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Abstract

Ralfuranones are aryl-substituted furanone secondary metabolites
of the Gram-negative plant pathogen Ralstonia solanacearum.
New sulfur-containing ralfuranone derivatives were identified,
including the methyl thioether-containing ralfuranone D.
Isotopic labeling in vivo, as well as headspace analyses of volatiles
from R. solanacearum liquid cultures, established a mechanism
for the transfer of an intact methylthio group from l-methionine
or a-keto-g-methylthiobutyric acid. The methylthio acceptor
molecule ralfuranone I, a previously postulated biosynthetic
intermediate in ralfuranone biosynthesis, was isolated
and characterized by NMR. The highly reactive Michael acceptor system of this intermediate readily reacts with various thiols, including glutathione.