Carotenoids of the Sponge Polymastia Granulosa (Hadromerida)

The background information on natural carotenoids (new aspects), NMR spectroscopy of carotenoids (present status) and sponge chemosystematics, relevant to the present study, is briefly reviewed. The quantitative carotenoid composition of Polymastia granulosa has been determined by methods including TLC, HPLC, VIS, 1H NMR and MS. Isorenieracistene (7-cis-φ,φ-carotene) was the major carotenoid, further characterized by 2D 1H NMR (400 MHz), and isomerization studies. Its stability is discussed. The 1 H NMR spectrum of 7,9'-dicis isorenieratene, a likely isolation artifact, was fully assigned by 1D Double Indor Difference experiments and 2D 1H NMR. All three reports on Δ-cis aryl carotenes concern sponges of the order Hadromerida. Possible cis hydrogenation of algal carotenoid precursors is considered.