armando mateus pomini - Biblioteca do Instituto de Química - Unicamp

XIIIABSTRACTPh. D. ThesisAuthor: Armando Mateus PominiAdvisor: Prof. Dr. Anita Jocelyne MarsaioliGram-positive and Gram-negative bacteria use quorum sensing communicationcircuits to regulate a diverse array of physiological activities. In general, Gram-negativebacteria use acylated homoserine lactones (acyl-HSLs) as autoinducers, and Gram-positivebacteria use processed oligo-peptides. In the present work, we relate the absoluteconfiguration determination of the rare metabolite (S)-(-)-N-heptanoyl-HSL produced bythe phytopathogen Pantoea ananatis. The absolute configuration was determined by gaschromatography coupled to flame ionization detection with chiral column, throughretention time comparison and co-injections with synthetic products. The importance of theabsolute configuration for the antimicrobial activity of acyl-HSL against Gram-positivebacteria (Bacillus subtilis, Bacillus cereus and Staphylococcus aureus) was assessed.Curiously, non-natural (R)-N-3-oxo-octanoyl-HSL was as active as the natural product with(S) absolute configuration. The interaction of (S)-N-3-oxo-octanoil-HSL withAgrobacterium tumefaciens NTL4(pZLR4) cells was further studied using hydrogennuclear magnetic resonance experiments with saturation transfer difference (STD-NMR)revealing that the first binding event is the diffusion through the lipidic part of the outermembrane. Finally, we have investigated the chemical study of the signaling substancesproduced by Methylobacterium mesophilicum, which co-occurs with Xylella fastidiosa inorange trees affected by the citrus variegated chlorosis disease. Among several results, wereport herein the characterization and synthesis of a new natural product [(S)-N-(2E)-dodecenoyl-HSL], the first synthetic procedure for the rare (S)-N-(2E,7Z)-tetradecadienyl-HSL and the occurrence of a rare long, odd chain representative (N-tridecanoyl-HSL) intrace amounts. We report the first absolute configuration determination for five natural