Hyalachelins A–C, Unusual Siderophores Isolated from the Terrestrial Myxobacterium Hyalangium minutum

Three new siderophores, termed hyalachelins A–C (1–3), were isolated from the terrestrial myxobacterium Hyalangium minutum. Their structures were determined by 2D NMR and HR-MS/MS experiments, and their stereochemical configuration was established by a combination of NMR data, quantum mechanical calculations, and circular dichroism experiments. Hyalachelins are unusual catecholate-type siderophores that bear a 3,7,8-trihydroxy-1-oxo-1,2,3,4-tetra­hydro­isoquinoline-3-carbox­ylic acid. Their iron chelating activities were evaluated in a CAS assay showing EC₅₀ values of ∼30 μM.