Marine Pharmacology: Bioactive Molecules from the Sea

Mankind has known for at least several thousand years that marine organisms contain substances capable of potent biological activity (1). Undoubtedly we are aware that most of the currently available therapeutic agents stem either directly or indirectly from naturally occurring organic molecules derived from terrestrial plants and/or animals. However, the abundant floras and faunas inhabiting the 70% of the Earth's surface covered by the ocean waters remain relatively unexplored. It is only in the past three decades that a significant research activity has suggested that the sea offers an enormous biomedical potential yet to be harnessed by man. Attention to pharmacologically active substances in the sea in recent decades was first drawn by Emerson & Taft (2). Several subsequent reviews and monographs have dealt mostly with the pharmacology and toxicity of crude and semipurified extracts of marine organisms (3-13). More recent reviews, however, describe the pharmacology of some of the pure compounds of marine origin (14-17). This review focuses on pharmacological activities of pure compounds iso­ lated from marine organisms, as well as the pharmacologic activities of some highly potent substances broadly given the notorious name of marine toxins. Note that we take the same view of toxicity as Paracelsus-that at a given dosage level all compounds are toxic but that the right dose via the right route can make all the difference. Digitalis and tetrodotoxin (18) are but two ex­ amples among many that support this view.