Diphenyl diselenide and sodium selenite associated with chemotherapy in experimental toxoplasmosis: influence on oxidant/antioxidant biomarkers and cytokine modulation

Biogenic selenium nanoparticles: trace element with promising anti-toxoplasma effect

Toxoplasmosis is an opportunistic infection caused by the coccidian Toxoplasma gondii which represents a food and water contaminant. The available chemotherapeutic agents for toxoplasmosis are limited and the choice is difficult when considering the side effects. Selenium is an essential trace element. It is naturally found in dietary sources, especially seafood, and cereals. Selenium and selenocompounds showed anti-parasitic effects through antioxidant, immunomodulatory, and anti-inflammatory mechanisms. The present study evaluated the potential efficacy of environmentally benign selenium nanoparticles (SeNPs) against acute toxoplasmosis in a mouse model. SeNPs were fabricated by nanobiofactory Streptomyces fulvissimus and characterized by different analytical techniques including, UV-spectrophotometry, transmission electron microscopy, EDX, and XRD. Swiss albino mice were infected with Toxoplasma RH strain in a dose of 3500 tachyzoites in 100 μl saline to induce acute toxoplasmosis. Mice were divided into five groups. Group I: non-infected, non-treated, group II: infected, non-treated, group III: non-infected, treated with SeNPs, group IV: infected, treated with co-trimoxazole (sulfamethoxazole/trimethoprim) and group V: infected, treated with SeNPs. There was a significant increase in survival time in the SeNPs-treated group and minimum parasite count was observed compared to untreated mice in hepatic and splenic impression smears. Scanning electron microscopy showed tachyzoites deformity with multiple depressions and protrusions, while transmission electron microscopy showed excessive vacuolization and lysis of the cytoplasm, especially in the area around the nucleus and the apical complex, together with irregular cell boundary and poorly demarcated cell organelles. The present study demonstrated that the biologically synthesized SeNPs can be a potential natural anti-Toxoplasma agent in vivo.

Selenium and protozoan parasitic infections: selenocompounds and selenoproteins potential

The current drug treatments against protozoan parasitic diseases including Chagas, malaria, leishmaniasis, and toxoplasmosis represent good examples of drug resistance mechanisms and have shown diverse side effects. Therefore, the identification of novel therapeutic strategies and drug compounds against such life-threatening diseases is urgent. According to the successful usage of selenium (Se) compounds-based therapy against some diseases, this therapeutic strategy has been recently further underlined against these parasitic diseases by targeting different parasite´s essential pathways. On the other hand, due to the important functions played by parasite selenoproteins in their biology (such as modulating the host immune response), they can be also considered as a novel therapeutic strategy by designing specific inhibitors against these important proteins. In addition, the immunomodulatory potentiality of these compounds to trigger T helper type 1 (Th1) cells and cytokine-mediated immune response for the substantial induction of proinflammatory cytokines, thus, Se, selenoproteins, and parasite selenoproteins could be further investigated to find possible vaccine antigens. Herein, we collect and present the results of some studies regarding Se-based therapy against protozoan parasitic diseases and highlight relevant information and some viewpoints that might be insightful to advance toward more effective studies in the future.

Oxidative Stress as a Possible Target in the Treatment of Toxoplasmosis: Perspectives and Ambiguities

Toxoplasma gondii is an apicomplexan parasite causing toxoplasmosis, a common disease, which is most typically asymptomatic. However, toxoplasmosis can be severe and even fatal in immunocompromised patients and fetuses. Available treatment options are limited, so there is a strong impetus to develop novel therapeutics. This review focuses on the role of oxidative stress in the pathophysiology and treatment of T. gondii infection. Chemical compounds that modify redox status can reduce the parasite viability and thus be potential anti-Toxoplasma drugs. On the other hand, oxidative stress caused by the activation of the inflammatory response may have some deleterious consequences in host cells. In this respect, the potential use of natural antioxidants is worth considering, including melatonin and some vitamins, as possible novel anti-Toxoplasma therapeutics. Results of in vitro and animal studies are promising. However, supplementation with some antioxidants was found to promote the increase in parasitemia, and the disease was then characterized by a milder course. Undoubtedly, research in this area may have a significant impact on the future prospects of toxoplasmosis therapy.

Toxicology and pharmacology of synthetic organoselenium compounds: an update

Here, we addressed the pharmacology and toxicology of synthetic organoselenium compounds and some naturally occurring organoselenium amino acids. The use of selenium as a tool in organic synthesis and as a pharmacological agent goes back to the middle of the nineteenth and the beginning of the twentieth centuries. The rediscovery of ebselen and its investigation in clinical trials have motivated the search for new organoselenium molecules with pharmacological properties. Although ebselen and diselenides have some overlapping pharmacological properties, their molecular targets are not identical. However, they have similar anti-inflammatory and antioxidant activities, possibly, via activation of transcription factors, regulating the expression of antioxidant genes. In short, our knowledge about the pharmacological properties of simple organoselenium compounds is still elusive. However, contrary to our early expectations that they could imitate selenoproteins, organoselenium compounds seem to have non-specific modulatory activation of antioxidant pathways and specific inhibitory effects in some thiol-containing proteins. The thiol-oxidizing properties of organoselenium compounds are considered the molecular basis of their chronic toxicity; however, the acute use of organoselenium compounds as inhibitors of specific thiol-containing enzymes can be of therapeutic significance. In summary, the outcomes of the clinical trials of ebselen as a mimetic of lithium or as an inhibitor of SARS-CoV-2 proteases will be important to the field of organoselenium synthesis. The development of computational techniques that could predict rational modifications in the structure of organoselenium compounds to increase their specificity is required to construct a library of thiol-modifying agents with selectivity toward specific target proteins.

Diphenyl diselenide subcutaneous supplementation of dairy sheep: effects on oxidant and antioxidant status, inflammatory response and milk composition

Diphenyl diselenide ((PhSe)2) is a organoselenium compound with potent antioxidant properties. Therefore, the aim of the present study was to evaluate whether subcutaneous supplementation of (PhSe)2 in dairy sheep has positive effects on milk composition, as well as on the prevention of oxidative stress and exacerbated inflammatory response. For this, 16 primiparous recently calved sheep were divided into the following two groups, with eight animals in each: Group A, the control group; and Group B, the group subcutaneously supplemented with five doses of (PhSe)2 of 3.0µmol/kg each every 7 days. Blood samples from supplemented animals showed increased concentration of antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase and glutathione-S-transferase), and reduced reactive oxygen species and lipid peroxidation, which prevented oxidative damage in the lactation period, as well as increased seric interleukin-10, an anti-inflammatory cytokine. In the sera, supplemented animals showed increased total antioxidant capacity and ferric-reducing ability of plasma compared with the control group. As a consequence, supplemented animals showed increased antioxidant variables, as well as reduced protein oxidation in milk samples. Moreover, milk from supplemented sheep showed a higher fat content, and lower total protein and lactose contents in some periods in the study, than did not-supplemented ewes. Seric concentrations of interleukin-1 were lower on Days 30 and 45 in supplemented animals, as well as the concentrations of tumour necrosis factor α in all periods, than were those in the control group, whereas the interleukin-10 concentrations were higher. Thus, dairy sheep supplementation of (PhSe)2 activated antioxidant and anti-inflammatory responses, and increased milk fat content. Moreover, this protocol increased the antioxidant and, consequently, reduced the oxidant concentration in milk, which is desirable for product quality.

Diphenyl diselenide modulates nucleotidases, reducing inflammatory responses in the liver of Toxoplasma gondii-infected mice

The aim of this study was to verify the effect of diphenyl diselenide (PhSe)2 on hepatic nucleotidases and on the concentration of purines in mice infected by Toxoplasma gondii. The animals were divided into four groups: Group A (uninfected), Group B (uninfected and treated with (PhSe)2), Group C (infected), and Group D (infected and treated with (PhSe)2). The inoculation (groups C and D) was performed with 50 cysts of T. gondii (ME-49 strain). Mice from groups B and D were treated with 5 μmol kg-1 of (PhSe)2. Liver tissue from infected mice showed less severe inflammation, elevated ATP/ADO ratio, elevated NTPDase, 5'nucleotidase, and ADA activities compared to the uninfected group (Group A; P < 0.05). However, infected and treated mice showed decreased ATP levels and elevated ADO levels, as well as higher NTPDase and 5'nucleotidase activities and decreased ADA activity in the hepatic tissue compared to the infected group (P < 0.05). Moreover, the (PhSe)2 treatment of infected mice reduced the hepatic inflammation and showed an immunomodulatory effect on ectonucleotidases of hepatic lymphocytes, which it returned to basal levels. Therefore, chronic infection by T. gondii induces hepatic inflammation in mice, and it is possible that purine levels and nucleotidase activities in hepatic tissue are related to the pathogenesis of the infection in this tissue. The treatment with (PhSe)2 was able to reverse the hepatic inflammation in mice chronically infected, possibly due to the modulation of purinergic enzymes that produce an anti-inflammatory profile through the purinergic system in the liver tissue.

Toxoplasmosis treatment with diphenyl diselenide in infected mice modulates the activity of purinergic enzymes and reduces inflammation in spleen

Toxoplasma gondii, an intracellular protozoan, may cause chronic infection in the brain tissue of the host inducing a systemic pro-inflammatory profile. Chronic infections can induce numerous physiological changes, such as alterations in the immune and oxidative profiles. Diphenyl diselenide (PhSe)₂, an organoselenium compound, has shown antioxidant and immunomodulatory activities in recent studies. So, the aim of this study was to investigate the activity of purinergic enzymes and reactive oxygen species (ROS) in serum and spleen of mice chronically infected by T. gondii, untreated and treated with (PhSe)₂. For this experiment, were divided into four groups: Group A (healthy mice), Group B (healthy mice treated with (PhSe)₂), Group C (infected mice) and Group D (infected mice treated with (PhSe)₂). Group C and group D were infected via oral route with ME49 Toxoplasma gondii strain. Groups B and D were treated subcutaneously with 5 μmol kg^-1 of (PhSe)₂. Chronic T. gondii infection induced splenomegaly and physiological changes in the spleen and raised histologic inflammatory markers, ROS levels and the activity of purinergic enzymes activity such as NTPDase, 5´nucleotidase and ADA. In serum, the infection increased 5´nucleotidase and ADA activities. (PhSe)₂per se has managed to decrease ROS levels and ADA activity and increase NTPDase and 5´nucleotidase in spleen. In infected mice, treatment with (PhSe)₂ reversed splenomegaly, reduced histological inflammatory markers, ROS levels and ADA activity in the spleen. Our results prove that chronic toxoplasmosis can induce splenomegaly, heightens ROS levels and purinergic enzyme activity in mice. These results suggest that (PhSe)₂ is a potential therapy for the alterations found in the spleen in chronic T. gondii infection.

‘One-pot’ synthesis and redox evaluations of chiral chalcogenocysteinol and β-bis-chalcogenoamine derivatives from l-serine methyl ester

The synthesis of a new class of potential antioxidant chiral chalcogenocysteinols and bis-chalcogenoamines is described in this study.

Diphenyl diselenide supplementation in infected mice by Toxoplasma gondii: Protective effect on behavior, neuromodulation and oxidative stress caused by disease

The aim of this study was to evaluate the effect of subcutaneous administration of diphenyl diselenide (PhSe)2 on animal behavior and activities of acetylcholinesterase (AChE), adenylate kinase (AK), and creatine kinase (CK) in the brain of mice infected by Toxoplasma gondii. In addition, thiobarbituric acid reactive species (TBARS) levels and glutathione (GR, GPx and GST) activity were also evaluated. For the study, 40 female mice were divided into four groups of 10 animals each: group A (uninfected and untreated), group B (uninfected and treated with (PhSe)2), group C (infected and untreated) and group D (infected and treated with (PhSe)2). The mice were inoculated with 50 cysts of the ME49 strain of T. gondii. After infection the animals of the groups B and D were treated on days 1 and 20 post-infection (PI) with 5.0 μmol/kg of (PhSe)2 subcutaneously. Behavioral tests were conducted on days 29 PI to assess memory loss (object recognition), anxiety (elevated plus maze), locomotor and exploratory activity (Open Field) and it was found out that infected and untreated animals (group C) had developed anxiety and memory impairment, and the (PhSe)2 treatment did not reverse these behavioral changes on infected animals treated with (PhSe)2 (group D). The results showed an increase on AChE activity (P < 0.01) in the brain of infected and untreated animals (group C) compared to the uninfected and untreated animals (group A). The AK and CK activities decreased in infected and untreated animals (group C) compared to the uninfected and untreated animals (group A) (P < 0.01), however the (PhSe)2 treatment did not reverse these alterations. Infected and untreated animals (group C) showed increased TBARS levels and GR activity, and decreased GPx and GST activities when compared to uninfected and untreated animals (group A). Infected animals treated with (PhSe)2 (group D) decreased TBARS levels and GR activity, while increased GST activity when compared to infected and untreated animals (group C). It was concluded that (PhSe)2 showed antioxidant activity, but the dose used had no anti-inflammatory effect and failed to reverse the behavioral changes caused by the parasite.

Synergistic effects of resveratrol (free and inclusion complex) and sulfamethoxazole-trimetropim treatment on pathology, oxidant/antioxidant status and behavior of mice infected with Toxoplasma gondii

This study aimed to investigate the synergistic effects of resveratrol and sulfamethoxazole-trimethoprim (ST) on the treatment of mice experimentally infected by Toxoplasma gondii during the chronic phase of the disease considering infection, behavior, and oxidative/antioxidants profile aspects. For the study, 60 mice were initially divided into two groups: uninfected (n = 24) and infected by T. gondii (n = 36). These two groups were later subdivided into other groups and treated with resveratrol (free and inclusion complex containing resveratrol) alone and co-administered with ST: groups A to D were composed by healthy mice and groups E to J were consisted of animals infected by T. gondii (VEG strain). Treatments began 20 days post-infection for 10 consecutive days with oral doses of 0.5 mg kg(-1) of ST (groups B and F), 100 mg kg(-1) of free resveratrol (groups C and G) and inclusion complex of resveratrol (nanoparticles containing resveratrol) (groups D and H), and lastly an co-administration of both drugs (groups I and J). Behavioral tests (memory, anxiety and locomotion) were performed after treatment. Liver and brain fragments were collected to evaluate pathological changes, brain cysts counts, as well as oxidant and antioxidant levels. A reduction on the number of cysts in the brain of animals treated with both drugs combined was observed; there was also reduced number of lesions on both organs. This drug combined effect was also able to reduce oxidative and increase antioxidant levels in infected mice, which might be interpreted as a resveratrol protective effect. In addition, the combination of ST and resveratrol was able to prevent behavioral changes in infected mice. Therefore, the use of co-administration drugs enhances the therapeutic effect acting on a synergic way, reducing the oxidizing effects of the chemical treatment for toxoplasmosis. In addition, resveratrol in inclusion complex when co-administered with ST showed an improved therapeutic effect of ST reducing oxidative damage, liver damage and the number of cysts in the brain of T. gondii infected mice.

Effects of sulfamethoxazole-trimethoprim associated to resveratrol on its free form and complexed with 2-hydroxypropyl-β-cyclodextrin on cytokines levels of mice infected by Toxoplasma gondii

The aim of this study was to investigate the effects of resveratrol on its free form and complexed with 2-hydroxypropyl-β-cyclodextrin (HPβCD) when associated with sulfamethoxazole-trimethoprim (ST) on cytokines levels of mice (n = 60) experimentally infected by Toxoplasma gondii. Groups A and E were used as controls (untreated): negative and positive, respectively. The onset of treatment started 20 days post-infection (PI), and it lasted for 10 consecutive days. ST was administered orally in doses of 0.5 mg kg(-1) for groups B and F, while 100 mg kg(-1) was the dose for resveratrol in its free form (groups C - G), inclusion complex (groups D and H), and on free and inclusion complex together (groups I - J). On day 31 PI, blood samples were collected in order to evaluate the cytokine profile. The mice that received drug combination (I and J) showed a significant (P < 0.05) reduction in the number of cysts in the brain compared to other infected groups (E - H). The results showed that mice from the Group E had increased (P < 0.001) levels of pro-inflammatory cytokines, while IL-10 levels were reduced when compared to the Group A. Additionally, there were increased levels of IL-4 and IFN-γ in animals of groups C and D, respectively (P < 0.05). Animals of the Group B showed reduced levels of IL-1, IL-4, IL-6, TNF-α, and IFN-γ (P < 0.05). Mice infected and treated (groups F - J) showed increased levels of pro-inflammatory cytokines along with a reduction of IL-10. Treatment with the combination of drugs (the Group J) led to a protective effect, i.e. reduction in pro-inflammatory cytokines. Therefore, resveratrol associated with ST was able to modulate seric cytokine profile and moderate the tissue inflammatory process caused by T. gondii infection, as well as to reduce parasite multiplication.