RESUMO
Three new azaphilones with an unusual methylene bridge, named mycoleptones A, B, and C (2, 4, and 5), were isolated from cultures of Mycoleptodiscus indicus, a fungus associated with the South American medicinal plant Borreria verticillata. Additionally, four known polyketides, austdiol (1), eugenitin (3), 6-methoxyeugenin (6), and 9-hydroxyeugenin (7), were also isolated. The structural characterization of compounds was carried out by nuclear magnetic resonance spectroscopy, high-resolution mass spectrometry, electronic circular dichroism spectroscopy, time-dependent density functional theory calculations, and X-ray crystallography. Compounds 1-9 were weakly active when tested in antileishmanial and cytotoxicity assays.
Assuntos
Benzofuranos/isolamento & purificação , Endófitos/química , Policetídeos/isolamento & purificação , Benzofuranos/química , Benzofuranos/farmacologia , Brasil , Cristalografia por Raios X , Ensaios de Seleção de Medicamentos Antitumorais , Células HL-60 , Humanos , Leishmania/efeitos dos fármacos , Linfócitos/efeitos dos fármacos , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Policetídeos/química , Policetídeos/farmacologia , Rubiaceae/microbiologiaRESUMO
Eugenitin, a chromone derivative and a metabolite of the endophyte Mycoleptodiscus indicus, at 5 mM activated a recombinant GH11 endo-xylanase by 40 %. The in silico prediction of ligand-binding sites on the three-dimensional structure of the endo-xylanase revealed that eugenitin interacts mainly by a hydrogen bond with a serine residue and a stacking interaction of the heterocyclic aromatic ring system with a tryptophan residue. Eugenitin improved the GH11 endo-xylanase activity on different substrates, modified the optimal pH and temperature activities and slightly affected the kinetic parameters of the enzyme.
