Isolation and Characterization of Glycosylated Fatty Acid Amides from the Norwegian Deep-Sea Sponge Phakellia sp.

Marine organisms from deep-sea environments have attracted considerable attention in drug discovery because they produce structurally diverse natural products. However, Norwegian deep-sea ecosystems remain largely unexplored in terms of natural product chemistry and bioactivity. In this study, a deep-sea sponge belonging to the genus Phakellia was selectively collected using a low-impact, remotely operated vehicle approach from the Mohn’s Treasure area in the Norwegian Sea at a depth of 2858 m, representing one of the deepest sponge samples investigated in Norwegian waters to date. Chemical investigation of this specimen resulted in the isolation of three new glycosylated fatty acid amides, phakelliosides A–C (1–3), together with two known compounds, 11-(S)-myxillin B (4) and 11-(S)-myxillin C (5), which were isolated as pure individual compounds from natural sources for the first time, with their absolute configurations unambiguously established. These compounds were isolated using a combination of chromatographic techniques, and the structures of the isolated compounds were elucidated by comprehensive spectroscopic analyses, including 1D and 2D NMR and UHPLC–HRMS data. The absolute configurations were determined by optical rotation analysis following acid hydrolysis. Compounds 1–5 were subjected to preliminary antibacterial screening against Enterococcus faecalis, Staphylococcus aureus, Streptococcus agalactiae, Escherichia coli, and Pseudomonas aeruginosa at 100 µg/mL. Under the screening conditions, compound 3 produced the lowest OD600 value against E. faecalis (OD600 = 0.154), whereas generally higher OD600 values were observed against the Gram-negative strains. To the best of our knowledge, this is the first report describing the preliminary antibacterial screening of glycosylated fatty acid amides isolated from Norwegian deep-sea organisms. These findings expand current knowledge of the chemical diversity of natural products associated with Norwegian deep-sea sponges. The biosynthetic origin of these metabolites remains unresolved and warrants further investigation.