Coupling occurs before breakdown during biotransformation of Acid Blue 62 by white rot fungi

On the Mechanism of Biotransformation of the Anthraquinonic Dye Acid Blue 62 by Laccases

“…In a previous study on the biodegradation process of AB62 by crude fungal enzyme preparations, compound 4 is described to be an intermediate product transiently formed before its degradation. [14] In this work we have unambiguously identified the two main final reaction products {1-[4-amino-9,10-dioxo-3-sulfo-9,10-dihydroanthracen-1-yl)diazenyl]-4-cyclohexylamino-9,10-dioxo-9,10-dihydroanthracene-2-sulfonic acid (4) and cyclohexanone (3)} and a major intermediate [1,4-diamino-9,10-dioxo-3-sulfo-9,10-dihydroanthracene-2-sulfonic acid (2)]. The mechanistic scheme that can be drawn corresponds to a two-step sequence of oxidation reactions dominated by the loss of the cyclohexyl substituent of the amino group on AB62 and the further coupling of AB62 and DAAS radicals.…”

“…[15] From these results, we concluded that the compound is 1-[(4-amino-9,10-dioxo-3-sulfo-9,10-dihydroanthracen-1-yl)diazenyl]-4-cyclohexylamino-9,10-dioxo-9,10-dihydroanthracene-2-sulfonic acid) (4) previously identified by Vanhulle et al [14] LC-MS analysis of the total reaction mixtures after 2 h revealed the presence of 9 compounds: DAAS (2), compound 4 and compounds with m/z of 248, 576, 604, 622, 633, 715, 734 and 797 (Table 1) + . Incubation of 4 (M = 714), the main product of the reaction with CotA-laccase in different assay conditions did not result in any transformation of the compound in contrast to that observed in the study of Vanhulle et al [14] We simultaneously analysed the products of the biotransformation of AB62 by using LAC3 laccase from the fungus Trametes sp. C30.…”

“…In this study, we report on the enzymatic biotransformation of the anthraquinonic dye Acid Blue 62 (AB62, compound 1) into 1-[(4-amino-9,10-dioxo-3-sulfo-9,10-dihydroanthracen-1-yl)diazenyl]-4-cyclohexylamino-9,10-dioxo-9,10-dihydroanthracene-2-sulfonic acid) (compound 4 [14] ). The enzymatic reactions were followed by UV-vis and HPLC.…”

“…[9] However, limited information exists on their physicochemical or biological degradation [10][11][12] and even less is known on the molecular mechanisms of transformation. [13,14] Nevertheless, this knowledge is important, not only for the development of efficient bioremediation processes, but also in the search for harmless dyeing compounds to be synthesised by green chemistry processes.…”

Electrochemical degradation of the Acid Blue 62 dye on a β-PbO2 anode assessed by the response surface methodology

“…The degradation or removal of the Acid Blue 62 (AB 62) anthraquinonic dye from solution has almost not been investigated, and the existing few papers concern either adsorption, biological, or advanced oxidation processes [21][22][23]. Therefore, the purpose of this work is to find the best experimental conditions, using RSM, for the electrochemical degradation of the AB 62 dye on a Ti-Pt/b-PbO 2 anode.…”