Volatile Constituents of Cucumis sativus: Differences Between Five Tropical Cultivars

International audienceCucumis sativus L. (cucumber), a creeping plant of the Cucurbitaceae family, is widely cultivated for its fruit. It is a tender annual with a rough, succulent, trailing stem and hairy leaves with three to five pointed lobes; the stem bears branched tendrils by which the plant can be trained on supports. Depending on the cultivar, the fruits are available in many different sizes, shapes, and colors. They range from thick, stubby little fruits (10–12 cm long) to Dutch greenhouse varieties (of up to 50 cm long)

Chemical and biological investigation of Indigofera ammoxylum (DC.) Polhill. red and white phenotypes through feature-based molecular networking

peer reviewedChemical investigation of ethyl acetate bark extracts of Indigofera ammoxylum red and white phenotypes led to the bio-guided isolation of four previously undescribed flavonoids, named (2S,3R)-3′,7-dihydroxy-4′,6-dimethoxyflavanol (1), (2S,3R)-6-methoxy-7-hydroxyflavanol (2), 2′,3′,7-trihydroxy-4′,6-dimethoxyisoflavone (7) and 2′,5'-dimethoxy-4′,5,7-trihydroxyisoflavanone (8), along with 14 known compounds (3-6 and 9-18). The previously undescribed structures were characterized based on NMR, HRESIMS, UV and IR data. Published spectroscopic data were used to deduce the structure of the known compounds. Eleven of the 18 isolated metabolites were evaluated for anti-inflammatory activity and cytotoxic activity against human liver carcinoma cells and human colon and colorectal adenocarcinoma cells. All tested compounds showed an anti-inflammatory activity (IC 50 NO < 25 μg/mL), and compounds 2 and 3 were more selective than the positive control dexamethasone. Afromorsin (6) showed promising cytotoxic properties against both cancer cell lines (IC 50 18.9 and 11.4 μg/mL). Feature-based molecular networking approach applied to bark and leaves extracts of the two phenotypes allowed to detect bioactive analogues, belonging to the families of flavones, isoflavones, flavanones, flavanols and flavonols, and to explore the chemodiversity of the species. The red and white phenotypes have a similar composition, whereas bark and leaves contain specific chemical entities. Finally, this approach highlighted a cluster of potentially bioactive and undescribed metabolites

OSMAC Method to Assess Impact of Culture Parameters on Metabolomic Diversity and Biological Activity of Marine-Derived Actinobacteria

peer reviewedActinobacteria are known for their production of bioactive specialized metabolites, but they are still under-exploited. This study uses the “One Strain Many Compounds” (OSMAC) method to explore the potential of three preselected marine-derived actinobacteria: Salinispora arenicola (SH-78) and two Micromonospora sp. strains (SH-82 and SH-57). Various parameters, including the duration of the culture and the nature of the growth medium, were modified to assess their impact on the production of specialized metabolites. This approach involved a characterization based on chemical analysis completed with the construction of molecular networks and biological testing to evaluate cytotoxic and antiplasmodial activities. The results indicated that the influence of culture parameters depended on the studied species and also varied in relation with the microbial metabolites targeted. However, common favorable parameters could be observed for all strains such as an increase in the duration of the culture or the use of the A1 medium. For Micromonospora sp. SH-82, the solid A1 medium culture over 21 days favored a greater chemical diversity. A rise in the antiplasmodial activity was observed with this culture duration, with a IC50 twice as low as for the 14-day culture. Micromonospora sp. SH-57 produced more diverse natural products in liquid culture, with approximately 54% of nodes from the molecular network specifically linked to the type of culture support. Enhanced biological activities were also observed with specific sets of parameters. Finally, for Salinispora arenicola SH-78, liquid culture allowed a greater diversity of metabolites, but intensity variations were specifically observed for some metabolites under other conditions. Notably, compounds related to staurosporine were more abundant in solid culture. Consequently, in the range of the chosen parameters, optimal conditions to enhance metabolic diversity and biological activities in these three marine-derived actinobacteria were identified, paving the way for future isolation works

Sterols from the Madagascar Sponge Fascaplysinopsis sp

The sponge Fascaplysinopsis sp. (order Dictyoceratida, Family Thorectidae) from the west coast of Madagascar (Indian Ocean) is a particularly rich source of bioactive nitrogenous macrolides. The previous studies on this organism led to the suggestion that the latter should originate from associated microsymbionts. In order to evaluate the influence of microsymbionts on lipid content, 10 samples of Fascaplysinopsis sp. were investigated for their sterol composition. Contrary to the secondary metabolites, the sterol patterns established were qualitatively and quantitatively stable: 14 sterols with different unsaturated nuclei, Δ5, Δ7 and Δ5,7, were identified; the last ones being the main sterols of the investigated sponges. The chemotaxonomic significance of these results for the order Dictyoceratida is also discussed in the context of the literature. The conjugated diene system in Δ5,7 sterols is known to be unstable and easily photo-oxidized during storage and/or experiments to produce 5α,8α-epidioxy sterols. However, in this study, no 5α,8α-epidioxysterols (or only trace amounts) were observed. Thus, it was supposed that photo-oxidation was avoided thanks to the natural antioxidants detected in Fascaplysinopsis sp. by both the DPPH and β-caroten bleaching assays

Solid-phase microextraction of volatile compounds from the fragrant liverwort Drepanolejeunea madagascariensis Steph. (Grolle)

International audienceThree populations of the epiphyllous liverwort Drepanolejeunea madagascariensis collected in the cloud forests of Réunion Island (Mascarenes archipelago) were investigated for their volatile compounds because of its pleasant, sweet, warm, woody-spicy and herbaceous fragrance, slightly reminiscent of dill. By applying the headspace solid phase micro-extraction (HS-SPME) technique coupled to gas chromatography-mass spectrometry (GC-MS) analysis, 34 compounds were detected in total with p-menth-1-en-9-ol (28.8-43.5%), limonene (10.5-14.7%), β-phellandrene (8.8-11.6%), and the so-called dill ether (8.5-16.6%) as the main components. The presence of 1-epi-α-pinguisene confirms the possible use of pinguisane-type sesquiterpenoids as a characteristic chemical marker for the order Jungermanniales

24-O-Ethylmanoalide, a Manoalide-related Sesterterpene from the Marine sponge Luffariella cf. variabilis

A new manoalide-related sesterterpene, 24-O-ethylmanoalide (3), was isolated from the Indian Ocean sponge Luffariella cf. variabilis, together with the known compounds manoalide (1), seco-manoalide, manoalide monoacetate and 24-O-methylmanoalide (2). The structure of compound 3 was elucidated by interpretation of its spectroscopic data

Etude chimiotaxonomique des espèces du genre Psiadia et Melicope endémiques de l’île de La Réunion: isolement et identification de trois nouveaux terpènes.

International audienceLe Laboratoire de Chimie des Substances Naturelles et des Sciences des Aliments (LCSNSA) et l’Unité Mixte de Recherche C53 « Peuplement Végétaux et Bioagresseurs en Milieu Tropical (PVBMT) sont impliqués depuis 2005 dans un vaste programme relatif à la gestion et à la conservation de la biodiversité de l’île de la Réunion, haut lieu (hotspot) de la biodiversité mondiale. Dans ce cadre, ils ont mis en place un important projet de reconnaissance et de classification des plantes endémiques de l’île. Ce projet s’inscrit dans le domaine de l’écologie évolutive, dont la finalité est de mettre en évidence l’influence des mécanismes de l’évolution (sélection naturelle, mutation, hasard, migration…) sur le devenir des populations végétales et animales, leur type d’organisation et leur mode d’adaptation à l’environnement. Afin d’aboutir à une classification juste et précise des espèces végétales endémiques de l’île, le choix des chercheurs s’est fixé sur la mise en œuvre d’une étude scientifique combinant à la fois des données chimiques, botaniques et de phylogénie biomoléculaire.Ce vaste projet a débuté avec l’étude des espèces des genres Psiadia (Astéracées) et Melicope (Rutacées). L’analyse de leurs huiles essentielles a conduit en particulier à l’isolement et l’identification par spectrométrie de masse et résonance magnétique nucléaire mono- et bidimensionnelle de trois nouveaux terpènes : un monoterpène acétylé dérivé du alpha-pinène, l’acétate de 6-(7,7-diméthyl-2-méthylène-bicyclo[3.1.1])heptanoyle (1) ; un alcool sesquiterpénique au squelette tricyclique inhabituel, le 6,6,8,9-tétraméthyl-tricyclo[3.3.3.0]undéc-7-én-2-ol (2) ; et un sesquiterpène dioxygéné, le 2-hydroxy-6,10-diméthyl-6-vinylundéca-2,9-dièn-4-one (mélicopénol) (3). Les composés (1) et (2) ont été détectés en forte proportion dans les huiles essentielles de quatre des espèces du genre Psiadia (P. anchusifolia, P. argentea, P. boivinii et P. salaziana). Le composé (3) quant à lui, constitue le composé majoritaire de l’huile essentielle de Melicope obscura.En raison de leur forte proportion et de l’originalité de leur structure, il a été envisagé pour ces trois nouveaux composés, la possibilité d’un rôle de marqueurs chimiotaxonomiques

A comparative study of the volatiles emitted by flowers of three <i>Hedychium</i> species from La Réunion

With the objective to develop a scent database that could be used for perfume and cosmetics applications, a comparative analysis of the floral profiles close to one hundred odorous flowering plants found in Reunion Island has been undertaken for the last few years in our laboratory. A part of this work relating to three Hedychium species (the well-known H. coronarium but also H. flavescens and H. gardnerianum) is presented here. To achieve this, the solid-phase microextraction (SPME) on living flowers coupled to GC/MS was used. A total of 53 volatiles were identified belonging to aliphatic ketones, monoterpenes (hydrocarbons and oxygenated), sesquiterpenes (hydrocarbons and oxygenated), phenylpropanoids/benzenoids and miscellaneous. The phenylpropanoid/benzenoid and terpenoid classes were the main volatile classes. (E)-β-ocimene, linalool, (E,E)-α-farnesene, (E)-nerolidol, methyl benzoate, methyl salicylate, (E)-isoeugenol and indole were the major compounds detected. Results also revealed significant aroma variation among the different flowers.</p

Article 24-O-Ethylmanoalide, a Manoalide-related Sesterterpene from the Marine sponge Luffariella cf. variabilis

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Auto-pollination in a long-spurred endemic orchid (Jumellea stenophylla) on Reunion Island (Mascarene Archipelago, Indian Ocean)

International audienceSince Darwin, long-spurred angraecoid orchids have been known for their fascinating evolutionary relationship with long-tongued hawkmoths (Sphingidae) on Madagascar. We studied the reproductive biology of the long-spurred endemic Jumellea stenophylla on Reunion. Despite the species exhibits flowers with the typical sphingophilous pollination syndrome (i.e. spur length averaged 137.9 mm, mean nectar volume was 6.1 µl, and nectar concentration was 10.7% sugar in sucrose equivalent), it does not require pollinators to achieve fruits. Compared with other hawkmoth-pollinated orchids, flower longevity was very short, lasting less than 5 days, and the species did not emit the characteristic strong and sweet scent at dusk. Fruit set ranged from 66.7 to 83.9% when pollinators were excluded, and 56–77.5% under natural conditions. Auto-pollination is a consequence of structural modifications. On Reunion, such breeding system is not rare within long-spurred species, and seems linked to the absence of specific pollinator during island colonization, and species establishment