Studies in Bioactive Marine Alkaloids

In our continuing search for bioactive substances from marine organisms, novel alkaloids were isolated. The structures and functions of these marine alkaloids are described here. Pinnatoxins and pteriatoxins, potent shellfish poisons, were purified from the Okinawan bivalve Pinna muricata. Pinnatoxins activate Ca²⁺ channels. Halichlorine was isolated from the marine sponge Halichondria okadai. This compound inhibits the induction of VCAM-1. Drugs that block VCAM-1 may be useful for treating coronary artery diseases, angina, and noncardiovascular inflammatory diseases. Pinnaic acids, which are cPLA₂ inhibitors, were also obtained from P. muricata. Interestingly, the structures of pinnaic acids are closely related to that of halichlorine. Norzoanthamine hydrochloride, isolated from the colonial zoanthid Zoanthus sp., suppresses decreases in bone weight and strength in ovariectomized mice, and could be a good candidate for an osteoporotic drug. Aburatubolactams, inhibitors of Superoxide anion generation, were isolated from Streptomyces sp.