Pure and Applied Chemistry

Abstract: Marine macro- and micro-organisms collected in Okinawa are good sources of compounds with intriguing structures and interesting biological activities. Synthetic hybrid molecules of caffeine and eudistomin D from tunicates Eudistoma sp. were found to show better potency as adenosine receptor ligands than caffeine, and one of them exhibits potent activity for adenosine receptors tested, especially for A₃ subtype. Potent cytotoxic polyene macrolides from a tunicate Cystodytes sp. were found to be potent osteoclast inhibitors and to inhibit vacuolar type H+-ATPase (V-ATPase) of both mammalian and yeast cells. Amphidinolactones A and B are new macrolides from a dinoflagellate Amphidinium sp., and a potent cytotoxic macrolide from another strain was found to target actin cytoskeleton. Theonezolide A, a long-chain polyketide from a sponge Theonella sp., induces a drastic shape change in platelets by reorganization of microtubules. The stereochemistry of many chiral centers in theonezolide A was elucidated by spectral data and chemical means. Metachromins L-Q are new sesquiterpenoid quinones with an amino acid residue, while nakijiquinones E and F were the first dimeric sesquiterpenoid quinones possessing a 3-aminobenzoate moiety. Halichonadin E is the first hetero-dimeric sesquiterpenoid with eudesmane and aromadendrane skeletons linked through a urea fragment isolated from a sponge Halichondria sp. Pyrinadine A and nakinadine A are novel bis-pyridine alkaloids from sponges, while nagelamides are new bromopyrrole alkaloids from a sponge Agelas sp. Here, the structures and bioactivities of these interesting marine natural products will be described.