Publications

[Background] Several Serratula species are used in folk medicine and showed interesting biological activities. The objective of this work was to continue the investigation of the chemical composition of the ethyl acetate extract of the flowers of Serratula cichoracea which in our previous study showed a significant antioxidant activity in 1,1-diphenyl-2-picrylhydrazyl radical (DPPH•) essay compared to quercetin used as control molecule and to evaluate the isolated compounds for their antioxidant and antimicrobial activities, [Methods] Ethyl acetate extract (15 g) was fractionated by column chromatography on silica gel. After purification on preparative plates, the isolated compounds were identified by spectral analyses mainly high resolution electrospray ionisation mass spectrometry (HR-ESIMS) and one-and two-dimensionnal nuclear magnetic resonance spectroscopy experiments, and were evaluated in vitro for antioxidant activity using 1,1-diphenyl-2-picrylhydrazyl radical and for antimicrobial properties, [Results] A new phytoecdysteroid named 22-epi-ajugasterone C (1) together with ajugasterone C (2), were isolated. Compounds 1 and 2 had weak scavenging effect compared with myricetin used as positive control, whereas the two compounds showed antimicrobial properties against multiresistant strains like Staphylococcus aureus, Escherichia coli, Serratia sp., Klebsiella pneumoniae and Candida albicans, [Conclusion] The new isolated phytoecdysteroid and its epimer ajugasterone C, responded to their effectiveness against different various antibiotic-resistant bacteria.

Understanding patterns of community structure and the causes for their variation can be furthered by comparative biogeographic analyses of island biotas. We used woody plant data at the local scale to investigate variations in species rarity, alpha, beta, and gamma diversity within and between three islands from the oceanic archipelagoes of Azores, Canaries and Mascarene. We used standardized protocols to sample ten 50 m × 50 m forest plots in each of the three islands with contrasting climate and regional species pools: Terceira (Azores), Tenerife (Canaries), and Reunion (Mascarene Islands). Occupancy frequency distributions and species abundance distributions were used to investigate rarity. The partitioning of beta diversity in a distance-decay framework was used to test for spatial patterns of community composition. Rarity was much more pronounced in the highly diverse islands of Tenerife and Reunion than in the regionally poorer island of Terceira. The number of species rose faster with increasing sample area in both Tenerife and Reunion. The slope of the species rank abundance curve was steeper in Terceira whereas the richer island assemblages approached a lognormal model. Compositional changes according to spatial distance were mostly due to replacement of species in Terceira and Reunion. Our results point to important differences in the community structure of Terceira, which is the less diverse and temperate region in comparison to Tenerife and Reunion which are highly diverse.

Self-assembled supramolecular gels have recently emerged as promising confined media for the incorporation of a wide range of donor–acceptor chromophoric assemblies, allowing highly efficient photon upconversion processes at weak solar irradiance even under aerobic conditions in some cases. Supramolecular gels made of dense intermo-lecular interaction networks such as hydrogen bonding have been demonstrated to offer effective protection to the excited species against oxygen quenching. This supramolecular approach is reminiscent to biological photon-harvesting systems and constitutes a new paradigm in photon upconversion research. This minireview summarizes the advances in this approach since its first report a few years ago. The possibility of carrying out photon upconversion in supramolecular gel matrices under aerobic conditions has also enabled to combine this process with a single electron transfer in order to carry out challenged chemical reactions such as the photoreduction of aryl halides in air using visible light. The main aspects of this combined strategy and future perspectives are also discussed.

Several extracts from pre-domesticated Lavandula luisieri (Rozeira) Riv-Mart. (Lamiaceae) (essential oil, EO; hexane, Hx and the organic fraction of the residual hydrolate, WRO) showed larvicidal effects against the hard tick Hyalomma lusitanicum, being WRO the most active. Their content in the necrodane-type monoterpenes (2,2,3,4-tetramethyl-5-oxocyclopent-3-en-1-yl)-methyl acetate (2), 5-hydroxymethyl-2,3,4,4-tetramethylcyclopent-2-en-1-one (1) and 2-(hydroxymethyl)-3,4,4-trimethyl-5-methylenecyclopent-2-en-1-one (5) correlated with these effects. Among the isolated compounds, 3,3,4,5-tetramethyl-2H-pyran-2,6(3H)-dione (7) and (2,2,3,4-tetramethyl-5-oxocyclopent-3-en-1-yl)-methyl acetate (2) were the most potent ones, with activity levels within the range of the positive control thymol. These compounds represent a new class of ixodicidal agents.

We report a new and efficient synthetic strategy that allows access to flexible and functionalized benzocyclotrimers under mild conditions and in few steps. The Negishi cross-coupling reaction was used for the C-C bond formation, whereas intramolecular O-alkylations provided the oxepane rings.

In this study we evaluated the effect of a pressure gradient (1–2 atm) in the extraction and composition of the essential oil (EO) of Piper hispidinervum by steam distillation. We also evaluated the insect antifeedant effects (Spodoptera littoralis, Leptinotarsa decemlineata, Myzus persicae and Rhopalosiphum padi) and nematicidal activity (Meloidogyne javanica) of the oils, their major components and their synergistic interactions. Safrole was the major component (78–81%) followed by terpinolene (5–9%). The EOs tested were effective insect antifeedants. Safrole, explained most of the insect antifeedant action of P. hispidinervum EOs. When safrole and terpinolene were tested in binary combinations, low ratios of safrole improved the antifeedant effects of terpinolene. P. hispidinervum EOs caused higher mortality of M. javanica juveniles than their major components. In binary combinations, low ratios of terpinolene increased the nematicidal effects of safrole. The EO treatment strongly suppressed nematode egg hatching and juvenile infectivity. P. hispidinervum EOs affected the germination of S. lycopersicum and L. sativa mostly at 24 h of treatment, being L. sativa the most sensitive. Safrole moderately affected germination and root growth of L. sativa, S. lycopersicum and L. perenne. Terpinolene only affected S. lycopersicum root growth.

Type 2 diabetes (T2DM) is a complex disease linked to pancreatic beta-cell failure and insulin resistance. Current antidiabetic treatment regimens for T2DM include insulin sensitizers and insulin secretagogues. We have previously demonstrated that leptolide, a member of the furanocembranolides family, promotes pancreatic beta-cell proliferation in mice. Considering the beneficial effects of leptolide in diabetic mice, in this study, we aimed to address the capability of leptolide to improve insulin resistance associated with the pathology of obesity. To this end, we tested the hypothesis that leptolide should protect against fatty acid-induced insulin resistance in hepatocytes. In a time-dependent manner, leptolide (0.1 µM) augmented insulin-stimulated phosphorylation of protein kinase B (PKB) by two-fold above vehicle-treated HepG2 cells. In addition, leptolide (0.1 µM) counteracted palmitate-induced insulin resistance by augmenting by four-fold insulin-stimulated phosphorylation of PKB in HepG2 cells. In vivo, acute intraperitoneal administration of leptolide (0.1 mg/kg and 1 mg/kg) improved glucose tolerance and insulin sensitivity in lean mice. Likewise, prolonged leptolide treatment (0.1 mg/kg) in diet-induced obese mice improved insulin sensitivity. These effects were paralleled with an ~50% increased of insulin-stimulated phosphorylation of PKB in liver and skeletal muscle and reduced circulating pro-inflammatory cytokines in obese mice. We concluded that leptolide significantly improves insulin sensitivity in vitro and in obese mice, suggesting that leptolide may be another potential treatment for T2DM

Endophytes fungi have been widely bioprospected to find new drugs and drug leads including antimicrobial agents and antifungals. However, an important role in host plant protection has been suggested for their presence and their metabolites. Therefore, nematicidal and insecticidal effects of their metabolites should be expected. In this review, the literature data available on insecicidal and nematicidal compounds identified from fungal endophytes are presented. Additionally we present a recent study on the endophytic biodiversity of a unique paleoflora, the Macaronesian laurel forest, in the light of their role in plant protection.

A new, direct, and diastereoselective synthesis of activated 2,3,4,6-tetrasubstituted tetrahydro-2H-pyrans is described. In this reaction, iron(III) catalyzed an SN2′–Prins cyclization tandem process leading to the creation of three new stereocenters in one single step. These activated tetrahydro-2H-pyran units are easily derivatizable through CuAAC conjugations in order to generate multifunctionalized complex molecules. DFT calculations support the in situ SN2′ reaction as a preliminary step in the Prins cyclization.

Seed dispersal and seedling recruitment are crucial phases in the life cycle of all spermatophyte plants. The net contribution of seed dispersers to plant establishment is known as seed dispersal effectiveness (SDE) and is defined as the product of a quantitative (number of seeds dispersed) and a qualitative (probability of recruitment) component. In Galápagos, we studied the direct contribution to SDE (number of seeds dispersed and effect on seedling emergence) provided by the five island groups of frugivores (giant tortoises, lizards, medium-sized passerine birds, small non-finch passerine birds, and finches) in the two main habitats in this archipelago: the lowland and the highland zones, and found 16 vertebrate species dispersing 58 plant species. Data on frequency of occurrence of seeds in droppings and number of seeds dispersed per unit area produced contrasting patterns of seed dispersal. Based on the former, giant tortoises and medium-sized passerines were the most important seed dispersers. However, based on the latter, small non-finch passerines were the most important dispersers, followed by finches and medium-sized passerines. The effect of disperser gut passage on seedling emergence varied greatly depending on both the disperser and the plant species. Although the contribution to SDE provided by different disperser guilds changed across plant species, medium-sized passerines (e.g., mockingbirds) provided a higher contribution to SDE than lava lizards in 10 out of 16 plant species analysed, whereas lava lizards provided a higher contribution to SDE than birds in five plant species. While both the quantitative and qualitative components addressed are important, our data suggests that the former is a better predictor of SDE in the Galápagos archipelago.