Leishmaniasis is a neglected tropical disease caused by Ͼ20 species of the protozoan parasite Leishmania. Meglumine antimoniate (Glucantime) is the firstchoice drug recommended by the World Health Organization for the treatment of all types of leishmaniasis. However, the mechanisms of action and toxicity of pentavalent antimonials, including genotoxic effects, remain unclear. Therefore, the mechanism by which meglumine antimoniate causes DNA damage was investigated for BALB/c mice infected by Leishmania (Leishmania) infantum and treated with meglumine antimoniate (20 mg/kg for 20 days). DNA damage was analyzed by a comet assay using mouse leukocytes. Furthermore, comet assays were followed by treatment with formamidopyrimidine-DNA glycosylase and endonuclease III, which remove oxidized DNA bases. In addition, the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in the animals' sera were assessed. To investigate mutagenicity, we carried out a micronucleus test. Our data demonstrate that meglumine antimoniate, as well as L. infantum infection, induces DNA damage in mammalian cells by the oxidation of nitrogenous bases. Additionally, the antileishmanial increased the frequency of micronucleated cells, confirming its mutagenic potential. According to our data, both meglumine antimoniate treatment and L. infantum infection promote oxidative stress-derived DNA damage, which promotes overactivation of the SOD-CAT axis, whereas the SOD-GPx axis is inhibited as a probable consequence of glutathione (GSH) depletion. Finally, our data enable us to suggest that a meglumine antimoniate regimen, as recommended by the World Health Organization, would compromise GPx activity, leading to the saturation of antioxidant defense systems that use thiol groups, and might be harmful to patients under treatment.

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Isoflavones are phytoestrogens reported to be potent antioxidant agents. In contrast, the antileishmanial meglumine antimoniate has mutagenic activities. This study evaluated the ability of soy isoflavones to reduce DNA damage induced by meglumine antimoniate. Antimutagenic effects (by micronucleus test) were tested using Swiss mice divided into seven groups treated with meglumine antimoniate (425 mg/kg bw pentavalent antimony); cyclophosphamide (50 mg/kg bw); water (negative control); single isoflavones dose (1.6 mg/kg bw), and three groups received one dose of isoflavones via gavage (0.4 mg/kg bw, 0.8 mg/kg bw or 1.6 mg/kg bw) plus meglumine antimoniate via intraperitoneal, simultaneously. To evaluate antigenotoxicity (by Comet assay), each group with 10 animals received the above-mentioned control doses; single dose of isoflavones 0.8 mg/kg bw, and three groups received isoflavones (0.8 mg/kg bw) by gavage along with intraperitoneal meglumine antimoniate, which were treated with isoflavones 24 h before or after receiving meglumine antimoniate (pre-treatment and post-treatment, respectively) or simultaneously. Cells were harvested 24 h after the treatment, and the data were evaluated by ANOVA followed by Tukey's test (p < 0.05). The data from the simultaneous treatment by micronucleus test revealed that isoflavones (0.4 and 0.8 mg/kg) were able to reverse the mutagenic effect of Glucantime. Moreover, all regimes of the treatment with 0.8 mg/kg bw dose were able to reduce the genotoxicity caused by meglumine antimoniate. It is suggested that the protective effect of isoflavones against DNA damage is related to their ability to reduce oxidative stress caused by the trivalent Sb(III) metabolite of meglumine antimoniate.

Meglumine antimoniate (Glucantime) is a pentavalent antimonial used to treat leishmaniasis, despite its acknowledged toxic effects, such as its ability to cause oxidative damage to lipids and proteins. Recently, our group demonstrated that meglumine antimoniate causes oxidative stress-derived DNA damage. Knowing that antioxidants modulate reactive oxygen species, we evaluated the capacity of genistein and ascorbic acid for preventing genotoxicity caused by meglumine antimoniate. For that, mice (n= 5/group) received genistein (via gavage) in doses of 5, 10, and 20 mg/kg for three consecutive days. After this period, they were treated with 810 mg/kg meglumine antimoniate via intraperitoneal (i.p.) route. Furthermore, mice (n= 5/group) simultaneously received ascorbic acid (i.p.) in doses of 30, 60, and 120 mg/kg and 810 mg/kg meglumine antimoniate. We also conducted post- and pretreatment assays, in which animals received ascorbic acid (60 mg/kg) 24 h prior to or after receiving meglumine antimoniate. Genomic instability and mutagenicity were analyzed through conventional comet assay and enzymatic assay using formamide pyrimidine DNA glycosylase (Fpg) enzyme, as well as the micronucleus test, respectively. Meglumine antimoniate induced an increase in the DNA damage after digestion with Fpg, reinforcing its mutagenic potential by oxidizing DNA bases, which was prevented by genistein. Similarly, ascorbic acid was capable of reducing mutagenic effects in simultaneous treatment as well as in posttreatment. Therefore, our results demonstrate that both compounds are efficient in preventing mutations in mammalian cells treated with meglumine antimoniate.

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