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ID: ALA4480461
Journal: J Nat Prod
Title: Karamomycins A-C: 2-Naphthalen-2-yl-thiazoles from Nonomuraea endophytica.
Authors: Shaaban KA, Shaaban M, Rahman H, Grün-Wollny I, Kämpfer P, Kelter G, Fiebig HH, Laatsch H.
Abstract: Karamomycins A-C (2-4), the first natural 2-naphthalen-2-yl-thiazole derivatives, were isolated along with a plausible precursor molecule, 1-hydroxy-4-methoxy-2-naphthoic acid (1), uracil, 1-acetyl-β-carboline, and actinomycin C2 from the culture broth of the terrestrial actinomycete strain GW58/450, identified as Nonomuraea endophytica. These compounds were characterized by analysis of their NMR and mass spectrometry (MS) data; the absolute configurations of 2 and 4 were determined by comparison of 13C NMR, NOESY, and circular dichroism (CD) spectra with density functional theory (DFT)-calculated data. In karamomycin C (4), the thiazole of 2 is connected to an unusual iminothiazolo[4,3- c][1,4]thiazepinone, for which we proposed a biosynthetic origin from two cysteine residues. It is closely related to ulbactin F; however, the heterocycle is enantiomeric to the latter and connected to phenol instead of 4-methoxy-1-naphthol. Karamomycins A (2) and C (4) were cytotoxic.
CiteXplore: 30907593