Division of Applied Life Science (BK21 plus), IALS, Gyeongsang National University, Jinju 52828, Korea.
Molecules. 2019 Jan 16;24(2):317. doi: 10.3390/molecules24020317.
In this study, the inhibitory potential of bacterial neuraminidase (NA) was observed on the leaves of Nakai, which is a popular ingredient in traditional herbal medicine. This study attempted to isolate the relevant, responsible metabolites and elucidate their inhibition mechanism. The methanol extraction process yielded eight flavonoids (⁻), of which compounds and were new compounds named koreanoside F and koreanoside G, respectively. All the compounds (⁻) showed a significant inhibition to bacterial NA with IC values of 0.17⁻106.3 µM. In particular, the prenyl group on the flavonoids played a critical role in bacterial NA inhibition. Epimedokoreanin B (compound , IC = 0.17 µM) with two prenyl groups on C8 and C5' of luteolin was 500 times more effective than luteolin (IC = 85.6 µM). A similar trend was observed on compound (IC = 0.68 µM) versus dihydrokaempferol (IC = 500.4 µM) and compound (IC = 12.6 µM) versus apigenin (IC = 107.5 µM). Kinetic parameters (, , and /) evaluated that all the compounds apart from compound showed noncompetitive inhibition. Compound was proven to be a mixed type inhibitor. In an enzyme binding affinity experiment using fluorescence, affinity constants () were tightly related to inhibitory activities.
在这项研究中，观察到细菌神经氨酸酶（NA）对纳卡（Nakai）叶片的抑制潜力，纳卡是传统草药中一种常见的成分。本研究试图分离相关的、负责的代谢物，并阐明其抑制机制。甲醇提取过程得到了八种类黄酮（⁻），其中化合物 和 是分别命名为高丽糖苷 F 和高丽糖苷 G 的新化合物。所有化合物（⁻）均对细菌 NA 表现出显著的抑制作用，IC 值为 0.17⁻106.3 µM。特别是，类黄酮上的 prenyl 基团在细菌 NA 抑制中起着关键作用。具有两个 prenyl 基团在芹菜素的 C8 和 C5'上的淫羊藿素 B（化合物 ，IC = 0.17 µM）比芹菜素（IC = 85.6 µM）有效 500 倍。类似的趋势也出现在化合物 （IC = 0.68 µM）与二氢山柰酚（IC = 500.4 µM）和化合物 （IC = 12.6 µM）与芹菜素（IC = 107.5 µM）之间。评估动力学参数（，，和 /）表明，除化合物 外，所有化合物均表现出非竞争性抑制。化合物 被证明是一种混合类型抑制剂。在使用荧光的酶结合亲和力实验中，亲和力常数（）与抑制活性密切相关。
