Oleanolic acid glycosides from Scabiosa caucasica and Scabiosa ochroleuca: Structural analysis and cytotoxicity

The Scabiosa genus includes therapeutic herbs recognised in traditional Armenian medicine for their ability to heal skin irritation and are also used predominantly as a tea to cure or prevent influenza. The objective of the study was to identify novel applications of certain species belonging to the Scabiosa genus in pharmaceutical and cosmetic industry. The phytochemical investigation of two Armenian plants, Scabiosa caucasica and Scabiosa ochroleuca allowed the discovery of five previously unreported oleanolic acid glycosides (compound 1-5, [Fig. 1]) in their roots. Extensive 1D and 2D NMR experiments, as well as mass spectrometry analysis, were used to identify them as triterpenoid glycosides, with the aglycon part identified as oleanolic acid with an oligosaccharidic chain attached to the C3 position through glycosylation, and a disaccharide chain identified as a gentiobiose unit attached to the C28 (except compound 3) position through esterification. These structures are similar to those isolated from some Weigela species, which belong to the Dipsacales order, Caprifoliaceae family and Diervilloideae subfamily. The Scabiosa genus belongs to the same order and family, but to the Dipsacoideae subfamily. The saponins from the two genera share the same 3-O-β-D-xylopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyloleanolic acid sequence, which might be a chemotaxonomic marker of these two subfamilies. The cytotoxicity of all the isolated compounds against a mouse colon cancer cell line (MC-38) was evaluated by MTS assay. Compound 3 exhibits potent cytotoxicity on a mouse colon cancer cell line (MC-38), highlighting the key role of the lack or the presence of esterification at C-28 position.

Fig. 1  The structures of compound 1-5.

 

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Publication History

Article published online:
16 November 2023