Anti-trypanosomal activity of (8-hydroxymethylen)-trieicosanyl acetate against infective forms of Trypanosoma cruzi

Drugs in preclinical and early clinical development for the treatment of Chagas´s disease: the current status

INTRODUCTION

Chagas disease is spreading faster than expected in different countries, and little progress has been reported in the discovery of new drugs to combat Trypanosoma cruzi infection in humans. Recent clinical trials have ended with small hope. The pathophysiology of this neglected disease and the genetic diversity of parasites are exceptionally complex. The only two drugs available to treat patients are far from being safe, and their efficacy in the chronic phase is still unsatisfactory.

AREAS COVERED

This review offers a comprehensive examination and critical review of data reported in the last 10 years, and it is focused on findings of clinical trials and data acquired in vivo in preclinical studies.

EXPERT OPINION

The in vivo investigations classically in mice and dog models are also challenging and time-consuming to attest cure for infection. Poorly standardized protocols, availability of diagnosis methods and disease progression markers, the use of different T. cruzi strains with variable benznidazole sensitivities, and animals in different acute and chronic phases of infection contribute to it. More synchronized efforts between research groups in this field are required to put in evidence new promising substances, drug combinations, repurposing strategies, and new pharmaceutical formulations to impact the therapy.

A Review of Recent Studies on the Antioxidant and Anti-Infectious Properties of Senna Plants

The use of phytochemicals is gaining interest for the treatment of metabolic syndromes over the synthetic formulation of drugs. Senna is evolving as one of the important plants which have been vastly studied for its beneficial effects. Various parts of Senna species including the root, stem, leaves, and flower are found rich in numerous phytochemicals. In vitro, in vivo, and clinical experiments established that extracts from Senna plants have diverse beneficial effects by acting as a strong antioxidant and antimicrobial agent. In this review, Senna genus is comprehensively discussed in terms of its botanical characteristics, traditional use, geographic presence, and phytochemical profile. The bioactive compound richness contributes to the biological activity of Senna plant extracts. The review emphasizes on the in vivo and in vitro antioxidant and anti-infectious properties of the Senna plant. Preclinical studies confirmed the beneficial effects of the Senna plant extracts and its bioactive components in regard to the health-promoting activities. The safety, side effects, and therapeutic limitations of the Senna plant are also discussed in this review. Additional research is necessary to utilize the phenolic compounds towards its use as an alternative to pharmacological treatments and even as an ingredient in functional foods.

Review on Experimental Treatment Strategies Against Trypanosoma cruzi

Chagas disease is a neglected tropical disease caused by the protozoan Trypanosoma cruzi. Currently, only nitroheterocyclic nifurtimox (NFX) and benznidazole (BNZ) are available for the treatment of Chagas disease, with limitations such as variable efficacy, long treatment regimens and toxicity. Different strategies have been used to discover new active molecules for the treatment of Chagas disease. Target-based and phenotypic screening led to thousands of compounds with anti-T. cruzi activity, notably the nitroheterocyclic compounds, fexinidazole and its metabolites. In addition, drug repurposing, drug combinations, re-dosing regimens and the development of new formulations have been evaluated. The CYP51 antifungal azoles, as posaconazole, ravuconazole and its prodrug fosravuconazole presented promising results in experimental Chagas disease. Drug combinations of nitroheterocyclic and azoles were able to induce cure in murine infection. New treatment schemes using BNZ showed efficacy in the experimental chronic stage, including against dormant forms of T. cruzi. And finally, sesquiterpene lactone formulated in nanocarriers displayed outstanding efficacy against different strains of T. cruzi, susceptible or resistant to BNZ, the reference drug. These pre-clinical results are encouraging and provide interesting evidence to improve the treatment of patients with Chagas disease.

Bioassay-guided chemical study of the anti-inflammatory effect of Senna villosa (Miller) H.S. Irwin & Barneby (Leguminosae) in TPA-induced ear edema

Senna villosa (Miller) is a plant that grows in México. In traditional Mexican medicine, it is used topically to treat skin infections, pustules and eruptions and to heal wounds by scar formation. However, studies of its potential anti-inflammatory effects have not been performed. The aim of the present study was to determine the anti-inflammatory effect of extracts from the leaves of Senna villosa and to perform a bioassay-guided chemical study of the extract with major activity in a model of ear edema induced by 12-O-tetradecanoylphorbol 13-acetate (TPA). The results reveal that the chloroform extract from Senna villosa leaves has anti-inflammatory and anti-proliferative properties. Nine fractions were obtained from the bioassay-guided chemical study, including a white precipitate from fractions 2 and 3. Although none of the nine fractions presented anti-inflammatory activity, the white precipitate exhibited pharmacological activity. It was chemically characterized using mass spectrometry and infrared and nuclear magnetic resonance spectroscopy, resulting in a mixture of three aliphatic esters, which were identified as the principal constituents: hexyl tetradecanoate (C20H40O2), heptyl tetradecanoate (C21H42O2) and octyl tetradecanoate (C22H44O2). This research provides, for the first time, evidence of the anti-inflammatory and anti-proliferative properties of compounds isolated from Senna villosa.

In vivo activity of (8-hydroxymethylen)-trieicosanyl acetate against Trypanosoma cruzi during acute phase of the infection

The antiprotozoal activity in vivo against Trypanosoma cruzi of (8-hydroxymethylen)-trieicosanyl acetate was evaluated in BALB/c mice during the acute phase of Chagas' disease (15 days after infection). Animals were treated during 15 days at doses of 16.8 and 33.6 µg/g, reduced parasitemia of 77.6 and 64.1% was observed respectively, in comparison with positive control mice (allopurinol 8.5 µg/g) which reduced only 29.7%. Also, amastigote nests in cardiac tissue were significant reduced in treated mice groups. The regression of effect induced after the suppression of the treatment with the compound was evaluated; animals were infected and simultaneously began the treatment with the compound during 20 days (16.8 and 33.6 µg/g). Mice were monitored after the end of the treatment for one more week. A good antitrypanosomal response was observed (66.1 and 68.9% less than untreated mice) during treatment, but 8 days after suspension of treatment, parasitemia level increased, reducing only 58.6 and 56.29 % respectively in treated animals compared with no treated.

Antitrypanosomal activity of Senna villosa in infected BALB/c mice with Trypanosoma cruzi during the sub acute phase of infection

Antitrypanosomal activity of chloroform extract of Senna villosa leaves was evaluated in the sub acute phase of mice infected with Trypanosoma cruzi. Oral doses of 3.3, 6.6 and 13.2 µg/g were tested during 15 days on infected mice BALB/c, beginning treatment 40 days after infection to evaluate specifically the antitrypanosomal activity over the amastigote form of the parasite. Two different amount of parasites (100 and 500) were inoculated to 25 mice for each doses tested. At the end of the assay the animals were sacrificed and cardiac and skeletal tissue sections were stained with hematoxylin-eosin (HE) for identification and quantification of amastigote nest. In mice infected with 100 parasites, a significant reduction in the number of amastigote nest was observed in cardiac tissue of treated animals at all doses evaluated (p<0.05). An important reduction of amastigote nest was also observed in treated animals and infected with 500 parasites in comparison with no treated mice or treated with allopurinol.