Synthesis of neosaponins and neoglycolipids containing a chacotriosyl moiety

Alpha-L-rhamnopyranosyl-(1-->4)-[alpha-L-rhamnopyranosyl-(1-->2)]-beta-D-glucopyranose (chacotriose) is the oligosaccharide moiety of dioscin. Chacotriosyl trichloroacetimidate was synthesized from d-glucose and l-rhamnose, and glycosylated to mevalonate (diosgenin, cholesterol, and glycyrrhetic acid) to yield dioscin and neosaponins. In order to simplify the structure of the aglycone part, the mevalonate moiety was replaced with double-chain neoglycolipids that mimicked glycosyl ceramides. A cytotoxicity test revealed the importance of the glycosidic linkage of the naturally occurring beta-form and that dioscin and the neoglycolipid with the longest chain showed a moderate activity.