Starfish Saponins, Part 18. Steroidal Glycoside Sulfates from the Starfish Linckia laevigata

Chemical Constituents and Bioactivities of Starfish

“…), which were two saponins that were based on the skeleton of the sapogenin 24-northornasterol A, while O. ophidianus also contained ophidianoside E, which was identical to the thornasteroside A (466) and ophidianoside F (480) [133]. The saponins from Linckia laevigata were identified as thornasteroside A (466), marthasteroside A 1 (473), ophidianoside F (480), maculatoside (477), and laevigatoside (481) [144]. Protoreasteroside (482) was obtained from Protoreaster nodosus and Pentaceraster alveolatus [145].…”

Asterosaponins Isolated from the Starfish Asterias amurensis

“…In addition, the characteristic carbon signals at d C 145.68 (C-9) and 116.48 (C-11) revealed the chol-9(11)-en-23-one skeleton. 11,14,21) 22) and the nuclear Overhauser effect (NOE) correlation between H-3 and H-5 (Fig. 2).…”

“…The proton signal of H-3 at d H 4.77 (W 1/2 ϭ22 Hz) as well as the NOE correlation between H-3 and H-5 suggested the a-configuration of H-3 (alternative 3b-sulfate). 14,16,22) On the basis of the difference of 2 (Fig. 3).…”

“…Through the analysis of 2D-NMR data, the aglycone structure of 4 was identified as a 5a -cholest-9(11)-en-23-one-3b ,6a ,20-triol 3-sulfate. [12][13][14][15][16][17][18][19] Glycosilation at C-6 and other interglycosidic linkages were confirmed by the following HMBC and NOESY correlations: d 24) Considering all the NMR and MS data, compound 4 was identified as thornasteroside A, [12][13][14][15][16][17][18] …”

“…8) Due to the widespread interest in their biological and structural significance, we have undertaken structural studies on the saponins of A. amurensis. Our recent investigation on the n-BuOH soluble fraction of A. amurensis resulted in the isolation of three new asterosaponins 1-3, and four known saponins, thornasteroside A (4), [12][13][14][15][16][17][18] versicoside A (5), 18,19) anasteroside B (6), 11) and asteronyl pentaglycoside sulfate (7). 15,20) Although the chemical structures of asterosaponins 4-7 have been already determined using hydrolyzed molecules, there are few reports on the full NMR assignment for undegraded saponins.…”