The structures of pyridovericin and pyridomacrolidin, new metabolites from the entomopathogenic fungus, Beauveria bassiana.

Entomopathogenic fungi seem to be interesting as a source of biologically active compounds such as an insecticides1) and immunosuppressants2,3), because all insect orders are susceptible to fungal diseases. With the goal of finding novel bioactive compounds from fungi, we investigated metabolite diversity using an HPLC screening program. During the screening process, we isolated two novel metabolites named pyridovericin (1) and pyridomacrolidin (2) (Fig. 1) from the mycelial cake of the entomopathogenic fungus, Beauveria bassiana EPF-54). In this paper, we describe the physico-chemical properties and structural determination of 1 and 2. Structure of Pyridovericin (1) The physico-chemical properties of 1 and 2 are summarized in Table 1. The molecular formula of 1 was determined to be C21H23NO5 [Found m/z 369.1580 (M+), Calcd for C21H23NO5 369.1576] by highresolution EI-MS measurement. The IR spectrum (KBr) suggested the presence of the hydroxy group (3403cm-1), amide carbonyl (1661cm-1) and hydrogen bonded carbonyl (1611cm-1), respectively. The 13C NMR spectrum of 1 accounts for the presence of 21 carbon signals. The analyses of 1H NMR and