Sesquiterpene lactone in nanostructured parenteral dosage form is efficacious in experimental Chagas disease

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.

Nanomedicines against Chagas disease: a critical review

Chagas disease (CD) is the most important endemic parasitosis in South America and represents a great socioeconomic burden for the chronically ill and their families. The only currently available treatment against CD is based on the oral administration of benznidazole, an agent, developed in 1971, of controversial effectiveness on chronically ill patients and toxic to adults. So far, conventional pharmacological approaches have failed to offer more effective and less toxic alternatives to benznidazole. Nanomedicines reduce toxicity and increase the effectiveness of current oncological therapies. Could nanomedicines improve the treatment of the neglected CD? This question will be addressed in this review, first by critically discussing selected reports on the performance of benznidazole and other molecules formulated as nanomedicines in in vitro and in vivo CD models. Taking into consideration the developmental barriers for nanomedicines and the degree of current technical preclinical efforts, a prospect of developing nanomedicines against CD will be provided. Not surprisingly, we conclude that structurally simpler formulations with minimal production cost, such as oral nanocrystals and/or parenteral nano-immunostimulants, have the highest chances of making it to the market to treat CD. Nonetheless, substantive political and economic decisions, key to facing technological challenges, are still required regarding a realistic use of nanomedicines effective against CD.

Lychnopholide loaded in surface modified polylactide nanocapsules (LYC-PLA-PEG-NC) cure mice infected by Trypanosoma cruzi strain a prototype of resistance to benznidazole and nifurtimox: First insights of its mechanism of action

Chagas disease (CD) remains neglected and causes high morbidity and mortality. The great difficulty is the lack of effective treatment. The current drugs cause side effects and have limited therapeutic efficacy in the chronic phase. This study aims to fulfil some gaps in studies of the natural substance lychnopholide nanoencapsulated LYC-PLA-PEG-NC (LYC-NC) and free (Free-LYC): the activity in epimastigotes and amastigotes to determine its selectivity index (SI), the therapeutic efficacy in mice infected with Colombian Trypanosoma cruzi strain and insight of the mechanism of LYC-NC action on T. cruzi. The SI was obtained by calculation of the ratio between the IC50 value toward H9c2 cells divided by the IC50 value in the anti-T. cruzi test. Infected Swiss mice were treated with 2 and 12 mg/kg/day via intravenous and oral, respectively, and the therapeutic efficacy was determined. The IC50 of LYC-NC and Free-LYC for epimastigotes of T. cruzi were similar. Both were active against amastigotes in cell culture, particularly Free-LYC. The SI of LYC-NC and Free-LYC were 45.38 and 32.11, respectively. LYC-NC 2 and 12 mg/kg/day cured parasitologically, 62.5% and 80% of the animals, respectively, infected with a strain resistant to treatment. The fluorescent NC was distributed in the cardiomyocyte cytoplasm, infected or not, and interacted with the trypomastigotes. Together, these results represent advances in demonstrating LYC as a potent new therapeutic option for treating CD.

From Benznidazole to New Drugs: Nanotechnology Contribution in Chagas Disease

Chagas disease is a neglected tropical disease caused by the protozoan Trypanosoma cruzi. Benznidazole and nifurtimox are the two approved drugs for their treatment, but both drugs present side effects and efficacy problems, especially in the chronic phase of this disease. Therefore, new molecules have been tested with promising results aiming for strategic targeting action against T. cruzi. Several studies involve in vitro screening, but a considerable number of in vivo studies describe drug bioavailability increment, drug stability, toxicity assessment, and mainly the efficacy of new drugs and formulations. In this context, new drug delivery systems, such as nanotechnology systems, have been developed for these purposes. Some nanocarriers are able to interact with the immune system of the vertebrate host, modulating the immune response to the elimination of pathogenic microorganisms. In this overview of nanotechnology-based delivery strategies for established and new antichagasic agents, different strategies, and limitations of a wide class of nanocarriers are explored, as new perspectives in the treatment and monitoring of Chagas disease.

Use of Nanocarriers Containing Antitrypanosomal Drugs for the Treatment of Chagas Disease

Chagas disease, caused by the Trypanosoma cruzi parasitic protozoan, is a neglected tropical disease (NTD) of significant incidence in Latin America. Transmission to humans and other mammals is mainly via the vector insect from the Reduviidae family, popularly known as the kissing bug. There are other transmission means, such as through congenital transmission, blood transfusions, organ transplantations, and the consumption of contaminated food. For more than 50 years, the disease has been treated with benznidazole and nifurtimox, which are only effective during the acute phase of the disease. In addition to their low efficacy in the chronic phase, they cause many adverse effects and are somewhat selective. The use of nanocarriers has received significant attention due to their ability to encapsulate and release therapeutic agents in a controlled manner. Generally, their diameter ranges from 100 to 300 nanometers. The objective of this scoping review was to perform a search of the literature for the use of nanocarriers as an alternative for improving the treatment of Chagas disease and to suggest future research. Bibliographic searches were carried out in the Web of Science and PubMed scientific databases from January 2012 to May 2023, using the "Chagas disease and Trypanosoma cruzi and nanoparticles" keywords, seeking to gather the largest number of articles, which were evaluated using the inclusion and exclusion criteria. After analyzing the papers, the results showed that nanocarriers offer physiological stability and safety for the transport and controlled release of drugs. They can increase solubility and selectivity against the parasite. The in vitro assays showed that the trypanocidal activity of the drug was not impaired after encapsulation. In the in vivo assays, parasitemia reduction and high survival and cure rates in animals were obtained during both phases of the disease using lower doses when compared to the standard treatment. The scoping review showed that nanocarriers are a promising alternative for the treatment of Chagas disease.

Theracurmin Modulates Cardiac Inflammation in Experimental Model of Trypanosoma cruzi Infection

Theracurmin is a nanoparticle formulation derived from curcumin, a bioactive compound known for its antioxidant and anti-inflammatory properties. Trypanosoma cruzi, the etiological agent of Chagas disease, triggers an intense inflammatory response in mammals and also causes severe tissue damage. To evaluate the immunomodulatory and antiparasitic effects of Theracurmin, Swiss mice were experimentally infected with 10³ trypomastigote forms of the Colombian strain of T. cruzi and submitted to daily therapy with 30 mg/kg of Theracurmin. In addition, daily benznidazole therapy (100 mg/kg) was performed as a positive control. We evaluated the systemic and tissue parasitism, the survival and the body mass rate, the release of inflammatory mediators (TNF, IL-6, IL-15, CCL2 and creatine kinase) and the tissue inflammation at day 30 post-infection. Theracurmin therapy reduced the parasitemia curve without altering the animals' survival rate, and it protected mice from losing body mass. Theracurmin also reduced CCL2 in cardiac tissue, IL-15 in cardiac and skeletal tissue, and plasma CK. Even without effects on TNF and IL-6 production and tissue amastigote nests, Theracurmin reduced the leukocyte infiltrate in both evaluated tissues, even in the case of more effective results observed to the benznidazole treatment. Our data suggest Theracurmin has an immunomodulatory (CCL2, IL-15, CK and tissue leukocyte infiltration) and a trypanocidal effect (on circulating parasites) during experimental infection triggered by the Colombian strain of T. cruzi. Further investigations are necessary to comprehend the Theracurmin role performed in combination with benznidazole or other potential anti-T. cruzi chemical compounds.

Trypanosoma cruzi: Does the intake of nanoencapsulated benznidazole control acute infections?

Chagas Disease (CD) affects around eight million people worldwide. It is considered a neglected disease that presents few treatment options with efficacy only in the acute phase. Nanoparticles have many positive qualities for treating parasite infections and may be effectively and widely employed in clinical medicine. This research aimed to evaluate the nanoencapsulated benznidazole treatment in animals experimentally infected with Trypanosoma cruzi. To analyze the treatment efficacy, we evaluated survival during thirty days, parasitemia, genotoxicity, and heart and liver histopathology. Thirty-five female Swiss mice were organized into seven groups characterizing a dose curve: A - Negative control (uninfected animals), B - Positive control (infected animals), C - Benznidazole (BNZ) 100 mg/kg (infected animals), D - 5 mg/kg Benznidazole nanocapsules (NBNZ) (infected animals), E - 10 mg/kg Benznidazole nanocapsules (infected animals), F - 15 mg/kg Benznidazole nanocapsules (infected animals), G - 20 mg/kg Benznidazole nanocapsules (infected animals). The animals were infected with the Y strain of T. cruzi intraperitoneally. The treatment was administered for eight days by oral gavage. It was possible to observe that the treatment with the highest NBNZ dose presented efficacy similar to the standard benznidazole drug. The 20 mg/kg NBNZ dose was able to reduce parasitemia, increase survival, and drastically reduce heart and liver tissue damage compared to the 100 mg/kg BNZ dose. Moreover, it showed a lower DNA damage index than the BNZ treatment. In conclusion, the nanoencapsulation of BNZ promotes an improvement in parasite proliferation control with a five times smaller dose relative to the standard dose of free BNZ, thus demonstrating to be a potential innovative therapy for CD.

PEGylated and functionalized polylactide-based nanocapsules: An overview

Polymeric nanocapsules (NC) are versatile mixed vesicular nanocarriers, generally containing a lipid core with a polymeric wall. They have been first developed over four decades ago with outstanding applicability in the cosmetic and pharmaceutical fields. Biodegradable polyesters are frequently used in nanocapsule preparation and among them, polylactic acid (PLA) derivatives and copolymers, such as PLGA and amphiphilic block copolymers, are widely used and considered safe for different administration routes. PLA functionalization strategies have been developed to obtain more versatile polymers and to allow the conjugation with bioactive ligands for cell-targeted NC. This review intends to provide steps in the evolution of NC since its first report and the recent literature on PLA-based NC applications. PLA-based polymer synthesis and surface modifications are included, as well as the use of NC as a novel tool for combined treatment, diagnostics, and imaging in one delivery system. Furthermore, the use of NC to carry therapeutic and/or imaging agents for different diseases, mainly cancer, inflammation, and infections is presented and reviewed. Constraints that impair translation to the clinic are discussed to provide safe and reproducible PLA-based nanocapsules on the market. We reviewed the entire period in the literature where the term "nanocapsules" appears for the first time until the present day, selecting original scientific publications and the most relevant patent literature related to PLA-based NC. We presented to readers a historical overview of these Sui generis nanostructures.

Antiparasitic Meroterpenoids Isolated from Memnoniella dichroa CF-080171

Memnoniella is a fungal genus from which a wide range of diverse biologically active compounds have been isolated. A Memnoniella dichroa CF-080171 extract was identified to exhibit potent activity against Plasmodium falciparum 3D7 and Trypanosoma cruzi Tulahuen whole parasites in a high-throughput screening (HTS) campaign of microbial extracts from the Fundación MEDINA's collection. Bioassay-guided isolation of the active metabolites from this extract afforded eight new meroterpenoids of varying potencies, namely, memnobotrins C-E (1-3), a glycosylated isobenzofuranone (4), a tricyclic isobenzofuranone (5), a tetracyclic benzopyrane (6), a tetracyclic isobenzofuranone (7), and a pentacyclic isobenzofuranone (8). The structures of the isolated compounds were established by (+)-ESI-TOF high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy. Compounds 1, 2, and 4 exhibited potent antiparasitic activity against P. falciparum 3D7 (EC₅₀ 0.04-0.243 μM) and T. cruzi Tulahuen (EC₅₀ 0.266-1.37 μM) parasites, as well as cytotoxic activity against HepG2 tumoral liver cells (EC₅₀ 1.20-4.84 μM). The remaining compounds (3, 5-8) showed moderate or no activity against the above-mentioned parasites and cells.

In vitro interaction of polyethylene glycol-block-poly(D,L-lactide) nanocapsule devices with host cardiomyoblasts and Trypanosoma cruzi-infective forms

Chagas disease, caused by the protozoan Trypanosoma cruzi, is an important public health problem in Latin America. Nanoencapsulation of anti-T. cruzi drugs has significantly improved their efficacy and reduced cardiotoxicity. Thus, we investigated the in vitro interaction of polyethylene glycol-block-poly(D,L-lactide) nanocapsules (PEG-PLA) with trypomastigotes and with intracellular amastigotes of the Y strain in cardiomyoblasts, which are the infective forms of T. cruzi, using fluorescence and confocal microscopy. Fluorescently labeled nanocapsules (NCs) were internalized by non-infected H9c2 cells toward the perinuclear region. The NCs did not induce significant cytotoxicity in the H9c2 cells, even at the highest concentrations and interacted equally with infected and non-infected cells. In infected cardiomyocytes, NCs were distributed in the cytoplasm and located near intracellular amastigote forms. PEG-PLA NCs and trypomastigote form interactions also occurred. Altogether, this study contributes to the development of engineered polymeric nanocarriers as a platform to encapsulate drugs and to improve their uptake by different intra- and extracellular forms of T. cruzi, paving the way to find new therapeutic strategies to fight the causative agent of Chagas disease.

Gum-based nanocapsules comprising naphthoquinones enhance the apoptotic and trypanocidal activity against Trypanosoma evansi

Nanoencapsulation is a promising approach to enhance the therapeutic potential of a drug. Herein, three selected naphthoquinone (NTQ) derivatives, based on the IC₅₀ value against Trypanosoma evansi, were encapsulated using gum damar as biocompatible and biodegradable natural gum via nanoprecipitation method. Nanoformulation of NTQs (NNTQs) was less than 150 nm in size, was found to be stable and released the drug in a sustained manner. All the three NNTQs exhibited significant antitrypanosomal effect and morphological changes at approximately two to three times lesser drug concentrations. The nanoformulations exhibited enhanced production of reactive oxygen species (ROS) in the axenic culture of T. evansi and less cytotoxic effect on horse peripheral blood mononuclear cells relative to pure NTQs. As evidenced by flow cytometry, the NNTQs showed dose-dependent and time-dependent increased transition of live cells (AV^-PI^-) to early apoptotic cells (AV⁺PI^-), late apoptotic cells (AV^-PI⁺), and necrotic cells (AV⁺PI⁺) using annexin V/propidium iodide probe analysis. The results concluded that NNTQs induced more ROS, apoptosis and necrotic effects that exhibited more inhibitory effect on the growth of T. evansi with respect to respective NTQ by themselves.

Repositioning of Tamoxifen in Surface-Modified Nanocapsules as a Promising Oral Treatment for Visceral Leishmaniasis

Standards of care for human visceral leishmaniasis (VL) are based on drugs used parenterally, and oral treatment options are urgently needed. In the present study, a repurposing strategy was used associating tamoxifen (TMX) with polyethylene glycol-block-polylactide nanocapsules (NC) and its anti-leishmanial efficacy was reported in vivo. Stable surface modified-NC (5 mg/mL of TMX) exhibited 200 nm in size, +42 mV of zeta potential, and 98% encapsulation efficiency. Atomic force microscopy evidenced core-shell-NC. Treatment with TMX-NC reduced parasite-DNA quantified in liver and spleen compared to free-TMX; and provided a similar reduction of parasite burden compared with meglumine antimoniate in mice and hamster models. Image-guided biodistribution showed accumulation of NC in liver and spleen after 30 min post-administration. TMX-NC reduced the number of liver granulomas and restored the aspect of capsules and trabeculae in the spleen of infected animals. TMX-NC was tested for the first time against VL models, indicating a promising formulation for oral treatment.

Dogs as a Model for Chemotherapy of Chagas Disease and Leishmaniasis

BACKGROUND

Dogs are natural reservoir of Chagas disease (CD) and leishmaniasis and have been used for studies of these infections as they develop different clinical forms of these diseases similar to humans.

OBJECTIVE

This article describes publications on the dog model relative to CD and leishmaniasis chemotherapy.

METHODS

The search of articles was based on PubMed, Scopus and MESH using the keywords: dog, Trypanosoma cruzi, treatment (T. cruzi chemotherapy analysis), Leishmania chagasi, Leishmania infantum, canine visceral leishmaniasis, treatment (Leishmania chemotherapy evaluation).

RESULTS

Benznidazole and nifurtimox were used as a reference in the treatment of CD and in combination with other compounds. Eleven out of the fifteen studies have authors from the same team, using similar protocols and post-treatment evaluations, which assured more reproducibility and credibility. Twenty leishmaniasis studies, especially on visceral leishmaniasis, presenting at least one parasitological analysis tested in distinct monochemotherapy and polychemotherapy approaches were accessed. Data demonstrated that polychemotherapy was more effective in improving the clinical signs and parasitism control.

CONCLUSION

The benefits of treatment in terms of reducing or eliminating lesions and/or cardiac dysfunctions were demonstrated at acute and/or chronic phases relative to parasite load and/or the T. cruzi strain resistance to treatment. BZ presented better therapeutic results than the two EBI compounds evaluated. Although treatment of the canine visceral leishmaniasis was not able to induce complete parasite clearance, it can improve clinical recovery. Thus, the dog is a good model for CD and leishmaniasis studies of chemotherapy and may be indicated for pre-clinical trials of new treatments.

Nano-Medicines a Hope for Chagas Disease!

Chagas disease, is a vector-mediated tropical disease whose causative agent is a parasitic protozoan named Trypanosoma cruzi. It is a very severe health issue in South America and Mexico infecting millions of people every year. Protozoan T. cruzi gets transmitted to human through Triatominae, a subfamily of the Reduviidae, and do not have any effective treatment or preventative available. The lack of economic gains from this tropical parasitic infection, has always been the reason behind its negligence by researchers and drug manufacturers for many decades. Hence there is an enormous requirement for more efficient and novel strategies to reduce the fatality associated with these diseases. Even, available diagnosis protocols are outdated and inefficient and there is an urgent need for rapid high throughput diagnostics as well as management protocol. The current advancement of nanotechnology in the field of healthcare has generated hope for better management of many tropical diseases including Chagas disease. Nanoparticulate systems for drug delivery like poloxamer coated nanosuspension of benzimidazole have shown promising results in reducing toxicity, elevating efficacy and bioavailability of the active compound against the pathogen, by prolonging release, thereby increasing the therapeutic index. Moreover, nanoparticle-based drug delivery has shown promising results in inducing the host’s immune response against the pathogen with very few side effects. Besides, advances in diagnostic assays, such as nanosensors, aided in the accurate detection of the parasite. In this review, we provide an insight into the life cycle stages of the pathogen in both vertebrate host and the insect vector, along with an overview of the current therapy for Chagas disease and its limitations; nano carrier-based delivery systems for antichagasic agents, we also address the advancement of nano vaccines and nano-diagnostic techniques, for treatment of Chagas disease, majorly focusing on the novel perspectives in combating the disease.

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.

Chagas Disease Chemotherapy: What Do We Know So Far?

Chagas disease is a Neglected Tropical Disease (NTD), and although endemic in Latin America, affects around 6-7 million people infected worldwide. The treatment of Chagas disease is based on benznidazole and nifurtimox, which are the only available drugs. However, they are not effective during the chronic phase and cause several side effects. Furthermore, BZ promotes cure in 80% of the patients in the acute phase, but the cure rate drops to 20% in adults in the chronic phase of the disease. In this review, we present several studies published in the last six years, which describes the antiparasitic potential of distinct drugs, from the synthesis of new compounds aiming to target the parasite, as well as the repositioning and the combination of drugs. We highlight several compounds for having shown results that are equivalent or superior to BZ, which means that they should be further studied, either in vitro or in vivo. Furthermore, we stand out the differences in the effects of BZ on the same strain of T. cruzi, which might be related to methodological differences such as parasite and cell ratios, host cell type and the time of adding the drug. In addition, we discuss the wide variety of strains and also the cell types used as a host cell, which makes it difficult to compare the trypanocidal effect of the compounds.

Efficacy of nanoemulsion with Pterodon emarginatus Vogel oleoresin for topical treatment of cutaneous leishmaniasis

Cutaneous leishmaniasis (CL) is a neglected tropical skin disease caused by the protozoan genus Leishmania. The treatment is restricted to a handful number of drugs that exhibit toxic effects, limited efficacy, and drug resistance. Additionally, developing an effective topical treatment is still an enormous unmet medical challenge. Natural oils, e.g. the oleoresin from P. emarginatus fruits (SO), contain various bioactive molecules, especially terpenoid compounds such as diterpenes and sesquiterpenes. However, its use in topical formulations can be impaired due to the natural barrier of the skin for low water solubility compounds. Nanoemulsions (NE) are drug delivery systems able to increase penetration of lipophilic compounds throughout the skin, improving their topical effect. In this context, we propose the use of SO-containing NE (SO-NE) for CL treatment. The SO-NE was produced by a low energy method and presented suitable physicochemical characteristic: average diameter and polydispersity index lower than 180 nm and 0.2, respectively. Leishmania (Leishmania) amazonensis-infected BALB/c mice were given topical doses of SO or SO-NE. The topical use of a combination of SO-NE and intraperitoneal meglumine antimoniate reduced lesion size by 41 % and tissue regeneration was proven by histopathological analyses. In addition, a reduction in the parasitic load and decreased in the level of IFN-γ in the lesion may be associated, as well as a lower level of the cytokine IL-10 may be associated with a less intense inflammatory process. The present study suggests that SO-NE in combination meglumine antimoniate represents a promising alternative for the topical treatment of CL caused by L. (L.) amazonensis.

Evaluation of the anti-Trypanosoma cruzi activity in vitro and in vivo of silibinin and silibinin in association to benznidazole

Chagas disease (CD) is endemic in Latin America. Drugs available for its treatment are benznidazole (BZ)/nifurtimox (NF), both with low efficacy in the late infection and responsible for several side effects. Studies of new drugs for CD among natural products, and using drug combinations with BZ/NF are recommended. Silibinin (SLB) is a natural compound that inhibits the efflux pump (Pgp) of drugs in host cell membranes, causes death of trypanosomatids, has anti-inflammatory activity, and was never assayed against T. cruzi. Here, in vitro and in vivo activities of SLB, SLB+BZ, and BZ against T. cruzi Y strain were evaluated. Cytotoxicity of SLB in VERO cells by the MTT method revealed IC50 of 250.22 μM. The trypanocidal activity evaluated by resazurin method in epimastigotes showed that SLB 25 μM inhibited parasite growth. SLB IC50 and selectivity index (SI) for amastigote were 79.81 μM and 3.13, respectively. SLB100+BZ10 showed higher parasite inhibition (91.44%) than SLB or BZ. Swiss mice infected with Y strain were treated with SLB, SLB+BZ, and BZ. Parasitemia was evaluated daily and 90, 180, and 240 days after treatment in surviving animals by hemoculture, blood qPCR, and after euthanasia, by qPCR in heart tissue. SLB monotherapy was not able to control the parasitemia/mortality of the animals. Parasitological negativation of 85.7-100% was observed in the experimental groups treated with SLB+BZ. Although SLB had shown activity against T. cruzi in vitro, it was not active in mice. Thus, the results of the therapeutic effect observed with SLB+BZ may be interpreted as a result from BZ action.

Recent Nano-based Therapeutic Intervention of Bioactive Sesquiterpenes: Prospects in Cancer Therapeutics

In the recent scenario, nanotechnology-based therapeutics intervention has gained tremendous impetus all across the globe. Nano-based pharmacological intervention of various bioactive compounds has been explored on an increasing scale. Sesquiterpenes are major constituents of essential oils (EOs) present in various plant species which possess intriguing therapeutic potentials. However, owing to their poor physicochemical properties; they have pharmacological limitations. Recent advances in nano-based therapeutic interventions offer various avenues to improve their therapeutic applicability. Reckoning with these, the present review collates various nano-based therapeutic intervention of sesquiterpenes with prospective potential against various debilitating diseases especially cancer. In our viewpoint, considering the burgeoning advancement in the field of nanomedicine; in the near future, the clinical applicability of these nano-formulated sesquiterpenes can be foreseen with great enthusiasm.

Current trends in the pharmacological management of Chagas disease

Chagas disease (CD) is a tropical neglected illness, affecting mainly populations of low socioeconomic status in Latin America. An estimated 6 to 8 million people worldwide are infected with Trypanosoma cruzi, the etiological agent of CD. Despite being one of the main global health problems, this disease continues without effective treatment during the chronic phase of the infection. The limitation of therapeutic strategies has been one of the biggest challenges on the fight against CD. Nifurtimox and benznidazole, developed in the 1970s, are still the only commercial options with established efficacy on CD. However, the efficacy of these drugs have a proven efficacy only during early infection and the benefits in the chronic phase are questionable. Consequently, there is a growing need for new pharmacological alternatives, either by optimization of existing drugs or by the formulation of new compounds. In the present study, a literature review of the currently adopted therapy, its concomitant combination with other drugs, and potential future treatments for CD was performed, considering articles published from 2012. The revised articles were selected according to the protocol of treatment: evaluation of drug association, drug repositioning and research of new drugs. As a result of the present revision, it was possible to conclude that the use of benznidazole in combination with other compounds showed better results when compared with its use as a single therapy. The search of new drugs has been the strategy most used in pursuing more effective forms of treatment for CD. However, studies have still focused on basic research, that is, they are still in a pre-clinical stage, using methodologies based on in vitro or in animal studies.

Lychnopholide in Poly(d,l-Lactide)-Block-Polyethylene Glycol Nanocapsules Cures Infection with a Drug-Resistant Trypanosoma cruzi Strain at Acute and Chronic Phases

Chagas disease remains neglected, and current chemotherapeutics present severe limitations. Lychnopholide (LYC) at low doses loaded in polymeric poly(d,l-lactide)-block-polyethylene glycol (PLA-PEG) nanocapsules (LYC-PLA-PEG-NC) exhibits anti-Trypanosoma cruzi efficacy in mice infected with a partially drug-resistant strain. This study reports the efficacy of LYC-PLA-PEG-NC at higher doses in mice infected with a T. cruzi strain resistant to benznidazole (BZ) and nifurtimox (NF) treated at both the acute phase (AP) and the chronic phase (CP) of infection by the oral route. Mice infected with the T. cruzi VL-10 strain were treated by the oral route with free LYC (12 mg/kg of body weight/day), LYC-PLA-PEG-NC (8 or 12 mg/kg/day), or BZ at 100 mg/kg/day or were not treated (controls). Treatment efficacy was assessed by hemoculture (HC), PCR, enzyme-linked immunosorbent assay (ELISA), heart tissue quantitative PCR (qPCR), and histopathology. According to classical cure criteria, treatment with LYC-PLA-PEG-NC at 12 mg/kg/day cured 75% (AP) and 88% (CP) of the animals, while at a dose of 8 mg/kg/day, 43% (AP) and 43% (CP) were cured, showing dose-dependent efficacy. The negative qPCR results for heart tissue and the absence of inflammation/fibrosis agreed with the negative results obtained by HC and PCR. Thus, the mice treated with the highest dose could be considered 100% cured, in spite of a low ELISA reactivity in some animals. No cure was observed in animals treated with free LYC or BZ or the controls. These results are exceptional in terms of experimental Chagas disease chemotherapy and provide evidence of the outstanding contribution of nanotechnology in mice infected with a T. cruzi strain totally resistant to BZ and NF at both phases of infection. Therefore, LYC-PLA-PEG-NC has great potential as a new treatment for Chagas disease and deserves further investigations in clinical trials.

The effect of benznidazole dose among the efficacy outcome in the murine animal model. A quantitative integration of the literature

Despite more than 100 years since it was firstly described Chagas disease, only two drugs are available to treat Chagas disease: Nifurtimox launched by Bayer in 1965 and benznidazole launched by Roche in 1971. Drug discovery initiatives have been looking for new compounds as an alternative to these old drugs. Although new platforms have been used with the latest technologies, a critical step on that process still relies on the in vivo model. Unfortunately, to date, available animal models have limited predictive value and there is no standardization. With the aim to better understand the role of benznidazole, the current standard of care of Chagas disease, we performed this review. We intend to analyze the influence of the experimental design of the most used animal model, the murine model, in the assessment of the efficacy endpoint.

Activity of the sesquiterpene lactone goyazensolide against Trypanosoma cruzi in vitro and in vivo

BACKGROUND

The current drugs for Chagas disease treatment present several limitations.

METHODS

The sesquiterpene lactone goyazensolide (GZL) was evaluated regarding to cytotoxicity and trypanocidal activity against amastigotes, selectivity index (SI) in vitro, acute toxicity and anti-Trypanosoma cruzi activity in vivo.

RESULTS

The in vitro cytotoxicity in H9c2 cells was observed at doses >250 ng mL-1 of GZL and the SI were of 52.82 and 4.85 (24 h) and of 915.00 and 41.00 (48 h) for GZL and BZ, respectively. Nephrotoxicity and hepatotoxicity were not verified. Treatment with GZL of mice infected with CL strain led to a significant decrease of parasitaemia and total survival at doses of 1 and 3 mg kg-1 day-1 by oral and IV, respectively. This last group cured 12.5% of the animals (negativation of HC, PCR, qPCR and ELISA). Animals infected with Y strain showed significant decrease of parasitaemia and higher negativation in all parasitological tests in comparison to BZ and control groups, but were ELISA reactive, as well as the BZ group, but mice treated with 5.0 mg kg-1 day-1 by oral were negative in parasitological tests and survived.

CONCLUSION

GZL was more active against T. cruzi than benznidazole in vitro and presented important therapeutic activity in vivo in both T. cruzi strains.

Advances in nanocarriers as drug delivery systems in Chagas disease

Chagas disease is one of the most important public health problems in Latin America due to its high mortality and morbidity levels. There is no effective treatment for this disease since drugs are usually toxic with low bioavailability. Serious efforts to achieve disease control and eventual eradication have been unsuccessful to date, emphasizing the need for rapid diagnosis, drug development, and a reliable vaccine. Novel systems for drug and vaccine administration based on nanocarriers represent a promising avenue for Chagas disease treatment. Nanoparticulate systems can reduce toxicity, and increase the efficacy and bioavailability of active compounds by prolonging release, and therefore improve the therapeutic index. Moreover, nanoparticles are able to interact with the host's immune system, modulating the immune response to favour the elimination of pathogenic microorganisms. In addition, new advances in diagnostic assays, such as nanobiosensors, are beneficial in that they enable precise identification of the pathogen. In this review, we provide an overview of the strategies and nanocarrier-based delivery systems for antichagasic agents, such as liposomes, micelles, nanoemulsions, polymeric and non-polymeric nanoparticles. We address recent progress, with a particular focus on the advances of nanovaccines and nanodiagnostics, exploring new perspectives on Chagas disease treatment.

Nanoparticulate drug delivery systems for the treatment of neglected tropical protozoan diseases

Neglected Tropical Diseases (NTDs) comprise of a group of seventeen infectious conditions endemic in many developing countries. Among these diseases are three of protozoan origin, namely leishmaniasis, Chagas disease, and African trypanosomiasis, caused by the parasites Leishmania spp., Trypanosoma cruzi, and Trypanosoma brucei respectively. These diseases have their own unique challenges which are associated with the development of effective prevention and treatment methods. Collectively, these parasitic diseases cause more deaths worldwide than all other NTDs combined. Moreover, many current therapies for these diseases are limited in their efficacy, possessing harmful or potentially fatal side effects at therapeutic doses. It is therefore imperative that new treatment strategies for these parasitic diseases are developed. Nanoparticulate drug delivery systems have emerged as a promising area of research in the therapy and prevention of NTDs. These delivery systems provide novel mechanisms for targeted drug delivery within the host, maximizing therapeutic effects while minimizing systemic side effects. Currently approved drugs may also be repackaged using these delivery systems, allowing for their potential use in NTDs of protozoan origin. Current research on these novel delivery systems has provided insight into possible indications, with evidence demonstrating their improved ability to specifically target pathogens, penetrate barriers within the host, and reduce toxicity with lower dose regimens. In this review, we will examine current research on these delivery systems, focusing on applications in the treatment of leishmaniasis, Chagas disease, and African trypanosomiasis. Nanoparticulate systems present a unique therapeutic alternative through the repositioning of existing medications and directed drug delivery.

Nanoencapsulation of benznidazole in calcium carbonate increases its selectivity to Trypanosoma cruzi

Chagas disease is a public health problem, affecting about 7 million people worldwide. Benznidazole (BZN) is the main treatment option, but it has limited effectiveness and can cause severe adverse effects. Drug delivery through nanoparticles has attracted the interest of the scientific community aiming to improve therapeutic options. The aim of this study was to evaluate the cytotoxicity of benznidazole-loaded calcium carbonate nanoparticles (BZN@CaCO3) on Trypanosoma cruzi strain Y. It was observed that BZN@CaCO3 was able to reduce the viability of epimastigote, trypomastigote and amastigote forms of T. cruzi with greater potency when compared with BZN. The amount of BZN necessary to obtain the same effect was up to 25 times smaller when loaded with CaCO3 nanoparticles. Also, it was observed that BZN@CaCO3 enhanced the selectivity index. Furthermore, the cell-death mechanism induced by both BZN and BZN@CaCO3 was evaluated, indicating that both substances caused necrosis and changed mitochondrial membrane potential.

Optimization of Curcuma Oil/Quinine-Loaded Nanocapsules for Malaria Treatment

Quinine, a treatment used in chloroquine-resistant falciparum malaria, was loaded into poly(ɛ-caprolactone) or Eudragit^® RS100 nanocapsules using Curcuma oil as the oil-based core. Until now, the effect of cationic nanocapsules on malaria has not been reported. A 2⁴ factorial design was adopted using, as independent variables, the concentration of Curcuma oil, presence of quinine, type of polymer, and aqueous surfactant. Diameter, zeta potential, and pH were the responses studied. The formulations were also evaluated for drug content, encapsulation efficiency, photostability, and antimalarial activity against Plasmodium berghei-infected mice. The type of polymer influenced all of the responses studied. Quinine-loaded Eudragit^® RS100 (F13) and PCL nanocapsules (F9), both with polysorbate 80 coating, showed nanometric particle size, positive zeta potential, neutral pH, high drug content, and quinine photoprotection ability; thus, these nanocapsules were selected for in vivo tests. Both formulations showed lower levels of parasitemia from the beginning of the experiment (5.78 ± 3.60 and 4.76 ± 3.46% for F9 and F13, respectively) and highest survival mean time (15.3 ± 2.0 and 14.9 ± 5.6 days for F9 and F13, respectively). F9 and F13 showed significant survival curve compared to saline, thus demonstrating that nanoencapsulation improved bioefficacy of QN and co-encapsulated curcuminoids, regardless of the surface charge.

Increased Body Exposure to New Anti-Trypanosomal Through Nanoencapsulation

Lychnopholide, a lipophilic sesquiterpene lactone, is efficacious in mice at the acute and chronic phases of Chagas disease. Conventional poly-ε-caprolactone (PCL) and long-circulating poly(D,L-lactide)-block-polyethylene glycol (PLA-PEG) nanocapsules containing lychnopholide were developed and characterized. Lychnopholide presented high association efficiency (>90%) with the nanocapsules. A new, fast and simple HPLC-UV-based bioanalytical method was developed, validated in mouse plasma and applied to lychnopholide quantification in in vitro release kinetics and pharmacokinetics. The nanocapsules had mean hydrodynamic diameters in the range of 100-250 nm, negative zeta potentials (-30 mV to -57 mV), with good physical stability under storage. Atomic force microscopy morphological analysis revealed spherical monodispersed particles and the absence of lychnopholide crystallization or aggregation. Association of lychnopholide to PLA-PEG nanocapsules resulted in a 16-fold increase in body exposure, a 26-fold increase in plasma half-life and a dramatic reduction of the lychnopholide plasma clearance (17-fold) in comparison with free lychnopholide. The improved pharmacokinetic profile of lychnopholide in long-circulating nanocapsules is in agreement with the previously reported improved efficacy observed in Trypanosoma cruzi-infected mice. The present lychnopholide intravenous dosage form showed great potential for further pre-clinical and clinical studies in Chagas disease and cancer therapies.

Ravuconazole self-emulsifying delivery system: in vitro activity against Trypanosoma cruzi amastigotes and in vivo toxicity

Self-emulsifying drug delivery systems (SEDDSs) are lipid-based anhydrous formulations composed of an isotropic mixture of oil, surfactant, and cosurfactants usually presented in gelatin capsules. Ravuconazole (Biopharmaceutics Classification System [BCS] Class II) is a poorly water-soluble drug, and a SEDDS type IIIA was designed to deliver it in a predissolved state, improving dissolution in gastrointestinal fluids. After emulsification, the droplets had mean hydrodynamic diameters <250 nm, zeta potential values in the range of −45 mV to −57 mV, and showed no signs of ravuconazole precipitation. Asymmetric flow field-flow fractionation with dynamic and multiangle laser light scattering was used to characterize these formulations in terms of size distribution and homogeneity. The fractograms obtained at 37°C showed a polydisperse profile for all blank and ravuconazole–SEDDS formulations but no large aggregates. SEDDS increased ravuconazole in vitro dissolution extent and rate (20%) compared to free drug (3%) in 6 h. The in vivo toxicity of blank SEDDS comprising Labrasol^® surfactant in different concentrations and preliminary safety tests in repeated-dose oral administration (20 days) showed a dose-dependent Labrasol toxicity in healthy mice. Ravuconazole–SEDDS at low surfactant content (10%, v/v) in Trypanosoma cruzi-infected mice was safe during the 20-day treatment. The anti-T. cruzi activity of free ravuconazole, ravuconazole–SEDDS and each excipient were evaluated in vitro at equivalent ravuconazole concentrations needed to inhibit 50% or 90% (IC₅₀ and IC₉₀), respectively of the intracellular amastigote form of the parasite in a cardiomyocyte cell line. The results showed a clear improvement of the ravuconazole anti-T. cruzi activity when associated with SEDDS. Based on our results, the repurposing of ravuconazole in SEDDS dosage form is a strategy that deserves further in vivo investigation in preclinical studies for the treatment of human T. cruzi infections.

Biodegradable Polymeric Nanocapsules Prevent Cardiotoxicity of Anti-Trypanosomal Lychnopholide

Chagas disease is a neglected parasitic disease caused by the protozoan Trypanosoma cruzi. New antitrypanosomal options are desirable to prevent complications, including a high rate of cardiomyopathy. Recently, a natural substance, lychnopholide, has shown therapeutic potential, especially when encapsulated in biodegradable polymeric nanocapsules. However, little is known regarding possible adverse effects of lychnopholide. Here we show that repeated-dose intravenous administration of free lychnopholide (2.0 mg/kg/day) for 20 days caused cardiopathy and mortality in healthy C57BL/6 mice. Echocardiography revealed concentric left ventricular hypertrophy with preserved ejection fraction, diastolic dysfunction and chamber dilatation at end-stage. Single cardiomyocytes presented altered contractility and Ca²⁺ handling, with spontaneous Ca²⁺ waves in diastole. Acute in vitro lychnopholide application on cardiomyocytes from healthy mice also induced Ca²⁺ handling alterations with abnormal RyR2-mediated diastolic Ca²⁺ release. Strikingly, the encapsulation of lychnopholide prevented the cardiac alterations induced in vivo by the free form repeated doses. Nanocapsules alone had no adverse cardiac effects. Altogether, our data establish lychnopholide presented in nanocapsule form more firmly as a promising new drug candidate to cure Chagas disease with minimal cardiotoxicity. Our study also highlights the potential of nanotechnology not only to improve the efficacy of a drug but also to protect against its adverse effects.

Natural Sesquiterpene Lactones as Potential Trypanocidal Therapeutic Agents: A Review

Chagas’ disease and Human African Trypanosomiasis are parasitic diseases that remain major health problems, mainly among the poorest and the most marginalized communities from Latin America and Africa. The scarcity of effective chemotherapy, due to the low investment in the research and development (R&D) of new drugs, together with a high incidence of side effects, and the emergence of drug resistance phenomena emphasize the urgent need for new prophylactic and therapeutic agents. Over the ages, humans have employed natural products to treat a wide spectrum of diseases. Recently, the pharmaceutical industry has focused on plant research and a large body of evidence has been collected to demonstrate the immense potential of medicinal plants as a source of bioactive compounds and lead molecules. In the field of parasitic diseases, drug development from plants has been successful for the sesquiterpene lactone (STL) artemisinin, which is employed as an antimalarial agent. STLs are a large group of naturally occurring terpenoids derived from plants that mostly belong to the Asteraceae family which exhibit a variety of skeletal arrangements and are the largest and most diverse category of natural products with an α-methylene-λ-lactone motif. STLs display a broad spectrum of biological activities such as antitumor, cytotoxic, antibacterial, anthelmintic, uterus contracting, antimalarial, neurotoxic, antiprotozoal and allergic (contact dermatitis) activities. In this context, the purpose of the present review is to provide an overview of the trypanocidal activity reported for STLs against Trypanosoma cruzi and T. brucei rhodesiense over the period 1993–2015.

Efficacy of Lychnopholide Polymeric Nanocapsules after Oral and Intravenous Administration in Murine Experimental Chagas Disease

The etiological treatment of Chagas disease remains neglected. The compounds available show several limitations, mainly during the chronic phase. Lychnopholide encapsulated in polymeric nanocapsules (LYC-NC) was efficacious in mice infected with Trypanosoma cruzi and treated by intravenous administration during the acute phase (AP). As the oral route is preferred for treatment of chronic infections, such as Chagas disease, this study evaluated the use of oral LYC-NC in the AP and also compared it with LYC-NC administered to mice by the oral and intravenous routes during the chronic phase (CP). The therapeutic efficacy was evaluated by fresh blood examination, hemoculture, PCR, and enzyme-linked immunosorbent assay (ELISA). The cure rates in the AP and CP were 62.5% and 55.6%, respectively, upon oral administration of LYC-poly(d,l-lactide)-polyethylene glycol nanocapsules (LYC-PLA-PEG-NC) and 57.0% and 30.0%, respectively, with LYC-poly-ε-caprolactone nanocapsules (LYC-PCL-NC). These cure rates were significantly higher than that of free LYC, which did not cure any animals. LYC-NC formulations administered orally during the AP showed cure rates similar to that of benznidazole, but only LYC-NC cured mice in the CP. Similar results were achieved with intravenous treatment during the CP. The higher cure rates obtained with LYC loaded in PLA-PEG-NC may be due to the smaller particle size of these NC and the presence of PEG, which influence tissue diffusion and the controlled release of LYC. Furthermore, PLA-PEG-NC may improve the stability of the drug in the gastrointestinal tract. This work is the first report of cure of experimental Chagas disease via oral administration during the CP. These findings represent a new and important perspective for oral treatment of Chagas disease.

Polymeric nanocapsules prevent oxidation of core-loaded molecules: evidence based on the effects of docosahexaenoic acid and neuroprostane on breast cancer cells proliferation

Background

Nanocapsules, as a delivery system, are able to target drugs and other biologically sensitive molecules to specific cells or organs. This system has been intensively investigated as a way to protect bioactives drugs from inactivation upon interaction with the body and to ensure the release to the target. However, the mechanism of improved activity of the nanoencapsulated molecules is far from being understood at the cellular and subcellular levels. Epidemiological studies suggest that dietary polyunsaturated fatty acids (PUFA) can reduce the morbidity and mortality from breast cancer. This influence could be modulated by the oxidative status of the diet and it has been suggested that the anti-proliferative properties of docosahexaenoic acid (DHA) are enhanced by pro-oxidant agents.

Methods

The effect of encapsulation of PUFA on breast cancer cell proliferation in different oxidative medium was evaluated in vitro. We compared the proliferation of the human breast cancer cell line MDA-MB-231 and of the non-cancer human mammary epithelial cell line MCF-10A in different experimental conditions.

Results

DHA possessed anti-proliferative properties that were prevented by alpha-tocopherol (an antioxidant) and enhanced by the pro-oxidant hydrogen peroxide that confirms that DHA has to be oxidized to exert its anti-proliferative properties. We also evaluated the anti-proliferative effects of the 4(RS)-4-F_4t-neuroprostane, a bioactive, non-enzymatic oxygenated metabolite of DHA known to play a major role in the prevention of cardiovascular diseases. DHA-loaded nanocapsules was less potent than non-encapsulated DHA while co-encapsulation of DHA with H₂O₂ maintained the inhibition of proliferation. The nanocapsules slightly improves the anti-proliferative effect in the case of 4(RS)-4-F_4t-neuroprostane that is more hydrophilic than DHA.

Conclusion

Overall, our findings suggest that the sensitivity of tumor cell lines to DHA involves oxidized metabolites. They also indicate that neuroprostane is a metabolite participating in the growth reducing effect of DHA, but it is not the sole. These results also suggest that NC seek to enhance the stability against degradation, enhance cellular availability, and control the release of bioactive fatty acids following their lipophilicities.

Nanomedicines against Chagas disease: an update on therapeutics, prophylaxis and diagnosis

Chagas disease is a neglected parasitic infection caused by the protozoan Trypanosoma cruzi. After a mostly clinically silent acute phase, the disease becomes a lifelong chronic condition that can lead to chronic heart failure and thromboembolic phenomena followed by sudden death. Antichagasic treatment is only effective in the acute phase but fails to eradicate the intracellular form of parasites and causes severe toxicity in adults. Although conventional oral benznidazol is not a safe and efficient drug to cure chronic adult patients, current preclinical data is insufficient to envisage if conventional antichagasic treatment could be realistically improved by a nanomedical approach. This review will discuss how nanomedicines could help to improve the performance of therapeutics, vaccines and diagnosis of Chagas disease.