Two New Cytotoxic Nonsulfated Pentasaccharide Holostane (=20‐Hydroxylanostan‐18‐oic Acid <i>γ</i>‐Lactone) Glycosides from the Sea Cucumber <i>Holothuria grisea</i>

Abstract

Abstract Two new lanostane‐type nonsulfated pentasaccharide triterpene glycosides, 17‐dehydroxyholothurinoside A ( 1 ) and griseaside A ( 2 ), were isolated from the sea cucumber Holothuria grisea. Their structures were elucidated by spectroscopic methods, including 2D‐NMR and MS experiments, as well as chemical evidence. Compounds 1 and 2 possess the same pentasaccharide moieties but differ slightly in their side chains of the holostane‐type triterpene aglycone. The structures of the two new glycosides were established as (3 β ,12 α )‐22,25‐epoxy‐3‐{( O ‐ β ‐ D ‐glucopyranosyl‐(1→4)‐ O ‐[ O ‐3‐ O ‐methyl‐ β ‐ D ‐glucopyranosyl‐(1→3)‐ O ‐ β ‐ D ‐glucopyranosyl‐(1→4)‐6‐deoxy‐ β ‐ D ‐glucopyranosyl‐(1→2)]‐ β ‐ D ‐xylopyranosyl)oxy}‐12,20‐dihydroxylanost‐9(11)‐en‐18‐oic acid γ ‐lactone ( 1 ) and (3 β ,12 α )‐3‐{( O ‐ β ‐ D ‐glucopyranosyl‐(1→4)‐ O ‐[ O ‐3‐ O ‐methyl‐ β ‐ D ‐glucopyranosyl‐(1→3)‐ O ‐ β ‐ D ‐glucopyranosyl‐(1→4)‐6‐deoxy‐ β ‐ D ‐glucopyranosyl‐(1→2)]‐ β ‐ D ‐xylopyranosyl)oxy}‐12,20,22‐trihydroxylanost‐9(11)‐en‐18‐oic acid γ ‐lactone ( 2 ). The 17‐dehydroxyholothurinoside A ( 1 ) and griseaside A ( 2 ) exhibited significant cytotoxicity against HL‐60, BEL‐7402, Molt‐4, and A‐549 cancer cell lines.