polyketide

In organic chemistry, polyketides are a class of natural products derived from a precursor molecule consisting of a chain of alternating ketone (, or its reduced forms) and methylene () groups: {{chem2|[\sC(\dO)\sCH2\s]_{n}|}}. First studied in the early 20th century, discovery, biosynthesis, and application of polyketides has evolved. It is a large and diverse group of secondary metabolites caused by its complex biosynthesis which resembles that of fatty acid synthesis. Because of this diversity, polyketides can have various medicinal, agricultural, and industrial applications. Many polyketides are medicinal or exhibit acute toxicity. Biotechnology has enabled discovery of more naturally occurring polyketides and evolution of new polyketides with novel or improved bioactivity.

== History == Naturally produced polyketides by various plants and organisms have been used by humans since before studies on them began in the 19th and 20th century. In 1893, J. Norman Collie synthesized detectable amounts of orcinol by heating dehydracetic acid with barium hydroxide causing the pyrone ring to open into a triketide. Further studies in 1903 by Collie on the triketone polyketide intermediate noted the condensation occurring amongst compounds with multiple keten groups coining the term polyketides. thumb|400px|Biosynthesis of orsellinic acid from polyketide intermediate. It wasn't until 1955 that the biosynthesis of polyketides were understood. Arthur Birch used radioisotope labeling of carbon in acetate to trace the biosynthesis of 2-hydroxy-6-methylbenzoic acid in Penicillium patulum and demonstrate the head-to-tail linkage of acetic acids to form the polyketide. In the 1980s and 1990s, advancements in genetics allowed for isolation of the genes associated to polyketides to understand the biosynthesis.