Four New Steroidal Glycosides, Protolinckiosides A – D, from the Starfish Protoreaster lincki

Four new steroidal glycosides, protolinckiosides A – D ( 1 – 4 , resp.), were isolated along with four previously known glycosides, 5 – 8 , from the Me OH /Et OH extract of the starfish Protoreaster lincki . The structures of 1 – 4 were elucidated by extensive NMR and ESI ‐ MS techniques as (3 β ,4 β ,5 α ,6 β ,7 α ,15 α ,16 β ,25 S )‐4,6,7,8,15,16,26‐heptahydroxycholestan‐3‐yl 2‐ O ‐methyl‐ β ‐ d ‐xylopyranoside ( 1 ), (3 β ,5 α ,6 β ,15 α ,24 S )‐3,5,6,8,15‐pentahydroxycholestan‐24‐yl α ‐ l ‐arabinofuranoside ( 2 ), sodium (3 β ,6 β ,15 α ,16 β ,24 R )‐29‐( β ‐ d ‐galactofuranosyloxy)‐6,8,16‐trihydroxy‐3‐[(2‐ O ‐methyl‐ β ‐ d ‐xylopyranosyl)oxy]stigmast‐4‐en‐15‐yl sulfate ( 3 ), and sodium (3 β ,6 β ,15 α ,16 β ,22 E ,24 R )‐28‐( β ‐ d ‐galactofuranosyloxy)‐6,8,16‐trihydroxy‐3‐[(2‐ O ‐methyl‐ β ‐ d ‐xylopyranosyl)oxy]ergosta‐4,22‐dien‐15‐yl sulfate ( 4 ). The unsubstituted β ‐ d ‐galactofuranose residue at C(28) or C(29) of the side chains was found in starfish steroidal glycosides for the first time. Compounds 1 – 4 significantly decreased the intracellular reactive oxygen species ( ROS ) content in RAW 264.7 murine macrophages at induction by proinflammatory endotoxic lipopolysaccharide ( LPS ) from E . coli .