Abstract
Among marine organisms, sponges are the richest sources of pharmacologically-active compounds. Stemming from a previous lead discovery program that gathered a comprehensive library of organic extracts of marine sponges from the off-shore region of Portugal, crude extracts of Erylus cf. deficiens collected in the Gorringe Bank (Atlantic Ocean) were tested in the innovative high throughput screening (HTS) assay for inhibitors of indoleamine 2,3-dioxygenase (IDO) and showed activity. Bioassay guided fractionation of the dichloromethane extract led to the isolation of four new glycolipids, named erylusamide A–D. The structures of the isolated compounds were established by 1D and 2D nuclear magnetic resonance (NMR) spectroscopy, high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) and chemical derivatization. The metabolites shared a pentasaccharide moiety constituted by unusual highly acetylated d-glucose moieties as well as d-xylose and d-galactose. The aglycones were unprecedented long chain dihydroxyketo amides. Erylusamides A, B and D differ in the length of the hydrocarbon chain, while erylusamide C is a structural isomer of erylusamide B.
Highlights
The secondary metabolites found in marine invertebrates represent a rich source of novel chemical diversity for lead compounds, with sponges being the most prolific source of new molecules.Between these structurally unique metabolites, glycolipids play an important role
The extracts were screened as modulators ofinvolved proteins and Gorringe bank) was constructed
The extracts were screened as modulators of proteins involved in cancer and neurodegenerative diseases using the Screening for Drug in cancer and neurodegenerative diseases using the Global technology developed by the Portuguese biotech company
Summary
The secondary metabolites found in marine invertebrates represent a rich source of novel chemical diversity for lead compounds, with sponges being the most prolific source of new molecules. Between these structurally unique metabolites, glycolipids play an important role. Glycolipids belong to the broad class of glycoconjugates and are characterized by having one or more monosaccharide residues linked by a glycosidic bond to a hydrophobic moiety, such as an acylglycerol, a sphingoid, Mar. Drugs 2016, 14, 179; doi:10.3390/md14100179 www.mdpi.com/journal/marinedrugs. Sponges of the genus Erylus Gray, 1867 (Tetractinellida, Geodiidae) were reported to produce uncommon phospholipid methyl branched fatty and unusual glycolipids, some of which have interesting pharmacological activities, such as anticancer and interleukin-6 (IL-6) receptor antagonists (Table 1).
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