Abstract
In our ongoing search for bioactive substances from marine organisms, novel alkaloids have been isolated. Pinnatoxins and pinnamine, 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. Ircinamine, purified from the marine sponge Ircinia sp., has a reactive thioester. Aburatubolactams, inhibitors of superoxide anion generation, were isolated from Streptomyces sp. This article covers the bioactive marine alkaloids that have been recently isolated by this research group.
Highlights
Chinese investigators have reported that a toxic extract from P. attenuata, referred to as pinnatoxin, is a Ca2+ channel activator [2]
Specific inhibitors of phospholipase A2 (PLA2) have been considered as potential drugs for the treatment of inflammation and other disease states, since PLA2 is linked to the initial step in the cascade of enzymatic reactions that lead to the generation of inflammatory mediators [20,21,22]
The Danishefsky group has achieved the total synthesis of pinnaic acid [31,32] and halichlorine [17,18] in an asymmetric manner
Summary
Alkaloids are nitrogen-containing compounds that occur naturally in plants and in microorganisms, marine organisms, and animals. It is not clear why alkaloids show significant biological activity, they are often useful as drugs or biological probes for physiological studies. As new and more complicated diseases are encountered worldwide, the importance of bioactive alkaloids has increased due to their potential application in chemotherapy. As the application of alkaloids has expanded, the definition of alkaloids has become less restricted
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