C15 acetogenins with antistaphylococcal activity from the red alga Laurencia glandulifera

Five new C₁₅ eight-membered cyclic ethers (1, 3–6) with a characteristic terminal cis ene–yne moiety, along with the previously reported acetylenic chloro diol (2) were isolated from the organic extract of the red alga Laurencia glandulifera, collected at Crete island in South Greece. Full assignment of all ¹H and ¹³C resonances were carried out by extensive analysis of their NMR spectra. All metabolites were tested for their antistaphylococcal activity and the minimum inhibitory concentrations (MICs) of 2–5 were in the range of 8–256 μg/ml.