Separation and structural analysis of some saponins from Quillaja saponaria Molina

A fraction of saponins from Quillaja saponaria Molina, QH-B, was fractionated by consecutive separations on three different reverse-phase HPLC systems. Eight compounds were isolated and the structures of these were elucidated mainly by sugar analysis and NMR spectroscopy. The structures consisted of a quillaic acid substituted with two different trisaccharides at C-3, β-d-Galp-(1→2)-[α-l-Rhap-(1→3)]-β-d-GlcpA and β-d-Galp-(1→2)-[β-d-Xylp-(1→3)]-β-d-GlcpA, and a tetra- or pentasaccharide at C-28, β-d-Xylp-(1→4)-[β-d-Glcp-(1→3)]-α-l-Rhap-(1→2)-β-d-Fucp and β-d-Apif-(1→3)-β-d-Xylp-(1→4)-[β-d-Glcp-(1→3)]-α-l-Rhap-(1→2)-β-d-Fucp. These compounds were further substituted with an acyl group either at O-3 or O-4 of the fucose residue, which is the sugar linked to C-28 of the quillaic acid.