Natural products in drug discovery: present status and perspectives.

Natural products and their derivatives have been and continue to be rich sources for drug discovery. However, natural products are not drugs. They are produce in nature and through biological assays they are identified as leads, which become candidates for drug development. More than 60% of the drugs that are in the market derive from natural sources. During the last two decades, research aimed at exploiting natural products as a resource has seriously declined. This is in part due to the development of new technologies such as combinatorial chemistry, metagenomics and high-throughput screening. However, the new drug discovery approaches did not fulfilled the initial expectations. This has lead to a renewed interest in natural products, determined by the urgent need for new drugs, in particular to fight against infections caused by multi-resistant pathogens.