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New 5-substituted vitamin E derivatives were semisynthesized, and their antibacterial activity against human Gram-positive and Gram-negative pathogens was evaluated. Several vitamin E analogues were active against methicillin-resistant Staphylococcus aureus (MRSA) and/or methicillin-resistant Staphylococcus epidermidis (MRSE); structure-activity relationships (SARs) are discussed. As a result, it is shown that the presence of a carboxylic acid function at the C-5 position and/or at the end of the side chain is crucial for the antibacterial activity. The bactericidal or bacteriostatic action of three compounds against MRSA and MRSE was confirmed in a time-kill kinetics study, and the cytotoxicity on human cells was evaluated. The preliminary mechanism study by confocal microscopy indicated that those vitamin E analogues led to bacterial cell death through membrane disruption.

Chalcone-vitamin E hybrids 6’-O-tosyl-3,4,5-trimethoxy-δ-tocopherol-chalcone (1), 3,4,5-trimethoxy-δ-tocopherol-chalcone (2), 6’-O-tosyl-3,4,5-trimethoxy-δ-tocopherol-retrochalcone (3) and 3,4,5-trimethoxy-δ-tocopherol-retrochalcone (4) were synthesized as part of a search for new biological activities in these types of derivatives. We report herein on the photoisomerization products of hybrids 1-4, and the effects of the solvent and substitution patterns in producing secondary products such as flavanone 6, 3-deoxyanthocyanidin 8, and hemiketal 10. Photochemically-induced changes are considered important since structural modifications and/or the presence of additional products can affect the biological activity of this type of semisynthetic hybrids. Resumen. Los híbridos de chalcona-vitamina E, 6’-O-tosil-3,4,5-trimetoxi-δ-tocoferol-chalcona (1), 3,4,5-trimetoxi-δ-tocoferol-chalcona (2), 6’-O-tosil-3,4,5-trimetoxi-δ-tocoferol-retrochalcona (3) y 3,4,5-trimetoxi-δ-tocoferol-retrochalcona (4), fueron sintetizados como parte de la búsqueda de nuevos perfiles de actividad biológica para este tipo de derivados. En este trabajo reportamos los productos de fotoisomerización de los híbridos 1-4, y los efectos del disolvente, así como de distintos patrones de sustitución en la generación de productos secundarios como la flavanona 6, la 3-deoxiantocianidina 8, y el hemicetal 10. Los cambios fotoinducidos son considerados de gran importancia debido a que la modificación en la estructura y/o la presencia de productos adicionales puede afectar la actividad biológica de este tipo de híbridos semisintéticos.

Specialized pro-resolving mediators (SPMs) comprise lipid mediators (LMs) produced from polyunsaturated fatty acids (PUFAs) via stereoselective oxygenation particularly involving 12/15-lipoxygenases (LOXs). In contrast to pro-inflammatory LMs such as leukotrienes formed by 5-LOX and prostaglandins formed by cyclooxygenases, the SPMs have anti-inflammatory and inflammation-resolving properties. Although glucocorticoids and non-steroidal anti-inflammatory drugs (NSAIDs) that block prostaglandin production are still prime therapeutics for inflammation-related diseases despite severe side-effects, novel concepts focus on SPMs as immunoresolvents for anti-inflammatory pharmacotherapy. Here, we studied the natural chalcone MF-14 and the corresponding dihydrochalcone MF-15 from Melodorum fruticosum, for modulating the biosynthesis of LM including leukotrienes, prostaglandins, SPM and their 12/15-LOX-derived precursors in human monocyte-derived macrophage (MDM) M1- and M2-like phenotypes. In MDM challenged with Staphylococcus aureus-derived exotoxins both compounds (10 µM) significantly suppressed 5-LOX product formation but increased the biosynthesis of 12/15-LOX products, especially in M2-MDM. Intriguingly, in resting M2-MDM, MF-14 and MF-15 strikingly evoked generation of 12/15-LOX products and of SPMs from liberated PUFAs, along with translocation of 15-LOX-1 to membranous compartments. Enhanced 12/15-LOX product formation by the chalcones was evident also when exogenous PUFAs were supplied, excluding increased substrate supply as sole underlying mechanism. Rather, MF-14 and MF15 stimulate the activity of 15-LOX-1, supported by experiments with HEK293 cells transfected with either 5-LOX, 15-LOX-1 and 15-LOX-2. Together, the natural chalcone MF-14 and the dihydrochalcone MF-15 favorably modulate LM biosynthesis in human macrophages by suppressing pro-inflammatory leukotrienes but stimulating formation of SPMs by differential interference with 5-LOX and 15-LOX-1.

Endogenous long-chain metabolites of vitamin E (LCMs) mediate immune functions by targeting 5-lipoxygenase (5-LOX) and increasing the systemic concentrations of resolvin E3, a specialized proresolving lipid mediator. SAR studies on semisynthesized analogues highlight α-amplexichromanol (27a), which allosterically inhibits 5-LOX, being considerably more potent than endogenous LCMs in human primary immune cells and blood. Other enzymes within lipid mediator biosynthesis were not substantially inhibited, except for microsomal prostaglandin E2 synthase-1. Compound 27a is metabolized by sulfation and β-oxidation in human liver-on-chips and exhibits superior metabolic stability in mice over LCMs. Pharmacokinetic studies show distribution of 27a from plasma to the inflamed peritoneal cavity and lung. In parallel, 5-LOX-derived leukotriene levels decrease, and the inflammatory reaction is suppressed in reconstructed human epidermis, murine peritonitis, and experimental asthma in mice. Our study highlights 27a as an orally active, LCM-inspired drug candidate that limits inflammation with superior potency and metabolic stability to the endogenous lead.

International audience; A selection of bioactive polyphenols of different structural classes, such as the ellagitannins vescalagin and vescalin, the flavanoids catechin, epicatechin, epigallocatechin gallate (EGCG), and procyanidin B2, and the stilbenoids resveratrol and piceatannol, were chemically modified to bear a biotin unit for enabling their immobilization on streptavidin-coated sensor chips. These sensor chips were used to evaluate in real time by surface plasmon resonance (SPR) the interactions of three different surface-bound polyphenolic ligands per sensor chip with various protein analytes, including human DNA topoisomerase IIα, flavonoid leucoanthocyanidin dioxygenase, B-cell lymphoma 2 apoptosis regulator protein, and bovine serum albumin. The types and levels of SPR responses unveiled major differences in the association, or lack thereof, and dissociation between a given protein analyte and different polyphenolic ligands. Thus, this multi-analysis SPR technique is a valuable methodology to rapidly screen and qualitatively compare various polyphenol-protein interactions.

Whether chemists or biologists, researchers dealing with metabolomics require tools to decipher complex mixtures. As a part of metabolomics and initially dedicated to identifying bioactive natural products, dereplication aims at reducing the usual time-consuming process of known compounds isolation. Mass spectrometry and nuclear magnetic resonance are the most commonly reported analytical tools during dereplication analysis. Though it has low sensitivity

Whether chemists or biologists, researchers dealing with metabolomics require tools to decipher complex mixtures. As a part of metabolomics and initially dedicated to identifying bioactive natural ...

Systemic vitamin E metabolites have been proposed as signaling molecules, but their physiological role is unknown. Here we show, by library screening of potential human vitamin E metabolites, that long-chain ω-carboxylates are potent allosteric inhibitors of 5-lipoxygenase, a key enzyme in the biosynthesis of chemoattractant and vasoactive leukotrienes. 13-((2R)-6-hydroxy-2,5,7,8-tetramethylchroman-2-yl)-2,6,10-trimethyltridecanoic acid (α-T-13′-COOH) can be synthesized from α-tocopherol in a human liver-on-chip, and is detected in human and mouse plasma at concentrations (8–49 nM) that inhibit 5-lipoxygenase in human leukocytes. α-T-13′-COOH accumulates in immune cells and inflamed murine exudates, selectively inhibits the biosynthesis of 5-lipoxygenase-derived lipid mediators in vitro and in vivo, and efficiently suppresses inflammation and bronchial hyper-reactivity in mouse models of peritonitis and asthma. Together, our data suggest that the immune regulatory and anti-inflammatory functions of α-tocopherol depend on its endogenous metabolite α-T-13′-COOH, potentially through inhibiting 5-lipoxygenase in immune cells.

Background and Purpose The paradigm that GPCRs are able to prolong or initiate cellular signalling through intracellular receptors recently emerged. Melatonin binds to G protein-coupled MT1 and MT2 receptors. In contrast to most other hormones targeting GPCRs, melatonin and its synthetic analogues are amphiphilic molecules easily penetrating into cells, but the existence of intracellular receptors is still unclear mainly due to a lack of appropriate tools. Experimental Approach We therefore designed and synthesized a series of hydrophilic melatonin receptor ligands coupled to the Cy3 cyanin fluorophore to reliably monitor its inability to penetrate cells. Two compounds, one lipophilic and one hydrophilic, were then functionally characterized in terms of their affinity for human and murine melatonin receptors expressed in HEK293 cells and their signalling efficacy. Key Results Among the different ligands, ICOA-13 showed the desired properties as it was cell-impermeant and bound to human and mouse MT1 and MT2 receptors. ICOA-13 showed differential activities on melatonin receptors ranging from partial to full agonistic properties for the Gi/cAMP and ERK pathway and β-arrestin 2 recruitment. Notably, ICOA-13 enabled us to discriminate between Gi/cAMP signalling of the MT1 receptor initiated at the cell surface and neuronal mitochondria. Conclusions and Implications We report here the first cell-impermeant melatonin receptor agonist, ICOA-13, which allows us to discriminate between signalling events initiated at the cell surface and intracellular compartments. Detection of mitochondrial MT1 receptors may have an important impact on the development of novel melatonin receptor ligands relevant for neurodegenerative diseases, such as Huntington disease.

Recent studies have highlighted the biological potential of tocotrienols, a vitamin E subfamily. The major natural sources of tocotrienols are complex mixtures requiring particularly challenging purification processes. The present study describes efficient semi-synthetic strategies toward relevant δ-( R)-tocotrienol derivatives, using as a starting material δ-( R)-garcinoic acid, the major vitamin E derivative isolated from Garcinia kola nuts, a renewable vegetal source.

Inflammation contributes to the development of various pathologies, e.g. asthma, cardiovascular diseases, some types of cancer, and metabolic disorders. Leukotrienes (LT), biosynthesized from arachidonic acid by 5-lipoxygenase (5-LO), constitute a potent family of pro-inflammatory lipid mediators. δ-Garcinoic acid (δ-GA) (1), a natural vitamin E analogue, was chosen for further structural optimization as it selectively inhibited 5-LO activity in cell-free and cell-based assays without impairing the production of specialized pro-resolving mediators by 15-LO. A model of semi-quantitative prediction of 5-LO inhibitory potential developed during the current study allowed the design of 24 garcinamides that were semi-synthesized. In accordance with the prediction model, biological evaluations showed that eight compounds potently inhibited human recombinant 5-LO (IC50

International audience; Phytochemical investigation of the root extracts of Hypericum perforatum led to the isolation of two biphenyl derivatives named hyperbiphenyls A and B (1 and 2) and four known xanthones (3−6). These structures were elucidated by spectroscopic and spectrometric methods including UV, NMR, and HRMS. The absolute configuration of the biphenyl derivatives was defined by two different approaches: biomimetic total synthesis of racemic hyper-biphenyl A followed [1]H and [19]F NMR Mosher's esters analysis and stereoselective total synthesis of hyperbiphenyl B, permitting assignment of the S absolute configuration for both compounds. The bioactivity of compounds 1−6 toward a set of biomolecules, including major histocompatibility complex (MHC) molecules expressed on vascular endothelial cells, was measured. The results showed that the major xanthone, i.e., 5-O-methyl-2-deprenylrheediaxanthone B (3), is a potent inhibitor of MHC that efficiently reduces HLA-E, MHC-II, and MICA biomolecules on cell surfaces.

International audience; A regioselective method for the semisynthesis of phenazine derivatives has been disclosed through an efficient IBX mediated ortho-quinone formation from vitamin E derivatives. High chemo- and regio-selectivity was observed during the oxidation step and the corresponding 5,6-ortho-quinones could react with various phenylenediamines. Thus, this methodology proves its interest as a concise semisynthetic pathway to phenazine-vitamin E hybrids with moderate to good yields.

The asymmetric phase-transfer catalytic effect of chiral Cinchona alkaloid-derived quaternary ammonium salts was investigated in the context of the λ3-iodane-mediated dearomative spirolactonization of naphthols. The scope and limitations of this methodology were evaluated using various substrates, which were converted into spirolactones in good yields and with enantiomeric excesses up to 58%.

International audience; Semi-synthesis of 5- and 7-formyltocopherols and tocotrienols has been developed by ortho-formylation of C-5 or C-7-unsubstituted vitamin E derivatives (14 examples) up to 90% yield, through heating in the presence of respectively 10-10-15 equivalents of MgCl2-Et3N-(CH2O)n. Formylation of 5-bromo-δ-tocotrienol revealed an unprecedented 5-bromo/7-formyl exchange and yielded 7-bromo-5-formyl-δ-tocotrienol as major product. The minor 5-bromo-7-formyl-δ-tocotrienol led in three steps to 7-formyl-δ-tocotrienol previously isolated from the stem bark of Garcinia virgata.

We have developed an efficient diastereoselective synthetic route towards a nardosinane sesquiterpene scaffold. The strategy used a key bicyclic diene intermediate 11a, and allowed access to valuable polyoxygenated sesquiterpenes 21 and 22, which may be regarded as analogues of the natural sesquiterpenes laevinol B and fulvol acetate, respectively.

International audience; Over the last twenty years, tocotrienol analogues raised great interest because of their higher level and larger domain of biological activities when compared with tocopherols. Amongst the most promising therapeutic application, anti-inflammatory potency has been evaluated through the inhibition of various mediators of inflammation. Here, we worked on the isolation of two natural isoforms of garcinoic acid (i.e., δ and γ) from two different sources, respectively, Garcinia kola seeds and Garcinia amplexicaulis bark. We also developed semisynthetic strategies to access the other two non-natural α- and β-garcinoic acid isoforms. In the next stage of our work, microsomal prostaglandin E2 synthase was defined as a target to evaluate the anti-inflammatory potential of the four garcinoic acid isomers. Both dimethylated isoforms, β- and γ-garcinoic acid, exhibited the lowest IC50, 2.8 µM and 2.0 µM, respectively. These results showed that the affinity of tocotrienol analogues to microsomal prostaglandin E2 synthase-1 most probably contributes to the anti-inflammatory potential of this class of derivatives.

A versatile strategy is described for the synthesis of new 2-amino-1,4-dihydroquinolines. It involved a Knoevenagel condensation of N-protected-2-amino-5-bromobenzaldehyde with ethylcyanoacetate, followed by a cyclization and protection of the NH group to afford the key intermediates 7 or 19. Then various 1,4 addition reactions have been performed to introduce substituents on the upper part of the 2-amino-1,4-dihydroquinolines.

The efficient synthesis of novel polyhydroxy-tetrahydropyrano-pyrroles from acetylenic carbohydrate precursors in three to four steps is described. The methodology involves, as key steps, the ring contraction of pyridazine intermediates obtained by an inverse-demand Diels–Alder reaction and subsequent intramolecular lactonization. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

The stereoselective access to original polyhydroxylated tetrahydropyranopyrroles is described. The key steps involve an inverse-demand Diels-Alder reaction and a ring contraction of a pyridazine heterocycle.

A new and versatile strategy has been developed towards HA 14-1 analogues, selectively modified on position 4 and/or on the primary amine function. An important aspect was the appropriate selection of the phenol protective group in the 5-bromosalicylaldehyde, allowing the isolation of the key intermediate the 2H-benzopyrane-2-imine 2′.

International audience; Embelin is a natural product, inhibitor of XIAP (X-chromosome-linked Inhibitor of APoptosis) with strong proapoptotic properties on cancer cells. In order to clarify the role of two OH groups on benzoquinone core, we have prepared by hemisynthesis close analogs of embelin, where these OH groups have been replaced in a systematic manner by OMe and OAc groups. Proapoptotic activities of six embelin derivatives have been studied as single agent, or in combination with TRAIL, and their abilities to interact with XIAP have been evaluated by Surface Plasmon Biacore. Our results show that these new embelin analogs have good proapoptotic properties against selected cancer cells, often higher than the natural product itself. Further, this activity is not directly mediated by XIAP. Altogether these preliminary results demonstrate that for active embelin analogs, the two OH groups are not absolutely required for anticancer activity, opening new possibilities for the design of proapoptotic derivatives in these series.

International audience; The cover picture shows the design and synthesis of two successive generations of analogues of embelin, a natural product with proapoptotic and anticancer properties. This research was performed in the Indo-French "Joint Laboratory for Sustainable Chemistry at Interfaces&2dquo; between the University of Rennes I/CNRS and the Indian Institute of Chemical Technology/CSIR, Hyderabad. This cooperation is highlighted by the best-known monuments from both cities (Charminar in Hyderabad and Parliament of Brittany in Rennes). Details of this research are discussed in the article by R. Grée, et al. on p. 1233 ff.

The cover picture shows the design and synthesis of two successive generations of analogues of embelin, a natural product with proapoptotic and anticancer properties. This research was performed in the Indo-French “Joint Laboratory for Sustainable Chemistry at Interfaces&2dquo; between the University of Rennes I/CNRS and the Indian Institute of Chemical Technology/CSIR, Hyderabad. This cooperation is highlighted by the best-known monuments from both cities (Charminar in Hyderabad and Parliament of Brittany in Rennes). Details of this research are discussed in the article by R. Gree, et al. on p. 1233 ff.

A versatile strategy is described for the synthesis of new 2-amino-1,4-dihydroquinolines. It involved a Knoevenagel condensation of N-protected-2-amino-5-bromobenzaldehyde with ethylcyanoacetate, followed by a cyclization and protection of the NH group to afford the key intermediates 7 or 19. Then various 1,4 addition reactions have been performed to introduce substituents on the upper part of the 2-amino-1,4-dihydroquinolines.

International audience; The synthesis and applications of the first water-soluble benzene derivative bearing a set of three different and orthogonal bioconjugatable groups (aminooxy, azido and thiol) are described. The combined use of a 5-amino isophthalic acid scaffold and unusual acid-labile protecting groups for temporarily masking aminooxy and thiol moieties has enabled the development of a highly convergent approach towards the synthesis of such a trivalent bioconjugation platform in good yields. The potential utility of this "ready-to-use" cross-linking reagent for creating complex and fragile tri-component (bio)molecular systems was illustrated through (1) the rapid preparation of a three-colour FRET cascade with valuable spectral properties and (2) the luminescent/fluorescent labelling of peptides and peptide-oligonucleotide conjugates. Thus, such (bio)molecular assemblies were readily obtained via a three-step process or in a "one-pot" manner, both involving oxime ligation, thiol-alkylation (S(N)2 or Michael addition) and copper-catalysed azide-alkyne 1,3-dipolar cycloaddition (CuAAC) reactions.