Natural products

A natural product is a chemical compound or substance produced by a living organism, that is, found in nature2,3. In the broadest sense, a natural product is any substance produced by life4,5. Natural products can also be prepared by chemical synthesis (semi-synthesis and total synthesis) and have played a central role in the development of the field of organic chemistry by providing difficult synthetic targets. The term “natural product” has also been extended for commercial purposes to refer to cosmetics, dietary supplements and foods produced from natural sources with no added artificial ingredients6[insufficient source].

Thanks to technical improvements (high-throughput screening programs, separation and isolation techniques), the number of natural products discovered at the beginning of the 21st century exceeded one million (an overestimated number compared to what is accessible)7. 50 to 60% of these compounds are produced by plants and approximately 5% have a microbial origin8. 20 to 25% of these products are natural bioactive compounds and nearly 10% are isolated from microorganisms (22,500 of which 9,000 are from fungi)8,9.

In the field of organic chemistry, the definition of natural products is usually limited to purified organic compounds isolated from natural sources that are produced by primary or secondary metabolic pathways10. In the field of medicinal chemistry, the definition is often limited to secondary metabolites11,12. Secondary metabolites are not essential for survival, but nevertheless provide the organisms that produce them with an evolutionary advantage13. Many secondary metabolites are cytotoxic and have been evolutionarily selected and optimized for use as “chemical warfare” agents against prey, predators and competing organisms14.