RESUMO
Plasmodium vivax's biological complexity has restricted in vitro culture development for characterising antigens involved in erythrocyte invasion and their immunological relevance. The murine model is proposed as a suitable alternative in the search for therapeutic candidates since Plasmodium yoelii uses homologous proteins for its invasion. The AMA-1 protein is essential for parasite invasion of erythrocytes as it is considered an important target for infection control. This study has focused on functional PyAMA-1 peptides involved in host-pathogen interaction; the protein is located in regions under negative selection as determined by bioinformatics analysis. It was found that pyama1 has two highly conserved regions amongst species (>70%) under negative selection. Fourteen synthetic peptides spanning both conserved regions were evaluated; 5 PyAMA-1 peptides having high specific binding (HABP) to murine erythrocytes were identified. The parasite's invasion inhibition capability was analysed through in vitro assays, suggesting that peptides 42681 (43-ENTERSIKLINPWDKYMEKY-62), 42903 (206-RYSSNDANNENQPFSFTPEK-225) and 42904 (221-FTPEKIENYKDLSYLTKNLR-240) had greater than 50% inhibition profile and restricted P. yoelii intra-erythrocyte development. This work proposes that the screening of conserved HABPs under negative selective pressure might be good candidates for developing a synthetic anti-malarial vaccine since they share functionally-relevant characteristics, such as interspecies conservation, specific RBC binding profile, invasion and parasite development inhibition capability, and the predicted B-epitopes within were recognised by sera obtained from experimentally-infected mice.
Assuntos
Antimaláricos , Animais , Camundongos , Antimaláricos/farmacologia , Antimaláricos/metabolismo , Sequência de Aminoácidos , Plasmodium falciparum , Proteínas de Protozoários , Peptídeos , Eritrócitos/metabolismo , Antígenos de ProtozoáriosRESUMO
Cryptococcus gattii and Cryptococcus neoformans are the main etiological agents of cryptococcosis, an invasive mycosis treated with amphotericin B, 5-fluorocytosine, and fluconazole. This limited arsenal is toxic and is associated with antifungal resistance. Cryptococcosis and malaria pathogens are eukaryotic organisms that have a high incidence in Sub-Saharan Africa. The antimalarials (ATMs) halofantrine (HAL) and amodiaquine (AQ) block Plasmodium heme polymerase, and artesunate (ART) induces oxidative stress. Considering that Cryptococcus spp. is susceptible to reactive oxygen species and that iron is essential for metabolism, the repurposing of ATMs for treating cryptococcosis was tested. ATMs reduced fungal growth, induced oxidative and nitrosative stresses, and altered ergosterol content, melanin production, and polysaccharide capsule size in C. neoformans and C. gattii, revealing a dynamic effect on fungal physiology. A comprehensive chemical-genetic analysis using two mutant libraries demonstrated that the deletion of genes involved in synthesizing components of the plasma membrane and cell wall, and oxidative stress responses are essential for fungal susceptibility to ATMs. Interestingly, the amphotericin B (AMB) fungicidal concentrations were â¼10 times lower when combined with ATMs, demonstrating a synergistic interaction. Further, the combinations showed reduced toxicity to murine macrophages. Finally, HAL+AMB and AQ+AMB efficiently reduced lethality and fungal burden in the lungs and brain in murine cryptococcosis. These findings provide perspectives for further studies with ATMs against cryptococcosis and other fungal infections.
Assuntos
Antimaláricos , Criptococose , Cryptococcus gattii , Cryptococcus neoformans , Animais , Camundongos , Anfotericina B/farmacologia , Anfotericina B/uso terapêutico , Antifúngicos/farmacologia , Antifúngicos/uso terapêutico , Antifúngicos/metabolismo , Antimaláricos/farmacologia , Antimaláricos/uso terapêutico , Antimaláricos/metabolismo , Criptococose/tratamento farmacológico , Criptococose/microbiologia , Fluconazol/farmacologia , Fluconazol/uso terapêutico , Testes de Sensibilidade MicrobianaRESUMO
Seven phenolic compounds (ferulic acid, caffeic acid, 4-methoxycinnamic acid, 3,4-dimethoxycinnamic acid, 3-hydroxy-4-methoxybenzaldehyde, 3-methoxy-4-hydroxypropiophenone and 1-O,2-O-digalloyl-6-O-trans-p-coumaroyl-ß-D-glucopyranoside), a flavanonol (7-O-methylaromadendrin), two lignans (pinoresinol and matairesinol) and six diterpenic acids/alcohol (19-acetoxy-13-hydroxyabda-8(17),14-diene, totarol, 7-oxodehydroabietic acid, dehydroabietic acid, communic acid and isopimaric acid) were isolated from the hydroalcoholic extract of a Brazilian Brown Propolis and characterized by NMR spectral data analysis. The volatile fraction of brown propolis was characterized by CG-MS, composed mainly of monoterpenes and sesquiterpenes, being the major α-pinene (18.4 %) and ß-pinene (10.3 %). This propolis chemical profile indicates that Pinus spp., Eucalyptus spp. and Araucaria angustifolia might be its primary plants source. The brown propolis displayed significant activity against Plasmodium falciparum D6 and W2 strains with IC50 of 5.3 and 9.7â µg/mL, respectively. The volatile fraction was also active with IC50 of 22.5 and 41.8â µg/mL, respectively. Among the compounds, 1-O,2-O-digalloyl-6-O-trans-p-coumaroyl-ß-D-glucopyranoside showed IC50 of 3.1 and 1.0â µg/mL against D6 and W2 strains, respectively, while communic acid showed an IC50 of 4.0â µg/mL against W2 strain. Cytotoxicity was determined on four tumor cell lines (SK-MEL, KB, BT-549, and SK-OV-3) and two normal renal cell lines (LLC-PK1 and VERO). Matairesinol, 7-O-methylaromadendrin, and isopimaric acid showed an IC50 range of 1.8-0.78â µg/mL, 7.3-100â µg/mL, and 17-18â µg/mL, respectively, against the tumor cell lines but they were not cytotoxic against normal cell lines. The crude extract of brown propolis displayed antimicrobial activity against C.â neoformans, methicillin-resistant Staphylococcus aureus, and P.â aeruginosa at 29.9â µg/mL, 178.9â µg/mL, and 160.7â µg/mL, respectively. The volatile fraction inhibited the growth of C.â neoformans at 53.0â µg/mL. The compounds 3-hydroxy-4-methoxybenzaldehyde, 3-methoxy-4-hydroxypropiophenone and 7-oxodehydroabietic acid were active against C.â neoformans, and caffeic and communic acids were active against methicillin-resistant Staphylococcus aureus.
Assuntos
Antibacterianos/farmacologia , Antimaláricos/farmacologia , Antineoplásicos Fitogênicos/farmacologia , Compostos Fitoquímicos/farmacologia , Própole/química , Animais , Antibacterianos/biossíntese , Antibacterianos/química , Antimaláricos/química , Antimaláricos/metabolismo , Antineoplásicos Fitogênicos/biossíntese , Antineoplásicos Fitogênicos/química , Abelhas , Brasil , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Cryptococcus neoformans/efeitos dos fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Testes de Sensibilidade Parasitária , Compostos Fitoquímicos/biossíntese , Compostos Fitoquímicos/química , Plasmodium falciparum/efeitos dos fármacos , Pseudomonas aeruginosa/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacosRESUMO
ACT's low levels of Plasmodium parasitemia clearance are worrisome since it is the last treatment option against P. falciparum. This scenario has led to investigations of compounds with different mechanisms of action for malaria treatment. Natural compounds like ursolic acid (UA) and betulinic acid (BA), distinguished by their activity against numerous microorganisms, including P. falciparum, have become relevant. This study evaluated the antiplasmodial activity of imidazole derivatives of UA and BA against P. falciparum in vitro. Eight molecules were obtained by semisynthesis and tested against P. falciparum strains (NF54 and CQ-resistant 106/cand isolated in Porto Velho, Brazil); 2a and 2b showed activity against NF54 and 106/cand strains with IC50 < 10 µM. They presented high selectivity indexes (SI > 25) and showed synergism when combined with artemisinin. 2b inhibited the parasite's ring and schizont forms regardless of when the treatment began. In silico analysis presented a tight bind of 2b in the topoisomerase II-DNA complex. This study demonstrates the importance of natural derivate compounds as new candidates for malarial treatment with new mechanisms of action. Semisynthesis led to new triterpenes that are active against P. falciparum and may represent new alternatives for malaria drug development.
Assuntos
Antimaláricos/farmacologia , Resistência a Medicamentos/efeitos dos fármacos , Triterpenos Pentacíclicos/química , Plasmodium falciparum/efeitos dos fármacos , Triterpenos/química , Antimaláricos/química , Antimaláricos/isolamento & purificação , Antimaláricos/metabolismo , Sítios de Ligação , Brasil , Cloroquina/farmacologia , DNA Topoisomerases Tipo II/química , DNA Topoisomerases Tipo II/metabolismo , Estágios do Ciclo de Vida/efeitos dos fármacos , Simulação de Acoplamento Molecular , Triterpenos Pentacíclicos/isolamento & purificação , Triterpenos Pentacíclicos/farmacologia , Plasmodium falciparum/metabolismo , Proteínas de Protozoários/química , Proteínas de Protozoários/metabolismo , Relação Estrutura-Atividade , Triterpenos/isolamento & purificação , Triterpenos/farmacologia , Ácido Betulínico , Ácido UrsólicoRESUMO
ETHNOPHARMACOLOGICAL RELEVANCE: 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. AIMS OF STUDY: 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. MATERIALS AND METHODS: 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. RESULTS: Nine extracts were active (IC50 ≤ 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. CONCLUSIONS: 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.
Assuntos
Antiprotozoários/metabolismo , Etnofarmacologia/métodos , Medicina Tradicional/métodos , Metabolômica/métodos , Piper/metabolismo , Extratos Vegetais/metabolismo , Animais , Antimaláricos/isolamento & purificação , Antimaláricos/metabolismo , Antimaláricos/uso terapêutico , Antiprotozoários/isolamento & purificação , Antiprotozoários/uso terapêutico , Feminino , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana/metabolismo , Humanos , Leishmania donovani/efeitos dos fármacos , Leishmania donovani/metabolismo , Mesocricetus , Camundongos , Peru/etnologia , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/uso terapêutico , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/metabolismo , Células RAW 264.7 , Inquéritos e QuestionáriosRESUMO
BACKGROUND: Plasmodium vivax malaria is characterized by the presence of dormant liver-stage parasites, called hypnozoites, which can cause malaria relapses after an initial attack. Primaquine, which targets liver hypnozoites, must be used in combination with a schizonticidal agent to get the radical cure. However, relapses can sometimes occur in spite of correct treatment, due to different factors such as a diminished metabolization of primaquine. CASE PRESENTATION: In January 2019, a 21 years old woman with residence in Madrid, returning from a trip to Venezuela with clinical symptoms compatible with malaria infection, was diagnosed with vivax malaria. Chloroquine for 3 days plus primaquine for 14 days was the elected treatment. Two months later and after a second trip to Venezuela, the patient presented a second P. vivax infection, which was treated as the previous one. A third P. vivax malaria episode was diagnosed 2 months later, after returning from a trip to Morocco, receiving chloroquine for 3 days but increasing to 28 days the primaquine regimen, and with no more relapses after 6 months of follow up. The genotyping of P. vivax in the three malaria episodes revealed that the same strain was present in the different relapses. Upon confirmation of correct adherence to the treatment, non-description of resistance in the infection area and the highly unlikely re-infection on subsequent trips or stays in Spain, a possible metabolic failure was considered. CYP2D6 encodes the human cytochrome P450 isoenzyme 2D6 (CYP2D6), responsible for primaquine activation. The patient was found to have a CYP2D6*4/*1 genotype, which turns out in an intermediate metabolizer phenotype, which has been related to P. vivax relapses. CONCLUSIONS: The impairment in CYP2D6 enzyme could be the most likely cause of P. vivax relapses in this patient. This highlights the importance of considering the analysis of CYP2D6 gene polymorphisms in cases of P. vivax relapses after a correct treatment and, especially, it should be considered in any study of dosage and duration of primaquine treatment.
Assuntos
Antimaláricos/uso terapêutico , Citocromo P-450 CYP2D6/metabolismo , Malária Vivax/tratamento farmacológico , Primaquina/uso terapêutico , Antimaláricos/metabolismo , Feminino , Humanos , Malária Vivax/parasitologia , Fenótipo , Plasmodium vivax/fisiologia , Primaquina/metabolismo , Recidiva , Espanha , Venezuela , Adulto JovemRESUMO
Malaria is a devastating disease depending only on chemotherapy as treatment. However, medication is losing efficacy, and therefore, there is an urgent need for the discovery of novel pharmaceutics. Recently, plasmepsin V, an aspartic protease anchored in the endoplasmaic reticulum, was demonstrated as responsible for the trafficking of parasite-derived proteins to the erythrocytic surface and further validated as a drug target. In this sense, ligand-based virtual screening has been applied to design inhibitors that target plasmepsin V of P. falciparum (PMV). After screening 5.5 million compounds, four novel plasmepsin inhibitors have been identified which were subsequently analyzed for the potency at the cellular level. Since PMV is membrane-anchored, the verification in vivo by using transgenic PMV overexpressing P. falciparum cells has been performed in order to evaluate drug efficacy. Two lead compounds, revealing IC50 values were 44.2 and 19.1 µm, have been identified targeting plasmepsin V in vivo and do not significantly affect the cell viability of human cells up to 300 µm. We herein report the use of the consensus of individual virtual screening as a new technique to design new ligands, and we propose two new lead compounds as novel protease inhibitors to target malaria.
Assuntos
Antimaláricos/química , Ácido Aspártico Endopeptidases/metabolismo , Ligantes , Plasmodium falciparum/metabolismo , Proteínas de Protozoários/metabolismo , Antimaláricos/metabolismo , Antimaláricos/farmacologia , Ácido Aspártico Endopeptidases/antagonistas & inibidores , Ácido Aspártico Endopeptidases/genética , Sítios de Ligação , Domínio Catalítico , Sobrevivência Celular/efeitos dos fármacos , Células Hep G2 , Humanos , Concentração Inibidora 50 , Simulação de Acoplamento Molecular , Organismos Geneticamente Modificados/metabolismo , Plasmodium falciparum/efeitos dos fármacos , Inibidores de Proteases/química , Inibidores de Proteases/metabolismo , Proteínas de Protozoários/antagonistas & inibidores , Proteínas de Protozoários/genéticaRESUMO
Malaria is the world's most widespread protozoan infection, being responsible for more than 445,000 annual deaths. Among the malaria parasites, Plasmodium falciparum is the most prevalent and lethal. In this context, the search for new antimalarial drugs is urgently needed. P. falciparum superoxide dismutase (PfSOD) is an important enzyme involved in the defense mechanism against oxidative stress. The goal of this study was to identify through hierarchical screening on pharmacophore models and molecular dynamics (MD), promising allosteric PfSOD inhibitors that do not show structural requirements for human inhibition. MD simulations of 1000 ps were performed on PfSOD using GROMACS 5.1.2. For this, the AMBER99SB-ILDN force field was adapted to describe the metal-containing system. The simulations indicated stability in the developed system. Therefore, a covariance matrix was generated, in which it was possible to identify residues with correlated and anticorrelated movements with the active site. These results were associated with the results found in the predictor of allosteric sites, AlloSitePro, which affirmed the ability of these residues to delimit an allosteric site. Then, after successive filtering of the Sigma-Aldrich® compounds database for HsSOD1 and PfSOD pharmacophores, 152 compounds were selected, also obeying Lipinski's rule of 5. Further filtering of those compounds based on molecular docking results, toxicity essays, availability, and price filtering led to the selection of a best compound, which was then submitted to MD simulations of 20,000 ps on the allosteric site. The study concludes that the ZINC00626080 compound could be assayed against SODs. Graphical Abstract Plasmodium falciparum superoxide dismutase.
Assuntos
Antimaláricos/química , Inibidores Enzimáticos/química , Simulação de Dinâmica Molecular , Plasmodium falciparum/química , Proteínas de Protozoários/química , Superóxido Dismutase/química , Regulação Alostérica , Sequência de Aminoácidos , Antimaláricos/metabolismo , Bases de Dados de Compostos Químicos , Descoberta de Drogas , Inibidores Enzimáticos/metabolismo , Humanos , Simulação de Acoplamento Molecular , Plasmodium falciparum/enzimologia , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Estrutura Secundária de Proteína , Proteínas de Protozoários/antagonistas & inibidores , Proteínas de Protozoários/metabolismo , Homologia de Sequência de Aminoácidos , Especificidade da Espécie , Relação Estrutura-Atividade , Superóxido Dismutase/antagonistas & inibidores , Superóxido Dismutase/metabolismo , Termodinâmica , Interface Usuário-ComputadorRESUMO
The Fenton-like reductive cleavage of antimalarial peroxides like artemisinin by iron(II) species is a chemical reaction whose mechanistic pathway has not been yet fully understood; it is, however, known that there is considerable production of radical species centered at both the oxygen and carbon, which are important to the therapeutical effects of those compounds. This article reports kinetic data for the reaction of artemisinin and two model 1,2,4-trioxolanes with iron(II) species and also a mechanistic interpretation of this reductive cleavage from transition state thermodynamics. The suggestion of the presence of an enhancing specific factor inside the plasmodium is made.
Assuntos
Antimaláricos/química , Artemisininas/química , Compostos Ferrosos/química , Compostos Heterocíclicos/química , Antimaláricos/metabolismo , Artemisininas/metabolismo , Carbono/química , Desenho de Fármacos , Compostos Ferrosos/metabolismo , Radicais Livres/química , Compostos Heterocíclicos/metabolismo , Cinética , Oxirredução , Oxigênio/química , TermodinâmicaRESUMO
Angiotensin II (Ang II) is a natural mammalian hormone that has been described to exhibit antiplasmodial activity therefore constituting a promising alternative for the treatment of malaria. Despite its promise, the development of Ang II as an antimalarial is limited by its potent induction of vasoconstriction and its rapid degradation within minutes. Here, we used peptide design to perform targeted chemical modifications to Ang II to generate conformationally restricted (disulfide-crosslinked) peptide derivatives with suppressed vasoconstrictor activity and increased stability. Designed constrained peptides were synthesized chemically and then tested for antiplasmodial activity. Two lead constrained peptides were identified (i.e., peptides 1 and 2), each composed of 10 amino acid residues. These peptides exhibited very promising activity in both our Plasmodium gallinaceum (>80%) and Plasmodium falciparum (>40%) models, an activity that was equivalent to that of Ang II, and led to complete suppression of vasoconstriction. In addition, peptide 5 exhibited selective activity towards the pre-erythrocytic stage (98% of activity against P. gallinaceum), thus suggesting that it may be possible to design peptides that target specific stages of the malaria life cycle. The Ang II derived stable scaffolds presented here may provide the basis for development of a new generation of peptide-based drugs for the treatment of malaria.