PDFFirst Paragraph
Natural products are organic molecules derived from plants, animals, or microorganisms, and represent the starting point for most of the anti-infective and anti-cancer drugs on the market today. Until recently, the majority of natural products has been isolated from terrestrial sources. During the last two decades, however, the rate of discovery of novel compounds has declined significantly, as exemplified by the fact that extracts from soil-derived actinomycetes have yielded unacceptably high numbers of previously described metabolites (Mincer et al., 2002). In addition to the redundancy and associated issue of de-replication, an innovation gap has been postulated as a cause for the dramatic reduction in small molecule novelty. Even today, most microbiologists are constrained by the use of traditional cultivation methods, which primarily target previously cultured microbes (“microbial weeds”). As a result, most pharmaceutical companies no longer place an emphasis on natural-product discovery as a source of lead compounds (Walsh, 2003).