Novel South African Rare Actinomycete Strain SK5: A Prolific Producer of Hydroxamate Siderophores Including New Dehydroxylated Congeners.

In this paper, we report on the chemistry of the rare South African Actinomycete strain SK5, a prolific producer of hydroxamate siderophores and their congeners. Two new analogues, dehydroxylated desferrioxamines, speibonoxamine and desoxy-desferrioxamine D , have been isolated, together with four known hydroxamates, desferrioxamine D , desferrioxamine B , desoxy-nocardamine and nocardamine , and a diketopiperazine (DKP) . The structures of - were characterized by the analysis of HRESIMS and 1D and 2D NMR data, as well as by comparison with the relevant literature. Three new dehydroxy desferrioxamine derivatives - were tentatively identified in the molecular network of strain SK5 extracts, and structures were proposed based on their MS/MS fragmentation patterns. A plausible biosynthetic pathway was proposed. To the best of our knowledge, this is the first report of the isolation of desferrioxamines from the actinobacterial genus .