Monodesmosidic oleanene-type saponins from kidney vetch (Anthyllis vulneraria L.) with hemolytic activity

Two undescribed monodesmosidic oleanene-type saponins, namely 3 beta-O-{[beta-D-glucopyranosyl-(1 -> 4)]-alpha-L-ara-binopyranosyl}-saikogenin G (1) and 3 beta-O-{[beta-D-glucopyranosyl-(1 -> 4)]-alpha-L-arabinopyranosyl}-16-deoxysaikogenin F (2), named anthylloside A and B, have been isolated from an acetone-water extract from aerial parts of kidney vetch (A. vulneraria L.). Isolation of 1 and 2 was achieved by solvent partition with EtOAc and subsequent repeated chromatographic purification. The structures of the isolated compounds were elucidated by spectrometric (HR-MS) and spectroscopic methods (H-1-and C-13-NMR, UV, IR and CD), as well as GC-MS analysis of samples after 1 N HCl hydrolysis and subsequent derivatization. The configuration and conformation of both 1 and 2 were assigned by means of comprehensive 2D-NMR analyses including H-1-H-1-COSY, ROESY, decoupled gHSQC, gHMBC and selective 1D-TOCSY experiments. Moreover, 1 and 2 possess significant hemolytic activity, which was assessed in a blood agar assay and compared to that of three reference saponins.