[(25R)-2α-Hydroxyspirost-5-en-3β-yl]4-O-[2-O-(β-D-glucopyranosyl)-3-O-[4-O-(4-carboxy-3-hydroxy-3-methylbutyryl)-β-D-xylopyranosyl]-β-D-glucopyranosyl]-β-D-galactopyranoside