Cordycicadins A-D, Antifeedant Polyketides from the Entomopathogenic Fungus JXCH1.

Cordycicadins A-D (-) are four novel polyketides that were isolated from the liquid fermentation of the insect-pathogenic fungus JXCH1. The structures were determined by a combination of spectroscopic analysis, single-crystal X-ray diffraction, and computational methods. Compounds , , and harbor an unusual exocyclic enol ether bridge that connects the separated ring systems. Hypothetical biosynthetic pathways for - were proposed. Cordycicadins A () and B () showed antifeedant activity against silkworm larvae () with EC values of 65.4 and 57.0 μg/cm, respectively.