Resveratrol prevents p53 aggregation in vitro and in breast cancer cells Resveratrol prevents p53 aggregation in vitro and in breast cancer cells

Chagas disease is a life-threatening infection caused by a variety of genetically diverse strains of the protozoan parasite Trypanosoma cruzi . The current treatment (benznidazole and nifurtimox) is unsatisfactory, and potential alternatives include inhibitors of sterol 14α-demethylase (CYP51), the cytochrome P450 enzyme essential for the biosynthesis of sterols in eukaryotes and the major target of clinical and agricultural antifungals. Here we performed a comparative investigation of two protozoon-specific CYP51 inhibitors, VNI and its CYP51 structure-based derivative VFV, in the murine models of infection caused by the Y strain of T. cruzi . The effects of different treatment regimens and drug delivery vehicles were evaluated in animals of both genders, with benznidazole serving as the reference drug. Regardless of the treatment scheme or delivery vehicle, VFV was more potent in both genders, causing a >99.7% peak parasitemia reduction, while the VNI values varied from 91 to 100%. Treatments with VNI and VFV resulted in 100% animal survival and 0% natural relapse after the end of therapy, though, except for the 120-day treatment schemes with VFV, relapses after three cycles of immunosuppression were observed in each animal group, and quantitative PCR analysis revealed a very light parasite load in the blood samples (sometimes below or near the detection limit, which was 1.5 parasite equivalents/ml). Our studies support further investigations of this class of compounds, including their testing against other T. cruzi strains and in combination with other drugs.

Chagas disease (CD), a neglected tropical disease caused by Trypanosoma cruzi , remains a serious public health problem in several Latin American countries. The available chemotherapies for CD have limited efficacy and exhibit undesirable side effects. Aromatic diamidines and arylimidamides (AIAs) have shown broad-spectrum activity against intracellular parasites, including T. cruzi . Therefore, our aim was to evaluate the biological activity of eight novel AIAs (16DAP002, 16SAB079, 18SAB075, 23SMB022, 23SMB026, 23SMB054, 26SMB070, and 27SMB009) against experimental models of T. cruzi infection in vitro and in vivo . Our data show that none of the compounds induced a loss of cellular viability up to 32 μM. Two AIAs, 18SAB075 and 16DAP002, exhibited good in vitro activity against different parasite strains (Y and Tulahuen) and against the two relevant forms of the parasite for mammalian hosts. Due to the excellent selective indexes of 18SAB075, this AIA was moved to in vivo tests for acute toxicity and parasite efficacy; nontoxic doses (no-observed-adverse-effect level [NOAEL], 50 mg/kg) were employed in the tests for parasite efficacy. In experimental models of acute T. cruzi infection, 18SAB075 reduced parasitemia levels only up to 50% and led to 40% protection against mortality (at 5 mg/kg of body weight), being less effective than the reference drug, benznidazole.

Arylimidamides (AIAs) have been shown to have considerable biological activity against intracellular pathogens, including Trypanosoma cruzi , which causes Chagas disease. In the present study, the activities of 12 novel bis-AIAs and 2 mono-AIAs against different strains of T. cruzi in vitro and in vivo were analyzed. The most active was m -terphenyl bis-AIA (35DAP073), which had a 50% effective concentration (EC ₅₀ ) of 0.5 μM for trypomastigotes (Y strain), which made it 26-fold more effective than benznidazole (Bz; 13 μM). It was also active against the Colombiana strain (EC ₅₀ = 3.8 μM). Analysis of the activity against intracellular forms of the Tulahuen strain showed that this bis-AIA (EC ₅₀ = 0.04 μM) was about 100-fold more active than Bz (2 μM). The trypanocidal effect was dissociated from the ability to trigger intracellular lipid bodies within host cells, detected by oil red labeling. Both an active compound (35DAP073) and an inactive compound (26SMB060) displayed similar activation profiles. Due to their high selectivity indexes, two AIAs (35DAP073 and 35DAP081) were moved to in vivo studies, but because of the results of acute toxicity assays, 35DAP081 was excluded from the subsequent tests. The findings obtained with 35DAP073 treatment of infections caused by the Y strain revealed that 2 days of therapy induced a dose-dependent action, leading to 96 to 46% reductions in the level of parasitemia. However, the administration of 10 daily doses in animals infected with the Colombiana strain resulted in toxicity, preventing longer periods of treatment. The activity of the combination of 0.5 mg/kg of body weight/day 35DAP073 with 100 mg/kg/day Bz for 10 consecutive days was then assayed. Treatment with the combination resulted in the suppression of parasitemia, the elimination of neurological toxic effects, and survival of 100% of the animals. Quantitative PCR showed a considerable reduction in the parasite load (60%) compared to that achieved with Bz or the amidine alone. Our results support further investigations of this class with the aim of developing novel alternatives for the treatment of Chagas disease.

The lack of translation between preclinical assays and clinical trials for novel therapies for Chagas disease (CD) indicates a need for more feasible and standardized protocols and experimental models. Here, we investigated the effects of treatment with benznidazole (Bz) and with the potent experimental T. cruzi CYP51 inhibitor VNI in mouse models of Chagas disease by using different animal genders and parasite strains and employing distinct types of therapeutic schemes. Our findings confirm that female mice are less vulnerable to the infection than males, show that male models are less susceptible to treatment with both Bz and VNI, and thus suggest that male models are much more suitable for selection of the most promising antichagasic agents. Additionally, we have found that preventive protocols (compound given at 1 dpi) result in higher treatment success rates, which also should be avoided during advanced steps of in vivo trials of novel anti- T. cruzi drug candidates. Another consideration is the relevance of immunosuppression methods in order to verify the therapeutic profile of novel compounds, besides the usefulness of molecular diagnostic tools (quantitative PCR) to ascertain compound efficacy in experimental animals. Our study aims to contribute to the development of more reliable methods and decision gates for in vivo assays of novel antiparasitic compounds in order to move them from preclinical to clinical trials for CD.