In Vitro and In Vivo Studies of the Antiparasitic Activity of Sterol 14α-Demethylase (CYP51) Inhibitor VNI against Drug-Resistant Strains of Trypanosoma cruzi

Abstract

Chagas disease affects more than 10 million people worldwide, and yet, as it has historically been known as a disease of the poor, it remains highly neglected. Two currently available drugs exhibit severe toxicity and low effectiveness, especially in the chronic phase, while new drug discovery has been halted for years as a result of a lack of interest from pharmaceutical companies. Although attempts to repurpose the antifungal drugs posaconazole and ravuconazole (inhibitors of fungal sterol 14␣-demethylase [CYP51]) are finally in progress, development of cheaper and more efficient, preferably Trypanosoma cruzi-specific, chemotherapies would be highly advantageous. We have recently reported that the experimental T. cruzi CYP51 inhibitor VNI cures with 100% survival and 100% parasitological clearance both acute and chronic murine infections with the Tulahuen strain of T. cruzi. In this work, we further explored the potential of VNI by assaying nitro-derivative-resistant T. cruzi strains, Y and Colombiana, in highly stringent protocols of acute infection. The data show high antiparasitic efficacy of VNI and its derivative (VNI/VNF) against both forms of T. cruzi that are relevant for mammalian host infection (bloodstream and amastigotes), with the in vivo potency, at 25 mg/kg twice a day (b.i.d.), similar to that of benznidazole (100 mg/kg/day). Transmission electron microscopy and reverse mutation tests were performed to explore cellular ultrastructural and mutagenic aspects of VNI, respectively. No mutagenic potential could be seen by the Ames test at up to 3.5 M, and the main ultrastructural damage induced by VNI in T. cruzi was related to Golgi apparatus and endoplasmic reticulum organization, with membrane blebs presenting an autophagic phenotype. Thus, these preliminary studies confirm VNI as a very promising trypanocidal drug candidate for Chagas disease therapy. Chagas disease (CD), a neglected lifelong malady caused by the intracellular protozoan parasite Trypanosoma cruzi, is a notorious health problem in Latin America and an emerging global health issue, mainly due to immigration of infected individuals to other continents (primarily to North America and Europe) but also because of broadening of the insect vector distribution areas (1). No vaccine is available, and the current therapy for the infection (nifurtimox [Nf] and benznidazole [Bz]) is largely insufficient, having undesirable side effects and limited efficacy especially in the later chronic stages (2). However, novel compounds for CD do not attract the investment of most pharmaceutical companies, especially due to large costs versus low economic profits, exposing the importance of academic research and technological development support for drug design and development of new leads and hits for this as well as other neglected parasitic illnesses that afflict millions of the poorest people worldwide. In this vein, for over 3 decades inhibitors of sterol biosynthesis have been considered potential antichagasic agents (3-6), because, similar to the...

In Vitro and In Vivo Biological Effects of Novel Arylimidamide Derivatives against Trypanosoma cruzi

“…Both cause severe side effects, resulting in discontinuation of the treatment and low effectiveness, especially in the later chronic phase of the disease, demanding the identification of novel drugs to treat this devastating chronic pathology. However, there is a lack of interest from most pharmaceutical companies for discovery of new anti-T. cruzi agents mainly due to the long time and high costs associated with the drug pipeline for this and other neglected parasitic illnesses that afflict millions of the poorest people worldwide (28). In this context, our aim was to explore the possibility of finding new amidine derivatives with considerable activity against T. cruzi in vitro and in vivo which possess the potential to act as clinical candidates against this neglected parasitic disease.…”

Different Therapeutic Outcomes of Benznidazole and VNI Treatments in Different Genders in Mouse Experimental Models of Trypanosoma cruzi Infection

“…It has been suggested that at least part of this unexpected failure could be due to the lack of translation from in vitro and in vivo models to the clinic and that a redesign of the current screening strategy during the drug discovery process should be considered (5). On the other hand, recent data demonstrated the potency and selectivity of a novel experimental inhibitor of T. cruzi CYP51, the VNI molecule, which yielded promising in vivo findings even with highly resistant T. cruzi strains (6). In this vein, we evaluated the effects and outcomes of the treatment with benznidazole and VNI using mouse models of T. cruzi infection assaying different animal genders and parasite strains and employing distinct types of drug administration schemes (preventive, i.e., starting therapy at 1 day postinfection [dpi], and therapeutic, i.e., starting at parasitemia onset, 5 to 6 dpi).…”

In Vitro and In Vivo Studies of the Biological Activity of Novel Arylimidamides against Trypanosoma cruzi

“…The Y strain of T. cruzi was used, and bloodstream trypomastigotes (BT) and intracellular trypomastigote forms were assayed as described previously (18,23). Mammalian cell cytotoxicity of AIAs was evaluated on uninfected CC incubated up to 48 h at 37°C with each compound (0 to 32 M); morphology, spontaneous contractibility, and cell death rates were measured for determination of the 50% effective compound concentrations (EC 50 s) (24). For trypanocidal analysis, BT were incubated at 37°C for 24 h with nontoxic concentrations of the compounds to determine the EC 50 (24).…”

“…Mammalian cell cytotoxicity of AIAs was evaluated on uninfected CC incubated up to 48 h at 37°C with each compound (0 to 32 M); morphology, spontaneous contractibility, and cell death rates were measured for determination of the 50% effective compound concentrations (EC 50 s) (24). For trypanocidal analysis, BT were incubated at 37°C for 24 h with nontoxic concentrations of the compounds to determine the EC 50 (24). For analysis with intracellular amastigotes, after 24 h of parasite-host cell interaction, increasing nontoxic doses of the compounds were added for 48 h, and drug activity was estimated by calculating the infection index (II) as reported (12,24).…”