3-O-(beta-D-glucopyranosyl(1-->4))(alpha-L-rhamnopyranosyl(1-->2))-alpha-L-arabinopyranosyl-23-hydroxybetulinic acid 28-O-alpha-L-rhamnopyranosyl(1-->4)-beta-D-glucopyranosyl(1-->6)-beta-D-glucopyranosyl ester