Synthesis of a chlorogenin glycoside library using an orthogonal protecting group strategy

• An efficient method for the construction of a glycoside library of chlorogenin.
• Ten different glycosyl donors to afford more than twenty di-, tri-, and tetra-saccharides of chlorogenin glycosides.
• The compounds were subjected to anti-cytotoxic, and anti-influenza entry assays, and the results show that the 2′-O-, and 4′-O-rhammosyl moieties of dioscin are essential for activity.

Naturally occurring spirostanol saponins bear a chacotriose, α-l-rhamnopyranosyl-(1→2)-[α-l-rhamnopyranosyl-(1→4)]-β-d-glucopyranose residue as the oligosaccharide moiety which is believed to be important for biological activity. Herein the development of a concise, combinatorial method for the synthesis of two series of glycan variants at the 2′ and/or 4′ positions of chacotriose is described and the structure–activity relationships of the glycone part at 3-OH of chlorogenin investigated. These compounds were found to be weakly-cytotoxic toward leukemia cell lines CCRF and HL-20, indicating that the chacotriose moiety is important for anticancer activity.

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