Sustainable Setups for the Biocatalytic Production and Scale-Up of Panthenyl Monoacyl Esters under Solvent-Free Conditions

A sustainable scaling-up process for the biocatalytic production of new bioactive provitamin-B5 monoacyl esters has been demonstrated. A solvent-free reaction protocol, based on the formation of eutectic mixtures between neat substrates, renders highly efficient direct esterification of free fatty acids (i.e., from C6 to C18 alkyl-chain length) with panthenol catalyzed by lipase. The scale-up from 0.5 to 500 g was evaluated by means of using several reaction systems (i.e., ultrasound assistance, orbital shaking, rotary evaporator, and mechanical stirring coupled to vacuum). For all reactor systems, the yield in panthenyl monoacyl esters was improved by increasing the length of the alkyl chain of the fatty acid (i.e., from 63% yield for panthenyl butyrate to 83% yield for panthenyl myristate). The best results (87-95% product yield, for all cases) were obtained upon a scale-up (50-500 g size) and when a vacuum system was coupled to the biocatalytic reaction unit. Under the optimized conditions, a 5-fold reduction of the amount of biocatalysts with respect to reactors without vacuum was achieved. The recovery and reuse of the immobilized enzyme for five operation cycles were also demonstrated. Finally, different metrics have been applied to assess the greenness of the solvent-free biocatalytic synthesis of panthenyl monoesters here reported.

Automated summary

A sustainable and efficient process for the biocatalytic production of new bioactive provitamin-B5 monoacyl esters has been demonstrated. A solvent-free reaction protocol using lipase as the catalyst allows for direct esterification of fatty acids with panthenol, with improved yields achieved by increasing the alkyl chain length. Scale-up from 0.5 to 500g was successfully achieved using a variety of reaction systems, with the best results obtained when a vacuum system was coupled to the biocatalytic reaction unit. The recovery and reuse of the immobilized enzyme were also shown, and the greenness of the solvent-free biocatalytic synthesis was assessed using different metrics.