Structural analysis of complex saponins of Balanites aegyptiaca by 800 MHz 1H NMR spectroscopy

✍ Scribed by Dan Stærk; Bishnu P. Chapagain; Therese Lindin; Zeev Wiesman; Jerzy W. Jaroszewski

• Book ID: 102525700
• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 204 KB
• Volume: 44
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1879

✦ Synopsis

Abstract

The main saponin (1) present in the mesocarp of Balanites aegyptiaca fruit is a mixture of 22__R__ and 22__S__ epimers of 26‐(O‐β‐D‐glucopyranosyl)‐3‐β‐[4‐O‐(β‐D‐glucopyranosyl)‐2‐O‐(α‐L‐rhamnopyranosyl)‐β‐D‐glucopyranosyloxy]‐22,26‐dihydroxyfurost‐5‐ene. This structure differs from a previously reported saponin isolated from this source by the site of attachment of the rhamnosyl residue, and presumably represents a structural revision of the latter. The main saponin (2) present in the kernel is a xylopyranosyl derivative of 1. The use of high‐field NMR enabled the practically complete assignment of ^1^H and ^13^C chemical shifts of these complex saponins, existing as a mixture of C‐22 epimers. Moreover, the work represents a new approach to structural elucidation of saponins: direct preparative‐scale HPLC‐RID of crude extracts followed by high‐field NMR investigations supported by ESI‐MS^n^. Copyright © 2006 John Wiley & Sons, Ltd.