Department of Biopharmaceutical Convergence, Sungkyunkwan University, Suwon16419, Republic of Korea.
School of Pharmacy, Sungkyunkwan University, Suwon16419, Republic of Korea.
J Nat Prod. 2022 Oct 28;85(10):2461-2467. doi: 10.1021/acs.jnatprod.2c00694. Epub 2022 Oct 12.
Balsamisides A-D (-) are anti-inflammatory and neurotrophic biflavonoidal glycosides originally proposed to possess an epoxide functionality at the C-2/C-3 position. However, there are inconsistencies in their C NMR chemical shift values with those of previously reported analogs, indicating that reanalysis of NMR data for structures of - is necessary. Computational methods aided by the DP4+ probability technique and ECD calculations enabled structural reassignment of - to have a 2,3-dihydro-3-hydroxyfuran (3-DHF) instead of an epoxide. Additionally, two new biflavonoidal glycosides, balsamisides E and F ( and ), possessing a 2,3-dihydro-2-hydroxyfuran (2-DHF) and a 1,4-dioxane ring, respectively, were characterized by conventional NMR and MS data analysis as well as DP4+ and ECD methods. Systematic C NMR analysis was performed on the four aforementioned classes of biflavonoids with a 2- or 3-DHF, epoxide, or 1,4-dioxane. As a result, diagnostic C NMR chemical shift values of C-2/C-3 for rapid determination of these four biflavonoid classes were formulated, and based on this first empirical rule for (bi)flavonoids eight previously reported ones were structurally revised.
巴尔萨米昔 A-D(-) 是具有抗炎和神经营养作用的双黄酮类糖苷，最初被认为在 C-2/C-3 位置具有环氧化物官能团。然而，它们的 C NMR 化学位移值与以前报道的类似物不一致，这表明需要重新分析-的 NMR 数据。计算方法辅助 DP4+ 概率技术和 ECD 计算，使-的结构重新分配为 2,3-二氢-3-羟基呋喃 (3-DHF) 而不是环氧化物。此外，通过常规 NMR 和 MS 数据分析以及 DP4+ 和 ECD 方法，鉴定了两种新的双黄酮类糖苷，巴尔萨米昔 E 和 F( 和 )，分别具有 2,3-二氢-2-羟基呋喃 (2-DHF) 和 1,4-二氧杂环己烷环。对具有 2-DHF、环氧化物或 1,4-二氧杂环己烷的上述四类双黄酮类化合物进行了系统的 C NMR 分析。结果，制定了这些四类双黄酮类化合物中 C-2/C-3 的快速鉴定的 C NMR 化学位移值的诊断规则，并基于该规则对 8 个以前报道的化合物进行了结构修订。
