Recent Advances in Cofactor Regeneration Systems Applied to Biocatalyzed Oxidative Processes

Nowadays, the design of sustainable processes applicable at industrial scale is highly desirable due to environmental reasons. The use of biocatalytic reactions to carry out oxidative transformations is one of the possible strategies framed in here due to the mildness and usually high selectivities achieved with these methods. Anyway, while implementing this type of system at industrial scale several drawbacks must be overcome in order to obtain efficient setups. Historically, one of the main issues has been the cofactor-dependency of these biocatalysts to be active. Herein, we will show the state-of-the-art concerning the recent efforts developed in the design of (potentially) efficient methods to regenerate the cofactor in oxidative transformations. Thus, the more studied enzymatic methods will be discussed to highlight some recent examples dealing with the co-expression of both oxidative and recycling enzymes in one host or the development of self-sufficient biocatalysts. Furthermore, novel applications of these systems to couple two productive synthetic reactions will also be reviewed. Subsequently, we will focus on some recent examples related with the employment of electrochemical, photochemical, and chemical strategies to carry out the nicotinamide coenzyme or the flavin/heme prosthetic group regeneration. In the case of biocatalysts that use NAD(P) as electron shuttle, these systems have also been employed to replace it, allowing the design of nicotinamide-free recycling setups. In all cases, the (dis) advantages that these methodologies present will be briefly discussed.