Natural products and drug discovery

For more than 50 yr, natural products have served us well in combating infectious bacteria and fungi. During the 20th century, microbial and plant secondary metabolites helped to double our life span, reduced pain and suffering, and revolutionized medicine. The increased development of resistance to older antibacterial, antifungal, and antitumor drugs has been challenged by (1) newly discovered antibiotics (e.g., candins, epothilones); (2) new semisynthetic versions of old antibiotics (e.g., ketolides, glycylcyclines); (3) older underutilized antibiotics (e.g., teicoplainin); and (4) new derivatives of previously undeveloped narrow-spectrum antibiotics (e.g., streptogramins). In addition, many antibiotics are used commercially, or are potentially useful in medicine for purposes other than their antimicrobial action. They are used as antitumor agents, enzyme inhibitors including powerful hypocholesterolemic agents, immunosuppressive agents, antimigraine agents, and so on. A number of these products were first discovered as antibiotics that failed in their development as such, or as mycotoxins.