We report NMR- and MS-based structural characterizations of siderophores and related compounds from Beauveria bassiana (Balsamo-Crivelli) Vuillemin, including ten new chemical entities (2-4, 6-9, 11-12, and 15) and five known compounds, (1, 5, 10, 13, and 14). The siderophore mixture from ARSEF strain #2680 included two compounds in which N5-mevalonyl-N5-hydroxyornithine replaces both (2) or one (3) of the N5-anhydromevalonyl-N5-hydroxyornithine units of dimerumic acid (1). Mevalonolactone (14) was present as a degradation product of 2 and 3. ARSEF #2860 also produced compounds that have mannopyranose (5, 6) or 4-O-methyl-mannopyranose units (4, 7), two compounds (8, 9) that can be rationalized as 4-O-methyl-mannopyranosyl analogues of the esterifying acid moieties of metachelins A and B, respectively, and two probable decomposition products of 1, a nitro compound (11) and a formate (12). Beauverichelin A (15), a coprogen-type siderophore that represents the di-4-O-methyl-mannopyranosyl analogue of metachelin A, was detected in crude extracts of ARSEF #2860, but only in trace amounts. ARSEF strains #252 and #1955 yielded beauverichelin A in quantities that were sufficient for NMR analysis. Only the di- (1-7) and trihydroxamate (15) siderophores showed iron-binding activity in the CAS assay and, when ferrated, showed strong ESIMS signals consistent with 1:1 ligand/iron complexes.
NMR, MS, siderophores, Beauveria bassiana, beaverichelin A
NCBI PubMed ID: 32058711Publication DOI: 10.1021/acs.jnatprod.9b00698Journal NLM ID: 7906882Publisher: American Society of Pharmacognosy
Correspondence: Krasnoff SB
; Krasnoff SB
Institutions: USDA-ARS, Robert W. Holley Center for Agriculture & Health, Ithaca, USA, Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, USA, Boyce Thompson Institute, Ithaca, USA
Methods: 13C NMR, 1H NMR, NMR-2D, biological assays, extraction, optical rotation measurement, reduction, hydrolysis, CC, RP-HPLC, cell growth, HR-ESI-MS, filtration
Found