Iron-binding catechols oxidating lignin and chlorolignin.
Iron-chelating low-molecular-weight compounds or catecholate siderophores have been suggested to be involved in wood biodegradation. To help in understanding the mechanism involved in the enzyme-like activity of catecholate siderophores, the oxidative properties of 2,3-dihydroxybenzoic acid (DHBA) and 3, 4-dihydroxyphenylacetic acid (DHPAA) chelated with iron were studied. The pH and catechol/Fe(III) ratios were optimized for o-dianisidine oxidation, obtaining a maximum at pH 7.0, in the absence of buffer, and a catechol/Fe(III) ratio of 1:2 to DHBA and 1:1 to DHPAA was found. Under these conditions, the catechols were able to reduce Fe(III) to Fe(II) acting like siderophore models. The Fe(III) complex of DHBA and of DHPAA degraded dioxane-lignin in 60% after 2 h and 85% after 24 h, respectively. DHBA/Fe(III) oxidized the bleaching effluent (E1) in 80% in 5 min under the studied conditions.
Parra
C
C
Renewable Resources Laboratory, Universidad de Concepción, Chile.
Rodriguez
J
J
Baeza
J
J
Freer
J
J
Durán
N
N
D015102:3,4-Dihydroxyphenylacetic Acid / Q000737:chemistry*; D004146:Dioxanes; D062385:Hydroxybenzoates / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D007502:Iron Chelating Agents / Q000737:chemistry*; D007700:Kinetics; D008031:Lignin / Q000031:analogs & derivatives* / Q000737:chemistry*; D010084:Oxidation-Reduction; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry
D004146:Dioxanes; D062385:Hydroxybenzoates; D007502:Iron Chelating Agents; D015102:3,4-Dihydroxyphenylacetic Acid; C009135:2,3-dihydroxybenzoic acid; C076152:chlorolignin; D008031:Lignin; D007501:Iron; C025223:1,4-dioxane