Plant tissue cultures as sources of new ene- and ketoreductase activities

While many redox enzymes are nowadays available for synthetic applications, the toolbox of ene-reductases is still limited. Consequently, the screening for these enzymes from diverse sources in the search of new biocatalyst suitable for green chemistry approaches is needed. Among 13 plant tissue cultures, Medicago sativa and Tessaria absinthioides calli, as well as Capsicum annuum hairy roots, were selected due to their ability to hydrogenate the C=C double bond of the model substrate 2-cyclohexene-1-one. The three axenic plant cultures showed more preference toward highly activated molecules such as nitrostyrene and maleimide rather than the classical substrates of the well-known Old Yellow Enzymes, resembling the skills of the NAD(P)H-dependent flavinin-dependent enzymes. When the three biocatalytic systems were applied in the reduction of chalcones, T. absinthioides showed high chemoselectivity toward the C=C double bond whereas the other two demonstrated abilities to biohydrogenate the C=C double bounds and the carbonyl groups in a sequential fashion.