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Structural analysis of complex saponins of Balanites aegyptiaca by 800 MHz 1 H NMR spectroscopy
Author(s) -
Stærk Dan,
Chapagain Bishnu P.,
Lindin Therese,
Wiesman Zeev,
Jaroszewski Jerzy W.
Publication year - 2006
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1879
Subject(s) - balanites aegyptiaca , chemistry , nuclear magnetic resonance spectroscopy , spectroscopy , two dimensional nuclear magnetic resonance spectroscopy , stereochemistry , physics , medicine , alternative medicine , pathology , quantum mechanics
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.