Sponges (phylum Porifera) are sessile marine filter feeders that have developed efficient defense mechanisms against foreign attackers such as viruses, bacteria, or eukaryotic organisms. Marine sponges are among the richest sources of pharmacologically-active chemicals from marine organisms. It is suggested that (at least) some of the bioactive secondary metabolites isolated from sponges are produced by functional
enzyme clusters, which originated from the sponges and their associated microorganisms. More than 5,300 different products are known from sponges and their associated microorganisms, and more than 200 new metabolites from sponges are reported each year. As infectious microorganisms evolve and develop resistance to existing
pharmaceuticals, the marine sponge provides novel leads against bacterial, viral, fungal and
parasitic diseases. Many marine natural products have successfully advanced to the late stages of clinical trials, as for example
ara-A (
vidarabine), an anti-viral
drug used against the
herpes simplex encephalitis virus. This substance is in clinical use for many years. Moreover, a growing number of candidates have been selected as promising leads for extended preclinical assessment, including
manzamine A (activity against
malaria,
tuberculosis, HIV, and others), lasonolides (antifungal activity) and
psammaplin A (antibacterial activity). In this review we have surveyed the discoveries of products derived from marine sponges and associated bacteria that have shown in vivo efficacy or potent in vitro activity against infectious and
parasitic diseases, including bacterial, viral, fungal and
protozoan infections. Our objective was to highlight the substances that have the greatest potential to lead to clinically useful treatments.