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DOI: 10.1055/s-0028-1084427
New dolabellanes from the brown alga Dilophus spiralis
The brown alga Dilophus spiralis is a member of the family Dictyotaceae, which is considered a prolific source of secondary metabolites often exhibiting biological activities, such as algicidal, antibacterial, antifeedant, cytotoxic, and ichthyotoxic.
In the framework of our research program towards the isolation of bioactive natural products from marine organisms of the Greek Seas, we investigated the chemical composition of D. spiralis collected from Elafonissos island, south of Peloponnese. Extraction of the freeze-dried alga with dichloromethane, followed by a series of chromatographic separations led to the isolation of several dolabellane diterpenes, seven of which are new natural products (1-7).
The structure elucidation of 1-7 and the assignment of their relative configurations were based on analyses of their spectroscopic data (NMR, MS, IR) and chemical interconversions, whereas their absolute stereochemistry was determined, when possible, using the modified Mosher's method.
The antibacterial activity of the isolated dolabellanes was evaluated against multidrug-resistant (MDR) and methicillin-resistant (MRSA) strains of Staphylococcus aureus.