Evaluation of the non-clinical toxicity of an antiparasitic agent: diminazene aceturate

Therapeutic efficacy of β-sitosterol treatment on Trypanosoma congolense infection, anemia development, and trans-sialidase (TconTS1) gene expression

Background

African animal trypanosomiasis hinders sustainable livestock productivity in sub-Saharan Africa. About 17 million infected cattle are treated with trypanocides annually but most of the drugs are associated with drawbacks, necessitating the search for a promising chemotherapeutic agent.

Objectives

In this study, the effects of β-sitosterol on Trypanosoma congolense infection were investigated along with its effect on the trans-sialidase gene expressions.

Results

Oral treatment with β-sitosterol at 15 and 30 mg/kg body weight (BW) for 14 days significantly (p < 0.05) reduced parasitemia and ameliorated the parasite-induced anemia. Also, the parasite-induced increase in serum urea level and renal histopathological damage scores in addition to renal hypertrophy was significantly (p < 0.05) reverted following treatment with 30 mg/kg BW β-sitosterol. The compound also significantly (p < 0.05) down-regulated the expression of TconTS1 but not TconTS2, TconTS3, and TconTS4. Correlation analysis between free serum sialic acid with the TconTS1 and TconTS2 gene variants revealed negative correlations in the β-sitosterol-treated groups although they were non-significant (p > 0.05) in the group treated with 15 mg/kg BW β-sitosterol. Similarly, a non-significant negative (p > 0.05) correlation between the biomolecule and the TconTS3 and TconTS4 gene variants was observed in the β-sitosterol-treated groups while positive correlations were observed in the infected untreated control group.

Conclusion

The observed effect of β-sitosterol on T. congolense infection could make the compound a possible template for the design of novel trypanocides.

Synthesis and Evaluation of Antiproliferative Activity, Topoisomerase IIα Inhibition, DNA Binding and Non-Clinical Toxicity of New Acridine-Thiosemicarbazone Derivatives

In this study, we report the synthesis of twenty new acridine–thiosemicarbazone derivatives and their antiproliferative activities. Mechanisms of action such as the inhibition of topoisomerase IIα and the interaction with DNA have been studied for some of the most active derivatives by means of both in silico and in vitro methods, and evaluations of the non-clinical toxicities (in vivo) in mice. In general, the compounds showed greater cytotoxicity against B16-F10 cells, with the highest potency for DL-08 (IC₅₀ = 14.79 µM). Derivatives DL-01 (77%), DL-07 (74%) and DL-08 (79%) showed interesting inhibition of topoisomerase IIα when compared to amsacrine, at 100 µM. In silico studies proposed the way of bonding of these compounds and a possible stereoelectronic reason for the absence of enzymatic activity for CL-07 and DL-06. Interactions with DNA presented different spectroscopic effects and indicate that the compound CL-07 has higher affinity for DNA (Kb = 4.75 × 10⁴ M⁻¹; Ksv = 2.6 × 10³ M⁻¹). In addition, compounds selected for non-clinical toxicity testing did not show serious signs of toxicity at the dose of 2000 mg/kg in mice; cytotoxic tests performed on leukemic cells (K-562) and its resistant form (K-562 Lucena 1) identified moderate potency for DL-01 and DL-08, with IC₅₀ between 11.45 and 17.32 µM.

Angiotensin-(1-7) as a Potential Therapeutic Strategy for Delayed Cerebral Ischemia in Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is a substantial cause of mortality and morbidity worldwide. Moreover, survivors after the initial bleeding are often subject to secondary brain injuries and delayed cerebral ischemia, further increasing the risk of a poor outcome. In recent years, the renin-angiotensin system (RAS) has been proposed as a target pathway for therapeutic interventions after brain injury. The RAS is a complex system of biochemical reactions critical for several systemic functions, namely, inflammation, vascular tone, endothelial activation, water balance, fibrosis, and apoptosis. The RAS system is classically divided into a pro-inflammatory axis, mediated by angiotensin (Ang)-II and its specific receptor AT₁R, and a counterbalancing system, presented in humans as Ang-(1-7) and its receptor, MasR. Experimental data suggest that upregulation of the Ang-(1-7)/MasR axis might be neuroprotective in numerous pathological conditions, namely, ischemic stroke, cognitive disorders, Parkinson's disease, and depression. In the presence of SAH, Ang-(1-7)/MasR neuroprotective and modulating properties could help reduce brain damage by acting on neuroinflammation, and through direct vascular and anti-thrombotic effects. Here we review the role of RAS in brain ischemia, with specific focus on SAH and the therapeutic potential of Ang-(1-7).