Dihydromaltophilin; a novel fungicidal tetramic acid containing metabolite from Streptomyces sp.

A new tetramic acid containing metabolite, A90931a has been isolated from Streptomyces sp., along with a second factor (A90931b) recently described and known as maltophilin. The structures were determined from spectroscopic data of the isolates and their acetylated products. A90931a was spectroscopically identical to the previously described antibiotic TAN-883b whose structure was not reported. A90931a and A90931b exhibit fungicidal activity against the grape pathogen Plasmopara viticola. Due to its similarity to maltophilin, A90931a has been called dihydromaltophilin.