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In this work, we determined whether oxidative stress contributed to the activation of the kynurenine pathway by AgNPs. Male Wistar rats weighing between 130 and 146 g were randomly assigned into six groups. Animals in the negative control group were orally administered distilled water while, the other treatment groups were respectively given AgNPs (25 and 50 mg/kg bw) alone or in combination with Trolox (100 mg/kg bw). Results showed that treatments with AgNPs significantly raised protein carbonyl level in rat liver, but the co-treatment with Trolox attenuated the elevation. Conversely, AgNPs raised the level of reduced glutathione (GSH) in rat plasma and tissues compared to the negative control. Further, oral exposure to AgNPs (50 mg/kg bw) significantly elevated rat plasma and brain kynurenine levels compared to the negative control. Meantime, the co-treatment with Trolox appreciably restored kynurenine level in rat plasma, but not in the rat brain. Taken together, findings indicate that the oral administration of AgNPs alone at the doses used in this study, might not have caused oxidative stress. However, the co-treatment with Trolox appears to potentiate oxidative stress in rats following exposure to AgNPs. Furthermore, data support that the activation of the kynurenine pathway in the rat brain by AgNPs might be independent of oxidative stress. The findings are new and contribute to deepen our understanding of the cellular interaction by nanoparticles., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The interaction of nanoparticles with living cells is becoming one of the urgent areas of collaborative research in materials science and biology. Previously, we showed that nanoparticles have promising anti-Toxoplasma gondii properties. Meanwhile, Toxoplasma gondii has been shown to avert apoptosis in host cells whereas nanoparticles have been implicated for apoptotic tendency. Therefore, in the present study, we assessed the in vitro apoptotic properties of inorganic nanoparticles in the absence or presence of Toxoplasma infection and/or small molecules used as metabolic modulators. Results showed that inorganic nanoparticles dose-dependently caused cellular apoptosis. However, in the presence of infection by Toxoplasma gondii, nanoparticles-induced cellular apoptosis was not mitigated. Likewise, use of several small molecules (anti-metabolites) as metabolic modulators either mildly or nearly failed to abate cellular apoptosis by nanoparticles. Taken together, our findings do not only confirm the apoptotic potential of inorganic nanoparticles but show evidence that cellular apoptosis by inorganic nanoparticles of gold and silver might not be susceptible to modulation by Toxoplasma gondii infection. The findings are new and contribute to deepen our understanding of the cellular interaction of nanoparticles., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The Trypanosoma and Toxoplasma spp, are etiological agents of diseases capable of causing significant morbidity, mortality and economic burden, predominantly in developing countries. Currently, there are no effective vaccines for the diseases caused by these parasites; therefore, therapy relies heavily on antiprotozoal drugs. However, the treatment options for these parasitic diseases are limited, thus underscoring the need for new anti-protozoal agents. Here, we investigated the anti-parasite action of nanoparticles. We found that the nanoparticles have strong and selective in vitro activity against T. b. brucei but moderate in vitro activity against T. congolense and T. evansi. An estimation of the in vitro anti-Trypanosoma efficacy showed that the nanoparticles had ≥200-fold selective activity against the parasite versus mammalian cells. Moreover, the nanoparticle alloys moderately suppressed the in vitro growth of T. gondii by ≥60%. In our in vivo study, the nanoparticles appeared to exhibit a trypanostatic effect, but did not totally suppress the rat parasite burden, thereby failing to appreciably extend the survival time of infected animals compared with the untreated control. In conclusion, this is the first study to demonstrate the selective in vitro anti-Trypanosoma action of nanoparticles and thus supports the potential of nanoparticles as alternative anti-parasitic agents.