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Catechol amide iron chelators produced by a mangrove-derived Bacillus subtilis

Li, Jingyan, Liu, Shaowei, Jiang, Zhongke, Sun, Chenghang
Tetrahedron 2017
2,2-diphenyl-1-picrylhydrazyl, Bacillus subtilis, amino acids, antioxidant activity, biosynthesis, catechol, chelating agents, chemical reactions, chemical structure, free radical scavengers, iron, nuclear magnetic resonance spectroscopy, secondary metabolites, siderophores
A novel triscatecholamide siderophore derivative, linear tribenglthin A (1), together with well known congener, bacillibactin (2) as well as mentioned monomer unit, benglthin were found in the secondary metabolites of a magrove-derived Bacillus subtilis subsp. spizizenii MMB-016. The structure of 1, determined by extensive 1D and 2D NMR studies has an unusual nonproteinogenic amino acid, Z-dehydrobutyrine (Z-Dhb) residue to reveal a putative lantibiotic synthetase function involved in the iterative biosynthesis of non-ribosomal peptide (NRP). Our 1H–15N correlation spectroscopy of 2 resulted in a correction of previous NH assignment of bacillibactin, as well as a new evaluation of DPPH free radical scavenging potential suggested antioxidant activity. Benglthin monomer was isolated as a ferrous complex (3), unveiling an interestingly higher affinity for iron Fe(Ⅱ) than trimers, 1 and 2. No dimeric forms were found.