Oleanane-type saponins from the roots of Wisteria floribunda macrobotrys

The Fabaceae family is represented by numerous genera, which contains approximately 19500 species distributed around the world. The particularity of this family is to live in symbiosis with bacteria, which live in gall and assimilating atmospheric nitrogen. Wisteria is a genus of woody vines with alternate pinnately compound leaves and a large inflorescence of pendulous, showy purple, blue, or white flowers [1]. Previous phytochemical studies were published about three species of Wisteria: Triterpene saponins were isolated from the knots and vines of W. brachybotrys [2,3] and the leaves of W. sinensis yielded flavonoids derivatives and triterpenes [4,5]. Wisteria floribunda macrobotrys (L.) is a woody perennial climbing vine which has never been investigated from a phytochemical and pharmacological point of view. The study of the roots of W. floribunda macrobotrys led to the isolation of five oxygenated-oleanane-type glycosides using various solid/liquid chromatographic methods such as vacuum (VLC), medium (MPLC) and high-pressure liquid chromatography (HPLC), and size exclusion chromatography on Sephadex LH-20. Their structures were established by a detailed 600 MHz NMR analysis including 1D and 2D NMR experiments and mass spectrometry. Two types of original aglycons were found: a 16β,22β-hydroxy isomer of camelliagenin A and a 30-carboxy isomer of oxytrogenin. For each saponin, the oligosaccharidic part is linked at the C-3 position of the aglycon by a glucuronopyranosyl moiety. These aglycons were acylated by one or two acetyl groups.

As glycosylated derivatives were known to recognize autoantibody in sera of multiple sclerosis patients [6], like the N-glucosylated peptide CSF114(Glc), we decided to test some of these saponins to evaluate their capacity to recognize autoantibodies. The levels of IgG and IgM levels in multiple sclerosis patients and healthy blood donors will be presented to show the role of saponins as diagnostic tools.

Keywords: Oleanane-type saponins, 2D NMR, Wisteria, Fabaceae, diagnostic tools.

References:

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