Five hydroxamate siderophores, chaetomadramines A-E (1-5), along with seven known compounds were isolated from the fermented rice culture of the fungus Chaetomium madrasense cib-1. Compounds 1-5 were structurally elucidated on the basis of spectroscopic data, which were a group of unusual hydroxamate siderophores, bearing a long fatty acyl on the α-NH2 of the Nδ-hydroxylated ornithine. Compounds 2-5 were new. The structural elucidation and spectroscopic data of 1 were reported for the first time. Compounds 2-4 significantly improved the survival rates of PC12 cells in the neuroprotective activity assay at the concentration of 40 μM.
Keywords: Chaetomadramine; Chaetomium madrasense; Hydroxamate siderophore; Neuroprotective activity.
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