Pentavalent Antimony Compounds Research Articles

Antileishmanial Activity of Semisynthetic Lupane Triterpenoids Betulin and Betulinic Acid Derivatives: Synergistic Effects with Miltefosine

Leishmaniasis is a neglected tropical disease (NTDs), endemic in 88 countries, affecting more than 12 million people. The treatment consists in pentavalent antimony compounds, amphotericin B, pentamidine and miltefosine, among others. However, these current drugs are limited due to their toxicity, development of biological resistance, length of treatment and high cost. Thus, it is important to continue the search for new effective and less toxic treatments.The anti-Leishmania activity of sixteen semisynthetic lupane triterpenoids derivatives of betulin (BT01 to BT09) and betulinic acid (AB10 to AB16) were evaluated. Drug interactions between the active compounds and one current antileishmanial drug, miltefosine, were assessed using the fixed ratio isobologram method. In addition, effects on the cell cycle, apoptosis/necrosis events, morphology and DNA integrity were studied. The derivatives BT06 (3β-Hydroxy-(20R)-lupan-29-oxo-28-yl-1H-imidazole-1-carboxylate) and AB13 (28-(1H-imidazole-1-yl)-3,28-dioxo-lup-1,20(29)-dien-2-yl-1H-imidazole-1-carboxylate) were found to be the most active, with IC50 values of 50.8 µM and 25.8 µM, respectively. Interactions between these two compounds and miltefosine were classified as synergistic, with the most effective association being between AB13 and miltefosine, where decreases of IC50 values to 6 µM were observed, similar to the miltefosine activity alone. AB13 induced significant morphological changes, while both derivatives produced anti-proliferative activity through cell cycle arrest at the G0/G1 phase. Neither of these derivatives induced significant apoptosis/necrosis, as indicated by phosphatidylserine externalization and DNA fragmentation assays. In addition, neither of the derivatives induced death in macrophage cell lines. Thus, they do not present any potential risk of toxicity for the host cells.This study has identified the betulin derivative BT06 and the betulinic acid derivative AB13 as promising molecules in the development of new alternative therapies for leishmaniasis, including those involving combined-therapy with miltefosine.

In vitro antileishmanial activity of methanolic and aqueous extracts of Eucalyptus camaldulensis against Leishmania major.

Pentavalent antimony compounds are expensive, toxic and drug resistance is prevalent, whereas the plant extract derivatives are safe. In the present study, the effect of methanolic and aqueous extracts of Eucalyptus camaldulensis on the promastigotes of Leishmania major was evaluated. The methanolic and aqueous extracts of E. camaldulensis leaves were prepared. The compounds were dried and powdered. Serial dilutions of the extracts and control drugs in phosphate buffer solution were prepared. The stationary phase promastigotes of L. major were incubated to the methanolic and aqueous extractions in vitro. Tartar emetic was used as the positive control drug. After 72h of incubation the activity of the extracts was measured, using MTT method. The IC50 values (50% inhibitory concentration) were 586.2±47.6 and 1,108.6±51.9μg/ml for methanolic and aqueous extracts, respectively, whereas it was 32.5±6.8μg/ml for tartar emetic. The results indicated that the methanolic extract was more effective than aqueous extract, although there was no significant difference. The extracts were less effective as compared to the control drug. Further investigation is required to evaluate these extracts on clinical stage in macrophage-amastigote model.

Drug Resistance in Leishmaniasis: Current Drug-Delivery Systems and Future Perspectives

Leishmaniasis is a complex of diseases with numerous clinical manifestations for instance harshness from skin lesions to severe disfigurement and chronic systemic infection in the liver and spleen. So far, the most classical leishmaniasis therapy, despite its documented toxicities, remains pentavalent antimonial compounds. The arvailable therapeutic modalities for leishmaniasis are overwhelmed with resistance to leishmaniasis therapy. Mechanisms of classical drug resistance are often related with the lower drug uptake, increased efflux, the faster drug metabolism, drug target modifications and over-expression of drug transporters. The high prevalence of leishmaniasis and the appearance of resistance to classical drugs reveal the demand to develop and explore novel, less toxic, low cost and more promising therapeutic modalities. The review describes the mechanisms of classical drug resistance and potential drug targets in Leishmania infection. Moreover, current drug-delivery systems and future perspectives towards Leishmaniasis treatment are also covered.

Identification of antimony resistance markers in Leishmania tropica field isolates through a cDNA-AFLP approach

Pentavalent antimonial compounds have been the first line therapy for leishmaniasis; unfortunately the rate of treatment failure of anthroponotic cutaneous leishmaniasis (ACL) is increasing due to emerging of drug resistance. Elucidation of the molecular mechanisms operating in antimony resistance is critical for development of new strategies for treatment. Here, we used a cDNA-AFLP approach to identify gene(s) which are differentially expressed in resistant and sensitive Leishmania tropica field isolates. We identified five genes, aquaglyceroporin (AQP1) acts in drug uptake, ATP-binding cassette (ABC) transporter (MRPA) involved in sequestration of drug, phosphoglycerate kinase (PGK) implicated in glycolysis metabolism, mitogen activated protein kinase (MAPK) and protein tyrosine phosphatase (PTP) responsible for phosphorylation pathway. The results were confirmed using real time RT-PCR which revealed an upregulation of MRPA, PTP and PGK genes and downregulation of AQP1 and MAPK genes in resistant isolate. To our knowledge, this is the first report of identification of PTP and PGK genes potentially implicated in resistance to antimonials. Our findings support the idea that distinct biomolecules might be involved in antimony resistance in L. tropica field isolates.

Parasitic Infections in Solid Organ Transplantation

Parasitic Infections in Solid Organ Transplantation

Estado actual y futuro de la terapia anti-leishmaniásica en Colombia

Pentavalent antimonials are the first choice to treat leishmaniasis in Colombia. However, a 600% increase in the total dose has been necessary in order to maintain their efficacy. Cure rates varying between 93 and 25% can reflect differences in parasite susceptibility, but are more likely secondary to deficiencies in compliance with treatment guidelines. We review the current situation of efficacy and use of pentavalent antimony compounds, amphotericin B, pentamidine and miltefosine and attempt a projection for the next following years. To determine the real situation of response to antileishmanial drugs and to extend their useful life, the establishment of surveillance mechanisms to cover all factors involved is necessary. A sentinel site surveillance strategy to allow punctual observations in time, in specific geographical areas and in particular local situations, is proposed.

CXCL10 Is Critical for the Generation of Protective CD8 T Cell Response Induced by Antigen Pulsed CpG-ODN Activated Dendritic Cells

The visceral form of leishmaniasis is the most severe form of the disease and of particular concern due to the emerging problem of HIV/visceral leishmaniasis (VL) co-infection in the tropics. Till date miltefosine, amphotericin B and pentavalent antimony compounds remain the main treatment regimens for leishmaniasis. However, because of severe side effects, there is an urgent need for alternative improved therapies to combat this dreaded disease. In the present study, we have used the murine model of leishmaniasis to evaluate the potential role played by soluble leishmanial antigen (SLA) pulsed-CpG-ODN stimulated dendritic cells (SLA-CpG-DCs) in restricting the intracellular leishmanial growth. We found that mice vaccinated with a single dose of SLA-pulsed DC stimulated by CpG-ODN were protected against a subsequent leishmanial challenge and had a dramatic reduction in parasite burden along with the generation of parasite specific cytotoxic T lymphocytes. Moreover, we demonstrate that the induction of protective immunity conferred by SLA-CpG-DCs depends entirely on the CXC chemokine IFN-γ-inducible protein 10 (CXCL10; IP-10). CXCL10 is directly involved in the generation of a parasite specific CD8+ T cell-mediated immune response. We observed significant reduction of CD8+ T cells in mice depleted of CXCL10 suggesting a direct role of CXCL10 in the generation of CD8+ T cells in SLA-CpG-DCs vaccinated mice. CXCL10 also contributed towards the generation of perforin and granzyme B, two important cytolytic mediators of CD8+ T cells, following SLA-CpG-DCs vaccination. Together, these findings strongly demonstrate that CXCL10 is critical for rendering a protective cellular immunity during SLA-CpG-DC vaccination that confers protection against Leishmania donovani infection.

Evaluation of the cardiac toxicity of N-methyl-glucamine antimoniate in dogs with naturally occurring leishmaniasis

The aim of this study was to evaluate the cardiotoxic effects of pentavalent antimonial compounds in dogs with leishmaniasis. Twenty-eight dogs with clinical disease due to natural infection with Leishmania infantum were treated with 75mg/kg meglumine antimoniate SC every 12h for 60days. Serum cardiac troponin I (cTnI) concentrations were determined and routine and 24h ambulatory electrocardiographic monitoring was performed before the onset (T0) and at the end of treatment (T60). No abnormalities were found in routine and 24h electrocardiographic tracings before and after treatment. No statistical difference was found between serum cTnI concentrations or corrected QT intervals at T0 and T60. There was no evidence of laboratory or electrocardiographic features of cardiac toxicity in dogs with leishmaniasis treated with a therapeutic dose of meglumine antimoniate for 60days.

Liposomal amphotericin B in comparison to sodium stibogluconate for Leishmania braziliensis cutaneous leishmaniasis in travelers

New World cutaneous leishmaniasis is mostly acquired in the Amazon Basin of Bolivia where L viannia (V) braziliensis is endemic. Treatment with systemic pentavalent antimonial compounds has been shown to be effective in achieving clinical cure in only 75% of cases. We sought to assess the efficacy and safety of liposomal amphotericin B (L-AmB) treatment for primary infection of cutaneous L (V) braziliensis. A prospective observational evaluation was performed for cutaneous leishmaniasis due to L (V) braziliensis which was treated with L-AmB, 3 mg/kg, for 5 consecutive days, and a sixth dose on day 10. This therapy regimen was compared with the treatment regimen of sodium stibogluconate (SSG) 20 mg/kg for 3 weeks. Our study was divided into two groups; 34 patients received L-AmB and 34 received SSG treatment. Almost all patients were infected in Bolivia. In the L-AmB group, 29 patients (85%) had complete cure compared with 70% in the SSG group (P = not significant), 4 other patients were slow healers, and only one patient needed additional treatment with SSG. No relapses were seen during a mean 29-month follow-up period. Failure rate was 3% in the L-AmB versus 29% in the SSG group (P = .006). Treatment was interrupted in 65% of patients taking SSG because of adverse events, whereas all patients receiving L-AmB completed treatment. This was a non-blinded comparative study. Comparison of L-Amb to SSG treatment for L (V) braziliensis shows that the former is effective, better tolerated, and more cost effective. L-AmB should therefore be considered as the first-line treatment option for cutaneous L (V) braziliensis infection.

Epidemiological and clinical characteristics of 7172 patients with cutaneous leishmaniasis in Sanliurfa, between 2001 and 2008

Cutaneous leishmaniasis in Sanliurfa is still a public health problem. In this study, we report the epidemiological, clinical, and demographic properties from Sanliurfa. 7172 patients followed up in the Sanliurfa Leishmaniasis Treatment Center between January 2001 and December 2008. The rates of male and female patients were 46% and 54% of the 7172 cases, respectively. The incidence of ACL showed a typical trend of an increase between November and May and a decrease in the summer. The face and extremities were the most involved parts of the body. Clinical appearance and Giemsa smear were most used diagnostic tools and intralesional pentavalent antimony compounds were the first choice of treatment. The incidence of cutaneous leishmaniasis in Sanliurfa is still low but not zero.

Topical Treatment Modalities for Old World Cutaneous Leishmaniasis: A Review

Diagnosis and therapy of cutaneous leishmaniasis (CL) can be difficult due to the variability of the clinical pictures and resistance to therapy. There is no vaccine currently available for CL. The aim of the present review is to describe different topical treatment modalities for old world CL. The mainstays of treatment for old world CL are pentavalent antimony compounds which are administered parenterally or intralesionally. New topical treatment alternatives have been available within the past few years. Amongst several treatments used topically, physical therapies including cryotherapy, heat therapy and CO2 laser are promising for the treatment of old world CL. Along with that, other randomized placebo controlled trials should be designed to find new effective therapeutic regimens.

Comparison of intralesional two percent zinc sulfate and glucantime injection in treatment of acute cutaneous leishmaniasis

Introduction:Cutaneous leishmaniasis is an endemic disease in developing countries caused by different species of leishmania parasite, and if left untreated, it will result in a deformed scar after a relatively long period. Although various systemic and topical treatments have been proposed for leishmaniasis, pentavalent Antimony compounds remain the first-line treatment for it. Considering the cases with treatment failure, potential side effects and reluctance of patients to receive the drug, there are continuing efforts to find better treatment alternatives.Aim:Comparison of the effect of intralesional 2% zinc sulfate injection with Glucantime in treatment of acute cutaneous leishmaniasis.Materials and Methods:In this clinical trial, 45 patients with clinical diagnosis of cutaneous leishmaniasis and positive direct smear for leishman body were treated by intralesional injection of either 2% zinc sulfate or Glucantime. After simple randomization, in one group the patients were treated with 2 bouts of intralesional 2% zinc sulfate with a 2-week interval, and in the other group they were treated with 6 weekly bouts of intralesional Glucantime. The patients were monitored in two week intervals for 8 weeks. Healing of the lesions was evaluated clinically and by direct smear, and the data were analyzed using SPSS (11.5) software, t-Student, Mann-Whitney and Analysis of covariance (ANCOVA) statistical tests.Findings:In the end of study, 34 patients completed the study, 10 of whom received intralesional Glucantime and 24 of whom received intralesional 2% zinc sulfate. The healing rate after 8 weeks was 80% in the group receiving intralesional Glucantime and 33.3% in the one receiving 2% zinc sulfate (P=0.009).Conclusion:Based on the results of this study, intralesional injection of 2% zinc sulfate was less effective in treatment of cutaneous leishmaniasis than intralesional Glucantime.

Avanços no tratamento da leishmaniose tegumentar do novo mundo nos últimos dez anos: uma revisão sistemática da literatura

The therapeutic arsenal against cutaneous leishmaniasis is very limited. Pentavalent antimonial compounds have been the drugs of choice for treatment of this disease for over 50 years. Despite their effectiveness, these drugs require daily injections, have many side effects and present prolonged healing time. To carry out a systematic literature review on the advances in the treatment of cutaneous leishmaniasis in the new world in the last ten years. We conducted an electronic search on the Pubmed and LILACS database as well as on the SciELO electronic library in June 2009. The search words in English were: "cutaneous", "leishmaniasis" and "treatment". We included only randomized, double-blind and placebo controlled trials. We used the Jadad scale to assess the quality of the selected studies. According to the inclusion and exclusion criteria, only eight articles were selected. The drugs evaluated in the selected studies were glucantime®, miltefosine, immunotherapy, imiquimod, rhGM-CSF and pentoxifylline, and paromomycin. Although cutaneous leishmaniasis is a major public health issue, the published data on the use of new drugs for the treatment of cutaneous leishmaniasis in Brazil are still quite limited.

The fitness of antimony-resistant Leishmania parasites: lessons from the field

Because antimony compounds are the primary antileishmanial drugs in most developing countries, an understanding of the fitness cost associated with the acquisition of drug resistance is important for the management of leishmaniasis. The clinical manifestations of the disease range from self-healing cutaneous and mucocutaneous skin ulcers to a fatal visceral form, called visceral leishmaniasis or kala-azar. In the absence of effective vaccines, the only way to treat and control leishmaniasis is through the use of affordable medications.

Leishmania tropica–Induced Cutaneous and Presumptive Concomitant Viscerotropic Leishmaniasis With Prolonged Incubation

Leishmaniasis includes a spectrum of diseases caused by protozoan parasites belonging to the genus Leishmania. The disease is traditionally classified into visceral, cutaneous, or mucocutaneous leishmaniasis, depending on clinical characteristics as well as the species involved. Leishmania tropica is one of the causative agents of cutaneous leishmaniasis, with a typical incubation period of weeks to months. Observation We describe a 17-year-old Afghani girl who had lived in the United States for 4 years and who presented with a 6-month history of pretibial ulcerations, 9.1-kg weight loss, abdominal pain, splenomegaly, and extreme fatigue. Histopathologic examination and culture with isoenzyme electrophoresis speciation of her skin lesions confirmed the presence of L tropica. In addition, results of serum laboratory and serological studies were highly suggestive of concomitant visceral involvement. The patient was treated with a 28-day course of intravenous pentavalent antimonial compound sodium stibogluconate with complete resolution of her systemic signs and symptoms and improvement of her pretibial ulcerations. This is an exceptional case in that our patient presented with disease after an incubation period of years rather than the more typical weeks to months. In addition, this patient had confirmed cutaneous involvement, as well as strong evidence of viscerotropic disease caused by L tropica, a species that characteristically displays dermotropism, not viscerotropism.

Two cases of visceral leishmaniasis in Colombia resistant to meglumine antimonial treatment

Visceral leishmaniasis (VL) affects over 500,000 people worldwide each year. The disease occurs in the Mediterranean basin, Central and South America and is caused by Leishmania infantum (syn L. chagasi). VL is an endemic disease in Colombia, particularly along the Caribbean coast and the Magdalena River Valley and 90% of VL cases occur in children under the age of five. The first line of treatment is chemotherapy with pentavalent antimonial compounds, including sodium stibogluconate (Pentostam) and meglumine antimoniate (Glucantime). These compounds are the ones most used in Colombia, at a dose of 20 mg/kg/day for 28 days. Nevertheless resistance of L. infantum to pentavalent antimonials is becoming an important problem. No cases of VL resistant to pentavalent antimonial compounds have previously been reported from Colombia. This report describes the two cases of VL resistance to antimonial compounds in a girl and a boy who did not respond to previous treatment with Pentacarinat and Glucantime regimens but were treated successfully with liposomal amphotericin B. Based on our findings, we recommend liposomal amphotericin B as the first line of treatment for VL due to its low toxicity, shorter administration period and the low price obtained by WHO.

Severe adverse reactions to meglumine antimoniate in the treatment of visceral leishmaniasis: a report of 13 cases in the southwestern region of Brazil

Antimony-based medications continue to be the chosen drug for visceral leishmaniasis treatment in most countries. Pentavalent antimony compounds are highly effective but frequently have adverse reactions. Although toxic effects are almost always reversible, some of them can be severe. Clinical and laboratory data of 13 patients who developed severe adverse reactions to meglumine antimoniate in a teaching hospital in southwestern Brazil in 2004-2005 were analysed. Most patients were adults (10/13), mainly at the age of 50 or older (4/13). The main severe adverse reactions were renal failure (eight episodes), pancreatitis (six episodes) and hepatic failure/hepatitis (five episodes). Six patients died in the period; all presented acute renal failure and four presented hepatic failure. Meglumine antimoniate can cause severe reactions, which can lead to death if not promptly identified. Further studies are warrented on the effect of less toxic drugs.

Is Paromomycin an Effective and Safe Treatment against Cutaneous Leishmaniasis? A Meta-Analysis of 14 Randomized Controlled Trials

BackgroundHigh cost, poor compliance, and systemic toxicity have limited the use of pentavalent antimony compounds (SbV), the treatment of choice for cutaneous leishmaniasis (CL). Paromomycin (PR) has been developed as an alternative to SbV, but existing data are conflicting.Methodology/Principal FindingsWe searched PubMed, Scopus, and Cochrane Central Register of Controlled Trials, without language restriction, through August 2007, to identify randomized controlled trials that compared the efficacy or safety between PR and placebo or SbV. Primary outcome was clinical cure, defined as complete healing, disappearance, or reepithelialization of all lesions. Data were extracted independently by two investigators, and pooled using a random-effects model. Fourteen trials including 1,221 patients were included. In placebo-controlled trials, topical PR appeared to have therapeutic activity against the old world and new world CL, with increased local reactions, when used with methylbenzethonium chloride (MBCL) compared to when used alone (risk ratio [RR] for clinical cure, 2.58 versus 1.01: RR for local reactions, 1.60 versus 1.07). In SbV-controlled trials, the efficacy of topical PR was not significantly different from that of intralesional SbV in the old world CL (RR, 0.70; 95% confidence interval, 0.26–1.89), whereas topical PR was inferior to parenteral SbV in treating the new world CL (0.67; 0.54–0.82). No significant difference in efficacy was found between parenteral PR and parenteral SbV in the new world CL (0.88; 0.56–1.38). Systemic side effects were fewer with topical or parenteral PR than parenteral SbV.Conclusions/SignificanceTopical PR with MBCL could be a therapeutic alternative to SbV in selected cases of the old world CL. Development of new formulations with better efficacy and tolerability remains to be an area of future research.

Leishmaniose cutanée à Leishmania major avec atteinte de la moelle osseuse chez un malade infecté par le VIH au Burkina Faso

Leishmaniasis covers three well-individualized clinical variants, each due to individual species found in different geographic areas. Herein we report the first case of cutaneous leishmaniasis due to Leishmania major involving bone marrow in an AIDS patient in Burkina Faso. A 38-year-old HIV-positive man presented with generalized, copper-coloured, painless, infiltrated, itching, papulonodular lesions present over the previous 10 months. Skin biopsy confirmed the diagnosis of diffuse cutaneous leishmaniasis. The bone-marrow smear showed numerous leishmania. The culture was positive and L. major was identified. The patient was being treated with antiretroviral medication and a pentavalent antimonial compound. The disease progression consisted of attacks and remissions separated by an average of three weeks. L. major is the Leishmania species identified in Burkina Faso. It is responsible for typical cutaneous leishmaniasis but particular clinical forms have been described in immunodeficient patients, especially with diffuse cutaneous involvement. The spread of L. major infection to bone marrow could represent a public health problem in our country, where the HIV epidemic is still not under control, and particular vigilance is thus called for.

Anticancer Compounds as Leishmanicidal Drugs: Challenges in Chemotherapy and Future Perspectives

Leishmaniasis comprises a spectrum of parasitic illnesses caused by several species of the protozoan kinetoplastid parasite, Leishmania spp. The disease affects 12 million people around the world with an annual death rate of approximately 80,000 people. Several drugs are available for treating leishmaniasis. For example, pentavalent antimonial compounds, such as sodium stibogluconate and meglumine antimonite are the drugs used in first-line chemotherapy. As second-line drugs, amphotericin B and pentamidine are used. However, current treatments against leishmaniasis are usually unsatisfactory due to some limitations including the route of administration of the drugs, their unaffordable cost and toxicity. Efforts have been made to develop new leishmanicidal drugs and to find new strategies of drug design. Hence, it is interesting to point out that the effectiveness of certain molecules as both anticancer drugs and antiprotozoal agents suggested that this class of compounds and their derivatives might be useful as antileishmanial agents. This review summarizes the anticancer compounds that have been investigated against leishmaniasis. Some of such agents include: compounds with in vitro antileishmanial activities, molecules tested in clinical trials and registered patents. We finally discuss challenges in chemotherapy and future prospects in the treatment of leishmaniasis.