A new cyclopeptide with antifungal activity from the co-culture broth of two marine mangrove fungi

A new cyclic tetrapeptide, cyclo-(l-leucyl-trans-4-hydroxy-l-prolyl-d-leucyl-trans-4-hydroxy-l-proline) (1), was isolated from the co-culture broth of two mangrove fungi Phomopsis sp. K38 and Alternaria sp. E33. The structure of 1 was determined by analysis of spectroscopic data and Marfey's analytic method. Primary bioassay demonstrated that compound 1 exhibited moderate to high inhibitory activity against four crop-threatening fungi including Gaeumannomyces graminis, Rhizoctonia cerealis, Helminthosporium sativum and Fusarium graminearum as compared with triadimefon.