Biosynthesis of lambertellols based on the high specific incorporation of the 13C-labeled acetates and their biological properties

Biosyntheses of lambertellols A (1) and B (2) as well as lambertellin (3) were investigated by isotope labeling experiments. Nearly 40% of specific incorporation of 1,2-(13)C(2)]acetate was achieved, and all the carbons in 1 and 2 were labeled. This high incorporation of the labeled acetate was realized by providing INADEQUATE spectra by employing only 0.4 and 0.7 mg of 1 and 2, respectively. Our studies revealed that 1-3 are biogenetically synthesized via loss of two carbons from octameric acetate. A biological assay against Monilinia fructicola revealed those remarkably inhibited hyphal germinations. However, neither of them killed the spores immediately, even in high concentration. These conditions induced the formation of microconidia.