Chemoenzymatic\nEpoxidation of Terpenes by Lyophilized\nMycelium of Psychrophilic Cladosporium cladosporioides 01

Terpene epoxides constitute a group of compounds of particular\nimportance due to their biological activity or use in the production\nof polymers. It is important to develop a universal, inexpensive,\nand sustainable method to obtain these compounds from readily available\nterpenes. Chemoenzymatic epoxidation by the freeze-dried mycelium\nof Cladosporium cladosporioides01 is\nan alternative to processes based on the well-known and expensive\nlipase B fromCandida antarctica. In\nthe present work, we studied the kinetics of limonene epoxidation\nby the fungal biocatalyst and found the highest epoxidation activity\nin the “green” solvent ethyl acetate with a 4-fold excess\nof H<sub>2</sub>O<sub>2</sub> relative to the substrate. Epoxidation\nfollowed a two-way sequential mechanism in which the major initial\nproduct limonene 1,2-epoxide and the minor intermediate product limonene\n8,9-epoxide were further converted to limonene diepoxide. Substrate\nspecificity studies revealed that a wide number of linear and cyclic\nmonoterpenes, e.g., linalool, citronellene, citronellal, α-pinene,\nβ-pinene, myrtenol, and perillyl alcohol, were efficiently converted\nto their respective epoxides by this biocatalyst. The biocatalyst\nmay show activity in the direct oxidation of a double bond without\nthe use of a peracid. The freeze-dried mycelium exhibited higher biocatalytic\nactivity after defatting and high stability in ethyl acetate and in\nthe presence of an oxidant. No decrease in its activity was observed\nafter eight biocatalytic cycles. Therefore, the mycelium can be successfully\nused for the sustainable large-scale production of terpene epoxides.