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Medical countermeasures to treat biothreat agent infections require broad-spectrum therapeutics that do not induce agent resistance. A cell-based high-throughput screen (HTS) against ricin toxin combined with hit optimization allowed selection of a family of compounds that meet these requirements. The hit compound Retro-2 and its derivatives have been demonstrated to be safe in vivo in mice even at high doses. Moreover, Retro-2 is an inhibitor of retrograde transport that affects syntaxin-5-dependent toxins and pathogens. As a consequence, it has a broad-spectrum activity that has been demonstrated both in vitro and in vivo against ricin, Shiga toxin-producing O104:H4 entero-hemorrhagic E. coli and Leishmania sp. and in vitro against Ebola, Marburg and poxviruses and Chlamydiales. An effect is anticipated on other toxins or pathogens that use retrograde trafficking and syntaxin-5. Since Retro-2 targets cell components of the host and not directly the pathogen, no selection of resistant pathogens is expected. These lead compounds need now to be developed as drugs for human use., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Membrane sterol profiles differ between humans and Leishmania parasites, and the sterol pathway has been investigated for potential therapeutic targets. Recently, mutants of the C14α-sterol demethylase in Leishmania major were found to have several major alterations such as increased membrane fluidity, hypersensitivity to heat stress, and severe reduction of virulence., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Background: This study aimed to investigate compounds acting on the host cell machinery to impair parasite installation with the possible advantage of limiting drug resistance. The strategy therefore consisted of selecting compounds that are poorly active on the axenic parasite, but very active on the intramacrophage form of Leishmania.Objectives: To identify a drug candidate from focused screening of adamantamine derivatives that can inhibit the development of Leishmania infantum in macrophages.Methods: In vitro screening was performed on a library of 142 adamantamine derivatives with axenic and intramacrophage forms of L. infantum, as well as cytotoxicity assays, allowing selection of the most promising compound. Absorption, distribution, metabolism and excretion (ADME) experiments, including pharmacokinetics and microsomal stability, were performed and finally the physicochemical stability of the compound was investigated to assess its suitability for further drug development.Results: VP343 was identified first in vitro, with a CC50 value of 63.7 μM and an IC50 value of 0.32 μM for L. infantum intramacrophage amastigotes and then in vivo, with a 59% reduction of the liver parasite burden after oral administration at 10 mg/kg/day for 5 days. In addition, the ADME data were compatible with moving this compound further through the antileishmanial drug candidate pipeline.Conclusions: VP343 has the properties of a good drug candidate and merits further investigations. [ABSTRACT FROM AUTHOR]

We conducted a study to decipher the mechanism of the formation of the large communal Leishmania amazonensis‐containing parasitophorous vacuole (PV) and found that the macrophage microtubule (MT) network dynamically orchestrates the intracellular lifestyle of this intracellular parasite. Physical disassembly of the MT network of macrophage‐like RAW 264.7 cells or silencing of the dynein gene, encoding the MT‐associated molecular motor that powers MT‐dependent vacuolar movement, by siRNA resulted in most of the infected cells hosting only tight parasite‐containing phagosome‐like vacuoles randomly distributed throughout the cytoplasm, each insulating a single parasite. Only a minority of the infected cells hosted both isolated parasite‐containing phagosome‐like vacuoles and a small communal PV, insulating a maximum of two to three parasites. The tight parasite‐containing phagosome‐like vacuoles never matured, whereas the small PVs only matured to a small degree, shown by the absence or faint acquisition of host‐cell endolysosomal characteristics. As a consequence, the parasites were unable to successfully complete promastigote‐to‐amastigote differentiation and died, regardless of the type of insulation. [ABSTRACT FROM AUTHOR]

Ethnopharmacological relevance In the Peruvian Amazon, the use of medicinal plants is a common practice. However, there is few documented information about the practical aspects of their use and few scientific validation. The starting point for this work was a set of interviews of people living in rural communities from the Peruvian Amazon about their uses of plants. Protozoan diseases are a public health issue in the Amazonian communities, who partly cope with it by using traditional remedies. Validation of these traditional practices contributes to public health care efficiency and may help identify new antiprotozoal compounds. Aims of study to inventory and validate the use of medicinal plants by rural people of Loreto region. Materials and methods Rural mestizos were interviewed about traditional medication of parasite infections with medicinal plants. Ethnopharmacological surveys were undertaken in two villages along Iquitos-Nauta road (Loreto region, Peru), namely 13 de Febrero and El Dorado communities. Forty-six plants were collected according to their traditional use for the treatment of parasitic diseases, 50 ethanolic extracts (different parts for some of the plants) were tested in vitro on Plasmodium falciparum (3D7 sensitive strain and W2 chloroquine resistant strain), Leishmania donovani LV9 strain and Trypanosoma brucei gambiense. Cytotoxic assessment (HUVEC cells) of the active extracts was performed. Two of the most active plants were submitted to preliminary bioguided fractionation to ascertain and explore their activities. Results From the initial plants list, 10 were found to be active on P. falciparum , 15 on L. donovani and 2 on the three parasites. The ethanolic extract from Costus curvibracteatus (Costaceae) leaves and Grias neuberthii (Lecythidaceae) bark showed strong in vitro activity on P. falciparum (sensitive and resistant strain) and L. donovani and moderate activity on T. brucei gambiense. Conclusions The Amazonian forest communities in Peru represents a source of knowledge on the use of medicinal plants. In this work, several extracts with antiprotozoal activity were identified. This work contributes to validate some traditional uses and opens subsequent investigations on active compounds isolation and identification. [ABSTRACT FROM AUTHOR]

Sterol 14α-demethylases (CYP51) are the enzymes essential for sterol biosynthesis. They serve as clinical targets for antifungal azoles and are considered as targets for treatment of human Trypanosomatidae infections. Recently, we have shown that VNI, a potent and selective inhibitor of trypanosomal CYP51 that we identified and structurally characterized in complex with the enzyme, can cure the acute and chronic forms of Chagas disease. The purpose of this work was to apply the CYP51 structure/function for further development of the VNI scaffold. As anticipated, VFV (R)-N-(1-(3,4'-difluorobiphenyl-4-yl)-2-(1H-imidazol-1-yl)ethyl)-4-(5-phenyl-1,3,4-oxadiazol-2-yl)benzamide, the derivative designed to fill the deepest portion of the CYP51 substrate-binding cavity, reveals a broader antiprotozoan spectrum of action. It has stronger antiparasitic activity in cellular experiments, cures the experimental Chagas disease with 100% efficacy, and suppresses visceral leishmaniasis by 89% (vs 60% for VNI). Oral bioavailability, low off-target activity, favorable pharmacokinetics and tissue distribution characterize VFV as a promising new drug candidate. [ABSTRACT FROM AUTHOR]

Abstract: Importance of heme in African trypanosomes, Leishmania sp. and Plasmodium sp. metabolisms justifies considering the potential of porphyrins and their precursors and derivatives as potential antiparasitic agents by interfering with heme metabolism. Consequently, twenty-four porphyrin precursors and derivatives were evaluated against Leishmania donovani, Trypanosoma brucei and Plasmodium sp. The best active compound against Trypanosoma brucei brucei was a new porphyrin derivative; compound 4i, with a MEC value of 6.25 μM justifying further in vivo evaluation. Whereas these compounds were not active against intramacrophage amastigotes of L. donovani, another new porphyrin derivative, compound 4f was active in vitro against Plasmodium falciparum at 20 nM and a slight delay of mice survival was observed on the Plasmodium berghei/Swiss mice model at 50 μmol/kg/day × 4. Pharmacomodulations should be further developed relying on a better knowledge on the porphyrin behaviour into the parasites comparatively to host cells. [Copyright &y& Elsevier]

Abstract: A Leishmania donovani promastigote line resistant to 160μM sitamaquine, named SITA-160R, was selected in vitro by continuous stepwise drug pressure. SITA-160R line was able to infect murine peritoneal macrophages in vitro in the same manner as the wild-type line (WT) but was less infective for Balb/c mice than its parent WT clone. This line was about five and three times more resistant to sitamaquine than the WT line on promastigote and intramacrophage amastigote forms, respectively. No cross-resistance with other antileishmanial agents was observed and this resistance was stable when parasites were subcultured in drug-free medium for a long time or after in vivo passage. [Copyright &y& Elsevier]

[Display omitted] • Biological evaluation of 3,5-disubstituted 1,2-dioxolanes was for the first time reported. • Compounds 5a and 10c showed excellent antimalarial activity. • Compounds 8c, 9c, 15c and 16c displayed potential antileishmanial activities. Endoperoxides are a class of compounds, which is well-known for their antimalarial properties, but few reports exist about 3,5-disubstituted 1,2-dioxolanes. After having designed a new synthetic route for the preparation of these substances, they were evaluated against 4 different agents of infectious diseases, protozoa (Plasmodium and Leishmania) and Fungi (Candida and Aspergillus). Whereas moderate antifungal activity was found for our products, potent antimalarial and antileishmanial activities were observed for a few compounds. The nature of the substituents linked to the endoperoxide ring seems to play an important role in the bioactivities. [ABSTRACT FROM AUTHOR]

The article discusses a decreased in vitro miltefosine susceptibility of serial Leishmania isolates obtained from an HIV-infected woman who was not responding to treatment. A Leishmania donovani miltefosine transporter (Ldmt) gene analysis was performed to determine an association between miltefosine resistance of reference L. donovani lines and variability in L. infantum isolates' miltefosine response. A molecular marker of miltefosine resistance is suggested.

A chemically diverse range of novel tetraoxanes was synthesized and evaluated in vitro against intramacrophage amastigote forms of Leishmania donovani. All 15 tested tetraoxanes displayed activity, with IC50 values ranging from 2 to 45 µm. The most active tetraoxane, compound LC140, exhibited an IC50 value of 2.52 ± 0.65 µm on L. donovani intramacrophage amastigotes, with a selectivity index of 13.5. This compound reduced the liver parasite burden of L. donovani-infected mice by 37% after an intraperitoneal treatment at 10 mg/kg/day for five consecutive days, whereas miltefosine, an antileishmanial drug in use, reduced it by 66%. These results provide a relevant basis for the development of further tetraoxanes as effective, safe, and cheap drugs against leishmaniasis. [ABSTRACT FROM AUTHOR]

Due to the lack of approved vaccines against human leishmaniasis and the limitations of the current chemotherapy inducing side effects and drug resistance, development of new, effective chemotherapeutic agents is essential. This study describes the synthesis of a series of novel oxadiazoles and indolizine-containing compounds. The compounds were screened in silico using an EIIP/AQVN filter followed by ligand-based virtual screening and molecular docking to parasite arginase. Top hits were further screened versus human arginase and finally against an anti-target battery to tag their possible interactions with proteins essential for the metabolism and clearance of many substances. Eight candidate compounds were selected for further experimental testing. The results show measurable in vitro anti-leishmanial activity for three compounds. One compound with an IC50 value of 2.18 µM on Leishmania donovani intramacrophage amastigotes is clearly better positioned than the others as an interesting molecular template for further development of new anti-leishmanial agents. [ABSTRACT FROM AUTHOR]

In our search for new protein farnesyltransferase inhibitors with improved antiparasitic activities, we modified our previously developed 3-arylthiophene series of inhibitors by replacing the thio iso propyl group by different substituted imidazolylmethanamino moieties. Twenty four new derivatives were synthesized and evaluated against human and parasite farnesyltransferases, and their anti-parasitic activity was determined against Plasmodium falciparum , Trypanosoma brucei , Trypanosoma cruzi , and Leishmania donovani . Introduction of a N-p -substituted-benzylimidazole led to significantly increase the inhibition of parasite proliferation in the submicromolar range. The structure of the best inhibitors was parasite dependent. Three compounds possess IC 50 values at the same range as the reference miltefosine against L. donovani proliferation and other new derivatives display high level of anti-trypanosomal activity against T. cruzi , higher or in the same order of magnitude as the reference compounds benznidazole and nifurtimox. [ABSTRACT FROM AUTHOR]

In the Peruvian Amazon as in the tropical countries of South America, the use of medicinal Piper species (cordoncillos) is common practice, particularly against symptoms of infection by protozoal parasites. However, there is few documented information about the practical aspects of their use and few scientific validation. The starting point of this work was a set of interviews of people living in six rural communities from the Peruvian Amazon (Alto Amazonas Province) about their uses of plants from Piper genus: one community of Amerindian native people (Shawi community) and five communities of mestizos. Infections caused by parasitic protozoa take a huge toll on public health in the Amazonian communities, who partly fight it using traditional remedies. Validation of these traditional practices contributes to public health care efficiency and may help to identify new antiprotozoal compounds. To record and validate the use of medicinal Piper species by rural people of Alto Amazonas Province (Peru) and annotate active compounds using a correlation study and a data mining approach. Rural communities were interviewed about traditional medication against parasite infections with medicinal Piper species. Ethnopharmacological surveys were undertaken in five mestizo villages, namely: Nueva Arica, Shucushuyacu, Parinari, Lagunas and Esperanza, and one Shawi community (Balsapuerto village). All communities belong to the Alto Amazonas Province (Loreto region, Peru). Seventeen Piper species were collected according to their traditional use for the treatment of parasitic diseases, 35 extracts (leaves or leaves and stems) were tested in vitro on P. falciparum (3D7 chloroquine-sensitive strain and W2 chloroquine-resistant strain), Leishmania donovani LV9 strain and Trypanosoma brucei gambiense. Assessments were performed on HUVEC cells and RAW 264.7 macrophages. The annotation of active compounds was realized by metabolomic analysis and molecular networking approach. Nine extracts were active (IC 50 ≤ 10 μg/mL) on 3D7 P. falciparum and only one on W2 P. falciparum , six on L. donovani (axenic and intramacrophagic amastigotes) and seven on Trypanosoma brucei gambiense. Only one extract was active on all three parasites (P. lineatum). After metabolomic analyses and annotation of compounds active on Leishmania , P. strigosum and P. pseudoarboreum were considered as potential sources of leishmanicidal compounds. This ethnopharmacological study and the associated in vitro bioassays corroborated the relevance of use of Piper species in the Amazonian traditional medicine, especially in Peru. A series of Piper species with few previously available phytochemical data have good antiprotozoal activity and could be a starting point for subsequent promising work. Metabolomic approach appears to be a smart, quick but still limited methodology to identify compounds with high probability of biological activity. Image 1 [ABSTRACT FROM AUTHOR]

Re-emergence and geographic expansion of leishmaniasis is accelerating efforts to develop a safe and effective Leshmania vaccine. Vaccines using Leishmania recombinant antigens, such as LiHyp1, which is mostly present in the amastigote parasite form , are being developed as a next generation to crude killed parasite-based vaccines. The main objective of this work was to develop a LiHyp1-based vaccine and determine if it can induce protective immunity in BALB/c mice when administered using a dissolvable microneedle (DMN) patch by the skin route. The LiHyp1 antigen was incorporated into cationic liposomes (CL), with or without the TLR9 agonist, CpG. The LiHyp1-liposomal vaccines were characterized with respect to size, protein encapsulation rates and retention of their physical characteristics after incorporation into the DMN patch. DMN mechanical strength and skin penetration ability were tested. A vaccine composed of LiHyp1, CpG and liposomes and subcutaneously injected or a vaccine containing antigen and CpG in DMN patches, without liposomes, induced high antibody responses and significant levels of protection against L. donovani parasite infection. This study progresses the development of an efficacious leishmania vaccine by detailing promising vaccine formulations and skin delivery technologies and it addresses protective efficacy of a liposome-based dissolvable microneedle patch vaccine system. [ABSTRACT FROM AUTHOR]