2-chloro-1-4-dimethoxybenzene and veratryl-alcohol

Veratrylchitosan, a polysaccharide-supported lignin model compound, has been synthesised by covalently attaching 3-(3,4-dimethoxybenzyloxy)propionic acid to the polysaccharide chitosan through an amide linkage. When this polymer was used as a substrate in the oxidation promoted by lignin peroxidase (LiP), significant decomposition of the lignin model resulted in the formation of veratraldehyde. The oxidation mechanism involves an initial transfer of one electron from chitosan to the active species of LiP (LiP I) followed by C(alpha)-H deprotonation of an aromatic cation radical. A benzylic radical is then formed which is further oxidised to a benzyl cation. Reaction with water and hydrolysis of the hemiacetal then lead to veratraldehyde formation. An increase in the yields of the oxidation product is observed in the presence of the mediator 2-chloro-1,4-dimethoxybenzene, thus indicating that a more efficient degradation results from the transfer of an electron from the polymer to the radical cation of the mediator.

Topics: Anisoles; Benzaldehydes; Benzyl Alcohols; Chitin; Chitosan; Chlorobenzenes; Free Radicals; Magnetic Resonance Spectroscopy; Oxidation-Reduction; Peroxidases

Poly R478, 4-methoxymandelic acid and oxalic acid were oxidized by lignin peroxidase (LiP) in the presence of the fungal metabolite 2-chloro-1,4-dimethoxybenzene (2Cl-14DMB), whereas no oxidation occurred in the absence of 2Cl-14DMB. These substrates clearly inhibited the consumption of 2Cl-14DMB and the formation of 2-chloro-1,4-benzoquinone from 2Cl-14DMB by LiP. The results suggest that 2Cl-14DMB can replace the function of veratryl alcohol as a redox mediator in lignin peroxidase catalyzed oxidations.

Topics: Anisoles; Anthraquinones; Benzyl Alcohols; Chlorobenzenes; Mandelic Acids; Oxalates; Oxidation-Reduction; Peroxidases; Polymers; Polyporales