18 research outputs found
Lipocarbazoles, Secondary Metabolites from <em>Tsukamurella pseudospumae</em> Acta 1857 with Antioxidative Activity
Elloxazinones A and B, new aminophenoxazinones from Streptomyces griseus Acta 2871<sup>+</sup>
Nocardichelins A and B, siderophores from Nocardia strain Acta 3026
An actinomycete, strain Acta 3026, isolated from mangrove soil was characterized and found to belong to the genus Nocardia. The strain produces two new cytotoxic metabolites, nocardichelins A (1) and B (2). Each of the compounds strongly inhibited human cell lines from gastric adenocarcinoma, breast carcinoma, and hepatocellular carcinoma with GI(50) values in a low micromolar to nanomolar range. The structural characterization of the compounds was performed by mass spectrometry and NMR spectroscopy. The nocardichelins represent a new group of siderophores that combine the structural elements of mycobactin-type siderophores from mycobacteria and hydroxamate-type siderophores (desferrioxamine B) produced by streptomycetes. The chromazurol S assay, characteristic for iron(III) complexation, was positive, confirming the role as a siderophore