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Non-geminal Aliphatic Dihalogenation Pattern in Dichlorinated Diaporthins from Hamigera fusca NRRL 35721.

Celso AlmeidaInmaculada LlamasVíctor González-MenéndezNuria de PedroJesús MartínGloria CrespoThomas MackenzieBastien CautainFernando ReyesFrancisca VicenteOlga Genilloud
Published in: Journal of natural products (2018)
Two new epimeric dihalogenated diaporthins, (9 R *)-8-methyl-9,11-dichlorodiaporthin (2) and (9 S *)-8-methyl-9,11-dichlorodiaporthin (3), have been isolated from the soil fungus Hamigera fusca NRRL 35721 alongside the known regioisomeric isocoumarin 8-methyl-11,11-dichlorodiaporthin (1). Their structures were elucidated by high-resolution mass spectrometry and NMR spectroscopy combined with molecular modeling. Compounds 1-3 are the first isocoumarins and the first halogenated metabolites ever reported from the Hamigera genus. The new compounds 2 and 3 display a non-geminal aliphatic dichlorination pattern unprecedented among known fungal dihalogenated aromatic polyketides. A bifunctional methyltransferase/aliphatic halogenase flavoenzyme is proposed to be involved in the biosynthesis of dichlorinated diaporthins 1-3. These metabolites are weakly cytotoxic.
Keyphrases
  • high resolution mass spectrometry
  • ms ms
  • liquid chromatography
  • ultra high performance liquid chromatography
  • mass spectrometry
  • cell wall
  • amino acid
  • tandem mass spectrometry