The biology of methyl ketones

Abstract

Examples of the biological occurrence of methyl ketones are reviewed. The lack of significant accumulations of these compounds in the biosphere indicates that a recycling of these organic molecules is occurring. Evidence for biodegradation of acetone by mammals and longer methyl ketones by microorganisms via terminal methyl-group oxidation is discussed. A new mechanism for the subterminal oxidation of methyl ketones by microorganisms is proposed whereby the first intermediate produced is an acetate ester which subsequently is cleaved to acetate and a primary alcohol two carbons shorter than the original ketone substrate.Methyl ketones can be produced by mammals and fungi by decarboxylation of β-keto acids. Some bacteria are able to form methyl ketones via the oxidation of aliphatic hydrocarbons at the methylene carbon α to the methyl group. Speculations on the biosynthesis of methyl ketones by insects and plants and a discussion of the possible biological roles of methyl ketones in diverse biological systems are presented.

Keywords

• ketones
• acetone
• plant oils
• insect secretions
• dairy products
• abortive β-oxidation