American tegumentary leishmaniasis in Brazil: a critical review of the current therapeutic approach with systemic meglumine antimoniate and short‐term possibilities for an alternative treatment

Development of a topical treatment for tegumentary leishmaniasis using 8-hydroxyquinoline

In the context of neglected diseases, tegumentary leishmaniasis (TL) presents an emerging and re-emerging character in the national territory and in the world. The treatment of TL has limitations, such as intravenous administration route, high toxicity, and high treatment costs. Thus, several researchers work on new therapeutic strategies to improve the effectiveness of the treatment of leishmaniasis. In this light, the present study used a topical formulation, containing 8-hydroquinoline (8-HQN), for the treatment of Balb/c mice infected with L. amazonensis. After the treatment, the mean diameter of the lesion was measured, as well as the parasite load in organs and immunological parameters associated with the treatment. The results showed that the animals treated with 8-HQN 5%, when compared to controls, showed a reduction in the mean diameter of the lesion and in the parasite load. The animals treated with the ointment showed a type 1 cellular immune response profile associated with the production of cytokines such as INF-γ and TNF-α. In addition, the treatment did not demonstrate toxicity to mice. Therefore, the topical formulation containing 8-HQN 5% is a promising candidate in the topical treatment and could be considered, in the future, as an alternative for the treatment of TL.

A review on potential therapeutic targets for the treatment of leishmaniasis

Leishmania, a protozoan parasite, is responsible for the occurrence of leishmaniasis, a disease that is prevalent in tropical regions. Visceral Leishmaniasis (VL), also known as kala-azar in Asian countries, is one of the most significant forms of VL, along with Cutaneous Leishmaniasis (CL) and Mucocutaneous Leishmaniasis (ML). Management of this condition typically entails the use of chemotherapy as the sole therapeutic option. The current treatments for leishmaniasis present several drawbacks, including a multitude of side effects, prolonged treatment duration, disparate efficacy across different regions, and the emergence of resistance. To address this urgent need, it is imperative to identify alternative treatments that are both safer and more effective. The identification of appropriate pharmacological targets in conjunction with biological pathways constitutes the initial stage of drug discovery. In this review, we have addressed the key metabolic pathways that represent potential pharmacological targets as well as prominent treatment options for leishmaniasis.

Amphotericin B resistance in Leishmania amazonensis: In vitro and in vivo characterization of a Brazilian clinical isolate

In Brazil, Leishmania amazonensis is the etiological agent of cutaneous and diffuse cutaneous leishmaniasis. The state of Maranhão in the Northeast of Brazil is prevalent for these clinical forms of the disease and also has high rates of HIV infection. Here, we characterized the drug susceptibility of a L. amazonensis clinical isolate from a 46-year-old man with diffuse cutaneous leishmaniasis coinfected with HIV from this endemic area. This patient underwent several therapeutic regimens with meglumine antimoniate, liposomal amphotericin B, and pentamidine, without success. In vitro susceptibility assays against promastigotes and intracellular amastigotes demonstrated that this isolate had low susceptibility to amphotericin B, when compared with the reference strain of this species that is considered susceptible to antileishmanial drugs. Additionally, we investigated whether the low in vitro susceptibility would affect the in vivo response to amphotericin B treatment. The drug was effective in reducing the lesion size and parasite burden in mice infected with the reference strain, whereas those infected with the clinical isolate and a resistant line (generated experimentally by stepwise selection) were refractory to amphotericin B treatment. To evaluate whether the isolate was intrinsically resistant to amphotericin B in animals, infected mice were treated with other drugs that had not been used in the treatment of the patient (miltefosine, paromomycin, and a combination of both). Our findings demonstrated that all drug schemes were able to reduce lesion size and parasite burden in animals infected with the clinical isolate, confirming the amphotericin B-resistance phenotype. These findings indicate that the treatment failure observed in the patient may be associated with amphotericin B resistance, and demonstrate the potential emergence of amphotericin B-resistant L. amazonensis isolates in an area of Brazil endemic for cutaneous leishmaniasis.

Efficacy of the treatment using a microemulsion loaded with epoxy-α-lapachone in combination with meglumine antimoniate against murine infection by Leishmania (Leishmania) amazonensis

Leishmaniasis is a disease caused by Leishmania spp., affecting millions of people around the world. For decades, its treatment has been based on pentavalent antimonials, which notoriously cause toxic side effects in patients. In this study, epoxy-α-lapachone incorporated into an oil-in-water-type microemulsion (ELAP-ME) and meglumine antimoniate (MA) were assayed in monotherapy and in combination (ELAP-ME/MA) in BALB/c mice infected with Leishmania (Leishmania) amazonensis. In general, there was a reduction in paw lesion size (up to 37% reduction) and decreases of parasite loads in the footpad (∼40%) and lymph nodes (∼31%) of animals treated with ELAP-ME/MA, when compared to the non-treated control groups. Analyses of serum biochemical parameters revealed that the ELAP-ME/MA showed lower renal and hepatic toxicity when compared to MA 2-doses/week monotherapy. These findings indicate that the ELAP-ME/MA combination may be a promising approach for the treatment of cutaneous leishmaniasis.

Design of Liquid Formulation Based on F127-Loaded Natural Dimeric Flavonoids as a New Perspective Treatment for Leishmaniasis

Infectious and Parasitic Diseases (IPD) remain a challenge for medicine due to several interconnected reasons, such as antimicrobial resistance (AMR). American tegumentary leishmaniasis (ATL) is an overlooked IPD causing persistent skin ulcers that are challenging to heal, resulting in disfiguring scars. Moreover, it has the potential to extend from the skin to the mucous membranes of the nose, mouth, and throat in both humans and various animals. Given the limited effectiveness and AMR of current drugs, the exploration of new substances has emerged as a promising alternative for ATL treatment. Arrabidaea brachypoda (DC). Bureau is a native Brazilian plant rich in dimeric flavonoids, including Brachydin (BRA), which displays antimicrobial activity, but still little has been explored regarding the development of therapeutic formulations. In this work, we present the design of a low-cost liquid formulation based on the use of Pluronic F127 for encapsulation of high BRA concentration (LF-B500). The characterization techniques revealed that BRA-loaded F127 micelles are well-stabilized in an unusual worm-like form. The in vitro cytotoxicity assay demonstrated that LF-B500 was non-toxic to macrophages but efficient in the inactivation of forms of Leishmania amazonensis promastigotes with IC50 of 16.06 µg/mL. The results demonstrated that LF-B500 opened a new perspective on the use of liquid formulation-based natural products for ATL treatment.

Effectiveness In Vivo and In Vitro of Polymeric Nanoparticles as a Drug Release System in the Treatment of Leishmaniasis

Leishmaniasis is a neglected disease caused by the parasite of the genus Leishmania. Current treatment regimens are obsolete and cause several side effects, promoting poor patient compliance, in addition to the vast majority already having the potential for resistance. Therefore, polymeric nanoparticles emerge as one of the viable alternatives to overcome existing limitations, through passive or active vectorization. This review aims to summarize the latest studies of polymeric nanoparticles as an alternative treatment for leishmaniasis. In the first section, the main pharmacokinetic and pharmacodynamic challenges of current drugs are reported. The second section details how nanoparticles with and without functionalization are efficient in the treatment of leishmaniasis, discussing the characteristics of the polymer in the formulation. In this way, polymeric nanoparticles can improve the physicochemical properties of leishmanicidal drugs, improving solubility and stability, as well as improve the release of these drugs, directly or indirectly reaching monocytes/macrophages. 64.28% drugs were focused on the treatment of visceral leishmaniasis, and 28.57% on cutaneous leishmaniasis. The most chosen polymers in the literature are chitosan (35.71%) and PLGA (35.71%), the others represented 14.30% drugs, with all able to manage the drug release and increase the in vitro and/or in vivo efficacy of the original molecule. However, there are several barriers for these nanoformulations to cross laboratory research and is necessary more in-depth studies about the metabolites and degradation pathways of the polymers used in the formulations and plasma proteomics studies.

Leishmanicidal activity of the venoms of the Scorpions Brotheas amazonicus and Tityus metuendus

Leishmaniasis is a vector-transmitted zoonosis caused by different species of the genus Leishmania, with a wide clinical spectrum. It is a public health problem aggravated by a series of limitations regarding treatment. In the search for new therapeutic alternatives, scorpion venoms are a source of multifunctional molecules that act against the natural resistance of pathogens. This work evaluated the antileishmanial potential of Brotheas amazonicus and Tityus metuendus venoms against the promastigote forms of Leishmania amazonensis e Leishmania guyanensis. The venoms of B. amazonicus and T. metuendus were evaluated for their constituents using Fourier Transform Infrared (FTIR). Growth inhibition and death of promastigotes were evaluated in the presence of diferente crude venom concentrations (100 µg/mL, 50 µg/mL, 10 µg/mL, 1 µg/mL) after one hour of incubation at 25 °C. The FTIR spectra of both venoms exhibited bands in approximate regions, revealing that both exhibit similar functional groups. Crude venom from both scorpion species showed similar or superior leishmanicidal effects to the standart drug N-methylglucamine antimoniate. At the highest concentration of 100 µg/mL, cultures of L. guyanensis treated with the venom of B. amazonicus showed the highest mortality percentages, above 28%, while T. metuendus venom showed the highest activity against L. amazonensis, with mortality above 7%. This preliminar study demonstrates that B. amazonicus and T. metuendus venoms can be important tools in the search for new drugs Against leishmaniasis. Next step involves evaluating the activity against the amastigote forms and purifying the venom proteins in order to identify the best anti-leishmania candidates.

Imidazo[1,2-a]pyrimidine as a New Antileishmanial Pharmacophore against Leishmania amazonensis Promastigotes and Amastigotes

Leishmania poses a substantial threat to the human population all over the globe because of its visceral and cutaneous spread engendered by all 20 species. Unfortunately, the available drugs against leishmania are already hobbled with toxicity, prolonged treatment, and increasing instances of acquirement of resistance. Under these grave circumstances, the development of new drugs has become imperative to keep these harmful microbes at bay. To this end, a Groebke-Blackburn-Bienaymé multicomponent reaction-based library of different imidazo-fused heterocycles has been synthesized and screened against Leishmania amazonensis promastigotes and amastigotes. Among the library compounds, the imidazo-pyrimidine 24 has been found to be the most effective (inhibitory concentration of 50% (IC50) < 10 μM), with selective antileishmanial activity on amastigote forms, a stage of the parasite related to human disease. The compound 24 has exhibited an IC50 value of 6.63 μM, being ∼two times more active than miltefosine, a reference drug. Furthermore, this compound is >10 times more destructive to the intracellular parasites than host cells. The observed in vitro antileishmanial activity along with suitable in silico physicochemical and absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties of compound 24 reinforce the imidazo-pyrimidine scaffold as a new antileishmanial pharmacophore and encourage further murine experimental leishmaniasis studies.

Biological Activities of Bismuth Compounds: An Overview of the New Findings and the Old Challenges Not Yet Overcome

Bismuth-based drugs have been used primarily to treat ulcers caused by Helicobacter pylori and other gastrointestinal ailments. Combined with antibiotics, these drugs also possess synergistic activity, making them ideal for multiple therapy regimens and overcoming bacterial resistance. Compounds based on bismuth have a low cost, are safe for human use, and some of them are also effective against tumoral cells, leishmaniasis, fungi, and viruses. However, these compounds have limited bioavailability in physiological environments. As a result, there is a growing interest in developing new bismuth compounds and approaches to overcome this challenge. Considering the beneficial properties of bismuth and the importance of discovering new drugs, this review focused on the last decade's updates involving bismuth compounds, especially those with potent activity and low toxicity, desirable characteristics for developing new drugs. In addition, bismuth-based compounds with dual activity were also highlighted, as well as their modes of action and structure-activity relationship, among other relevant discoveries. In this way, we hope this review provides a fertile ground for rationalizing new bismuth-based drugs.

Supramolecular assemblies from antimony(V) complexes for the treatment of leishmaniasis

The pentavalent meglumine antimoniate (MA) is still a first-line drug in the treatment of leishmaniasis in several countries. As an attempt to elucidate its mechanism of action and develop new antimonial drugs with improved therapeutic profile, Sb(V) complexes with different ligands, including β-cyclodextrin (β-CD), nucleosides and non-ionic surfactants, have been studied. Interestingly, Sb(V) oxide, MA, its complex with β-CD, Sb(V)-guanosine complex and amphiphilic Sb(V) complexes with N-alkyl-N-methylglucamide, have shown marked tendency to self-assemble in aqueous solutions, forming nanoaggregates, hydrogel or micelle-like nanoparticles. Surprisingly, the resulting assemblies presented in most cases slow dissociation kinetics upon dilution and a strong influence of pH, which impacted on their pharmacokinetic and therapeutic properties against leishmaniasis. To explain this unique property, we raised the hypothesis that multiple pnictogen bonds could contribute to the formation of these assemblies and their kinetic of dissociation. The present article reviews our current knowledge on the structural organization and physicochemical characteristics of Sb-based supramolecular assemblies, as well as their pharmacological properties and potential for treatment of leishmaniasis. This review supports the feasibility of the rational design of new Sb(V) complexes with supramolecular assemblies for the safe and effective treatment of leishmaniasis.

Is There Any Difference in the In Situ Immune Response in Active Localized Cutaneous Leishmaniasis That Respond Well or Poorly to Meglumine Antimoniate Treatment or Spontaneously Heal?

Localized cutaneous leishmaniasis caused by Leishmania braziliensis can either respond well or poorly to the treatment or heal spontaneously; It seems to be dependent on the parasite and/or host factors, but the mechanisms are not fully understood. We evaluated the in situ immune response in eighty-two active lesions from fifty-eight patients prior to treatment classified as early spontaneous regression (SRL-n = 14); treatment responders (GRL-n = 20); and non-responders (before first treatment/relapse, PRL1/PRL2-n = 24 each). Immunohistochemistry was used to identify cell/functional markers which were correlated with the clinical characteristics. PRL showed significant differences in lesion number/size, clinical evolution, and positive parasitological examinations when compared with the other groups. SRL presented a more efficient immune response than GRL and PRL, with higher IFN-γ/NOS2 and a lower percentage of macrophages, neutrophils, NK, B cells, and Ki-67+ cells. Compared to SRL, PRL had fewer CD4+ Tcells and more CD163+ macrophages. PRL1 had more CD68+ macrophages and Ki-67+ cells but less IFN-γ than GRL. PRL present a less efficient immune profile, which could explain the poor treatment response, while SRL had a more balanced immune response profile for lesion healing. Altogether, these evaluations suggest a differentiated profile of the organization of the inflammatory process for lesions of different tegumentary leishmaniasis evolution.

Temporal patterns, spatial risks, and characteristics of tegumentary leishmaniasis in Brazil in the first twenty years of the 21st Century

BACKGROUND

Tegumentary leishmaniasis (TL) is a significant public health issue in Brazil. The present ecological study describes the clinical and epidemiological characteristics of TL cases reported in the country, and analyzes the spatial and temporal patterns of the incidences and risks of occurrence across the five geopolitical regions and 27 federative units.

METHODOLOGY/PRINCIPAL FINDINGS

Data regarding new cases of TL notified between 2001 and 2020 were obtained from the Information System for Notifiable Diseases of the Brazilian Ministry of Health. Joinpoint and spatial and temporal generalized additive models were used to establish trends in the evolution of TL during the target period. The incidence rate for the entire period was 226.41 cases/100,000 inhabitants. All regions of Brazil showed trends of decreasing incidence rates, albeit with fluctuations at specific times, with the exception of the Southeast where rates have increased since 2014, most particularly in Minas Gerais state. The disease was concentrated predominantly in the North region, with Acre state leading the incidence rank in the whole country, followed by Mato Grosso (Midwest), Maranhão and Bahia (Northeast) states. The spatial distribution of the risk of TL occurrence in relation to the annual averages was relatively stable throughout the period. The cutaneous form of TL was predominant and cases most frequently occurred in rural areas and among men of working age. The ages of individuals contracting TL tended to increase during the time series. Finally, the proportion of confirmations by laboratory tests was lower in the Northeast.

CONCLUSION/SIGNIFICANCE

TL shows a declining trend in Brazil, but its widespread occurrence and the presence of areas with increasing incidence rates demonstrate the persistent relevance of this disease and the need for constant monitoring. Our findings reinforce the importance of temporal and spatial tools in epidemiologic surveillance routines and are valuable for targeting preventive and control actions.

Development of a microemulsion loaded with epoxy-α-lapachone against Leishmania (Leishmania) amazonensis murine infection

Epoxy-α-lapachone (ELAP), an oxirane-functionalized molecule synthesized from naturally occurring lapachol, has shown promising activity against murine infection with Leishmania (Leishmania) amazonensis. Herein, we report the successful development of oil-in-water-type (o/w) microemulsions (ME) loaded with ELAP (ELAP-ME) using Capmul MCM, Labrasol, and PEG 400. Stability studies revealed that ELAP-ME (100 µg/mL of ELAP), which was comprised of globule size smaller than 120.4 ± 7.7 nm, displayed a good stability profile over 73 days. ELAP-ME had an effect in BALB/c mice infected with L. (L.) amazonensis, causing reductions in paw lesions after two weeks of treatment (∼2-fold) when compared to untreated animals. Furthermore, there was also a reduction in the parasite load both in the footpad (60.3%) and in the lymph nodes (31.5%). Based on these findings, ELAP-ME emerges as a promising treatment for tegumentar leishmaniasis.

Cardiovascular Effects of Environmental Metal Antimony: Redox Dyshomeostasis as the Key Pathogenic Driver

Significance: Cardiovascular diseases (CVDs) are the leading cause of death worldwide, which may be due to sedentary lifestyles with less physical activity and over nutrition as well as an increase in the aging population; however, the contribution of pollutants, environmental chemicals, and nonessential metals to the increased and persistent CVDs needs more attention and investigation. Among environmental contaminant nonessential metals, antimony has been less addressed. Recent Advances: Among environmental contaminant nonessential metals, several metals such as lead, arsenic, and cadmium have been associated with the increased risk of CVDs. Antimony has been less addressed, but its potential link to CVDs is being gradually recognized. Critical Issues: Several epidemiological studies have revealed the significant deleterious effects of antimony on the cardiovascular system in the absence or presence of other nonessential metals. There has been less focus on whether antimony alone can contribute to the pathogenesis of CVDs and the proposed mechanisms of such possible effects. This review addresses this gap in knowledge by presenting the current available evidence that highlights the potential role of antimony in the pathogenesis of CVDs, most likely via antimony-mediated redox dyshomeostasis. Future Directions: More direct evidence from preclinical and mechanistic studies is urgently needed to evaluate the possible roles of antimony in mitochondrial dysfunction and epigenetic regulation in CVDs. Antioxid. Redox Signal. 38, 803-823.

Antileishmanial Screening, Cytotoxicity, and Chemical Composition of Essential Oils: A Special Focus on Piper callosum Essential Oil

Leishmania amazonensis is the etiological agent of tegumentary leishmaniasis, a disease characterized by the emergence of cutaneous and mucocutaneous ulcerated lesions that can evolve into severe destruction of skin tissue. Treatment of the disease is often accompanied by high toxicity and variable efficacy. Essential oils stand out for having diverse pharmacological properties. Here, we screened a panel of fourteen essential oils for their anti-L. amazonensis activity, cytotoxicity, and chemical profile. Lippia sidoides (LSEO) and Piper callosum (PCEO) oils displayed the best anti-promastigote and anti-amastigote activities with IC₅₀ of 31 and 21 μg/ml, respectively. PCEO was the safest oil with a desirable selectivity index >10. In addition, PCEO showed no cytotoxicity against the VERO line and erythrocytes. PCEO-treated amastigotes displayed mitochondrial membrane depolarization and high levels of intracellular ROS. Safrole (54.72 %) was the main component of PCEO. The results described here highlight the use of essential oils to combat tegumentary leishmaniasis.

Low doses of 3-phenyl-lawsone or meglumine antimoniate delivery by tattooing route are successful in reducing parasite load in cutaneous lesions of Leishmania (Viannia) braziliensis-infected hamsters

Current therapeutic ways adopted for the treatment of leishmaniasis are toxic and expensive including parasite resistance is a growing problem. Given this scenario, it is urgent to explore treatment alternatives for leishmaniasis. The aim of this study was to evaluate the effect of 3-phenyl-lawsone (3-PL) naphthoquinone on Leishmania (Viannia) braziliensis infection, both in vitro and in vivo, using two local routes of administration: subcutaneous (higher dose) and tattoo (lower dose). In vitro 3-PL showed low toxicity for macrophages (CC₅₀ >3200 µM/48h) and activity against intracellular amastigotes (IC₅₀ = 193 ± 19 µM/48h) and promastigotes (IC₅₀ = 116 ± 26 µM/72h), in which induced increased ROS generation. Additionally, 3-PL up-regulated the production of cytokines such as tumor necrosis factor alpha (TNF-α), monocyte chemotactic protein 1 (MCP-1), interleukin-6 (IL-6) and IL-10 in infected macrophages. However, the anti-amastigote action was independent of nitric oxide production. Treatment of hamsters infected with L. (V.) braziliensis from one week after infection with 3-PL by subcutaneous (25 µg/Kg) or tattooing (2.5 µg/Kg) route, during 3 weeks (3 times/week) or 2 weeks (2 times/week) significantly decreased the parasite load (p<0.001) in the lesion. The reduction of parasite load by 3-PL treatment was comparable to reference drug meglumine antimoniate administered by the same routes (subcutaneous 1mg/Kg and tattoo 0.1mg/Kg). In addition, treatment started from five weeks after infection with 3-PL per tattoo also decreased the parasite load. These results show the anti-leishmanial effect of 3-PL against L. (V.) braziliensis and its efficacy by subcutaneous (higher dose) and tattoo (lower dose) routes. In addition, this study shows that drug delivery by tattooing the lesion allows the use of lower doses than the conventional subcutaneous route, which may support the development of a new therapeutic strategy that can be adopted for leishmaniasis.

Leishmania spp. in indigenous populations: A mini-review

Leishmaniasis, considered a neglected vector-borne disease complex of global concern, has a significant impact on indigenous communities due to daily human and animal exposure in periurban, rural, and naturally preserved areas. This mini-review aims to assess and discuss studies of leishmaniasis in these communities of the New World and Old World, particularly those in the Americas and Asia. Such indigenous communities have been mostly built in poor traditional households with no mosquito-net protection, mostly located in environmentally protected areas, favoring vectors and reservoirs. The presence of leishmaniasis cases surrounding such indigenous areas indicated a high risk of infection, which may have been historically underestimated due to a lack of surveillance, even at present. The absence of studies of indigenous populations in recognized endemic areas may reflect insufficient health services. In conclusion, the persistence of this neglectful scenario may impact tragic outcomes and potential outbreaks in indigenous peoples and surroundings populations worldwide.

Cutaneous/Mucocutaneous Leishmaniasis Treatment for Wound Healing: Classical versus New Treatment Approaches

Cutaneous leishmaniasis (CL) and mucocutaneous leishmaniasis (ML) show clinical spectra that can range from a localized lesion (with a spontaneous healing process) to cases that progress to a generalized systemic disease with a risk of death. The treatment of leishmaniasis is complex since most of the available drugs show high toxicity. The development of an effective topical drug formulation for CL and ML treatment offers advantages as it will improve patient’s compliance to the therapy given the possibility for self-administration, as well as overcoming the first pass metabolism and the high costs of currently available alternatives. The most common dosage forms include solid formulations, such as membranes and semi-solid formulations (e.g., ointments, creams, gels, and pastes). Topical treatment has been used as a new route of administration for conventional drugs against leishmaniasis and its combinations, as well as to exploit new substances. In this review, we discuss the advantages and limitations of using topical drug delivery for the treatment of these two forms of leishmaniasis and the relevance of combining this approach with other pharmaceutical dosage forms. Emphasis will also be given to the use of nanomaterials for site-specific delivery.

Carajurin: a anthocyanidin from Arrabidaea chica as a potential biological marker of antileishmanial activity

Leishmaniasis is a group of neglected tropical diseases whose treatment with antimonials bears limitations and has changed little in over 80 years. Medicinal plants have been evaluated as a therapeutic alternative for leishmaniasis. Arrabidaea chica is popularly used as a wound healing and antiparasitic agent, especially as leishmanicidal agent. This study examined the leishmanicidal activity of a crude extract (ACCE), an anthocyanidin-rich fraction (ACAF), and three isolated anthocyanidins from A. chica: carajurin, 3'-hydroxy-carajurone, and carajurone. We evaluated the antileishmanial activity against promastigote and intracellular amastigote forms of Leishmania amazonensis and determined cytotoxicity in BALB/c peritoneal macrophages, as well as nitrite quantification, using the Griess method. Molecular docking was carried out to evaluate interactions of carajurin at the nitric oxide synthase enzyme. All compounds were active against promastigotes after 72 h, with IC₅₀ values of 101.5 ± 0.06 μg/mL for ACCE and 4.976 ± 1.09 μg/mL for ACAF. Anthocyanidins carajurin, 3'-hydroxy-carajurone, and carajurone had IC₅₀ values of 3.66 ± 1.16, 22.70 ± 1.20, and 28.28 ± 0.07 μg/mL, respectively. The cytotoxicity assay after 72 h showed results ranging from 9.640 to 66.74 µg/mL for anthocyanidins. ACAF and carajurin showed selectivity against intracellular amastigote forms (SI> 10), with low cytotoxicity within 24 h, a statistically significant reduction in all infection parameters, and induced nitrite production. Molecular docking studies were developed to understand a possible mechanism of activation of the nitric oxide synthase enzyme, which leads to an increase in the production of nitric oxide observed in the other experiments reported. These results encourage us to suggest carajurin as a biological marker of A. chica.

Analysis of the mechanisms of action of isopentenyl caffeate against Leishmania

Leishmaniasis is a neglected parasitic disease for which the conventional treatment can be considered inefficient and extremely aggressive, generating several and severe side effects. Therefore, the discovery of new drug candidates is important for the improvement in the quality of life of patients. Previously, we reported the promising results of isopentyl caffeate (ICaf) against Leishmania chagasi (agent of visceral leishmaniasis) and Leishmania amazonensis (agent of cutaneous leishmaniasis) promastigotes, displaying IC₅₀ of 1.56 and 1.71 μM, respectively. Herein, we aimed to decipher the mechanisms of anti-Leishmania action of ICaf. Light and scanning electron microscopy assays showed relevant morphological changes in promastigotes when treated with ICaf, including rounding of the parasite body, shortening of the flagellum, blebs on the plasma membrane and cellular aggregation. The parasite mitochondrion was targeted by ICaf, resulting in a significant reduction in its metabolic activity and electric membrane potential followed by an increase in the production of reactive oxygen species, which culminated in the loss of plasma membrane integrity and parasite death. Relevantly, ICaf also had a potent anti-amastigote action. The IC₅₀ values calculated for intracellular amastigotes of L. amazonensis were 3.27, 1.60 and 1.52 μM, while for L. chagasi the values were 2.48, 1.84 and 1.60 μM, respectively, after treating the infected macrophages with ICaf for 24, 48 and 72 h. ICaf was well tolerated by THP-1 macrophages, which gave rise to excellent selectivity indexes considering both Leishmania species. The current results suggest that ICaf may emerge as a chemotherapeutic alternative for the treatment of leishmaniasis.

In vivo efficacy of meglumine antimoniate-loaded nanoparticles for cutaneous leishmaniasis: a systematic review

Background: Nanotechnology is a promising strategy to improve existing antileishmanial agents. Objective: To explore the evidence of encapsulated meglumine antimoniate for cutaneous leishmaniasis treatment in animal models. Materials & methods: The studies were recovered from PubMed, Scopus, EMBASE, LILACS, WoS and Google according to eligibility criteria following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and the Population, Intervention, Comparison, Outcomes and Study design (PICOS) strategy. Study appraisal was assessed using the Animal Research Reporting of In Vivo Experiments, SYstematic Review Centre for Laboratory animal Experimentation (SYRCLE) and Grading of Recommendations Assessment, Development and Evaluation (GRADE) recommendations. Results: Five studies were included. Liposomes, metallic and polymeric nanoparticles were tested in BALB/c mice against Leishmania major, L. tropica or L. amazonensis. Limitations: Few studies were found to meet the eligibility criteria. Conclusion: All formulations had a significant efficacy, similar to the meglumine antimoniate reference treatment concerning the lesion size and parasite burden. The studies had a high and moderate risk of bias, and the confidence in cumulative evidence was considered low. Therefore, we encourage the development of high-quality preclinical studies. Registration: PROSPERO register CRD42020170191.

Nanoemulsified Butenafine for Enhanced Performance against Experimental Cutaneous Leishmaniasis

The production of ergosterol lipid involves the activity of different enzymes and is a crucial event for the Leishmania membrane homeostasis. Such enzymes can be blocked by azoles and allylamines drugs, such as the antifungal butenafine chloride. This drug was active on parasites that cause cutaneous and visceral leishmaniasis. Based on the leishmanicidal activity of butenafine chloride and considering the absence of reports about the therapeutic potential of this drug in cutaneous leishmaniasis, the present work is aimed at analyzing the efficacy of butenafine formulated in two different topical delivery systems, the self-nanoemulsifying drug delivery systems (BUT-SNEDDS) and in a SNEDDS-based nanogel (BUT-SNEDDS gel) as well as in the free form in experimental cutaneous leishmaniasis. Physical studies showed that both formulations were below 300 nm with low polydispersity (<0.5) and good colloidal stability (around -25 mV). Increased steady-state flux was reported for nanoenabled butenafine formulations with reduced lag time in Franz cell diffusion assays across Strat-M membranes. No toxic or inflammatory reactions were detected in animals treated with BUT-SNEDDS, BUT-SNEDDS gel, or butenafine. Animals topically treated with butenafine (free or nanoformulated) showed small dermal lesions and low tissue parasitism. Furthermore, BUT-SNEDD gel and butenafine presented similar efficacy than the standard drug Glucantime given by the intralesional route. Increased levels of IFN-γ were observed in animals treated with BUT-SNEDDS gel or butenafine. Based on these data, the antifungal drug butenafine chloride can be considered an interesting repurposed drug for the treatment of cutaneous leishmaniasis.

A retrospective cohort study of the effectiveness and adverse events of intralesional pentavalent antimonials in the treatment of cutaneous leishmaniasis

Introduction

The standard therapy for American cutaneous leishmaniasis (ACL) is intravenous meglumine antimoniate (IV-MA). However, treatment interruptions due to adverse events (AEs) and non-adherence are frequent. Consequently, intralesional MA (IL-MA) was proposed.

Objective

This study examined the effectiveness of and AEs associated with IL-MA.

Methods

We performed a retrospective cohort study of 240 patients with ACL. We excluded patients with mucous lesions and disseminated leishmaniasis and those who received treatment in the previous 6 months. We considered protocol treatments as the main risk factors. IL-MA was performed using a subcutaneous injection of MA in a volume sufficient to elevate the lesion base (approximately 1 mL/cm² of lesion area) once weekly for 1–8 weeks. IV-MA was performed via intravenous injections of MA at a dosage of 10–20 mg Sb⁵⁺/kg/day for 20 days. The primary outcome was defined as a lesion cure 3 months after treatment, and AEs were secondary outcomes.

Results

Seventy-three patients were included. The IL-MA group consisted of 21 patients, and the IV-MA group consisted of 52 patients. The IL-MA group was older, had more comorbidities and more previous unsuccessful treatment of ACL. The antimonial dose was significantly lower in this group. The cure rate for IL-MA was 66.7%, which was lower than that in the IV-MA group (relative risk (RR) = 0.68, 95% CI: 0.50–0.92, p < 0.001), while the rate of AEs was similar. Female sex (RR = 1.16, 95% CI: 1.02–1.33), lesion diameter ≤1 cm (RR = 1.25, 95% CI: 1.00–1.56) and treatment with IV-MA (RR = 1.43, 95% CI: 1.06–1.93) were independently associated with achieving a cure. Comorbidities (RR = 1.7, 95% CI: 1.06–2.98) were independently associated with AEs.

Conclusions

Patients of IL-MA group were older, had more comorbidities and more previous unsuccessful treatment of ACL. Nevertheless, IL-MA had a cure rate of 66.7%, and it was useful in this context. A prospective randomized trial is recommended.

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Intralesional antimonials (IL-MA) had a 66.7% lower cure compared to systemic.

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IL-MA group was older, had more comorbidities and unsuccessful previous treatment.

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IL-MA was useful in this group, where worse clinical responses are expected.

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Lesions larger than 3 cm did not have more chance of failure with IL-MA.

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There was no mucous recurrence after IL-MA in an area of New World Leishmaniasis.

Nanoparticles: New agents toward treatment of leishmaniasis

Leishmaniasis is a widespread disease that causes 20,000 to 30,000 deaths annually, making it a major health problem in endemic areas. Because of low-performance medications, drug delivery poses a great challenge for better treatment of leishmaniasis. The present study's purpose was to review the application of nanoparticles as a new method in leishmaniasis treatment. To identify all relevant literature, we searched Web of Sciences, Scopus, PubMed, NCBI, Scielo, and Google Scholar, and profiled studies published between 1986 and 2019. In the present study, we tried to identify different research efforts in different conditions that examined the influence of various nanoparticles on different forms of leishmaniasis. In this way, we could compare their results and obtain a reliable conclusion from the most recent studies on this subject. Our review's results indicate that incorporating nanoparticles with chemical drugs improves the quality, efficiency, and sustainability of drugs and reduces their costs. Finally, considering the use of nanoparticles in the destruction of parasites, their inhibitory effect (making drugs more effective and less harmful), and their utility in making effective vaccines to prevent and fight against parasites, further research on this issue is highly recommended.

Use of liposomal nanoformulations in antileishmania therapy: challenges and perspectives

Leishmaniasis is a parasitic disease treatable and curable, however, the chemotherapeutic agents for their treatment are limited. In South American countries, pentavalent antimonials are still the first line of treatment for cutaneous leishmaniasis with an efficacy of about 75%, but the toxicity of the drug causes serious side effects and remains as the main obstacle for treatment. New knowledge aimed to improve drug delivery into the intracellular environment is essential, especially for drugs currently used in the clinic, to develop new anti-Leishmania formulations. In the present study, we analysed the scientific literature to highlight the progress achieved in the last decade regarding the use of nanotechnology for improving the current leishmaniasis treatments. Results allowed us to conclude that the encapsulated Glucantime liposomal formulation can be improved by means of nanoparticle functionalization processes, resulting in new drug delivery systems that can be potentially proposed as alternative therapies for leishmaniasis treatment.

Geospatial analysis of tegumentary leishmaniasis in Rio de Janeiro state, Brazil from 2000 to 2015: Species typing and flow of travelers and migrants with leishmaniasis

Background

We identified the species of Leishmania isolated from traveling and migrant patients attended in a reference center from 2000 to 2015, we performed the georeferencing of these species in Rio de Janeiro (RJ) state and we had knowledge about the human flows between the likely location of infection (LLI) and place of residence (PR) in RJ state, Brazil.

Methodology/Principal findings

This is a retrospective cross-sectional study including 171 patients diagnosed with ATL. Google Maps, OpenStreetMap, and Bing Maps were tools used to georeference LLI and PR. For etiological identification, we used isoenzyme electrophoresis, polymerase chain reaction-restriction fragment length polymorphism (molecular target hsp70C with restriction enzymes HaeIII and BstUI), and sequencing of the internal transcribed spacer of ribosomal DNA. ARCGIS software was used to create maps of the geographic distribution of Leishmania species in the state and municipality of RJ, together with flows between the LLI and PR. Isolates from 104 patients were identified as: L. (Viannia) braziliensis (80.8%), L. (V.) naiffi (7.7%), L. (V.) guyanensis (6.7%), L. (Leishmania) amazonensis (1%), and genetic variants of L. (V.) braziliensis (3.8%). The flow maps showed that the LLI included 4 countries, 19 Brazilian states, and 18 municipalities of RJ state. The Brazilian states with the highest density of cases were Amazonas (n = 32), Bahia (n = 18), and Ceará (n = 15).

Conclusions/Significance

This work is the first contribution to the knowledge of the routes of Leishmania species introduced in RJ state by migrants and travelers patients. L. (V.) braziliensis, L. (V.) guyanensis, L. (V.) naiffi, L. (L.) amazonensis, and genetic variants of L. (V.) braziliensis were identified in RJ state. To determine whether the autochthonous transmission of these imported species is possible it is necessary the adaptation of these species to environmental conditions as well as the presence of reservoirs and phlebotomine vectors in this region.

Leishmaniasis is one of the most important neglected parasitic diseases in humans worldwide. American Tegumentary Leishmaniasis (ATL) is a disease caused by protozoa of the genus Leishmania, which are injected into the skin by small insects known by sandflies. Many different Leishmania species may cause ATL, which can affect the skin and/or oral and nasal mucosa. In this study, we analyzed flows between the likely location of infection (LLI) and the place of residence (PR) in Rio de Janeiro (RJ) state and identified Leishmania species isolated from travelers and migrants attended between 2000 and 2015 in a reference hospital for the care of patients with ATL. This work is the first contribution to knowledge about the routes of Leishmania species introduced to RJ state by migrant and traveling patients. In addition to Leishmania (Viannia) braziliensis, which was the most common species, other species have also been introduced to RJ state, including L. (V.) guyanensis, L. (V.) naiffi, L. (Leishmania) amazonensis, and genetic variants of L. (V.) braziliensis. Knowledge of the migratory flow and geographic location of these imported Leishmania species may contribute to the surveillance and control of ATL in RJ state, Brazil.

Semicarbazone derivatives as promising therapeutic alternatives in leishmaniasis

In the present study, we investigated the in vitro and in vivo leishmanicidal activity of synthetic compounds, containing a semicarbazone scaffold as a peptide mimetic framework. The leishmanicidal effect against amastigotes of Leishmania amazonensis was also evaluated at concentration of 100 μM-0.01 nM. The derivatives 2e, 2f, 2g and 1g, beyond the standards miltefosine and pentamidine, significantly diminished the number of L. amazonensis amastigotes in macrophages. These derivatives were also active against amastigotes of L. braziliensis. As 2g presented potent leishmanicidal activity against the amastigotes of L. amazonensis in macrophages, we also investigated the in vivo leishmanicidal activity of this compound against L. amazonensis. Approximately 10⁵L. amazonensis promastigotes were subcutaneously inoculated into the dermis of the right ear of BALB/c mice, which were subsequently treated with 2g (p.o. or i.p.), miltefosine (p.o.) or glucantime (i.p.) at 30 μmol/kg/day x 28 days. Thus, a similar reduction in the lesion size was observed after the administration of 2g through oral (63.7 ± 10.1%) and intraperitoneal (61.8 ± 3.7%) routes. A larger effect was observed after treatment with miltefosine (97.7 ± 0.4%), and glucantime did not exhibit activity at the dose administered. With respect to the ear parasite load, 2g diminished the number of parasites by p.o. (30.5 ± 5.1%) and i.p. (33.3 ± 4.3%) administration. In addition, 2g induced in vitro apoptosis, autophagy and cell cycle alterations on L. amazonensis promastigotes. In summary, the derivative 2g might represent a lead candidate for antileishmanial drugs, as this compound displayed pronounced leishmanicidal activity.