The bioactive ingredients of sea cucumber Holothuria moebii were investigated, and four sulfated saponins (1-4) and one desulfated saponin (3B) with an unusual 3,4-epoxy xylose were obtained from this study. Compound 2 is a new triterpenoid saponin and 3B is a new artificial compound. On the basis of the extensive NMR and HRESIMS data, their structures were assigned as 3-O-[β-D-quinovopyranosyl-(1 → 2)-4-sodium sulfato-β-D-xylopyranosyl]-25-acetoxy-22-oxo-9(11)-holostene-3β,12α,17α-triol (2) and 3-O-[β-D-quinovopyranosyl-(1 → 2)-3,4-epoxy-β-xylopyranosyl]-22,25-epoxy-9(11)-holostene-3β,12α,17α-triol (3B). Compounds 1-4 showed activity suppressing the proliferation of four different glioma cells with IC50 values ranging from 0.99 to 8.64 µM. New saponin 2 significantly induced apoptosis in human glioblastoma U87-MG cells and reduced the expression levels of several glioma metabolic enzymes of glycolysis and glutaminolysis. This study reveals for the first time that selectively targeting multiple glioma metabolic regulators of glycolysis and glutaminolysis might be one of the anti-glioma mechanisms of saponin 2.
Georg Thieme Verlag KG Stuttgart · New York.