Laccase–TEMPO as an Efficient System for Doxorubicin Removal from Wastewaters

Abstract

A large number of drugs are used to treat different diseases, and thus to improve the quality of life for humans. These represent a real ecological threat, as they end up in soil or ground waters in amounts that can affect the environment. Among these drugs, doxorubicin is a highly cytotoxic compound used as anticancer medicine. Doxorubicin can be efficiently removed from wastewater or polluted water using a simple enzymatic (biocatalytic) system, employing the oxidoreductase enzyme laccase and a stable organic nitroxide-free radical, TEMPO. Results presented in this work (as percentage of removal) were obtained at pH 5 and 7, after 2, 4, 6, and 24 h, using different ratios between doxorubicin, laccase, and TEMPO. It was shown that longer time, as well as an increased amount of catalyst, led to a higher percentage of removal, up to 100%. The influence of all these parameters is also discussed. In this way it was shown that the laccase–TEMPO biocatalytic system is highly efficient in the removal of the anticancer drug doxorubicin from wastewaters.

Laccases as Effective Tools in the Removal of Pharmaceutical Products from Aquatic Systems

“…They have been identified in wastewater near hospitals at concentrations ranging from 0.02 to 0.025 µg/L [7], and their removal in WWTP is not consistently effective [8,[88][89][90]. The effectiveness of laccase was evaluated using doxorubicin and etoposide as model anticancer drugs [83][84][85].…”

“…Doxorubicin is a widely used anticancer drug for the treatment of various types of cancer. In both studies that dealt with the elimination of this drug from a solution, laccase from T. versicolor (Sigma-Aldrich) was used [83,84]. In both cases, either fluorescence spectrophotometry (λ ex = 480 nm, λ em = 598 nm) [83] or VIS spectrophotometry (λ = 480 nm) [84] was used to determine the residual drug concentration.…”

“…In both studies that dealt with the elimination of this drug from a solution, laccase from T. versicolor (Sigma-Aldrich) was used [83,84]. In both cases, either fluorescence spectrophotometry (λ ex = 480 nm, λ em = 598 nm) [83] or VIS spectrophotometry (λ = 480 nm) [84] was used to determine the residual drug concentration. Kelbert et al [83] found that the highest percentage of removal was observed at pH 7.0 and a temperature of 30 • C, with a Vmax of 702.8 µg/h/L and Km of 4.05 µM, indicating a strong affinity of the enzyme for the substrate.…”

“…Kelbert et al [83] found that the highest percentage of removal was observed at pH 7.0 and a temperature of 30 • C, with a Vmax of 702.8 µg/h/L and Km of 4.05 µM, indicating a strong affinity of the enzyme for the substrate. In a study conducted by Jinga et al [84], the efficiency of doxorubicin elimination from a solution using the LMS with TEMPO (2,2,6,6-tetramethylpiperidin-1-yl)oxyl) as a mediator was evaluated. The complete elimination of doxorubicin was observed at a concentration of 50 mg/L at pH 7.0 for 24 h. Kelbert et al [83] tested the cytotoxic effect by altering the murine fibroblast cell line (L-929).…”

Bioremediation of Hazardous Pollutants Using Enzyme-Immobilized Reactors

“…Redox mediators are low-molecular-weight compounds that are easily oxidized by laccases and produce reactive radicals that can further oxidize complex organic compounds such as pollutants. In the laccase-mediator system (LMS) for degradation of pollutants, it was reported that 2,2 ′ -azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 1-hydrobenzotriazole (HBT), or (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) could enhance the oxidation rate of the laccase substrates [62,63]. Although these synthetic mediators are useful for the reactions of organic compounds, there are still challenges in their utilization in industrial processes owing to their high cost, toxicity, and reuse-associated problems.…”