Enzymatic oxidative transformation of phenols byTrametes trogiilaccases

Abstract

The removal of toxic phenolic compounds from industrial wastewater is an important issue to be addressed. Their presence in water and soil has become a great environmental concern, and effective methods for their removal need to be addressed. The feasibility of applying laccases for the degradation of phenolic compounds has received increasing attention. In the present work, the transformation of five phenolic compounds (catechol, hydroxytyrosol, tyrosol, guaiacol and p-coumaric acid), the main constituents of a typical wastewater derived from an olive oil factory, by Trametes trogii laccases was studied at concentrations ranging between 0.2 and 1.6 mM. High-performance liquid chromatography analysis showed high degradation rates of phenolic compounds by T trogii laccases. Independently of the used concentration, a complete transformation of guaiacol, p-coumaric acid, hydroxytyrosol and tyrosol occurred after 1 h of incubation. The transformation of catechol depends on its initial concentration. The liquid chromatography-mass spectrometry analysis showed that laccases catalysed transformation of p-coumaric acid and tyrosol, resulting in the formation of phenolic dimers. No reduction of enzyme activity has been observed during the oxidation of all phenolic compounds. These results suggest that the studied laccases were capable of efficiently removing phenolic compounds, as well as catalysing the production of novel phenolic dimers.

Enzymatic transformation of tyrosol by Trametes trogii laccases: Identification of the product and study of its biological activities

“…The MS 2 spectrum of the synthesised product (shown in Chakroun et al [25]) supported the structure 1 obtained by NMR experiment. In fact, the MS 2 spectrum was characterised by the loss of H 2 O and CH 2 OH, to give m/z 255 and m/z 243, respectively.…”

“…As demonstrated in our previous work, phytotoxicity of tyrosol was shown to be concentration dependant with a limited phytotoxicity effect since the GI was more than 50% with a concentration of 1.6 mM [25]. In the present study, at a concentration of 10 mM, tyrosol exerted a significant phytotoxic effect on L. esculentum seeds with a complete inhibition of the seed germination (Fig.…”

“…In our previous study on the transformation of phenolic compounds by T. trogii laccases, we have reported the laccase-mediated oxidation of a tyrosol to give a dimeric structure as the only isolated product [25]. This result prompted us to confirm the dimeric structure by NMR analysis and to investigate the potential of T. trogii laccases for the production of new biologically active compounds.…”

“…In our previous study about the oxidation of phenolic compounds by the laccases from T. trogii, it has been shown by LC/MS analysis that tyrosol was transformed into its dimer with a molecular formula C 16 H 18 O 4 (as shown in Chakroun et al [25]). In order to confirm the dimeric structure proposed, the synthesized compound was isolated by HPLC and analysed by NMR.…”

“…The phytotoxicity of the untreated and laccase-treated tyrosol solution monitored at a concentration of 10 mM was evaluated by static-type germination assays using Lycopersicon esculentum seeds as described by Chakroun et al [25].…”