Disulfated Ophiuroid Type Steroids from the Far Eastern Starfish Pteraster marsippus and Their Cytotoxic Activity on the Models of 2D and 3D Cultures

New steroidal 3β,21-disulfates (2–4), steroidal 3β,22-disulfate (5), and the previously known related steroidal 3β,21-disulfate (1) were isolated from the ethanolic extract of the Far Eastern starfish Pteraster marsippus, collected off Urup Island in the Sea of Okhotsk. The structures of these compounds were determined by intensive NMR and HRESIMS techniques as well as by chemical transformations. Steroids 2 and 3 have an oxo-group in the tetracyclic nucleus at position C-7 and differ from each other by the presence of the 5(6)-double bond. The Δ²⁴-22-sulfoxycholestane side chain of the steroid 5 has not been found previously in the starfish or ophiuroid steroids. The cytotoxic activities of 1, 4, 5, and the mixture of 2 and 3 were determined on the models of 2D and 3D cultures of human epithelial kidney cells (HEK293), melanoma cells (SK-MEL-28), small intestine carcinoma cells (HuTu80), and breast carcinoma cells (ZR-75-1). The mixture of 2 and 3 revealed a significant inhibitory effect on the cell viability of human breast carcinoma ZR-75-1 cells, but other tested compounds were less effective.

A New Steroidal Glycoside Granulatoside C from the Starfish Choriaster granulatus, Unexpectedly Combining Structural Features of Polar Steroids from Several Different Marine Invertebrate Phyla

A new unique steroidal glycoside, granulatoside C (1), was isolated from the ethanol extract of the starfish Choriaster granulatus. The structure of 1 was elucidated by extensive NMR and ESI-MS techniques as (20 R)-16,21- O-di-(P-D-fucopyranosyl)-24-methyl-cholesta-5,24(28)-diene-3p,7a,16a,21-tetraol (1). This glycoside is unusual one, because combines some characteristic structural peculiarities of steroids from several different phyla of marine invertebrates, it has a range of structural features that not previously found in starfish polyhydroxysteroidal glycosides, such as Δ5-3β,7α,16α-trihydroxysteroidal nucleus, Δ24(28)-21-hydroxy-24-methyl-cholestane side chain and 16,21-diglycosylation by D-fucopyranosyl residues, but also characteristic of sponges, ophiuroids and soft corals, respectively.

Three New Steroid Biglycosides, Plancisides A, B, and C, from the Starfish Acanthaster planci

Three new steroid biglycosides, plancisides A-C (1-3), were isolated from the ethanolic extract of the starfish Acanthaster planci. The structures of 1-3 were determined by extensive NMR and ESI-MS techniques, as (24 S)-28- O-[β-D-galactofuranosyl-(1→5)-α-L-arabinofuranosyl]-24-methyl-5α-cholestane-3β,4β,6α,8,15β,16β,28-heptol (1), (24 S)-28- O-[α-L-fucopyranosyl-(1→2)-3- O-methyl-β-D-xylopyranosyl]–24-methyl-5α-cholestane-3β,4β,6α,8,15β,16β,28-heptol (2) and (24 S)-28- O-[2,4-di- O-methyl-β-D-xylopyranosyl-(1→2)-α-L-arabinofuranosyl]-24-methyl-5α-cholestane-3β,4β,6α,8,15β,16β,28-heptol 6- O-sulfate (3), respectively. Compound 2 is the first steroid glycoside containing an α-fucopyranose unit found from starfish. Compound 1 slightly inhibits cell proliferation of HCT-116, T-47D, and RPMI-7951 cancer cell lines, but has no effect on colony formation of these cells in a soft agar clonogenic assay.