Paper Authors and Title
Hazel Browne (Technological University of the Shannon), Noreen Morris, “Use of the biocatalyst Laccase in the oxidation of secondary alcohols”
Abstract
Green Chemistry approaches, particularly biocatalysts, are quickly becoming the new way of conducting reactions in the pharmaceutical industry. In this project, Laccase was being used to conduct the oxidation of cinnamyl alcohol and of geraniol to cinnamaldehyde and citral respectively. Laccase has a low redox potential which means that a mediator was needed to complete the oxidation reaction. (Bassanini et al. 2021) Mediators act as electron shuttle transfers that are oxidised by Laccase and then reduced by the substrate which causes the substrate to become oxidised.
Artificial mediators such as TEMPO and ABTS are more popular in use but damage the enzyme over time (Mani et al. 2018) therefore there is an increase in research for the use of natural mediators such as Syringaldehyde, instead. This project used HPLC to follow the progression of the laccase mediated oxidation reactions, determining the rate of conversion of the substrates into their products.
From the analysis of the oxidation reactions, TEMPO was the most effective mediator for cinnamyl alcohol as there was a complete depletion of cinnamyl alcohol after 5 hours. ABTS was the second most effective mediator as it formed more of the cinnamaldehyde than syringaldehyde.
TEMPO was the most effective mediator for the oxidation of geraniol into citral as there was a complete depletion of geraniol after hour 5 and also formed the most citral compared to the other mediators. Syringaldehyde was the second most effective mediator for the oxidation of geraniol as no product was formed from the ABTS mediated reaction.
References
Bassanini, I., Ferrandi, E.E., Riva, S. and Monti, D. (2021). Biocatalysis with laccases: An updated overview. Catalysts, 11(1).
Mani, P., Kumar, V.T.F., Keshavarz, T., Sainathan Chandra, T. and Kyazze, G. (2018). The role of natural laccase redox mediators in simultaneous dye decolorization and power production in microbial fuel cells. Energies, 11(12).