Glycolipids from Sponges. 18. Corrugoside, a New Immunostimulatory alpha- Galactoglycosphingolipid from the Marine Sponge Axinella corrugata

Corrugoside (1a), a new immunostimulatory triglycosilated a-galactoglycosphingolipid, was isolated from the marine sponge Axinella corrugata, and its structure determined by spectral analysis and chemical degradation. Compound 1a activated murine NKT cells in vitro, with a potency of about 2 logs lower than that of aGalCer. Four stereoisomeric glycosphingolipids (2a–2d) were also obtained, b-glucosylceramides bearing unusual endoperoxide and allylic hydroperoxide functionalities on the sphinganine chain. They were shown to be photooxidation artifacts of the known glycosphingolipids 3, also present in the sponge. A possible role of compound 3 as a singlet oxygen scavenger to protect the organism from oxidative damage is proposed.