New therapeutic approaches by using microorganism-derived compounds.

The role of natural products as a source for remedies has been recognized since ancient times. Despite major scientific and technological progress in combinatorial chemistry, drugs derived from natural product still make an enormous contribution to drug discovery today. Nature is an attractive source of new therapeutic candidate compounds since a tremendous chemical diversity is found in millions of species of plants, animals, marine organisms and microorganisms. Microorganisms such as bacteria and fungi have been invaluable to discover drugs and lead compounds. These microorganisms produce a large variety of antimicrobial agents which have evolved to give their hosts an advantage over their competitors in the microbiological world. The screening of microorganisms became highly popular after the discovery of penicillin but in recent years the list of antibacterial agents (bacteria- or fungi-derived) has increased considerably with the arrival of cephalosporins, tetracyclines, aminoglycosides, rifamycins, and chloramphenicol. Although most of the drugs derived from microorganisms are used in antibacterial therapy, some microbial metabolites have provided lead compounds in other fields of medicine. For example: the fungal metabolite lovastatin, which was the lead compound for a series of drugs that lower cholesterol levels, the ciclosporin (fungal metabolite) currently used to suppress the immune response after transplantation operations and sirolimus- a bacterium-derived macrolide- used in the treatment of some cancers. The aim of this review is to analyze the current uses and the future applications in therapeutic treatments of microorganism-derived products (MdPs) and discuss the results obtained in the some clinical trials.