Acylated triterpene saponins from Atroxima liberica STAPF

The four new acylated triterpene saponins 1-4, isolated as two pairs of isomers and named libericosides A₁/A₂ and B ₁/B₂, one pair of isomers 5/6, the (Z)-isomer libericoside C₂ (5) being new, one new sucrose ester, atroximoside (7), and eight known compounds were isolated from the roots of Atroxima liberica by repeated MPLC and VLC on normal and reversed-phase silica gel. Their structures were elucidated on the basis of extensive 1D- and 2D-NMR studies (¹H- and ¹³C-NMR, DEPT, COSY, TOCSY, NOESY, HSQC, and HMBC) and mass spectrometry as 3-O-β-D-glucopyranosylpresenegenin 28-{O-α-L- arabinopyranosyl-(1→3)-O-β-D-xylopyranosyl-(1→4) -O-α-L-rhamnopyranosyl-(1→2)-4-O-[(E)-3,4-dimethoxycinnamoyl] -β-D-fucopyranosyl} ester (1) and its (Z)-isomer 2, 3-O-β-D- glucopyranosylpresenegenin 28-{O-α-L-arabinopyranosyl-(1→4)-O-β- D-xylopyranosyl-(1→4)-O-α-L-rhamnopyranosyl-(1→2) -O-[O-β-D-xylopyranosyl-(1→3)-β-D-glucopyranosyl-(1→3)] -4-O-[(E)-3,4-dimethoxycinnamoyl]-β-D-fucopyranosyl} ester (3) and its (Z)-isomer 4, 3-O-β-D-glucopyranosylpresenegenin 28-{O-β-D- xylopyranosyl-(1→4)-O-α-L-rhamnopyranosyl-(1→2) -O-[6-O-acetyl-β-D-glucopyranosyl-(1→3)]-4-O-[(Z)-3, 4-dimethoxycinnamoyl]-β-D-fucopyranosyl} ester (5), and 3-O-[(Z)-feruloyl]-β-D-fructofuranosyl α-D-glucopyranoside (7). Compounds 1-6 and the known saponins 8/9 were evaluated against the human colon cancer cells HCT 116 and HT-29 and showed moderate to weak cytotoxicity.