Submicro inverse-detection gradient NMR:: A powerful new way of conducting structure elucidation studies with <0.05 μmol samples
Submicro inverse-detection gradient NMR:: A powerful new way of conducting structure elucidation studies with <0.05 μmol samples
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DOI：
10.1021/np980099b
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发表时间：
1998-05-01
影响因子：
5.1
通讯作者：
Tackie, AN
中科院分区：
文献类型：
--
作者：
Martin, GE;Guido, JE;Tackie, AN
在1992年引入3 mm的微反和微双核磁共振探针后，结构分析所需的材料数量大大减少。我们现在报告使用新的1.7毫米亚微反向检测梯度或SMIDG核磁共振探头可以获得的第一个非常低水平的结果。在600 MHz下使用这项技术，可以完全表征自最初分离以来放置了2年以上的0.55亩摩尔隐碱(1)中所含的8%的杂质。通过对GHSQC、GHMBC、同核TOCSY和ROESY光谱的一致解释，结合从用于制备核磁共振样品的一部分系列稀释液中获得的APCLC/MS和CID数据，该杂质明确地被鉴定为隐孢子酮(2)。亚微米反向检测梯度探头有望进一步减少在有利条件下进行充分表征所需的样本量，使稀有和潜在的新天然产物能够进行结构测定。SMIDG核磁共振技术同样适用于一系列需要表征的小样本，如药物物质中分离的杂质、药物降解研究中的分离物质和次生代谢物。
Quantities of material required for structural analysis were reduced substantially following the introduction of 3 mm microinverse and microdual NMR probes in 1992. We now report the first very low-level results obtainable with a new 1.7 mm submicro-inverse-detection gradient or SMIDG NMR probe. Using this technology at 600 MHz, it was possible to fully characterize an 8% impurity contained in a 0.55 mu mol sample of cryptolepine (1) that had been standing in excess of 2 years since its initial isolation. The impurity was unequivocally identified as cryptolepinone (2) through the concerted interpretation of GHSQC, GHMBC, homonuclear TOCSY, and ROESY spectra in conjunction with APCI LC/MS and CID data acquired from a portion of the serial dilution solution used to prepare the NMR sample. Submicro-inverse-detection gradient probes offer the prospect of reducing still further the quantities of sample required for full characterization under favorable circumstances, making rare and potentially novel natural products amenable to structural determination. SMIDG NMR technology is equally applicable to a range of small samples requiring characterization such as isolated impurities from drug substances, isolates from drug degradation studies, and secondary metabolites.