Institute of Organic and Biomolecular Chemistry , University of Göttingen , Tammannstrasse 2 , D-37077 Göttingen , Germany.
Chemistry of Natural Compounds Department, Pharmaceutical and Drug Industries Research Division , National Research Centre , El-Behoos St. 33 , Dokki-Cairo 12622 , Egypt.
J Nat Prod. 2019 Apr 26;82(4):870-877. doi: 10.1021/acs.jnatprod.8b00928. Epub 2019 Mar 25.
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 C 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.
卡拉霉素 A-C（2-4），是第一个从陆地放线菌 Nonomuraea endophytica 发酵液中分离得到的天然 2-萘基-2-噻唑衍生物，同时还分离得到了一个可能的前体分子 1-羟基-4-甲氧基-2-萘酸（1）、尿嘧啶、1-乙酰-β-咔啉和放线菌素 C2。这些化合物的结构通过 NMR 和质谱（MS）数据分析得到了表征；通过与密度泛函理论（DFT）计算数据的比较，对 2 和 4 的绝对构型进行了确定，包括 C NMR、NOESY 和圆二色性（CD）光谱。在卡拉霉素 C（4）中，2 的噻唑与一个不寻常的亚胺噻唑并[4,3-c][1,4]噻嗪酮相连，我们提出了它可能由两个半胱氨酸残基生物合成而来。它与 ulbactin F 密切相关；然而，杂环与后者对映异构，与酚而不是 4-甲氧基-1-萘酚相连。卡拉霉素 A（2）和 C（4）具有细胞毒性。
