Neuroprotective Glycosylated Cyclic Lipodepsipeptides, Colletotrichamides A-E, from a Halophyte-Associated Fungus, Colletotrichum gloeosporioides JS419

Abstract

Glutamate neurotoxicity has been implicated in neuronal death in both acute CNS injury and in chronic neurodegenerative diseases. Five unique cyclic depsipeptides with neuroprotective activity, colletotrichamides A-E (1-5), were isolated from cultures of a halophyte Suaeda japonica-associated fungus, Colletotrichum gloeosporioides JS419. Spectroscopic analysis revealed that they were glycosylated cyclic lipodepsipeptides. Their relative configurations were determined by ROESY and J-based configuration analysis, and absolute configurations were established by chemical reactions including modified Mosher's method, advanced Marfey's method, and sugar derivatization. This is the first report of a glycosylated dimethyl-trioxygenated dodecanoyl moiety, and the relative as well as absolute stereochemistry was elucidated herein for the first time. Colletotrichamide C exhibited strong neuroprotective activity against glutamate in hippocampal HT22 cells.