Two New Steroidal Monoglycosides, Anthenosides A₁ and A₂, and Revision of the Structure of Known Anthenoside A with Unusual Monosaccharide Residue from the Starfish Anthenea aspera

Marine natural products

This review covers the literature published between January and December in 2018 for marine natural products (MNPs), with 717 citations (706 for the period January to December 2018) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1554 in 469 papers for 2018), together with the relevant biological activities, source organisms and country of origin. Reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included. The proportion of MNPs assigned absolute configuration over the last decade is also surveyed.

Unusual Polyhydroxylated Steroids from the Starfish Anthenoides laevigatus, Collected off the Coastal Waters of Vietnam

Four new polyhydroxylated steroids 1–4 were isolated along with two previously known related steroids 5 and 6 from the methanolic extract of the starfish Anthenoides laevigatus collected off the coastal waters of Vietnam. Structures of new compounds were substantially elucidated by one-dimensional (1D) and two-dimensional (2D) NMR spectroscopy and HRESIMS techniques. Heptaol 1 and hexaol 2 contain the common 5α-cholestane skeleton, while hexaol 3 and heptaol 4 have the rare among starfish steroid compounds 5β-cholestane skeleton. Compounds 1, 5, and 6 do not show cytotoxic effects against normal JB6 Cl41 and cancer HT-29 and MDA-MB-231 cells, however they inhibit cell proliferation and colony formation of cancer HT-29 and MDA-MB-231 cells.

Bright Spots in The Darkness of Cancer: A Review of Starfishes-Derived Compounds and Their Anti-Tumor Action

The fight against cancer represents a great challenge for researchers and, for this reason, the search for new promising drugs to improve cancer treatments has become inevitable. Oceans, due to their wide diversity of marine species and environmental conditions have proven to be precious sources of potential natural drugs with active properties. As an example, in this context several studies performed on sponges, tunicates, mollusks, and soft corals have brought evidence of the interesting biological activities of the molecules derived from these species. Also, echinoderms constitute an important phylum, whose members produce a huge number of compounds with diverse biological activities. In particular, this review is the first attempt to summarize the knowledge about starfishes and their secondary metabolites that exhibited a significant anticancer effect against different human tumor cell lines. For each species of starfish, the extracted molecules, their effects, and mechanisms of action are described.

In Vitro Anticancer and Proapoptotic Activities of Steroidal Glycosides from the Starfish Anthenea aspera

New marine glycoconjugates—the steroidal glycosides designated as anthenosides V–X (1–3)—and the seven previously known anthenosides E (4), G (5), J (6), K (7), S1 (8), S4 (9), and S6 (10) were isolated from the extract of the tropical starfish Anthenea aspera. The structures of 1–3 were elucidated by extensive NMR and ESIMS techniques. Glycoside 1 contains a rare 5α-cholest-8(14)-ene-3α,7β,16α-hydroxysteroidal nucleus. Compounds 2 and 3 were isolated as inseparable mixtures of epimers. All investigated compounds (1–10) at nontoxic concentrations inhibited colony formation of human melanoma RPMI-7951, breast cancer T-47D, and colorectal carcinoma HT-29 cells to a variable degree. The mixture of 6 and 7 possessed significant anticancer activity and induced apoptosis of HT-29 cells. The molecular mechanism of the proapoptotic action of this mixture was shown to be associated with the regulation of anti- and proapoptotic protein expression followed by the activation of initiator and effector caspases.