Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 166 10 Prague, Czech Republic.
Faculty of Science, Charles University, Hlavova 2030/8, 128 43 Prague, Czech Republic.
J Nat Prod. 2021 Jan 22;84(1):46-55. doi: 10.1021/acs.jnatprod.0c00930. Epub 2020 Dec 19.
Naphthoquinones isolated from (quambalarines) are natural pigments possessing significant cytotoxic and antimicrobial properties. Determining the structure of naphthoquinone compounds is important for the understanding of their biological activities and the informed synthesis of related analogues. Identifying quambalarines is challenging, because they contain a hydroxylated naphthoquinone scaffold and have limited solubility. Here, we report a detailed structural study of quambalarine derivatives, which form strong intramolecular hydrogen bonds (IMHBs) that enable the formation of several tautomers; these tautomers may complicate structural investigation due to their fast interconversion. To investigate tautomeric equilibria and identify new quambalarines, we complemented the experimental NMR spectroscopy data with density functional theory (DFT) calculations.
从 （黄麻醌）中分离得到的萘醌是具有显著细胞毒性和抗菌性能的天然色素。确定萘醌化合物的结构对于了解它们的生物活性和相关类似物的合理合成至关重要。由于黄麻醌含有一个羟基化的萘醌支架，并且溶解度有限，因此鉴定黄麻醌衍生物具有挑战性。在这里，我们报告了对黄麻醌衍生物的详细结构研究，这些衍生物形成了强的分子内氢键（IMHB），从而能够形成几种互变异构体；由于它们的快速互变异构，这些互变异构体可能会使结构研究复杂化。为了研究互变异构平衡并鉴定新的黄麻醌，我们用密度泛函理论（DFT）计算补充了实验 NMR 光谱数据。
