Karataviosides G–K, five new bisdesmosidic steroidal glycosides from the bulbs of Allium karataviense

•Karataviosides G–K (1–5) were isolated the bulbs of Allium karataviense.•Compounds 1–5 are new bisdesmosidic steroidal glycosides.•The structures were elucidated by NMR analysis and the results of hydrolysis.•Compound 1 is furostanol glycoside with a triglucosyl unit at C-26 of the aglycone.•Compounds 1–5 were evaluated for their cytotoxic activities against tumor cell lines.

We have analyzed the steroidal glycosides in Allium karataviense bulbs, and isolated five new bisdesmosidic steroidal glycosides: karataviosides G−K (1–5). The structures were elucidated by extensive spectroscopic analysis, including 2D NMR and enzymatic and hydrolytic cleavage. Karatavioside G (1) is an entirely novel furostanol glycoside, which has an O-β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranosyl unit at C-26 of the aglycone. Although a variety of cholestanol glycosides have been isolated, mainly from Liliaceae and Agavaceae, karataviosides J and K (4 and 5) are also notable because they are the most polar cholestanol bisdesmosides discovered, in which a lycotetraose is attached to C-3 of the aglycone, and a glucose or O-glucosyl-(1 → 3)-glucose is attached at C-16. The isolated glycosides were also evaluated for their cytotoxic activities against cultured tumor cell lines.

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