Dinoflagellates are widely known as the rich source of biologically active and structural unique secondary metabolites. Among them, large polyols and polyethers composed of a long carbon backbone that is highly functionalized by oxygen, as we say "super-carbon-chain compounds (SCCs)", are some of the most unusual compounds. In our quest for SCCs from marine dinoflagellates, we isolated a novel spiroketal compound, symbiospirol A, from Symbiodinium sp. that was the same strain which produced symbiodinolide. Its planar structure and partial relative stereochemistries were elucidated based on 1D and 2D-NMR and degradation reaction. Symbiospirol A was shown to inhibit PKC activation induced by phosphatidylserine. Symbiodinolide is the typical SCC with a molecular weight of 2,860, which we isolated from the dinoflagellate Symbiodinium sp. The chemical degradation reaction using the 2nd-generation Hoveyda-Grubbs catalyst was employed for the stereochemical assignment at 62-membered macrolactone of symbiodinolide. The absolute configurations at several chiral centers were determined by spectroscopic analysis of MTPA diesters. Further chemical degradation studies using the 2nd-generation Grubbs' catalyst have performed new reaction. In addition, the complete stereochemical assignment of symbiodinolide is in progress. In our continuing search for novel bioactive metabolites from symbiotic marine dinoflagellates, we found that the water layer from the symbiotic dinoflagellate with jellyfish Mastigias papua displayed considerable activity against the expression of vascular cell adhesion molecule-1 (VCAM-1) in human umbilical vein endothelial cells (HUVEC). Further purification of the water layer guided by the bioassay and mass measurement led to the isolation of an unknown bioactive SCC, which we named symbiopolyol, possessing the molecular weight of 1,220. Studies on the isolation, structure elucidation, and biological activities of symbiopolyol will be described.
