Malaria is an infectious disease that affects over 216 million people worldwide, killing over 445,000 patients annually. Due to the constant emergence of parasitic resistance to the current ...antimalarial drugs, the discovery of new drug candidates is a major global health priority. Aiming to make the drug discovery processes faster and less expensive, we developed binary and continuous Quantitative Structure-Activity Relationships (QSAR) models implementing deep learning for predicting antiplasmodial activity and cytotoxicity of untested compounds. Then, we applied the best models for a virtual screening of a large database of chemical compounds. The top computational predictions were evaluated experimentally against asexual blood stages of both sensitive and multi-drug-resistant Plasmodium falciparum strains. Among them, two compounds, LabMol-149 and LabMol-152, showed potent antiplasmodial activity at low nanomolar concentrations (EC50 <500 nM) and low cytotoxicity in mammalian cells. Therefore, the computational approach employing deep learning developed here allowed us to discover two new families of potential next generation antimalarial agents, which are in compliance with the guidelines and criteria for antimalarial target candidates.
Plasmodium falciparum dihydroorotate dehydrogenase (PfDHODH) has been clinically validated as a target for antimalarial drug discovery, as a triazolopyrimidine class inhibitor (DSM265) is currently ...undergoing clinical development. Here, we have identified new hydroxyazole scaffold-based PfDHODH inhibitors belonging to two different chemical series. The first series was designed by a scaffold hopping strategy that exploits the use of hydroxylated azoles. Within this series, the hydroxythiadiazole 3 was identified as the best selective PfDHODH inhibitor (IC50 12.0 μM). The second series was designed by modulating four different positions of the hydroxypyrazole scaffold. In particular, hydroxypyrazoles 7e and 7f were shown to be active in the low μM range (IC50 2.8 and 5.3 μM, respectively). All three compounds, 3, 7e and 7f showed clear selectivity over human DHODH (IC50 > 200 μM), low cytotoxicity, and retained micromolar activity in P. falciparum-infected erythrocytes. The crystallographic structures of PfDHODH in complex with compounds 3 and 7e proved their binding mode, supplying essential data for future optimization of these scaffolds.
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•Plasmodium falciparum DHODH is a validated target for malaria treatment.•New PfDHODH inhibitors are designed and synthetized using hydroxyazole scaffolds.•X-ray crystallography determined the binding mode inside the PfDHODH binding site.•Selectively over the human isoform, the hydroxypyrazole 7e inhibit PfDHODH (IC50 = 2.8 μM).•3 best compounds were tested against Pf-infected erythrocytes (EC50 between 26 and 40 μM).
The development of an effective immune response can help decrease mortality from malaria and its clinical symptoms. However, this mechanism is complex and has significant inter-individual variation, ...most likely owing to the genetic contribution of the human host. Therefore, this study aimed to investigate the influence of polymorphisms in genes involved in the costimulation of B-lymphocytes in the naturally acquired humoral immune response against proteins of the asexual stage of Plasmodium vivax. A total of 319 individuals living in an area of malaria transmission in the Brazilian Amazon were genotyped for four SNPs in the genes CD40, CD40L, BLYS and CD86. In addition, IgG antibodies against P. vivax apical membrane antigen 1 (PvAMA-1), Duffy binding protein (PvDBP) and merozoite surface protein 1 (PvMSP-119) were detected by ELISA. The SNP BLYS -871C>T was associated with the frequency of IgG responders to PvAMA-1 and PvMSP-119. The SNP CD40 -1C>T was associated with the IgG response against PvDBP, whereas IgG antibody titers against PvMSP-119 were influenced by the polymorphism CD86 +1057G>A. These data may help to elucidate the immunological aspects of vivax malaria and consequently assist in the design of malaria vaccines.
Drug resistance to commercially available antimalarials is a major obstacle in malaria control and elimination, creating the need to find new antiparasitic compounds with novel mechanisms of action. ...The success of kinase inhibitors for oncological treatments has paved the way for the exploitation of protein kinases as drug targets in various diseases, including malaria. Casein kinases are ubiquitous serine/threonine kinases involved in a wide range of cellular processes such as mitotic checkpoint signaling, DNA damage response, and circadian rhythm. In
, it is suggested that these protein kinases are essential for both asexual and sexual blood-stage parasites, reinforcing their potential as targets for multi-stage antimalarials. To identify new putative
CK2α inhibitors, we utilized an
chemogenomic strategy involving virtual screening with docking simulations and quantitative structure-activity relationship predictions. Our investigation resulted in the discovery of a new quinazoline molecule (
), which exhibited potent activity against asexual blood stages and a high selectivity index (>100). Subsequently, we conducted chemical-genetic interaction analysis on yeasts with mutations in casein kinases. Our chemical-genetic interaction results are consistent with the hypothesis that
inhibits yeast Cka1, which has a hinge region with high similarity to
CK2α. This finding is in agreement with our
results suggesting that
inhibits
CK2α via hinge region interaction.
•Infected individuals with rs6910730A allele had higher IL-6, IL-10, and IFN-γ levels.•IL-5, IL-6, IL-10, TNF-α, and IFN-γ were increased in rs2234237T and infected.•The rs2234246CT genotype group ...and infected had higher levels of TNF-α, and IFN-γ.•IFN-γ was higher in the infected group with rs4711668C allele.•The trem-1 polymorphisms had no impact of the sTREM-1 levels.
The immunopathology during malaria depends on the level of inflammatory response generated. In this scenario, the TREM-1 has been associated with the severity of infectious diseases and could play an important role in the inflammatory course of malaria. We aimed to describe the allelic and genotypic frequency of four polymorphisms in the trem-1 gene in Plasmodium vivax-infected patients and to verify the association of these polymorphisms with clinical and immunological factors in a frontier area of the Brazilian Amazon.
We included 76 individuals infected with P. vivax and 144 healthy controls living in the municipality of Oiapoque, Amapá, Brazil. The levels of TNF-α, IL-10, IL-2, IL-4, IL-5, and IFN-γ were measured by flow cytometry, while IL-6, sTREM-1, and antibodies against PvMSP-119 were evaluated by ELISA. The SNPs were genotyped by qPCR technique. Polymorphisms analysis, allelic and genotype, frequencies, and HWE calculation were determined by x2 test in R Software. The association between the parasitemia, gametocytes, antibodies, cytokines, and sTREM-1 with the genotypes of malaria and control groups was performed using the Kruskal-Wallis test, these analyzes were conducted in SPSS Software, at 5% significance level.
All SNPs were successfully genotyped. Allelic and genotypic distribution was in Hardy-Weinberg Equilibrium. Furthermore, several associations were identified between malaria and control groups, with increased levels of IL-5, IL-6, IL-10, TNF-α, and IFN-γ in the infected individuals with rs6910730A, rs2234237T, rs2234246T, rs4711668C alleles compared to the homozygous wild-type and heterozygous genotypes of the controls (p-value < 0.05). No association was found for these SNPs and the levels of IL-2, and sTREM-1.
The SNPs on the trem-1 gene are associated with the effector molecules of the innate immunity and may contribute to the identification and effective participation of trem-1 in the modulation of the immune response. This association may be essential for the establishment of immunization strategies against malaria.
•Cytokines: Cytokine levels contribute to clinical manifestations such as parasitemia, severity, and susceptibility in malaria infections.•MSP-119: No associations between SNPs studied of TLRs and ...antibody levels of MSP-1 were observed.•P. vivax: This is the predominant and spread worldwide malaria specie, despite an alarming number of people becoming infected each year, is still considered a neglected disease.•TLRs: Play a critical role in the innate immune response to malaria. They recognize specific parasite-derived molecules and initiate immune signaling pathways.•SNPs: In TLR genes play an important role in malaria pathogenesis and have been associated with susceptibility and parasitemia.
The innate immune response plays an important role during malaria. Toll-like receptors (TLR) are capable of recognizing pathogen molecules. We aimed to evaluate five polymorphisms in TLR-4, TLR-6, and TLR-9 genes and their association with cytokine levels and clinical parameters in malaria from the Brazil-French Guiana border.
A case-control study was conducted in Amapá, Brazil. P. vivax patients and individuals not infected were evaluated. Genotyping of five SNPs was carried out by qPCR. Circulating cytokines were measured by CBA. The MSP-119 IgG antibodies were performed by ELISA.
An association between TLR4 A299G with parasitemia was observed. There was an increase for IFN-ɤ, TNF-ɑ, IL-6, and IL-10 in the TLR-4 A299G and T3911, TLR-6 S249P, and TLR-9 1486C/T, SNPs for the studied malarial groups. There were significant findings for the TLR-4 variants A299G and T3911, TLR-9 1237C/T, and 1486C/T. For the reactivity of MSP-119 antibodies levels, no significant results were found in malaria, and control groups.
The profile of the immune response observed by polymorphisms in TLRs genes does not seem to be standard for all types of malaria infection around the world. This can depend on the human population and the species of Plasmodium.
Malaria is a tropical infectious disease that affects over 219 million people worldwide. Due to the constant emergence of parasitic resistance to the current antimalarial drugs, the discovery of new ...antimalarial drugs is a global health priority. Multi-target drug discovery is a promising and innovative strategy for drug discovery and it is currently regarded as one of the best strategies to face drug resistance. Aiming to identify new multi-target antimalarial drug candidates, we developed an integrative computational approach to select multi-kinase inhibitors for
calcium-dependent protein kinases 1 and 4 (CDPK1 and CDPK4) and protein kinase 6 (PK6). For this purpose, we developed and validated shape-based and machine learning models to prioritize compounds for experimental evaluation. Then, we applied the best models for virtual screening of a large commercial database of drug-like molecules. Ten computational hits were experimentally evaluated against asexual blood stages of both sensitive and multi-drug resistant
strains. Among them, LabMol-171, LabMol-172, and LabMol-181 showed potent antiplasmodial activity at nanomolar concentrations (EC
≤ 700 nM) and selectivity indices >15 folds. In addition, LabMol-171 and LabMol-181 showed good
inhibition of
ookinete formation and therefore represent promising transmission-blocking scaffolds. Finally, docking studies with protein kinases CDPK1, CDPK4, and PK6 showed structural insights for further hit-to-lead optimization studies.
Despite treatment with effective antimalarial drugs, the mortality rate is still high in severe cases of the disease, highlighting the need to find adjunct therapies that can inhibit the adhesion of ...Plasmodium falciparum-infected erythrocytes (Pf-iEs).
In this context, we evaluated a new heparan sulfate (HS) from Nodipecten nodosus for antimalarial activity and inhibition of P. falciparum cytoadhesion and rosetting.
Parasite inhibition was measured by SYBR green using a cytometer. HS was assessed in rosetting and cytoadhesion assays under static and flow conditions using Chinese hamster ovary (CHO) and human lymphatic endothelial cell (HLEC) cells expressing intercellular adhesion molecule-1 (ICAM1) and chondroitin sulfate A (CSA), respectively.
This HS inhibited merozoite invasion similar to heparin. Moreover, mollusk HS decreased cytoadherence of P. falciparum to CSA and ICAM-1 on the surface of endothelial cells under static and flow conditions. In addition, this glycan efficiently disrupted rosettes.
These findings support a potential use for mollusk HS as adjunct therapy for severe malaria.
Malaria is a life-threatening infectious disease caused by parasites of the genus
, affecting more than 200 million people worldwide every year and leading to about a half million deaths. Malaria ...parasites of humans have evolved resistance to all current antimalarial drugs, urging for the discovery of new effective compounds. Given that the inhibition of deoxyuridine triphosphatase of
(
dUTPase) induces wrong insertions in plasmodial DNA and consequently leading the parasite to death, this enzyme is considered an attractive antimalarial drug target. Using a combi-QSAR (quantitative structure-activity relationship) approach followed by virtual screening and
experimental evaluation, we report herein the discovery of novel chemical scaffolds with
potency against asexual blood stages of both
multidrug-resistant and sensitive strains and against sporogonic development of
. We developed 2D- and 3D-QSAR models using a series of nucleosides reported in the literature as
dUTPase inhibitors. The best models were combined in a consensus approach and used for virtual screening of the ChemBridge database, leading to the identification of five new virtual
dUTPase inhibitors. Further
testing on
multidrug-resistant (W2) and sensitive (3D7) parasites showed that compounds LabMol-144 and LabMol-146 demonstrated fair activity against both strains and presented good selectivity versus mammalian cells. In addition, LabMol-144 showed good
inhibition of
ookinete formation, demonstrating that hit-to-lead optimization based on this compound may also lead to new antimalarials with transmission blocking activity.
Increasing reports of multidrug-resistant malaria parasites urge the discovery of new effective drugs with different chemical scaffolds. Protein kinases play a key role in many cellular processes ...such as signal transduction and cell division, making them interesting targets in many diseases. Protein kinase 7 (PK7) is an orphan kinase from the Plasmodium genus, essential for the sporogonic cycle of these parasites. Here, we applied a robust and integrative artificial intelligence-assisted virtual-screening (VS) approach using shape-based and machine learning models to identify new potential PK7 inhibitors with in vitro antiplasmodial activity. Eight virtual hits were experimentally evaluated, and compound LabMol-167 inhibited ookinete conversion of Plasmodium berghei and blood stages of Plasmodium falciparum at nanomolar concentrations with low cytotoxicity in mammalian cells. As PK7 does not have an essential role in the Plasmodium blood stage and our virtual screening strategy aimed for both PK7 and blood-stage inhibition, we conducted an in silico target fishing approach and propose that this compound might also inhibit P. falciparum PK5, acting as a possible dual-target inhibitor. Finally, docking studies of LabMol-167 with P. falciparum PK7 and PK5 proteins highlighted key interactions for further hit-to lead optimization.
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