Compounds for flavours, new research

Researchers in the UK claim to have devised a new method of selectively oxidising terpenes to produce compounds of particular interest to the perfumery, flavour and pharmaceutical industries.

Terpenes and their derivatives are commonly used in industry to modify flavours and fragrances, and new compounds for trial are continuously needed. Terpenes themselves are not of commercial interest but rather the derivatives that commonly require stereoselective functionalisation at allylic as well as non-activated C-H bonds of the parent terpene.

According to a statement from scientists at Oxford University, this is one of the most difficult reactions to carry out by conventional reactions since the highly reactive chemical oxidising agents are typically non-selective.

Researchers in the Oxford laboratory have developed a method of oxidising terpenes, or other hydrocarbons of interest, by enzymatic techniques. Indeed, they report, non-activated C-H groups can be targeted. Typically, the oxidation produces high yields of relatively pure compounds.

The enzymes of particular interest are specific mutants of haem-containing enzymes, especially mutants of P450. Currently the mutant enzymes are expressed in E. coli as a host to produce an in vivo oxidation system which can be scaled up to large volumes. Initial work has demonstrated the oxidation of R-limonene to (+)-isopiperitenol or (+)-carveol depending on the enzyme and mutant, camphor to 5-exo-hydroxycamphor, (+)-alpha-pinene to (+)-verbenol and valencene to nootkatone.

Isis Innovation​, Oxford University's wholly-owned technology transfer company, is seeking partners for the licensing and commercial development of this technology. According to Oxford University, Isis currently files a patent a week and spins-out a company every two months based on academic research generated within and owned by the University. The combined value of Oxford's companies has reached £2 billion (€3.18bn).