Toxicological study of the degradation products of antineoplastic agent etoposide in commercial formulation treated by heterogeneous photocatalysis using SrSnO3.

Etoposide is an antineoplastic agent used for treating lung cancer, testicular cancer, breast cancer, pediatric cancers, and lymphomas. It is a pollutant due to its mutagenic and carcinogenic potential. Disposal of waste from this drug is still insufficiently safe, and there is no appropriate waste treatment. Therefore, it is important to use advanced oxidative processes (AOPs) for the treatment and disposal of medicines like this. The use of strontium stannate (SrSnO3) as a catalyst in heterogeneous photocatalysis reactions has emerged as an alternative for the removal of organic pollutants. In our study, SrSnO3 was synthesized by the combustion method and characterized by X-ray diffraction (XRD), Raman, UV-Vis, and scanning electron microscopy (SEM) techniques, obtaining a surface area of 3.28 m2 g-1 with cubic and well-organized crystallinity and a band gap of 4.06 eV. The experimental conditions optimized for degradation of an etoposide solution (0.4 mg L-1) were pH 5 and catalyst concentration of 1 g L-1. The results showed that the degradation processes using SrSnO3 combined with H2O2 (0.338 mol L-1) obtained total organic carbon removal from the etoposide solution, 97.98% (± 4.03 × 10-3), compared with TiO2, which obtained a mineralization rate of 72.41% (± 6.95 × 10-3). After photodegradation, the degraded solution showed no toxicity to zebrafish embryos through embryotoxicity test (OECD, 236), and no genotoxicity using comet assay and micronucleus test.

Application of Fenton, photo-Fenton, solar photo-Fenton, and UV/H2O2 to degradation of the antineoplastic agent mitoxantrone and toxicological evaluation.

In the present study, selected advanced oxidation processes (AOPs)-namely, photo-Fenton (with Fe(2+), Fe(3+), and potassium ferrioxalate-FeOx-as iron sources), solar photo-Fenton, Fenton, and UV/H2O2-were investigated for degradation of the antineoplastic drug mitoxantrone (MTX), frequently used to treat metastatic breast cancer, skin cancer, and acute leukemia. The results showed that photo-Fenton processes employing Fe(III) and FeOx and the UV/H2O2 process were most efficient for mineralizing MTX, with 77, 82, and 90% of total organic carbon removal, respectively. MTX probably forms a complex with Fe(III), as demonstrated by voltammetric and spectrophotometric measurements. Spectrophotometric titrations suggested that the complex has a 2:1 Fe(3+):MTX stoichiometric ratio and a complexation constant (K) of 1.47 × 10(4) M(-1), indicating high MTX affinity for Fe(3+). Complexation partially inhibits the involvement of iron ions and hence the degradation of MTX during photo-Fenton. The UV/H2O2 process is usually slower than the photo-Fenton process, but, in this study, the UV/H2O2 process proved to be more efficient due to complexing of MTX with Fe(III). The drug exhibited no cytotoxicity against NIH/3T3 mouse embryonic fibroblast cells when oxidized by UV/H2O2 or by UV/H2O2/FeOx at the concentrations tested.