules à base de poly- alkylcynamoacrylates (PACA) et de poly-alkylmethylidenemalonate (PAMM en particulier le PMM 2.1.2).   Une trajectoire de dynamique moléculaire pour chaque espèce a été générée à 300 K et étendue sur 1000 ps par pas de 1 fs. Les conformères échantillonnés toutes les 10 ps ont ensuite été minimisés en énergie en utilisant d'abord la méthode MM2 d'Allinger et la méthode Newton-Raphson bloc-diagonal jusqu'à ce que le gradient obtenu soit inférieur à 0,01 kcal/mol. Nous avons aussi utilisé les méthodes AMI et PM3, COSMO ainsi que les calculs théoriques et enfin les méthodes semi-empiriques SCF-MO AMI et PM3, telles qu'elles sont mises en œuvre dans l'ensemble CS MOPAC trouvé dans CS Chem3DPro 7.0.0. Nous avons adopté une approche tout à fait différente par rapport à celle précédemment combinant la dynamique moléculaire et la mécanique semi-quantique (AMI, PM3 et PM3 COSMO). Les oligomères de PAMM ont tendance à adopter une forme en U, contrairement à ceux de PACA qui adoptent préférentiellement des conformations hélicoïdales avec une disposition radiale des chaînes latérales. Ce résultat a été confirmé par plusieurs publications qui rapportent que, pendant la polymérisation anionique du monomère MM 2.1.2, un processus important de cyclotrimérisation a lieu, produisant un mélange de 4 diastéréo-isomères racémiques de cyclohexanone, c'est-à-dire 2S,4R,6R et 2S,4S,6S, et leurs contreparties énantiomériques. Ces études donnent un aperçu de l'architecture et de la dynamique des nanoparticules. L'approche in silico utilisée ici permet de prédire que le Taxol serait piégé plus efficacement dans le PAAM que dans le PACA, ce qui est en accord avec les résultats expérimentaux

Anti-plasmodial activity of Dicoma tomentosa (Asteraceae) and identification of urospermal A-15- O-acetate as the main active compound.

ABSTRACT: BACKGROUND: Natural products could play an important role in the challenge to discover new anti-malarial drugs. In a previous study, Dicoma tomentosa (Asteraceae) was selected for its promising anti-plasmodial activity after a preliminary screening of several plants traditionally used in Burkina Faso to treat malaria. The aim of the present study was to further investigate the antiplasmodial properties of this plant and to isolate the active anti-plasmodial compounds. METHODS: Eight crude extracts obtained from D. tomentosa whole plant were tested in vitro against two Plasmodium falciparum strains (3D7 and W2) using the p-LDH assay (colorimetric method). The Peters' four-days suppressive test model (Plasmodium berghei-infected mice) was used to evaluate the in vivo anti-plasmodial activity. An in vitro bioguided fractionation was undertaken on a dichloromethane extract, using preparative HPLC and TLC techniques. The identity of the pure compound was assessed using UV, MS and NMR spectroscopic analysis. In vitro cytotoxicity against WI38 human fibroblasts (WST-1 assay) and haemolytic activity were also evaluated for extracts and pure compounds in order to check selectivity. RESULTS: The best in vitro anti-plasmodial results were obtained with the dichloromethane, diethylether, ethylacetate and methanol extracts, which exhibited a high activity (IC50 [less than or equal to] 5 mug/ml). Hot water and hydroethanolic extracts also showed a good activity (IC50 [less than or equal to] 15 mug/ml), which confirmed the traditional use and the promising anti-malarial potential of the plant. The activity was also confirmed in vivo for all tested extracts. However, most of the active extracts also exhibited cytotoxic activity, but no extract was found to display any haemolytic activity. The bioguided fractionation process allowed to isolate and identify a sesquiterpene lactone (urospermal A-15-O-acetate) as the major anti-plasmodial compound of the plant (IC50 < 1 mug/ml against both 3D7 and W2 strains). This was also found to be the main cytotoxic compound (SI =3.3). While this melampolide has already been described in the plant, this paper is the first report on the biological properties of this compound. CONCLUSIONS: The present study highlighted the very promising anti-plasmodial activity of D. tomentosa and enabled to identify its main active compound, urospermal A-15-O-acetate. The high antiplasmodial activity of this compound merits further study about its anti-plasmodial mechanism of action. The active extracts of D. tomentosa, as well as urospermal A 15-Oacetate, displayed only a moderate selectivity, and further studies are needed to assess the safety of the use of the plant by the local population