Synthesis and antibacterial activities of cadiolides A, B and C and analogues

The one-pot multicomponent synthesis of natural butenolides named cadiolides A, B, C and analogues has been realized. The antibacterial structure activity relationship shows that the presence of phenolic hydroxyl groups and the number and position of bromine atoms on the different aromatic rings are important features for antibacterial activity, besides it was demonstrated the tolerance of both benzene and furan ring at position 3 of the butenolide nucleus. Furthermore, none of the most relevant antibacterial compounds showed any cytotoxicity in freshly isolated human neutrophils

Synthèse d'analogues de l'épicocconone par réaction d'oxydation désaromatisante : relation structure fluorescences et application en protéomique

Epicocconone is a tricyclic natural product of azaphilone family, isolated from the fungus Epicoccum nigrum. This compound covalently binds to primary amines, leading to a protein linked conjugate which is strongly fluorescent. This reaction, reversible according to the pH, makes of this compound an excellent proteins dye compatible with an analysis by mass spectrometry. Synthesis of epicocconone’s analogues has been undertaken in our laboratory.This synthesis is based on a key oxidative dearomatization. A study of this reaction allowed us to shed light on a high diastereoselectivity according to reaction conditions. After introduction of functionalized acylfuranone ring, a library of epicocconone’s analogues was obtained allowing us to establish the structure-fluorescence relationship and to estimate the use of these biomarkers in proteomics.L’epicocconone est un produit naturel tricyclique de la famille des azaphilones isolé en 2003 d’un champignon Epicoccum nigrum. Ce composé se lie de façon covalente aux amines, conduisant à la formation d’une énamine fluorescente. Cette réaction, réversible en fonction du pH, fait de ce composé un excellent marqueur de protéines pour la détection sur gels d’électrophorèse compatible avec une analyse par spectrométrie de masse. La synthèse d’analogues de l’épicocconone a été engagée au sein de notre laboratoire, en basant sur une étape clé d’oxydation désaromatisante. Une étude approfondie de cette réaction a permis de mettre en évidence une haute diastéréosélectivité en fonction des conditions opératoires.Après introduction d’un cycle acylfuranonique diversement fonctionnalisé, une série d’analogues de l’épicocconone a été obtenue permettant d’établir la relation structure fluorescence et évaluer l’utilisation de ces biomarqueurs en protéomique

Synthesis of epicocconone's analogues by oxydative dearomatization : structure-fluorescence relationship and application in proteomics

L’epicocconone est un produit naturel tricyclique de la famille des azaphilones isolé en 2003 d’un champignon Epicoccum nigrum. Ce composé se lie de façon covalente aux amines, conduisant à la formation d’une énamine fluorescente. Cette réaction, réversible en fonction du pH, fait de ce composé un excellent marqueur de protéines pour la détection sur gels d’électrophorèse compatible avec une analyse par spectrométrie de masse. La synthèse d’analogues de l’épicocconone a été engagée au sein de notre laboratoire, en basant sur une étape clé d’oxydation désaromatisante. Une étude approfondie de cette réaction a permis de mettre en évidence une haute diastéréosélectivité en fonction des conditions opératoires.Après introduction d’un cycle acylfuranonique diversement fonctionnalisé, une série d’analogues de l’épicocconone a été obtenue permettant d’établir la relation structure fluorescence et évaluer l’utilisation de ces biomarqueurs en protéomique.Epicocconone is a tricyclic natural product of azaphilone family, isolated from the fungus Epicoccum nigrum. This compound covalently binds to primary amines, leading to a protein linked conjugate which is strongly fluorescent. This reaction, reversible according to the pH, makes of this compound an excellent proteins dye compatible with an analysis by mass spectrometry. Synthesis of epicocconone’s analogues has been undertaken in our laboratory.This synthesis is based on a key oxidative dearomatization. A study of this reaction allowed us to shed light on a high diastereoselectivity according to reaction conditions. After introduction of functionalized acylfuranone ring, a library of epicocconone’s analogues was obtained allowing us to establish the structure-fluorescence relationship and to estimate the use of these biomarkers in proteomics

Diastereoselective IBX oxidative dearomatization of phenols by remote induction: towards the epicocconone core framework.

International audienc

Versatile Synthesis of Acylfuranones by Reaction of Acylketenes with α-Hydroxy Ketones: Application to the One-Step Multicomponent Synthesis of Cadiolide B and Its Analogues

International audienc

Excited State Dynamics of Brightly Fluorescent Second Generation Epicocconone Analogues

International audienceThe natural product epicocconone, owing to its unique fluorescence properties, has been developed into a range of products used in biotechnology, especially proteomics. However, its weak green fluorescence in its native state, while advantageous for proteomics applications, is a disadvantage in other applications that require two-color readouts. Here we report the photophysical characterization of two brightly fluorescent analogues of epicocconone. These analogues, with naphthyl or pyridyl groups replacing the heptatriene chain, resulted in bright fluorescence in both the native state and the long Stokes shifted enamine. Time-resolved fluorescence studies and DFT calculations were carried out to understand the excited state processes involved in fluorescence. Results showed the p-chloro group on the pyridyl is responsible for the high fluorescence of the native fluorophore. The application of one of these compounds for staining electrophoresis gels is exemplified

A theoretical study on diastereoselective oxidative dearomatization by iodoxybenzoic acid

International audienc

The role of different structural motifs in the ultrafast dynamics of second generation protein stains.

International audienceEngineering the properties of fluorescent probes through modifications of the fluorophore structure has become a subject of interest in recent times. By doing this, the photophysical and photochemical properties of the modified fluorophore can be understood and this can guide the design and synthesis of better fluorophores for use in biotechnology. In this work, the electronic spectra and fluorescence decay kinetics of four analogues of the fluorescent natural product epicocconone were investigated. Epicocconone is unique in that the native state is weakly green fluorescent, whereas the enamine formed reversibly with proteins is highly emissive in the red. It was found that the ultrafast dynamics of the analogues depends profoundly on the H-bonding effect of solvents and solvent viscosity though solvent polarity also plays a role. Comparing the steady state and time-resolved data, the weak fluorescence of epicocconone in its native state is most likely due to the photoisomerization of the hydrocarbon side chain, while the keto enol moiety also has a role to play in determining the fluorescence quantum yield. This understanding is expected to aid the design of better protein stains from the same family

Epicocconone–Hemicyanine Hybrids: Near Infrared Fluorophores for Protein Staining and Cell Imaging

International audienceThe development of new near infrared (NIR) dyes is crucial for diverse applications and especially bioimaging, as they absorb and emit light in the “therapeutic window“ (650–950 nm). We report here a new family of NIR fluorophores that has been obtained by hybridising hemicyanines with epicocconone. Emission wavelengths of these hybrid dyes is in the range 715–795 nm and is combined with large Stokes’ shifts (75–95 nm). The absorption and emission wavelength can be modulated according to the hemicyanine moiety and adding sulfonic acid moieties enhances water solubility. We demonstrate their application in the sensitive detection of proteins in gel electrophoresis and the staining of specific cellular organelles in confocal microscopy. These results are particularly encouraging and bring forward a new fluorescent skeleton for chemical biology

Evaluating Charge Transfer in Epicocconone Analogues: Toward a Targeted Design of Fluorophores

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