Application of capillary-scale NMR for the structure determination of phytochemicals

• Published in: Phytochemical analysis Vol. 16; no. 2; pp. 127 - 133
• Main Authors: Hu, J.F, Garo, E, Yoo, H.D, Cremin, P.A, Zeng, L, Goering, M.G, O'Neil-Johnson, M, Eldridge, G.R
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01-03-2005
• Subjects: 8-Epihastatoside; CapNMR™ probe; chemical analysis; chemical structure; Glycosides - chemistry; Glycosides - isolation & purification; High-throughput natural product chemistry; ipolamiide; iridoid glycosides; Iridoids - chemistry; Iridoids - isolation & purification; lamiide; Magnetic Resonance Spectroscopy - methods; miniaturisation; Miniaturization - methods; Molecular Structure; nuclear magnetic resonance spectroscopy; Penstemon; Penstemon - chemistry; Penstemon centranthifolius; penstemoside; phlomoside; phytochemicals; strictoloside; structure determination
• ISSN: 0958-0344; 1099-1565
• DOI: 10.1002/pca.831

Employing a capillary-scale NMR probe enables the miniaturisation of structure determination and de-replication of purified natural products from plants using only 5-100 microgram of material. Approximately 5 microgram are required to perform one-dimensional proton and two-dimensional homonuclear (COSY and NOESY) NMR experiments; some 30 microgram are needed to acquire HMQC- or HSQC-NMR spectra; ca. 75-100 microgram are necessary to measure HMBC-NMR spectra; and around 200 microgram of a compound are needed to perform 13C- and DEPT-NMR experiments. In order to illustrate the integration of the outputs from high-throughput natural product chemistry methods with the capabilities of the state-of-the-art CapNMR technology, the preparation of a natural product library from the extract of Penstemon centranthifolius, and the subsequent isolation, purification and structure determination of six known iridoid glycosides with 25-300 microgram of material are presented.