Triterpene Glycosides from the Viscera of Sea Cucumber Apostichopus japonicus with Embryotoxicity

Sea cucumbers release chemical repellents from their guts when they are in danger from predators or a hostile environment. To investigate the chemical structure of the repellent, we collected and chemically analyzed the viscera of stressed sea cucumbers ( Apostichopus japonicus ) in the Yellow Sea of China. Two undescribed triterpene glycosides ( 1 and 2 ), together with a known cladoloside A ( 3 ), were identified and elucidated as 3 β ‐ O ‐{2‐ O ‐[ β ‐ d ‐quinovopyranosyl]‐4‐ O ‐[3‐ O ‐methyl‐ β ‐ d ‐glucopyranosyl‐(1→3)‐ β ‐ d ‐glucopyranosyl]‐ β ‐ d ‐xylopyranosyl}‐holosta‐9(11),25(26)‐dien‐16‐one ( 1 ), 3 β ‐ O ‐{2‐ O ‐[ β ‐ d ‐glucopyranosyl]‐4‐ O ‐[3‐ O ‐methyl‐ β ‐ d ‐glucopyranosyl‐(1→3)‐ β ‐ d ‐glucopyranosyl]‐ β ‐ d ‐xylopyranosyl}‐holosta‐9(11),25(26)‐dien‐16‐one ( 2 ), 3 β ‐ O ‐{2‐ O ‐[3‐ O ‐methyl‐ β ‐ d ‐glucopyranosyl‐(1→3)‐ β ‐ d ‐xylopyranosyl‐(1→4)‐ β ‐ d ‐quinovopyranosyl]‐ β ‐ d ‐xylopyranosyl}‐holosta‐9(11),25(26)‐dien‐16‐one ( 3 ) by spectroscopic analysis, including HR‐ESI‐MS and NMR spectra. Compounds 1 , 2 , and 3 display embryonic toxicity, as indicated by their 96‐hour post‐fertilization lethal concentration (96 hpf‐LC 50 ) values of 0.289, 0.536, and 0.091 μM, respectively. Our study discovered a class of triterpene glycoside compounds consisting of an oligosaccharide with four sugar units and a holostane aglycone. These compounds possess embryotoxicity and may serve as chemical defense molecules in marine benthic ecosystems.