Biocatalytic synthesis of musk macrolides from fatty acids: combining unspecific peroxygenase and lipase

(1) A novel enzymatic synthesis pathway is proposed for the synthesis of musk macrolides from fatty acids. (2) Mro UPO from Marasmius rotula was used as oxyfunctionalisation catalyst to catalyse the selective ω-hydroxylation of fatty acids. (3) This reaction system was successfully applied in the production of ‘natural’ cyclotetradecanolide, cyclopentadecanolide and cyclohexadecanolide. Musk macrolides are a kind of rare flavors structurally featuring 14−16 membered rings in the flavour and fragrance industry. While various chemical synthesis routes for musk macrolides exist, there is a growing interest in biocatalytic approaches. In this study, a new biocatalytic approach is proposed for the synthesis of musk macrolides from fatty acids using unspecific peroxygenases (UPOs) in combination with lipase. Specifically, the UPO from Marasmius rotula ( Mro UPO) was utilized as an oxidation catalyst together with the choline oxidase from Arthrobacter nicotinate ( An ChOx) for the in situ generation of H 2 O 2 . The enzymatic cascade process involved the hydroxylation of fatty acids using Mro UPO as a catalyst to prepare terminal hydroxylated fatty acids. Under the optimized conditions, 14-hydroxy tetradecanoic acid, 15-hydroxy pentadecanoic acid and 16-hydroxy hexadecanoic acid were obtained at concentrations of 11.1, 18.2 and 17.1 mg/L in a 50-mL reaction system, respectively. These hydroxylated fatty acids were then separated and esterified by lipase Novozymes 435 to produce the desired macrolides. Various ω -hydroxy fatty acids were successfully converted into macrolides, with the concentrations of cyclotetradecanolide, cyclopentadecanolide and cyclohexadecanolide reaching 11, 29 and 23 mg/L, respectively, in a 10-mL reaction system. This new biocatalytic approach represents a promising method for synthesizing valuable natural flavour compounds.