Two New Retigerane-Type Sesterterpenoids from the Lichen Leprocaulon microscopicum

International audienceTwo new sesterterpenes, 1 and 2, have been isolated from the lichen Leprocaulon microscopicum. In addition to classic chromatographic methods, a liquid-liquid chromatography technique, namely centrifugal partition chromatography (CPC) was applied for the purification of compound 2. The structures were determined by analyses of mass spectrometry and 1D- and 2D-NMR data. The relative configuration of the isolated compounds was assigned on the basis of 2D-NOESY experiments. The two compounds possess a rare pentacyclic carbon skeleton typical for lichen metabolism, and quite unusual in the vegetal kingdom

Validation des activités antiparasitaires des constituants de Muntafara sessilifolia (Apocynaceae)

Muntafara sessilifolia (Baker) Pichon, traditionnellement utilisée à Madagascar lors de fièvres, a été sélectionnée par criblage basé sur l activité antiplasmodiale des extraits. L extraction sélective acide/base avec gradient de pH effectuée sur l extrait MeOH de la poudre d écorce a fournit un extrait alcaloïdique brut et un extrait AcOEt actifs in vitro sur P. falciparum. Leur fractionnement bioguidé a permis d isoler 29 composés : des alcaloïdes mono et bisindoliques et des terpénoïdes dont 11 nouveaux composés. Leurs activités antiparasitaires sur Plasmodium falciparum, Trypanosoma brucei brucei et Leishmania donovani, antibactériennes et cytotoxiques ont été évaluées. Des tests complémentaires ont été effectués afin de connaitre l influence des composants plasmatiques sur leur activité antiplasmodiale, le comportement de ces produits sur des souches de Plasmodium de sensibilité différente et sur le développement des stades précoces du parasite.Muntafara sessilifolia (Baker) Pichon traditionally used for the treatment of fevers in Madagascar, was selected by screening based on the antiplasmodial activity of the extracts. Selective acid-base extraction with gradient of pH performed on MeOH extract from the powdered stem-bark, yielded a crude alkaloid and EtOAc extracts, active in vitro against P. falciparum. Their bioassayguided fractionation led to isolation of 29 compounds : monomeric indole and bisindole alkaloids and terpenoïds, 11 compounds being new. The antiparasitic activities against Plasmodium falciparum, Trypanosoma brucei brucei and Leishmania donovani, were evaluated along with antibacterial and cytotoxic activities on all isolated molecules. Additional tests were conducted to know the influence of plasma components on their antiplasmodial activity, the behavior of the products against strains of P. falciparum of different sensitivity and the development of the early stage of the parasite.PARIS-Museum Hist.Naturelle (751052304) / SudocSudocFranceF

Influence de métabolites de Meiogyne cylindrocarpa dans la régulation de l'apoptose

LIMOGES-BU Médecine pharmacie (870852108) / SudocLYON1-BU Santé (693882101) / SudocSudocFranceF

Etude phytochimique et activités antiparasitaires de Teucrium ramosissimum

Au cours de ce travail, une étude phytochimique a été entreprise sur Teucrium ramosissimum, une plante endémique de l Afrique du Nord. Le fractionnement bioguidé de l extrait acétate d éthyle de cette plante a conduit à l isolement de 19 composés, dont 17 ont été identifiés. L élucidation structurale de ces composés a été réalisée à l aide des méthodes spectrométriques (IR, MS, RMN 1D (1H, 13C), et 2D (COSY, HSQC, HMBC et NOESY). La comparaison avec les données bibliographiques montre que 6 des composés identifiés (P1, P3, P4, P5, P6, P12) sont de structure nouvelle. La majorité des produits isolés sont des sesquiterpènes appartenant à différents squelettes : isodaucanes, trinoreudesmanes, eudesmanes, cadinanes et oplopanes. Un monoterpène P13 a été aussi isolé, il appartient à la classe des thujanes, ainsi que quatre flavonoïdes connus P14, P15, P16, et P17. L activité antipaludique des produits obtenus a été évaluée sur la souche FcB1 de Plasmodium falciparum résistante à la chloroquine. Le produit P2 (CI50= 1,2 g/ml) est celui qui possède l activité la plus intéressante avec un index de sélectivité supérieur à 83. Les produits P4, P8 et P10 ont montré des activités intéressantes avec des CI50 entre 3,3 et 5,0 g/ml et des index de sélectivité compris entre 20 et 30,3. L activité antileishmanienne des composés isolés a été effectuée sur des cultures des formes promastigotes de Leishmania donovani. Le produit P4 (CI50= 6 g/ml) possède la meilleure activité qui est comparable à celle de la pentamidine. L évaluation de la cytotoxicité de tous les composés isolés sur la lignée cellulaire MRC-5 a montré qu ils ne présentaient aucune cytotoxicité à une concentration de 100 g/ml.During this work, a phytochimical study was undertaken on Teucrium ramosissimum, an endemic plant of North Africa. The bioguided investigation of the ethyl acetate extract of this plant led to the isolation of 19 compounds, among them 17 were identified. The structural elucidation of these compounds was elucidated by extensive spectrometric methods (IR, MS, NMR 1D (1H, 13C), and 2D (COSY, HSQC, HMBC and NOESY). The comparison with the bibliographical data shows that 6 of the identified compounds (P1, P3, P4, P5, P6 and P12) are new structures. The majority of the isolated compounds are sesquiterpenoids belonging to various skeletons: isodaucanes, trinoreudesmanes, eudesmanes, cadinanes and oplopanes. A monoterpene P13 was isolated; it belongs to the class of thujanes, as well as four known flavonoïds P14, P15, P16, and P17. The antimalarial activity of the isolated compounds was evaluated against the chloroquine resistant Plasmodium falciparum strain FcB1. Compound P2 (IC50 = 1,2 g/ml) displayed the most interesting activity with a selectivity index (SI) upper to 83. Compounds P4, P8 and P10 showed interesting activities with IC50 between 3,3 and 5,0 g/ml and SI between 20 and 30,3. The antileishmanial activity of the isolated compounds was performed against promastigote form of Leishmania donovani. The compound P4 (IC50 = 6 g/ml) exhibited the most interesting activity in the same range of pentamidine. The evaluation of the cytotoxicity of all the isolated compounds on MRC-5 cell line showed that they were devoid of cytotoxicity.PARIS-Museum Hist.Naturelle (751052304) / SudocSudocFranceF

Activités antiparasitaires et antifongiques des plantes du Cerrado (Spiranthera odoratissima et Diospyros hispida)

PARIS-Museum Hist.Naturelle (751052304) / SudocSudocFranceF

Antifungal and Anti-Biofilm Activities of Acetone Lichen Extracts against Candida albicans

Candida albicans is a commensal coloniser of the human gastrointestinal tract and an opportunistic pathogen, especially thanks to its capacity to form biofilms. This lifestyle is frequently involved in infections and increases the yeast resistance to antimicrobials and immune defenses. In this context, 38 lichen acetone extracts have been prepared and evaluated for their activity against C. albicans planktonic and sessile cells. Minimum inhibitory concentrations of extracts (MICs) were determined using the broth microdilution method. Anti-biofilm activity was evaluated using tetrazolium salt (XTT) assay as the ability to inhibit the maturation phase (anti-maturation) or to eradicate a preformed 24 h old biofilm (anti-biofilm). While none of the extracts were active against planktonic cells, biofilm maturation was limited by 11 of the tested extracts. Seven extracts displayed both anti-maturation and anti-biofilm activities (half maximal inhibitory concentrations IC50_mat and IC50_biof ≤ 100 µg/mL); Evernia prunastri and Ramalina fastigiata were the most promising lichens (IC50_mat < 4 µg/mL and IC50_biof < 10 µg/mL). Chemical profiles of the active extracts performed by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC) have been analyzed. Depsides, which were present in large amounts in the most active extracts, could be involved in anti-biofilm activities. This work confirmed that lichens represent a reservoir of compounds with anti-biofilm potential

Microbial community associated with the crustose lichen Rhizocarpon geographicum L. ( DC .) living on oceanic seashore: A large source of diversity revealed by using multiple isolation methods

International audienceRecently, the study of the interactions within a microcosm between hosts and their associated microbial communities drew an unprecedented interest arising from the holobiont concept. Lichens, a symbiotic association between a fungus and an alga, are redefined as complex ecosystems considering the tremendous array of associated microorganisms that satisfy this concept. The present study focuses on the diversity of the microbiota associated with the seashore located lichen Rhizocarpon geographicum, recovered by different culture-dependent methods. Samples harvested from two sites allowed the isolation and the molecular identification of 68 fungal isolates distributed in 43 phylogenetic groups, 15 bacterial isolates distributed in five taxonomic groups and three microalgae belonging to two species. Moreover, for 12 fungal isolates belonging to 10 different taxa, the genus was not described in GenBank. These fungal species have never been sequenced or described and therefore non-studied. All these findings highlight the novel and high diversity of the microflora associated with R. geographicum. While many species disappear every day, this work suggests that coastal and wild environments still contain an unrevealed variety to offer and that lichens constitute a great reservoir of new microbial taxa which can be recovered by multiplying the culture-dependent techniques

Profiling and seasonal variation of chemical constituents from Pseudotsuga menziesii wood

International audienceThe composition of sapwood, transition zone and heartwood extracts from Pseudotsuga menziesii was studied using LC/ESI–MS/MS. Based on retention times, and MS fragmentation patterns, 40 phenolic compounds, 11 terpenes and 7 fatty and organic acids were identified or accordingly characterized. The flavonoids taxifolin-O-hexoside and the corresponding aglycon taxifolin, dihydrokaempferol, pinocembrin, pinobanksin, quercetin and flavan-3-ols, catechin and epicatechin were the main compounds detected in wood collected in the fall. Taxifolin derivatives were identified as monomers, dimers and flavonolignans. Comparative metabolite profiling of the three zones showed differences in metabolite distribution. Flavonoids were distributed in the 3 zones. Lignans, flavonolignans, phenolic acid derivatives and terpenes accumulated mainly in the transition zone while tannins were detected only in sapwood. Fatty and organic acids were present in sapwood and the transition zone. Multiple Reaction Monitoring (MRM) was used for the quantification of main metabolites of extracts in order to observe seasonal variations in the wood. The relative quantity of 35 selected compounds in each zone was discussed. The lowest metabolite content was usually observed in winter whereas flavonoids were found in high quantities in heartwood either in spring or autumn

Activity of Ocimum basilicum, Ocimum canum, and Cymbopogon citratus essential oils against Plasmodium falciparum and mature-stage larvae of Anopheles funestus s.s.

The biological activities of essential oils from three plants grown in Cameroon: Ocimum basilicum, Ocimum canum, and Cymbopogon citratus were tested against Plasmodium falciparum and mature-stage larvae of Anopheles funestus. Gas chromatography and gas chromatography – mass spectrometry analyses showed that the main compounds are geranial, 1,8-cineole and linalool in C. citratus, O. canum and O. basilicum, respectively. Larvicidal tests carried out according to the protocol recommended by the World Health Organization showed that the essential oil of leaves of C. citratus is the most active against larvae of An. funestus (LC50 values = 35.5 ppm and 34.6 ppm, respectively, for larval stages III and IV after 6 h of exposure). Besides, the in vitro anti-plasmodial activity evaluated by the radioisotopic method showed that the C. citratus oil is the most active against P. falciparum, with an IC50 value of 4.2 ± 0.5 μg/mL compared with O. canum (20.6 ± 3.4 μg/mL) and O. basilicum (21 ± 4.6 μg/mL). These essential oils can be recommended for the development of natural biocides for fighting the larvae of malaria vectors and for the isolation of natural products with anti-malarial activity

Activity of Ocimum basilicum, Ocimum canum, and Cymbopogon citratus essential oils against Plasmodium falciparum and mature-stage larvae of Anopheles funestus s.s.

International audienceThe biological activities of essential oils from three plants grown in Cameroon: Ocimum basilicum, Ocimum canum, and Cymbopogon citratus were tested against Plasmodium falciparum and mature-stage larvae of Anopheles funestus. Gas chromatography and gas chromatography - mass spectrometry analyses showed that the main compounds are geranial, 1,8-cineole and linalool in C. citratus, O. canum and O. basilicum, respectively. Larvicidal tests carried out according to the protocol recommended by the World Health Organization showed that the essential oil of leaves of C. citratus is the most active against larvae of An. funestus (LC50 values = 35.5 ppm and 34.6 ppm, respectively, for larval stages III and IV after 6 h of exposure). Besides, the in vitro anti-plasmodial activity evaluated by the radioisotopic method showed that the C. citratus oil is the most active against P. falciparum, with an IC 50 value of 4.2 ± 0.5 μg/mL compared with O. canum (20.6 ± 3.4 μg/mL) and O. basilicum (21 ± 4.6 μg/mL). These essential oils can be recommended for the development of natural biocides for fighting the larvae of malaria vectors and for the isolation of natural products with anti-malarial activity