Nine New Triterpene Glycosides, Magnumosides A₁-A₄, B₁, B₂, C₁, C₂ and C₄, from the Vietnamese Sea Cucumber Neothyonidium (=Massinium) magnum: Structures and Activities against Tumor Cells Independently and in Synergy with Radioactive Irradiation.

Nine new sulfated triterpene glycosides, magnumosides A₁ ( 1 ), A₂ ( 2 ), A₃ ( 3 ), A₄ ( 4 ), B₁ ( 5 ), B₂ ( 6 ), C₁ ( 7 ), C₂ ( 8 ) and C₄ ( 9 ) as well as a known colochiroside B₂ ( 10 ) have been isolated from the tropical Indo-West Pacific sea cucumber Neothynidium (= Massinium ) magnum (Phyllophoridae, Dendrochirotida) collected in the Vietnamese shallow waters. The structures of new glycosides were elucidated by 2D NMR spectroscopy and mass-spectrometry. All the isolated new glycosides were characterized by the non-holostane type lanostane aglycones having 18(16)-lactone and 7(8)-double bond and differed from each other by the side chains and carbohydrate moieties structures. Magnumoside A₁ ( 1 ) has unprecedented 20(24)-epoxy-group in the aglycone side chain. Magnumosides of the group A ( 1 - 4 ) contained disaccharide monosulfated carbohydrate moieties, of the group B ( 5 , 6 )-tetrasaccharide monosulfated carbohydrate moieties and, finally, of the group C ( 7 - 9 )-tetrasaccharide disulfated carbohydrate moieties. The cytotoxic activities of the compounds 1 - 9 against mouse spleen lymphocytes, the ascites form of mouse Ehrlich carcinoma cells, human colorectal carcinoma DLD-1 cells as well as their hemolytic effects have been studied. Interestingly, the erythrocytes were more sensitive to the glycosides action than spleenocytes and cancer cells tested. The compounds 3 and 7 significantly inhibited the colony formation and decreased the size of colonies of DLD-1 cancer cells at non-cytotoxic concentrations. Moreover, the synergism of effects of radioactive irradiation and compounds 3 and 7 - 9 at subtoxic doses on proliferation of DLD-1 cells was demonstrated.
Competing Interests: The authors declare no conflict of interest.