Unmasking the Mechanism behind Miltefosine: Revealing the Disruption of Intracellular Ca Homeostasis as a Rational Therapeutic Target in Leishmaniasis and Chagas Disease.

Originally developed as a chemotherapeutic agent, miltefosine (hexadecylphosphocholine) is an inhibitor of phosphatidylcholine synthesis with proven antiparasitic effects. It is the only oral drug approved for the treatment of Leishmaniasis and American Trypanosomiasis (Chagas disease). Although its precise mechanisms are not yet fully understood, miltefosine exhibits broad-spectrum anti-parasitic effects primarily by disrupting the intracellular Ca homeostasis of the parasites while sparing the human hosts.

Synthesis, Antimalarial, Antileishmanial, and Cytotoxicity Activities and Preliminary In Silico ADMET Studies of 2-(7-Chloroquinolin-4-ylamino)ethyl Benzoate Derivatives.

A series of heterocyclic chloroquine hybrids, containing a chain of two carbon atoms at position four of the quinolinic chain and acting as a link between quinoline and several benzoyl groups, is synthesized and screened in vitro as an inhibitor of β-hematin formation and in vivo for its antimalarial activity against chloroquine-sensitive strains of ANKA in this study. The compounds significantly reduced haeme crystallization, with IC values < 10 µM. The values were comparable to chloroquine's, with an IC of 1.

Effects of SQ109 on Trichomonas vaginalis.

Trichomonas vaginalis is a protozoan that causes human trichomoniasis, a sexually transmitted infection (STI) that affects approximately 278 million people worldwide. The current treatment for human trichomoniasis is based on 1-(2-hydroxyethyl)-2-methyl-5-nitroimidazole, known as Metronidazole (MTZ). Although effective in eliminating parasitic infection, MTZ is related to serious adverse effects and is not recommended during pregnancy.

Synthesis and Testing of Analogs of the Tuberculosis Drug Candidate SQ109 against Bacteria and Protozoa: Identification of Lead Compounds against and Malaria Parasites.

SQ109 is a tuberculosis drug candidate that has high potency against and is thought to function at least in part by blocking cell wall biosynthesis by inhibiting the MmpL3 transporter. It also has activity against bacteria and protozoan parasites that lack MmpL3, where it can act as an uncoupler, targeting lipid membranes and Ca homeostasis. Here, we synthesized 18 analogs of SQ109 and tested them against , , , , and , as well as against the protozoan parasites , , , , and .

Structural Analysis and Diversity of Calmodulin-Binding Domains in Membrane and Intracellular Ca-ATPases.

The plasma membrane and autoinhibited Ca-ATPases contribute to the Ca homeostasis in a wide variety of organisms. The enzymatic activity of these pumps is stimulated by calmodulin, which interacts with the target protein through the calmodulin-binding domain (CaMBD). Most information about this region is related to all calmodulin modulated proteins, which indicates general chemical properties and there is no established relation between Ca pump sequences and taxonomic classification.

Effects of amiodarone, amioder, and dronedarone on Trichomonas vaginalis.

Trichomonas vaginalis is a protozoan that causes human trichomoniasis, the most common non-viral sexually transmitted infection (STI) affecting approximately 278 million people worldwide. The current treatment for trichomoniasis is based on 1-(2-hydroxyethyl)-2-methyl-5-nitroimidazole, known as metronidazole (MTZ). Although effective in clearing the parasite infection, MTZ is related to provoking severe side effects, and it is not recommended during pregnancy.

A store-operated Ca-entry in Trypanosoma equiperdum: Physiological evidences of its presence.

The Trypanosomatidae family encompasses many unicellular organisms responsible of several tropical diseases that affect humans and animals. Livestock tripanosomosis caused by Trypanosoma brucei brucei (T. brucei), Trypanosoma equiperdum (T.

Determination of Intracellular Ca Concentration in the Human Pathogens Trypanosomatids and by the Use of the Fluorescent Ca Indicator Fura-2.

Ca is an essential signaling messenger in all eukariotic cells, playing a pivotal role in many cellular functions as cell growth control (differentiation, fertilization and apoptosis), secretion, gene expression, enzyme regulation, among many others. This basic premise includes trypanosomatids as and various species of , the causative agents of Chagas disease and leishmaniasis respectively, where intracellular Ca concentration ([Ca]) has been demonstrated to be finely regulated. Nevertheless [Ca] has been difficult to measure because of its very low cytoplasmic concentration (typically around 50-100 nM), when compared to the large concentration in the outside (around 2 mM in blood).

The Rationale for Use of Amiodarone and its Derivatives for the Treatment of Chagas' Disease and Leishmaniasis.

The repurposing or repositioning of previously-approved drugs has become an accepted strategy for the expansion of the pharmacopeia for neglected diseases. Accordingly, amiodarone, an inexpensive and extensively- used class III antiarrhythmic has been proposed as a treatment for Chagas' disease and leishmaniasis. Amiodarone has a potent trypanocidal and leishmanicidal action, mainly acting through the disruption of parasite intracellular Ca homeostasis, which is a recognized target of different drugs that have activity against trypanosomatids.

Disruption of Intracellular Calcium Homeostasis as a Therapeutic Target Against .

There is no effective cure for Chagas disease, which is caused by infection with the arthropod-borne parasite, . In the search for new drugs to treat Chagas disease, potential therapeutic targets have been identified by exploiting the differences between the mechanisms involved in intracellular Ca homeostasis, both in humans and in trypanosomatids. In the trypanosomatid, intracellular Ca regulation requires the concerted action of three intracellular organelles, the endoplasmic reticulum, the single unique mitochondrion, and the acidocalcisomes.

SQ109 inhibits proliferation of Leishmania donovani by disruption of intracellular Ca homeostasis, collapsing the mitochondrial electrochemical potential (ΔΨ) and affecting acidocalcisomes.

Leishmania donovani is the causative agent of visceral leishmaniasis. Annually, 500 million new cases of infection are reported mainly in poor communities, decreasing the interest of the pharmaceutical industries. Therefore, the repositioning of new drugs is an ideal strategy to fight against these parasites.

Investigation of a combination of amiodarone and itraconazole for treatment of American trypanosomiasis (Chagas disease) in dogs.

Objective: To evaluate clinical, serologic, parasitological, and histologic outcomes of dogs with naturally occurring infection treated for 12 months with amiodarone and itraconazole.

Animals: 121 dogs from southern Texas and southern Louisiana.

Procedures: Treatment group dogs (n = 105) received a combination of amiodarone hydrochloride (approx 7.

Identification and electrophysiological properties of a sphingosine-dependent plasma membrane Ca channel in Trypanosoma cruzi.

Trypanosoma cruzi is the causative agent of Chagas disease. The only two drugs accepted for the treatment of this infection are benznidazole and nifurtimox, which are of limited use in the predominant chronic phase. On the search for new drugs, the intracellular Ca regulation has been postulated as a possible target, due to differences found between host cells and the parasite.

Venezuela's humanitarian crisis, resurgence of vector-borne diseases, and implications for spillover in the region.

In the past 5-10 years, Venezuela has faced a severe economic crisis, precipitated by political instability and declining oil revenue. Public health provision has been affected particularly. In this Review, we assess the impact of Venezuela's health-care crisis on vector-borne diseases, and the spillover into neighbouring countries.

Antiproliferative effect of a benzofuran derivate based on the structure of amiodarone on Leishmania donovani affecting mitochondria, acidocalcisomes and intracellular Ca homeostasis.

Leishmaniasis is a parasitic disease representing an important problem of public health. Visceral leishmaniasis, resulting from infection with Leishmania donovani, causes considerable mortality and morbidity in the poorest region of the word. At present there is no current effective treatment, since the approved, drugs are expensive and are not free of undesirable side effects.

Identification and characterization of a calmodulin binding domain in the plasma membrane Ca-ATPase from Trypanosoma equiperdum.

The plasma membrane Ca-ATPase (PMCA) from trypanosomatids lacks a classical calmodulin (CaM) binding domain, although CaM stimulated activities have been detected by biochemical assays. Recently we proposed that the Trypanosoma equiperdum CaM-sensitive PMCA (TePMCA) contains a potential 1-18 CaM-binding motif at the C-terminal region of the pump. In the present study, we evaluated the potential CaM-binding motifs using CaM from Trypanosoma cruzi and either the recombinant full length TePMCA C-terminal sequence (P14) or synthetic peptides comprising different regions of the C-terminal domain.

Phosphorylation-induced conformational changes of photoactivated rhodopsin probed by fluorescent labeling at Cys and Cys.

In order to monitor conformational changes following photoactivation and phosphorylation of bovine rhodopsin, the two reactive sulfhydryl groups at Cys and Cys were specifically labeled with the monobromobimane (mBBr) fluorophore. Although alterations in conformation after light exposure of rhodopsin were not detected by fluorescence excitation scans (300-450 nm) of the mBBr-labeled protein, the fluorescence signal was reduced ∼ 90% in samples containing photoactivated phosphorhodopsin. Predominant labeling at either Cys or Cys in light-activated and phosphorylated rhodopsin merely generated a decrease of ∼38% and 28%, respectively, in the fluorescence excitation intensity.

Anti-Trypanosoma cruzi action of a new benzofuran derivative based on amiodarone structure.

Chagas disease is a neglected tropical affection caused by the protozoan parasite Trypanosoma cruzi. There is no current effective treatment since the only two available drugs have a limited efficacy and produce side effects. Thus, investigation efforts have been directed to the identification of new drug leads.

In vitro 4-Aryloxy-7-chloroquinoline derivatives are effective in mono- and combined therapy against Leishmania donovani and induce mitocondrial membrane potential disruption.

The present study evaluates in vitro the effect of two synthetic compounds of the 7-chloro-4-aryloxyquinoline series, QI (CHClNO) and QII (CHClNOS), on Leishmania donovani parasites. The results obtained demonstrate that these compounds are able to inhibit the proliferation of L. donovani promastigotes in a dose-dependent way (QI IC = 13.

Mechanism of Action of Miltefosine on Leishmania donovani Involves the Impairment of Acidocalcisome Function and the Activation of the Sphingosine-Dependent Plasma Membrane Ca Channel.

is the causing agent of visceral leishmaniasis, a common infection that affects millions of people from the most underdeveloped countries. Miltefosine is the only oral drug to treat infections caused by Nevertheless, its mechanism of action is not well understood. While miltefosine inhibits the synthesis of phosphatidylcholine and also affects the parasite mitochondrion, inhibiting the cytochrome oxidase, it is to be expected that this potent drug also produces its effect through other targets.

Evidence of the presence of a calmodulin-sensitive plasma membrane Ca-ATPase in Trypanosoma equiperdum.

Trypanosoma equiperdum belongs to the subgenus Trypanozoon, which has a significant socio-economic impact by limiting animal protein productivity worldwide. Proteins involved in the intracellular Ca regulation are prospective chemotherapeutic targets since several drugs used in experimental treatment against trypanosomatids exert their action through the disruption of the parasite intracellular Ca homeostasis. Therefore, the plasma membrane Ca-ATPase (PMCA) is considered as a potential drug target.

Inhibition of Leishmania mexicana Growth by the Tuberculosis Drug SQ109.

We report that the tuberculosis drug SQ109 [N-adamantan-2-yl-N'-((E)-3,7-dimethyl-octa-2,6-dienyl)-ethane-1,2-diamine] has potent activity against the intracellular amastigote form of Leishmania mexicana (50% inhibitory concentration [IC50], ∼11 nM), with a good selectivity index (>500). It is also active against promastigotes (IC50, ∼500 nM) and acts as a protonophore uncoupler, in addition to disrupting Ca(2+) homeostasis by releasing organelle Ca(2+) into the cytoplasm, and as such, it is an interesting new leishmaniasis drug hit candidate.