The headspace-GC/MS: Alternative methodology employed in the bioreduction of (4S)-(+)-carvone mediated by human skin fungus

The development of more efficient and environmentally friendly analytical methods represents a current focus for the fine chemical industry. In particular, microscale methodologies that are free of solvents/reagents. The headspace-GC/MS (HS-GC) methodology was employed in this study as a tool for monitoring a biocatalysed reaction of (4S)-(+)-carvone using Phoma sp., a filamentous fungus from human skin. Biocatalysis provides some advantages, such as high efficiency, high degrees of regioselectivity, chemoselectivity, and enantioselectivity. In order to optimize the small scale biocatalytic reaction of the (4S)-(+)-carvone by the filamentous fungus Phoma sp. was used headspace GC/MS methodology, factorial design of experiments and the response surface methodology (RSM) was performed using the biomass of the fungus, substrate mass and pH as parameters. It was observed that for all reactions conditions tested, forming the products (1 R,4S)-dihydrocarvone and (1S,4S)-dihydrocarvone. The most influential factor was pH, with the highest conversion rate (>95%) and diastereomeric excess (d.e.) (>80%) obtained at pH 5.0. Thus, it was demonstrated that human skin Phoma sp. fungus showed significant bioreduction activity and that headspace GC/MS is an efficient approach for real-time monitoring the biocatalysed reactions.