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  • Metachelins, mannosylated and N-oxidized coprogen-type siderophores from Metarhizium robertsii.

Metachelins, mannosylated and N-oxidized coprogen-type siderophores from Metarhizium robertsii.

Journal of natural products (2014-07-06)
Stuart B Krasnoff, Ivan Keresztes, Bruno G G Donzelli, Donna M Gibson
ABSTRACT

Under iron-depleted culture conditions, the entomopathogenic fungus Metarhizium robertsii (Bischoff, Humber, and Rehner) (= M. anisopliae) produces a complex of extracellular siderophores including novel O-glycosylated and N-oxidized coprogen-type compounds as well as the known fungal siderophores N(α)-dimethylcoprogen (NADC) and dimerumic acid (DA). Metachelin A (1), the most abundant component in the M. robertsii siderophore mixture, was characterized as a 1094 Da analogue of NADC that is O-glycosylated by β-mannose at both terminal hydroxyl groups and N-oxidized at the dimethylated α-nitrogen. The mixture also contained a 1078 Da analogue, metachelin B (2), which lacks the N-oxide modification. Also characterized were the aglycone of 1, i.e., the N-oxide of NADC (3), and the monomannoside of DA (6). N-Oxide and O-glycosyl substituents are unprecedented among microbial siderophores. At high ESIMS source energy and at room temperature in DMSO, 1 underwent Cope elimination, resulting in loss of the N(α)-dimethyl group and dehydration of the α-β bond. High-resolution ESIMS data confirmed that all tri- and dihydroxamate siderophores (1-6) complex with trivalent Fe, Al, and Ga. In a chrome azurol S assay, all of the M. robertsii siderophores showed iron-binding activity roughly equivalent to that of desferrioxamine B.

MATERIALS
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Product Description

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Iron, wire reel, 2000m, diameter 0.125mm, hard, 99.5%
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