Synthesis and antiplasmodial activity of regioisomers and epimers of second-generation dual acting ivermectin hybrids

© The Author(s) 2022. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.With its strong effect on vector-borne diseases, and insecticidal effect on mosquito vectors of malaria, inhibition of sporogonic and blood-stage development of Plasmodium falciparum, as well as in vitro and in vivo impairment of the P. berghei development inside hepatocytes, ivermectin (IVM) continues to represent an antimalarial therapeutic worthy of investigation. The in vitro activity of the first-generation IVM hybrids synthesized by appending the IVM macrolide with heterocyclic and organometallic antimalarial pharmacophores, against the blood-stage and liver-stage infections by Plasmodium parasites prompted us to design second-generation molecular hybrids of IVM. Here, a structural modification of IVM to produce novel molecular hybrids by using sub-structures of 4- and 8-aminoquinolines, the time-tested antiplasmodial agents used for treating the blood and hepatic stage of Plasmodium infections, respectively, is presented. Successful isolation of regioisomers and epimers has been demonstrated, and the evaluation of their in vitro antiplasmodial activity against both the blood stages of P. falciparum and the hepatic stages of P. berghei have been undertaken. These compounds displayed structure-dependent antiplasmodial activity, in the nM range, which was more potent than that of IVM, its aglycon or primaquine, highlighting the superiority of this hybridization strategy in designing new antiplasmodial agents.KS thanks SERB, DST for the grant (EMR/2017/000520) and Guru Nanak Dev University, Amritsar for funding under the RUSA-II scheme as well as facilities. MP acknowledges Fundação para a Ciência e Tecnologia, Portugal, for Grant PTDC-SAU-INF-29550/2017. LS is thankful to University Grants Commission (UGC), New Delhi for funding under Rajiv Gandhi National Fellowship.info:eu-repo/semantics/publishedVersio

Establishment of Murine Gammaherpesvirus latency in B cells is not a stochastic event

Copyright: © 2014 Decalf et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Murid γ-herpesvirus-4 (MuHV-4) promotes polyclonal B cell activation and establishes latency in memory B cells via unclear mechanisms. We aimed at exploring whether B cell receptor specificity plays a role in B cell susceptibility to viral latency and how this is related to B cell activation. We first observed that MuHV-4-specific B cells represent a minority of the latent population, and to better understand the influence of the virus on non-MuHV-4 specific B cells we used the SWHEL mouse model, which produce hen egg lysozyme (HEL)-specific B cells. By tracking HEL+ and HEL- B cells, we showed that in vivo latency was restricted to HEL- B cells while the two populations were equally sensitive to the virus in vitro. Moreover, MuHV-4 induced two waves of B cell activation. While the first wave was characterized by a general B cell activation, as shown by HEL+ and HEL- B cells expansion and upregulation of CD69 expression, the second wave was restricted to the HEL- population, which acquired germinal center (GC) and plasma cell phenotypes. Antigenic stimulation of HEL+ B cells led to the development of HEL+ GC B cells where latent infection remained undetectable, indicating that MuHV-4 does not benefit from acute B cell responses to establish latency in non-virus specific B cells but relies on other mechanisms of the humoral response. These data support a model in which the establishment of latency in B cells by γ-herpesviruses is not stochastic in terms of BCR specificity and is tightly linked to the formation of GCs.Research in JPS's lab was supported by a grant from the Portuguese Fundação para a Ciência e Tecnologia (FCT) (PTDC/SAU-MII/099314/2008). JD was recipient of a FCT fellowship.info:eu-repo/semantics/publishedVersio

A new strategy against malaria – antimalarial ionic liquids derived from aminoquinolines and fatty acids

Based on the recent promising results obtained by us, where ionic liquids (ILs) derived from primaquine were found as triple-stage antimalarial hits, we have now produced, by simple, quantitative, and low-cost methods, new ILs via simple acid-base titration of antimalarial aminoquinolines (primaquine and chloroquine) with natural fatty acids (Figure 1). We have also synthesized, in good to high yields, the covalent amide analogues of these ILs (Figure 1), in order to establish how the nature of the chemical bond (ionic ammonium carboxylate versus covalent amide) between both building blocks influences the physico-chemical and biological properties of the final compounds. Results obtained thus far allow us to conclude that both ionic and covalent compounds (i) have higher thermostability than the parent drugs, and (ii) display remarkable in vitro activity against liver-stage malaria parasites.info:eu-repo/semantics/publishedVersio

New 4-(N-cinnamoylbutyl)aminoacridines as potential multi-stage antiplasmodial leads

© 2023 The Authors. Published by Elsevier Masson SAS. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).A novel family of 4-aminoacridine derivatives was obtained by linking this heteroaromatic core to different trans-cinnamic acids. The 4-(N-cinnamoylbutyl)aminoacridines obtained exhibited in vitro activity in the low- or sub-micromolar range against (i) hepatic stages of Plasmodium berghei, (ii) erythrocytic forms of Plasmodium falciparum, and (iii) early and mature gametocytes of Plasmodium falciparum. The most active compound, having a meta-fluorocinnamoyl group linked to the acridine core, was 20- and 120-fold more potent, respectively, against the hepatic and gametocyte stages of Plasmodium infection than the reference drug, primaquine. Moreover, no cytotoxicity towards mammalian and red blood cells at the concentrations tested was observed for any of the compounds under investigation. These novel conjugates represent promising leads for the development of new multi-target antiplasmodials.This work received financial support from PT national funds (FCT/MCTES, Fundação para a Ciência e Tecnologia and Ministério da Ciência, Tecnologia e Ensino Superior) through the project CIRCNA/BRB/0281/2019. The authors further thank FCT/MCTES for supporting Research Units LAQV-REQUIMTE (UIDB/50006/2020) and for the Doctoral Grant to MF (SRFH/BD/147354/2019). MP further acknowledges the “la Caixa” Foundation for Grant HR21-848. ISGlobal and IBEC are members of the CERCA Programme, Generalitat de Catalunya. We acknowledge support from the Ministerio de Ciencia e Innovación/Agencia Estatal de Investigación (MCIN/AEI/ 10.13039/501100011033) through the “Centro de Excelencia Severo Ochoa 2019-2023” Program (CEX2018-000806-S). This research is part of ISGlobal's Program on the Molecular Mechanisms of Malaria which is partially supported by the Fundación Ramón Areces.info:eu-repo/semantics/publishedVersio

A crucial role for the C‐terminal domain of exported protein 1 during the mosquito and hepatic stages of the Plasmodium bergheilife cycle

© 2019 The Authors. Cellular Microbiology published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.Intracellular Plasmodium parasites develop inside a parasitophorous vacuole (PV), a specialised compartment enclosed by a membrane (PVM) that contains proteins of both host and parasite origin. Although exported protein 1 (EXP1) is one of the earliest described parasitic PVM proteins, its function throughout the Plasmodium life cycle remains insufficiently understood. Here, we show that whereas the N-terminus of Plasmodium berghei EXP1 (PbEXP1) is essential for parasite survival in the blood, parasites lacking PbEXP1's entire C-terminal (CT) domain replicate normally in the blood but cause less severe pathology than their wild-type counterparts. Moreover, truncation of PbEXP1's CT domain not only impairs parasite development in the mosquito but also abrogates PbEXP1 localization to the PVM of intrahepatic parasites, severely limiting their replication and preventing their egress into the blood. Our findings highlight the importance of EXP1 during the Plasmodium life cycle and identify this protein as a promising target for antiplasmodial intervention.This study was sup- ported by German Research Foundation (Deutsche Forschungsgemeinschaft ‐ DFG) Grants SPP 1580 (to A.‐K. M.) and SFB1129 (to A.‐K. M.); Fundação para a Ciência e Tecnologia, Portugal (FCT‐PT) Grants UID/BIM/50005/2019 (Ministério da Ciência, Tecnologia e Ensino Superior (MCTES) through Fundos do Orçamento de Estado) and 02/SAICT/2017 (to M. P.). M. S.‐V. was supported by an FCT‐PT Grant PD/BD/105838/2014. D. F. was supported by FEEI and FCT‐MEC. M. P. was supported by FCT‐PT Investigador FCT 2013 and CEEC 2018 fellowship. A.‐K. M. was a recipient of a Maternity Leave Stipend by the German Center for Infection Research (DZIF, Heidelberg Site)info:eu-repo/semantics/publishedVersio

Pre-erythrocytic activity of M5717 in monotherapy and combination in preclinical Plasmodium infection models

Copyright © 2022 The Authors. Published by American Chemical SocietyCombination therapies have emerged to mitigate Plasmodium drug resistance, which has hampered the fight against malaria. M5717 is a potent multistage antiplasmodial drug under clinical development, which inhibits parasite protein synthesis. The combination of M5717 with pyronaridine, an inhibitor of hemozoin formation, displays potent activity against blood stage Plasmodium infection. However, the impact of this therapy on liver infection by Plasmodium remains unknown. Here, we employed a recently described 3D culture-based hepatic infection platform to evaluate the activity of the M5717-pyronaridine combination against hepatic infection by P. berghei. This effect was further confirmed in vivo by employing the C57BL/6J rodent Plasmodium infection model. Collectively, our data demonstrate that pyronaridine potentiates the activity of M5717 against P. berghei hepatic development. These preclinical results contribute to the validation of pyronaridine as a suitable partner drug for M5717, supporting the clinical evaluation of this novel antiplasmodial combination therapy.This work was funded by the healthcare business of Merck KGaA, Darmstadt, Germany (CrossRef Funder ID: 10.13039/100009945). M.P. is a recipient of a “Concurso de Estímulo ao Emprego Científico” Principal Investigator award of Fundação para a Ciência e Tecnologia, Portugal (FCT), with ref. N. CEECIND/03539/2017. D.F. is funded by FCT project CRCNA/BRB/0281/2019. F.A. is recipient of a PhD fellowship PD/BD/128371/2017, funded by FCT.info:eu-repo/semantics/publishedVersio

A Histone Deacetylase (HDAC) inhibitor with pleiotropic in vitro anti-toxoplasma and anti-plasmodium activities controls acute and chronic toxoplasma infection in mice

© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).Toxoplasmosis is a highly prevalent human disease, and virulent strains of this parasite emerge from wild biotopes. Here, we report on the potential of a histone deacetylase (HDAC) inhibitor we previously synthesized, named JF363, to act in vitro against a large panel of Toxoplasma strains, as well as against the liver and blood stages of Plasmodium parasites, the causative agents of malaria. In vivo administration of the drug significantly increases the survival of mice during the acute phase of infection by T. gondii, thus delaying its spreading. We further provide evidence of the compound's efficiency in controlling the formation of cysts in the brain of T. gondii-infected mice. A convincing docking of the JF363 compound in the active site of the five annotated ME49 T. gondii HDACs was performed by extensive sequence-structure comparison modeling. The resulting complexes show a similar mode of binding in the five paralogous structures and a quite similar prediction of affinities in the micromolar range. Altogether, these results pave the way for further development of this compound to treat acute and chronic toxoplasmosis. It also shows promise for the future development of anti-Plasmodium therapeutic interventions.This research was funded by IDEX Innovation Grant, UGA, 2017 and The GIS ChemBioFranceinfo:eu-repo/semantics/publishedVersio

4,9-Diaminoacridines and 4-Aminoacridines as Dual-Stage Antiplasmodial Hits

Multi‐stage drugs have been prioritized in antimalarial drug discovery, as targeting more than one process in the Plasmodium life cycle is likely to increase efficiency, while decreasing the chances of emergence of resistance by the parasite. Herein, we disclose two novel acridine‐based families of compounds that combine the structural features of primaquine and chloroquine. Compounds prepared and studied thus far retained the in vitro activity displayed by the parent drugs against the erythrocytic stages of chloroquine‐sensitive and ‐resistant Plasmodium falciparum strains, and against the hepatic stages of Plasmodium berghei, hence acting as dual‐stage antiplasmodial hits.info:eu-repo/semantics/publishedVersio

Unexpected rearrangement of ivermectin in the synthesis of new derivatives with trypanocidal and antiplasmodial activities

Ivermectin is a sixteen-membered macrolactone “wonder drug” of Nobel prize-honored distinction that exhibits a wide range of antiparasitic activities. It has been used for almost four decades in the treatment of various parasitic diseases in humans and animals. In this paper, we describe the synthesis of the first-in-class ivermectin derivatives obtained via derivatization of the C13 position, along with the unexpected rearrangement of the oxahydrindene (hexahydrobenzofuran) unit of the macrolide ring. The structural investigation of the rearrangement has been performed using the single-crystal X-ray diffraction method. The antiparasitic and cytotoxic activities of the newly synthesized derivatives were determined in vitro with the bloodstream form of Trypanosoma brucei brucei, the hepatic stage of Plasmodium berghei, and human leukemia HL-60 cells. The compounds with the highest trypanocidal activity were the C13-epi-2-chloroacetamide analogs of native (6h) or rearranged (7h) ivermectin. Both 6h and 7h displayed trypanocidal activities within a similar mid-nanomolar concentration range as the commercially used trypanocides suramin and ethidium bromide. Furthermore, 6h and 7h exhibited a comparable cytotoxic to trypanocidal ratio as the reference drug ethidium bromide. The double-modified compound 7a (C13-epi-acetamide of rearranged ivermectin) exhibited the highest activity against P. berghei grown in human hepatoma cells, which was 2.5 times higher than that of ivermectin. The findings of this study suggest that C13-epi-amide derivatives of ivermectin are suitable leads in the rational development of new antiparasitic agents