Marine pharmacology: potentialities in the treatment of infectious diseases, osteoporosis and Alzheimer's disease.

Several molecules isolated from various marine organisms (microorganisms, algae, fungi, invertebrates, and vertebrates) are currently under study at an advanced stage of clinical trials, either directly or in the form of analogues deduced from structure-activity relationships. Some of them have already been marketed as drugs. The goal of this article is not to present a complete panorama of marine pharmacology but to show that new models and new mechanisms of action of marine substances bring new solutions for tackling some of the major public health problems of the 21st century. These include: malaria, which assails mainly the southern hemisphere; tuberculosis, an infectious disease once believed to be eliminated but alarmingly increasing, especially among HIV-positive populations; and osteoporosis and Alzheimer's disease, the extension of which are correlated with ageing populations, especially in the developed countries.