Clavariopsins C-I, Antifungal Cyclic Depsipeptides from the Aquatic Hyphomycete .

Seven new cyclic depsipeptides, clavariopsins C-I (-), together with two known congeners, clavariopsins A and B ( and ), were isolated from the aquatic hyphomycete . Their planar structures, which consist of nine amino acids and one α-hydroxy acid, were elucidated by NMR spectroscopy and HRESIMS. The absolute configurations were established by the advanced Marfey's method and chiral-phase HPLC analysis. Their antifungal and cytotoxic activities were evaluated against six plant pathogenic fungi (, , , , , and ) and a cancer cell line (HeLa-S3), respectively. The majority of the compounds exhibited potent antifungal activity against the fungi tested (minimum inhibition dose = 0.01-10 μg/disk) and induced hyphal swelling in (minimum effective dose = 0.3-3 μg/disk), whereas the compounds exhibited no cytotoxicity toward the cancer cell line. The results suggest that the clavariopsins could be a promising class of antifungal agents.