Phytotoxic metabolites from Neofusicoccum parvum, a pathogen of Botryosphaeria dieback of grapevine

Liquid chromatography-diode array screening of the organic extract of the cultures of 13 isolates of the fungus Neofusicoccum parvum, the main causal agent of botryosphaeria dieback of grapevine, showed similar metabolites. One strain was selected for further chemical studies and led to the isolation and characterisation of 13 metabolites. Structures were elucidated through spectroscopic analyses, including one- and two-dimensional NMR and mass spectrometry, and through comparison to literature data. The isolated compounds belong to four different chemical families: five metabolites, namely, ( )-terremutin (1), (+)-terremutin hydrate (2), (+)-epi-sphaeropsidone (3) ( )-4-chloro-terremutin hydrate (4) and(+)-4- hydroxysuccinate-terremutin hydrate (5), belong to the family of dihydrotoluquinones; two metabolites, namely, (6S,7R) asperlin (6) and (6R,7S)-dia-asperlin (7), belong to the family of epoxylactones; four metabolites, namely, (R)-( )-mellein (8), (3R,4R)-4-hydroxymellein (9), (3R,4S)-4-hydroxymellein (10) (R)( )-3-hydroxymellein (11), belong to the family of dihydroisocoumarins; and two of the metabolites, namely, 6-methyl-salicylic acid (12) and 2-hydroxypropyl salicylic acid (13), belong to the family of hydroxybenzoic acids. We determined the phytotoxic activity of the isolated metabolites through a leaf disc assay and the expression of defence-related genes in Vitis vinifera cells cv. Chardonnay cultured with ( )-terremutin (1), the most abundant metabolite. Finally, analysis of the brown stripes of grapevine wood from plants showing botryosphaeria dieback symptoms revealed the presence of two of the isolated phytotoxinsinfo:eu-repo/semantics/publishedVersio

Photoinduced acyl transfer

The acylation reaction occupies a central role in biochemistry and organic synthesis. On the one hand, it is by this very reaction that amino acids successively assemble to form peptides and proteins, and on the other hand it is a major synthetic method encompassing esterification, amidation, Friedel-Crafts reaction and many other processes routinely used both at the laboratory and the industrial scale. Photochemical activation is always an attractive alternative, because it is relatively mild (provided innocuous wavelengths are used), and no additional substance is added; thus no separation of the activator is necessary at the end of the process. In this paper, we briefly survey the most widely used methods of photoinduced acylations, and our own contribution to the field

Preparation of photoactivable amino acid derivatives

A range of N-protected-α-amino acyl-5,7-dinitroindolines 3a−z were prepared in good yields from commercially available N-protected-α-amino acids 1a−z by a two-step sequence of acylation and intramolecular amide N-arylation. Subsequent photochemical acylation of the N-protected-α-amino acyl-5,7-dinitroindolines 3e,g,r afforded the corresponding N-protected-α-amino acid amides 22e,g,r (77−92%) under mild conditions. All these reactions occurred with complete retention of chirality as evidenced by NMR analysis. This scheme provides an attractive and alternative method to the conventional acylation of α-amino acids, especially in cases where the amide bond needs to be formed without the use of a coupling reagent

Synthesis of Hexa-peri-hexobenzocoronenes Carrying Linear or Branched Perfluoroalkylated Side Chains

Substituted disc-shaped perfluoroalkylated hexa-peri-hexabenzocoronenes (HBC), known to self-assemble into conducting ordered architectures, were synthesized and characterized. A systematic variation of the linear or branched perfluoroalkylated side chains was performed in order to screen the influence of the lateral chain on their one-dimensional self-aggregation