Fusicoccins P and Q, and 3-Epifusicoccins H and Q, New Polar Fusicoccins from Isolate Niigata 2-A of a Peach Fusicoccum Canker Fungus

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  Our search for new polar fusicoccins biosynthetically related to fusicoccin A from the culture filtrate of isolate Niigata 2-A of a peach Fusicoccum canker fungus resulted in the isolation of new fusicoccins named fusicoccins P and Q, and 3-epifusicoccins H and Q, together with 3′-deacetylfusicoccin A and 16-O-demethyl-3-epifusicoccin J. The structures of fusicoccins P and Q, and of 3-epifusicoccin Q were determined to be those of deisopentenylfusicoccin J, 12α-hydroxyfusicoccin H and 12α-hydroxy-3-epifusicoccin H, respectively, by NMR spectrometry and chemical derivation from known fusicoccins. 3-Epifusicoccin H was identified by comparing its 400 MHz NMR spectra with those of fusicoccin H. The lettuce seed germination-stimulating activity of these new fusicoccins was examined in the presence of ABA: fusicoccin P was highly active, while 3-epifusicoccins H and Q were slightly active, and fusicoccins H and Q were almost inactive. Possible biosynthetic pathways incorporating these new fusicoccins and 3-epifusicoccins from geranylgeranyl diphosphate to 3′-deacetlyfusicoccin A and 16-O-demethyl-3-epifusicoccin J are discussed.