Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 8.925
Filtrar
1.
Exp Parasitol ; 206: 107769, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31580876

RESUMO

BACKGROUND: Mansonellosis arises from infections with threadlike filarial nematodes in millions of individuals, especially in sub-Saharan Africa. Since infections present no overt clinical symptoms but attenuate immune responses that might lead to increased susceptibility and worsened disease course of concomitant infections, it is truly a neglected tropical disease. Nevertheless, only few studies focus on identifying suitable safe drugs for its control and little is known about the requirements for in vitro maintenance of the Mansonella perstans transmission stage. This study, therefore, evaluated the survival of M. perstans microfilariae (mf) using in vitro conditions that have been shown to promote survival of Loa loa, a closely related filarial nematode. Furthermore, the in vitro microfilaricidal effect of 15 agents was assessed on this helminth. METHODS: The ability of two basic culture media; Dulbecco's Modified Eagle's Medium (DMEM) and Roswell Park Memorial Institute (RPMI-1640) supplemented with 10% fetal bovine serum (FBS) and a monkey kidney epithelial cell line (LLC-MK2) to support the survival of M. perstans microfilariae was investigated. Subsequently, 6 anti-helminthics, 5 anti-malarials, 1 anti-microbacterial, 2 trypanocidals and 1 anti-cancer agent were tested in vitro against mf. The suitability of the culture media as well as the effect of the anti-infective agents on mf survival was assessed by scoring their motility. RESULTS: FBS supplement and additional LLC-MK2 cells significantly improved the survival of mf in DMEM and RPMI-1640 culture. In detail, RPMI-1640 supplemented with 10% FBS and LLC-MK2 cells sustained the maintenance of mf for at least 20 days (100.00 ±â€¯0.00% survival). In co-cultures with LLC-MK2 cells without serum, M. perstans mf were maintained in DMEM and RPMI-1640 medium with a motility above 99% by day 5. Mefloquine displayed the highest microfilaricidal effect in vitro followed by artesunate. CONCLUSION: Both RPMI and DMEM in the presence of LLC-MK2 cells are suitable for the maintenance of M. perstans mf in vitro. In absence of the feeder cells, the addition of 10% FBS to RPMI-1640 medium improved the parasite survival rate and motility. The microfilaricidal activity of mefloquine and artesunate on M. perstans mf was documented for the first time in this study and can therefore be considered as reference for further screening of agents against this parasite stage.


Assuntos
Artesunato/farmacologia , Filaricidas/farmacologia , Mansonella/efeitos dos fármacos , Mansonella/crescimento & desenvolvimento , Mefloquina/farmacologia , Amodiaquina/farmacologia , Animais , Antimaláricos/farmacologia , Antinematódeos/farmacologia , Área Sob a Curva , Bovinos , Linhagem Celular , Meios de Cultura/química , Haplorrinos , Ivermectina/farmacologia , Mansonella/fisiologia , Microfilárias/efeitos dos fármacos , Microfilárias/crescimento & desenvolvimento , Microfilárias/fisiologia , Movimento/efeitos dos fármacos , Rifampina/farmacologia
2.
Life Sci ; 237: 116943, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31604109

RESUMO

AIMS: The purpose of this study was to investigate the therapeutic effect of artemisinin (ART) on atherosclerosis and explore the molecular mechanisms involved by RNA sequencing (RNA-Seq). MAIN METHODS: Eight-week-old male ApoE-/- mice were treated with ART for eight weeks. Atherosclerotic lesion sizes were determined by Oil Red O staining, and RNA-Seq was used to detect the profile of differentially expressed genes following the administration of ART. The expressions of contractile phenotypic markers were detected by western blot and qRT-PCR, and the ability of the MOVAS cells to migrate and proliferate were assessed using the wound healing and CCK8 assays. KEY FINDINGS: Artemisinin treatment significantly reduced plaque area in the ApoE-/- mice and increased the expression of contractile phenotypic markers. RNA-Seq of aorta tissue revealed a distinct change in gene expression patterns after the mice were treated with ART. Our bioinformatics analysis demonstrated that the most prominently enriched pathway was a set of genes involved in vascular smooth muscle contractile function. Using an in vitro cell model, we demonstrated that ART could effectively reverse PDGF-activated MOVAS migration and proliferation, and elevate the level of proteins involved in the contractile phenotype. SIGNIFICANCE: We provide in vivo and in vitro evidence supporting a role for ART in the suppression of atherosclerosis, partly through the inhibition of vascular smooth muscle cell phenotype switching to a de-differentiated phenotype. These data further advances our understanding for a potential role for ART and suggests that ART is an excellent candidate for the treatment of atherosclerosis.


Assuntos
Antimaláricos/farmacologia , Apolipoproteínas E/fisiologia , Artemisininas/farmacologia , Aterosclerose/prevenção & controle , Proliferação de Células , Modelos Animais de Doenças , Músculo Liso Vascular/citologia , Animais , Aterosclerose/etiologia , Aterosclerose/patologia , Células Cultivadas , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout para ApoE , Músculo Liso Vascular/efeitos dos fármacos , Músculo Liso Vascular/metabolismo , Fenótipo , Transdução de Sinais
3.
Zhongguo Xue Xi Chong Bing Fang Zhi Za Zhi ; 31(3): 346-348, 2019 Apr 18.
Artigo em Chinês | MEDLINE | ID: mdl-31544425

RESUMO

Malaria is a parasitic disease which threatens human life and health seriously. Sulfadoxine-pyrimethamine (SP) has been recommended for intermittent preventive treatment of malaria in children and pregnant women, and also used as a compound component of artemisinin based therapy. The mechanisms of SP resistance in P. falciparum involve point mutations in the genes encoding dihydrofolate reductase (DHFR) and dihydropteroate synthase (DHPS), and the drug pressure can also lead to the mutations in the two genes of P. vivax. To provide the information for the formulation of anti-malarial strategies, this article reviews the discovery, application, effect of SP, and the resistance mechanism and research progress of the related genes in P. vivax.


Assuntos
Antimaláricos , Resistência a Medicamentos , Plasmodium vivax , Antimaláricos/farmacologia , Di-Hidropteroato Sintase/genética , Combinação de Medicamentos , Resistência a Medicamentos/genética , Humanos , Malária Falciparum/genética , Mutação , Plasmodium vivax/efeitos dos fármacos , Plasmodium vivax/genética , Pirimetamina/farmacologia , Pesquisa/tendências , Sulfadoxina/farmacologia , Tetra-Hidrofolato Desidrogenase/genética
4.
Malar J ; 18(1): 261, 2019 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-31362744

RESUMO

BACKGROUND: More than 200 medicinal plants including Euphorbia abyssinica are utilized for treatment of malaria in Ethiopian traditional medical practices. However, the safety, efficacy and quality of these medicinal plants are largely unknown. Pharmacological and toxicological investigations of these plants are among the prioritized issues in every country. The aim of this study was, therefore, to evaluate the anti-malarial activity of Euphorbia abyssinica root extract against Plasmodium berghei infection in mice. METHODS: The fresh roots of Euphorbia abyssinica were identified and collected. They were dried and extracted by 80% methanol using maceration. Acute toxicity of the extract was done using female Swiss albino mice. Anti-malarial activity of the extract was done by a standard 4-day suppressive test using chloroquine-sensitive Plasmodium berghei. Twenty-five male Swiss albino mice were randomly grouped into 5 groups of 5 mice each. Group I was treated with distilled water (10 ml/kg), group II, III, and IV were treated with 200, 400, and 600 mg/kg of extract, respectively and group V was treated with chloroquine (25 mg/kg). The level of parasitaemia, survival time, and variation in weight were utilized to determine the anti-malarial activity of the extract. Data was analysed using ANOVA followed by Tukey test. RESULTS: The plant extract did not show any sign of toxicity and mortality at 2000 mg/kg. The 4-day chemosuppressive anti-malarial activities produced by the crude extract were 66.87% (P < 0.001), 84.94% (P < 0.001) and 93.69% (P < 0.001) at 200, 400 and 600 mg/kg extract, respectively, compared to distilled water treated group. Mice treated with 400 mg/kg (P < 0.01), and 600 mg/kg extract (P < 0.001) showed significant chemosuppressive anti-malarial activity variations as compared to mice treated with 200 mg/kg extract. Mice treated with 600 mg/kg extract significantly (P < 0.001) lived longer than distilled water treated mice. However, the crude extract did not cause any significant change on body weights of mice. CONCLUSIONS: From this study, it can be concluded that the root of Euphorbia abyssinica showed very good 4-day chemosuppressive anti-malarial activity. The plant might contain biologically active compounds which are relevant for treatment of malaria. Further phytochemical, toxicological and pharmacological investigations are, therefore, required to evaluate its anti-malarial potential.


Assuntos
Antimaláricos/farmacologia , Euphorbia/química , Malária/prevenção & controle , Extratos Vegetais/farmacologia , Plasmodium berghei/efeitos dos fármacos , Animais , Antimaláricos/química , Antimaláricos/toxicidade , Peso Corporal/efeitos dos fármacos , Relação Dose-Resposta a Droga , Feminino , Longevidade/efeitos dos fármacos , Malária/parasitologia , Masculino , Camundongos , Parasitemia/parasitologia , Parasitemia/prevenção & controle , Extratos Vegetais/química , Extratos Vegetais/toxicidade , Raízes de Plantas/química , Distribuição Aleatória
5.
Life Sci ; 233: 116730, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31390552

RESUMO

AIMS: Dihydroartemisinin (DHA) exhibits potential anticancer activity. However, the biological functions of DHA in prostate cancer remain largely unexplored. In this study, we aim to investigate the anti-proliferative effect and glycolysis regulation of DHA on prostate cancer cell LNCaP. MAIN METHODS: Cell proliferative activity and apoptosis inducing were detected. The gene expression was detected by mRNA microarray and results were analyzed by GO and KEGG pathway database. Expressions of glycolysis key enzymes and PI3K/AKT/HIF-1α were detected by Western blot. KEY FINDINGS: Results indicated that DHA could inhibit the LNCaP cell proliferation considerably and induce cell apoptosis. mRNA microarray showed 1293 genes were upregulated and 2322 genes were downregulated. GO and KEGG enrichment analysis suggested that glycolysis pathway was correlated with DHA inhibited the proliferation on the LNCaP cell. Western blot results showed that DHA can decrease GLUT1 and regulatory enzymes of glycolytic pathway expression probably by suppressing the activity of the intracellular Akt/mTOR and HIF-1 α. SIGNIFICANCE: Experimental validation results indicate that DHA treatment can inhibit the LNCaP cell proliferation and induce apoptosis, which may be related to glycolysis inhibition.


Assuntos
Artemisininas/farmacologia , Biomarcadores Tumorais/metabolismo , Glicólise/efeitos dos fármacos , Subunidade alfa do Fator 1 Induzível por Hipóxia/antagonistas & inibidores , Fosfatidilinositol 3-Quinases/antagonistas & inibidores , Neoplasias da Próstata/tratamento farmacológico , Proteínas Proto-Oncogênicas c-akt/antagonistas & inibidores , Antimaláricos/farmacologia , Apoptose , Biomarcadores Tumorais/genética , Proliferação de Células , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Masculino , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositol 3-Quinases/metabolismo , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais , Células Tumorais Cultivadas
6.
Mem Inst Oswaldo Cruz ; 114: e190054, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31411308

RESUMO

BACKGROUND: The central repetitive region (CRR) of the Plasmodium vivax circumsporozoite surface protein (CSP) is composed of a repetitive sequence that is characterised by three variants: VK210, VK247 and P. vivax-like. The most important challenge in the treatment of P. vivax infection is the possibility of differential response based on the parasite genotype. OBJECTIVES: To characterise the CSP variants in P. vivax isolates from individuals residing in a malaria-endemic region in Brazil and to profile these variants based on sensitivity to chloroquine and mefloquine. METHODS: The CSP variants were determined by sequencing and the sensitivity of the P. vivax isolates to chloroquine and mefloquine was determined by Deli-test. FINDINGS: Although five different allele sizes were amplified, the sequencing results showed that all of the isolates belonged to the VK210 variant. However, we observed substantial genetic diversity in the CRR, resulting in the identification of 10 different VK210 subtypes. The frequency of isolates that were resistant to chloroquine and mefloquine was 11.8 and 23.8%, respectively. However, we did not observe any difference in the frequency of the resistant isolates belonging to the VK210 subtypes. MAIN CONCLUSION: The VK210 variant is the most frequently observed in the studied region and there is significant genetic variability in the CRR of the P. vivax CSP. Moreover, the antimalarial drug sensitivity profiles of the isolates does not seem to be related to the VK210 subtypes.


Assuntos
Antimaláricos/farmacologia , Cloroquina/farmacologia , Malária Vivax/parasitologia , Mefloquina/farmacologia , Plasmodium vivax/efeitos dos fármacos , Proteínas de Protozoários/genética , Genótipo , Humanos , Testes de Sensibilidade Parasitária , Plasmodium vivax/genética , Plasmodium vivax/isolamento & purificação , Reação em Cadeia da Polimerase
7.
J Enzyme Inhib Med Chem ; 34(1): 1388-1399, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31392901

RESUMO

Fourteen novel dipeptide carboxamide derivatives bearing benzensulphonamoyl propanamide were synthesized and characterized using 1H NMR, 13C NMR, FTIR and MS spectroscopic techniques. In vivo antimalarial and in vitro antimicrobial studies were carried out on these synthesized compounds. Molecular docking, haematological analysis, liver and kidney function tests were also evaluated to assess the effect of the compounds on the organs. At 200 mg/kg body weight, 7i inhibited the multiplication of the parasite by 81.38% on day 12 of post-treatment exposure. This was comparable to the 82.34% reduction with artemisinin. The minimum inhibitory concentration (MIC) in µM ranged from 0.03 to 2.34 with 7h having MIC of 0.03 µM against Plasmodium falciparium. The in vitro antibacterial activity of the compounds against some clinically isolated bacteria strains showed varied activities with some of the new compounds showing better activities against the bacteria and the fungi more than the reference drug ciprofloxacin and fluconazole.


Assuntos
Antibacterianos/farmacologia , Antifúngicos/farmacologia , Antimaláricos/química , Antimaláricos/farmacologia , Dipeptídeos/química , Dipeptídeos/farmacologia , Sulfonamidas/farmacologia , Animais , Antibacterianos/síntese química , Antibacterianos/química , Antifúngicos/síntese química , Antifúngicos/química , Antimaláricos/síntese química , Bactérias/efeitos dos fármacos , Dipeptídeos/síntese química , Fungos/efeitos dos fármacos , Camundongos , Testes de Sensibilidade Microbiana , Testes de Sensibilidade Parasitária , Plasmodium falciparum/efeitos dos fármacos , Ratos , Sulfonamidas/química
8.
Gene ; 716: 144016, 2019 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-31377318

RESUMO

Drug resistance of malaria parasites remains a problem affecting antimalarial treatment and control of the disease. We previously synthesized an antimalarial endoperoxide, N-89, having high antimalarial effects in vitro and in vivo. In this study we seek to understand the resistant mechanism against N-89 by establishing a highly N-89-resistant clone, named NRC10H, of the Plasmodium falciparum FCR-3 strain. We describe gene mutations in the parent FCR-3 strain and the NRC10H clone using whole-genome sequencing and subsequently by expression profiling using quantitative real-time PCR. Seven genes related to drug resistance, proteolysis, glycophosphatidylinositol anchor biosynthesis, and phosphatidylethanolamine biosynthesis exhibited a single amino acid substitution in the NRC10H clone. Among these seven genes, the multidrug resistance protein 2 (mdr2) variant A532S was found only in NRC10H. The genetic status of the P. falciparum endoplasmic reticulum-resident calcium binding protein (PfERC), a potential target of N-89, was similar between the NRC10H clone and the parent FCR-3 strain. These findings suggest that the genetic alterations of the identified seven genes, in particular mdr2, in NRC10H could give rise to resistance of the antimalarial endoperoxide N-89.


Assuntos
Antimaláricos/farmacologia , Compostos Heterocíclicos com 2 Anéis/farmacologia , Plasmodium falciparum/efeitos dos fármacos , Compostos de Espiro/farmacologia , Resistência a Medicamentos/genética , Genômica , Plasmodium falciparum/genética , Plasmodium falciparum/metabolismo , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , RNA Mensageiro/metabolismo , Sequenciamento Completo do Genoma
9.
Planta Med ; 85(13): 1073-1079, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31365939

RESUMO

Zanthoxylum zanthoxyloides, syn. Fagara zanthoxyloides, is a tree growing in West Africa and is used in traditional medicine against a variety of diseases, including malaria. In the work reported here, root bark and stem bark extracts of this tree, as well as compounds isolated from the extracts, have been investigated for activity in vitro against chloroquine-sensitive and chloroquine-resistant strains of Plasmodium falciparum. In addition, toxicity against nauplii of the brine shrimp Artemia salina has been studied. Dichloromethane extracts of the root bark and stem bark, and a methanol extract of the stem bark, showed anti-parasitic activity towards chloroquine-sensitive as well as chloroquine-resistant P. falciparum, with IC50 values between 1 and 10 µg/mL. Among the isolated compounds, bis-dihydrochelerythrinyl ether, buesgenine, chelerythrine, γ-fagarine, skimmianine, and pellitorine were the most active, with IC50 values of less than 5 µg/mL. The dichloromethane extracts were toxic to brine shrimp nauplii, with LC50 values of less than 1 µg/mL. Methanol extracts were much less toxic (LC50 between 50 and 100 µg/mL). Among the isolated substances, bis-dihydrochelethrinyl ether was the most toxic (LC50 ca. 2 µg/mL).


Assuntos
Antimaláricos/farmacologia , Extratos Vegetais/farmacologia , Zanthoxylum/química , Casca de Planta/química , Folhas de Planta/química , Raízes de Plantas/química , Plasmodium falciparum/efeitos dos fármacos
10.
Malar J ; 18(1): 275, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31416468

RESUMO

BACKGROUND: Drug resistance within the major malaria parasites Plasmodium vivax and Plasmodium falciparum threatens malaria control and elimination in Southeast Asia. Plasmodium vivax first-line treatment drug is chloroquine together with primaquine, and the first-line treatment for P. falciparum malaria is artemisinin in combination with a partner drug. Plasmodium vivax and P. falciparum parasites resistant to their respective first-line therapies are now found within Southeast Asia. The resistance perimeters may include high transmission regions of Southern Thailand which are underrepresented in surveillance efforts. METHODS: This study investigated blood samples from malaria centres in Southern Thailand. Genetic loci associated with drug resistance were amplified and sequenced. Drug resistance associated genes Pvmdr1, Pvcrt-o, Pvdhfr, and Pvdhps were characterized for 145 cases of P. vivax malaria, as well as the artemisinin resistance-associated Pfkelch13 gene from 91 cases of P. falciparum malaria. RESULTS: Plasmodium vivax samples from Southern Thai provinces showed numerous chloroquine and antifolate resistance-associated mutations, including SNP and Pvcrt-o K10-insertion combinations suggestive of chloroquine resistant P. vivax phenotypes. A high proportion of the C580Y coding mutation (conferring artemisinin resistance) was detected in P. falciparum samples originating from Ranong and Yala (where the mutation was previously unreported). CONCLUSIONS: The results demonstrate a risk of chloroquine and antifolate resistant P. vivax phenotypes in Southern Thailand, and artemisinin resistant P. falciparum observed as far south as the Thai-Malaysian border region. Ongoing surveillance of antimalarial drug resistance markers is called for in Southern Thailand to inform case management.


Assuntos
Resistência a Medicamentos/genética , Mutação/genética , Plasmodium falciparum/efeitos dos fármacos , Plasmodium vivax/efeitos dos fármacos , Proteínas de Protozoários/análise , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Antimaláricos/farmacologia , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Tailândia , Adulto Jovem
11.
Malar J ; 18(1): 280, 2019 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-31438951

RESUMO

BACKGROUND: The ability of Plasmodium falciparum parasites to develop resistance to widely used anti-malarials threatens malaria control and elimination efforts. Regular drug efficacy monitoring is essential for ensuring effective treatment policies. In low transmission settings where therapeutic efficacy studies are often not feasible, routine surveillance for molecular markers associated with anti-malarial resistance provides an alternative for the early detection of emerging resistance. Such a longitudinal survey of changes in the prevalence of selected molecular markers of resistance was conducted in the malaria-endemic regions of Mpumalanga Province, South Africa, where malaria elimination at a district-level is being pursued. METHODS: Molecular analyses to determine the prevalence of alleles associated with resistance to lumefantrine (mdr86N, crt76K and mdr1 copy number variation) and sulfadoxine-pyrimethamine (dhfr triple, dhps double, SP quintuple) were conducted between 2001 and 2018, while artemisinin resistance markers (kelch13 mutations) were assessed only in 2018. RESULTS: Parasite DNA was successfully amplified from 1667/2393 (70%) of malaria-positive rapid diagnostic tests routinely collected at primary health care facilities. No artemisinin resistance-associated kelch13 mutations nor amplification of the mdr1 gene copy number associated with lumefantrine resistance were observed. However, prevalence of both the mdr86N and crt76K alleles increased markedly over the study period, with all isolates collected in 2018 carrying these markers. SP quintuple mutation prevalence increased steadily from 14% in 2001 to 96% in 2018. Mixed alleles at any of the codons assessed were rare by 2018. CONCLUSION: No kelch13 mutations confirmed or suspected to be associated with artemisinin resistance were identified in 2018. Although parasites carrying the mdr86N and crt76K alleles associated with reduced lumefantrine susceptibility were strongly selected for over the study period, nearing fixation by 2018, the marker for lumefantrine resistance, namely increased mdr1 copy number, was not observed in this study. The increase in mdr86N and crt76K allele prevalence together with intense regional artemether-lumefantrine drug pressure, raises concern regarding the sustained artemether-lumefantrine efficacy. Regular, rigorous anti-malarial resistance marker surveillance across all three South African malaria-endemic provinces to inform case management is recommended.


Assuntos
Antimaláricos/farmacologia , Artemisininas/farmacologia , Resistência a Medicamentos/genética , Lumefantrina/farmacologia , Plasmodium falciparum/efeitos dos fármacos , Proteínas de Protozoários/genética , Pirimetamina/farmacologia , Sulfadoxina/farmacologia , Testes Diagnósticos de Rotina , Combinação de Medicamentos , Quimioterapia Combinada , Marcadores Genéticos , Plasmodium falciparum/genética , Proteínas de Protozoários/metabolismo , Seleção Genética , África do Sul
12.
Malar J ; 18(1): 237, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31307493

RESUMO

BACKGROUND: Basic blue 3 is a promising anti-malarial lead compound based on the π-delocalized lipophilic cation hypothesis. Its derivatives with nitrogen atoms bonded to carbon atoms at the 3- and 7-positions on the phenoxazine ring were previously shown to exert potent antiprotozoal activity against Plasmodium falciparum, Trypanosoma cruzi, Trypanosoma brucei rhodesiense, and Leishmania donovani parasites in vitro. However, compounds with nitrogen modification at the 10-position on the phenoxazine ring were not evaluated. METHODS: Six acylphenoxazine derivatives (ITT-001 to 006) with nitrogen modification at the 10-position on the phenoxazine ring, which were synthesized from basic blue 3, were characterized and evaluated for anti-malarial activity in vitro with an automated haematology analyzer (XN-30) and light microscopy. Intensity of self-fluorescence was measured using a fluorometer. Localization of basic blue 3 was observed by fluorescence microscopy. Cytotoxicity was evaluated using human cell lines, HEK293T and HepG2 cells. Finally, anti-malarial activity was evaluated in a rodent malaria model. RESULTS: All the six derivatives showed anti-malarial efficacy even against chloroquine-, pyrimethamine-, and artemisinin-resistant field isolates similar to the sensitive strains and isolates in vitro. The efficacy of basic blue 3 was the strongest, followed by that of ITT-001 to 004 and 006, while that of ITT-005 was the weakest. Basic blue 3 showed strong self-fluorescence, whereas ITT derivatives had five- to tenfold lower intensity than that of basic blue 3, which was shown by fluorescence microscopy to be selectively accumulated in the plasmodial cytoplasm. In contrast, ITT-003, 004, and 006 exhibited the lowest cytotoxicity in HEK293T and HepG2 cells in vitro and the highest selectivity between anti-malarial activity and cytotoxicity. The in vivo anti-malarial assay indicated that oral administration of ITT-004 was the most effective against the rodent malaria parasite, Plasmodium berghei NK65 strain. CONCLUSIONS: The six ITT derivatives were effective against chloroquine- and pyrimethamine-resistant strains and artemisinin-resistant field isolates as well as the sensitive ones. Among them, ITT-004, which had high anti-malarial activity and low cytotoxicity in vitro and in vivo, is a promising anti-malarial lead compound.


Assuntos
Antimaláricos/farmacologia , Oxazinas/farmacologia , Plasmodium falciparum/efeitos dos fármacos , Antimaláricos/toxicidade , Células HEK293 , Células Hep G2 , Humanos , Oxazinas/toxicidade , Testes de Toxicidade
13.
Parasit Vectors ; 12(1): 329, 2019 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-31266522

RESUMO

BACKGROUND: Wickerhamomyces anomalus is a yeast associated with different insects including mosquitoes, where it is proposed to be involved in symbiotic relationships with hosts. Different symbiotic strains of W. anomalus display a killer phenotype mediated by protein toxins with broad-spectrum antimicrobial activities. In particular, a killer toxin purified from a W. anomalus strain (WaF17.12), previously isolated from the malaria vector mosquito Anopheles stephensi, has shown strong in vitro anti-plasmodial activity against early sporogonic stages of the murine malaria parasite Plasmodium berghei. RESULTS: Here, we provide evidence that WaF17.12 cultures, properly stimulated to induce the expression of the killer toxin, can directly affect in vitro P. berghei early sporogonic stages, causing membrane damage and parasite death. Moreover, we demonstrated by in vivo studies that mosquito dietary supplementation with activated WaF17.12 cells interfere with ookinete development in the midgut of An. stephensi. Besides the anti-sporogonic action of WaF17.12, an inhibitory effect of purified WaF17.12-killer toxin was observed on erythrocytic stages of P. berghei, with a consequent reduction of parasitaemia in mice. The preliminary safety tests on murine cell lines showed no side effects. CONCLUSIONS: Our findings demonstrate the anti-plasmodial activity of WaF17.12 against different developmental stages of P. berghei. New studies on P. falciparum are needed to evaluate the use of killer yeasts as innovative tools in the symbiotic control of malaria.


Assuntos
Anopheles/microbiologia , Antimaláricos/farmacologia , Malária/prevenção & controle , Mosquitos Vetores/microbiologia , Micotoxinas/farmacologia , Plasmodium berghei/efeitos dos fármacos , Saccharomycetales/fisiologia , Animais , Anopheles/parasitologia , Feminino , Malária/parasitologia , Malária/transmissão , Camundongos , Mosquitos Vetores/parasitologia , Simbiose
14.
Malar J ; 18(1): 225, 2019 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-31277713

RESUMO

BACKGROUND: Therapeutic efficacy studies in uncomplicated Plasmodium falciparum malaria are confounded by new infections, which constitute competing risk events since they can potentially preclude/pre-empt the detection of subsequent recrudescence of persistent, sub-microscopic primary infections. METHODS: Antimalarial studies typically report the risk of recrudescence derived using the Kaplan-Meier (K-M) method, which considers new infections acquired during the follow-up period as censored. Cumulative Incidence Function (CIF) provides an alternative approach for handling new infections, which accounts for them as a competing risk event. The complement of the estimate derived using the K-M method (1 minus K-M), and the CIF were used to derive the risk of recrudescence at the end of the follow-up period using data from studies collated in the WorldWide Antimalarial Resistance Network data repository. Absolute differences in the failure estimates derived using these two methods were quantified. In comparative studies, the equality of two K-M curves was assessed using the log-rank test, and the equality of CIFs using Gray's k-sample test (both at 5% level of significance). Two different regression modelling strategies for recrudescence were considered: cause-specific Cox model and Fine and Gray's sub-distributional hazard model. RESULTS: Data were available from 92 studies (233 treatment arms, 31,379 patients) conducted between 1996 and 2014. At the end of follow-up, the median absolute overestimation in the estimated risk of cumulative recrudescence by using 1 minus K-M approach was 0.04% (interquartile range (IQR): 0.00-0.27%, Range: 0.00-3.60%). The overestimation was correlated positively with the proportion of patients with recrudescence [Pearson's correlation coefficient (ρ): 0.38, 95% Confidence Interval (CI) 0.30-0.46] or new infection [ρ: 0.43; 95% CI 0.35-0.54]. In three study arms, the point estimates of failure were greater than 10% (the WHO threshold for withdrawing antimalarials) when the K-M method was used, but remained below 10% when using the CIF approach, but the 95% confidence interval included this threshold. CONCLUSIONS: The 1 minus K-M method resulted in a marginal overestimation of recrudescence that became increasingly pronounced as antimalarial efficacy declined, particularly when the observed proportion of new infection was high. The CIF approach provides an alternative approach for derivation of failure estimates in antimalarial trials, particularly in high transmission settings.


Assuntos
Antimaláricos/farmacologia , Malária Falciparum/tratamento farmacológico , Plasmodium falciparum/efeitos dos fármacos , Humanos , Meta-Análise em Rede , Reação em Cadeia da Polimerase , Recidiva , Análise de Regressão , Risco
15.
Eur J Med Chem ; 180: 121-133, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31301563

RESUMO

Phenyl- and bioisosteric ferrocenyl-derived aminoquinoline-benzimidazole hybrid compounds were synthesised and evaluated for their in vitro antiplasmodial activity against the chloroquine-sensitive NF54 and multi-drug resistant K1 strains of the human malaria parasite, Plasmodium falciparum. All compounds were active against the two strains, generally showing enhanced activity in the K1 strain, with resistance indices less than 1. Cytotoxicity studies using Chinese hamster ovarian cells revealed that the hybrids were relatively non-cytotoxic and demonstrated selective killing of the parasite. Based on favourable in vitro antiplasmodial and cytotoxicity data, the most active phenyl (4c) and ferrocenyl (5b) hybrids were tested in vivo against the rodent Plasmodium berghei mouse model. Both compounds caused a reduction in parasitemia relative to the control, with 5c displaying superior activity (92% reduction in parasitemia at 4 × 50 mg/kg oral doses). The most active phenyl and ferrocenyl derivatives showed inhibition of ß-haematin formation in a NP-40 detergent-mediated assay, indicating a possible contributing mechanism of antiplasmodial action. The most active ferrocenyl hybrid did not display appreciable reactive oxygen species (ROS) generation in a ROS-induced DNA cleavage gel electrophoresis study. The compounds were also screened for their in vitro activity against Mycobacterium tuberculosis. The hybrids containing a more hydrophobic substituent had enhanced activity (<32.7 µM) compared to those with a less hydrophobic substituent (>62.5 µM).


Assuntos
Antibacterianos/farmacologia , Antimaláricos/farmacologia , Benzimidazóis/farmacologia , Compostos Ferrosos/farmacologia , Malária/tratamento farmacológico , Plasmodium falciparum/efeitos dos fármacos , Quinolinas/farmacologia , Animais , Antibacterianos/síntese química , Antibacterianos/química , Antimaláricos/síntese química , Antimaláricos/química , Benzimidazóis/química , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Compostos Ferrosos/química , Camundongos , Estrutura Molecular , Mycobacterium tuberculosis/efeitos dos fármacos , Testes de Sensibilidade Parasitária , Quinolinas/química , Relação Estrutura-Atividade
16.
SAR QSAR Environ Res ; 30(8): 543-560, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31328578

RESUMO

The large collection of known and experimentally verified compounds from the ChEMBL database was used to build different classification models for predicting the antimalarial activity against Plasmodium falciparum. Four different machine learning methods, namely the support vector machine (SVM), random forest (RF), k-nearest neighbour (kNN) and XGBoost have been used for the development of models using the diverse antimalarial dataset from ChEMBL. A well-established feature selection framework was used to select the best subset from a larger pool of descriptors. Performance of the models was rigorously evaluated by evaluation of the applicability domain, Y-scrambling and AUC-ROC curve. Additionally, the predictive power of the models was also assessed using probability calibration and predictiveness curves. SVM and XGBoost showed the best performances, yielding an accuracy of ~85% on the independent test set. In term of probability prediction, SVM and XGBoost were well calibrated. Total gain (TG) from the predictiveness curve was more related to SVM (TG = 0.67) and XGBoost (TG = 0.75). These models also predict the high-affinity compounds from PubChem antimalarial bioassay (as external validation) with a high probability score. Our findings suggest that the selected models are robust and can be potentially useful for facilitating the discovery of antimalarial agents.


Assuntos
Antimaláricos/química , Desenho de Drogas , Aprendizado de Máquina , Antimaláricos/análise , Antimaláricos/farmacologia , Área Sob a Curva , Relação Quantitativa Estrutura-Atividade , Curva ROC
17.
Cell Host Microbe ; 26(1): 35-47, 2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-31295423

RESUMO

Intensified treatment and control efforts since the early 2000s have dramatically reduced the burden of Plasmodium falciparum malaria. However, drug resistance threatens to derail this progress. In this review, we present four antimalarial resistance case studies that differ in timeline, technical approaches, mechanisms of action, and categories of resistance: chloroquine, sulfadoxine-pyrimethamine, artemisinin, and piperaquine. Lessons learned from prior losses of treatment efficacy, drug combinations, and control strategies will help advance mechanistic research into how P. falciparum parasites acquire resistance to current first-line artemisinin-based combination therapies. Understanding resistance in the clinic and laboratory is essential to prolong the effectiveness of current antimalarial drugs and to optimize the pipeline of future medicines.


Assuntos
Antimaláricos/farmacologia , Antimaláricos/uso terapêutico , Resistência a Medicamentos , Malária Falciparum/tratamento farmacológico , Malária Falciparum/parasitologia , Plasmodium falciparum/efeitos dos fármacos , Quimioterapia Combinada/métodos , Humanos
18.
Acta Pharm ; 69(2): 233-248, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-31259728

RESUMO

The paper is focused on the synthesis and screening of the antiplasmodial activity of novel fumardiamides 5-10 with the mefloquine pharmacophore and a Michael acceptor motif. Multi-step reactions leading to the title compounds included two amide bond formations. The first amide bond was achieved by the reaction of (E)-ethyl 4-chloro-4-oxobut-2-enoate (1) and N1-(2,8-bis(trifluoromethyl)quinolin-4-yl) butane-1,4-diamine (2). The obtained ester 3 was hydrolyzed and gave acid 4, which then reacted with the selected halogenanilines in the presence of HATU/DIEA and formed products 5-10. Title compounds showed marked, dose dependent activity in vitro against hepatic stages of Plasmodium berghei. IC50 values of the most active compounds 5, 7 and 9 bearing 3-fluoro, 3-chloro and 3-trifluoromethyl substituents were 3.04-4.16 µmol L-1, respectively. On the other hand, the compounds exerted only weak activity against the erythrocytic stages of two P. falciparum strains (Pf3D7 and PfDd2) in vitro, with the exception of compound 5 (IC50 = 2.9 µmol L-1).


Assuntos
Amidas/farmacologia , Antimaláricos/farmacologia , Mefloquina/farmacologia , Amidas/síntese química , Amidas/química , Antimaláricos/síntese química , Antimaláricos/química , Relação Dose-Resposta a Droga , Concentração Inibidora 50 , Mefloquina/síntese química , Mefloquina/química , Plasmodium berghei/efeitos dos fármacos , Plasmodium falciparum/efeitos dos fármacos , Relação Estrutura-Atividade
19.
Chem Commun (Camb) ; 55(52): 7434-7437, 2019 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-31155628

RESUMO

Mortiamides A-D (1-4) are head-to-tail cyclic heptapeptides that were identified from a novel Mortierella sp. isolate obtained from marine sediments from Northern Canada. Herein we report the first total synthesis of mortiamides A-D (1-4) on a solid support by concomitant cyclization/cleavage without any oligomerization side reactions, and overall yields up to 48%. We also report on the antiplasmodial activity of mortiamides A-D (1-4). We show that three out of the four tested mortiamides (A, B and D) have moderate antiplasmodial activity, while mortiamide D (4) exhibits low micromolar activity.


Assuntos
Antimaláricos/síntese química , Peptídeos Cíclicos/síntese química , Antimaláricos/farmacologia , Ciclização , Peptídeos Cíclicos/farmacologia , Plasmodium falciparum/efeitos dos fármacos , Polimerização
20.
Curr Top Med Chem ; 19(10): 861-873, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31161990

RESUMO

The malaria parasite resistance to the existing drugs is a serious problem to the currently used antimalarials and, thus, highlights the urgent need to develop new and effective anti-malarial molecules. This could be achieved either by the identification of the new drugs for the validated targets or by further refining/improving the existing antimalarials; or by combining previously effective agents with new/existing drugs to have a synergistic effect that counters parasite resistance; or by identifying novel targets for the malarial chemotherapy. In this review article, a comprehensive collection of some of the novel molecular targets has been enlisted for the antimalarial drugs. The targets which could be deliberated for developing new anti-malarial drugs could be: membrane biosynthesis, mitochondrial system, apicoplasts, parasite transporters, shikimate pathway, hematin crystals, parasite proteases, glycolysis, isoprenoid synthesis, cell cycle control/cycline dependent kinase, redox system, nucleic acid metabolism, methionine cycle and the polyamines, folate metabolism, the helicases, erythrocyte G-protein, and farnesyl transferases. Modern genomic tools approaches such as structural biology and combinatorial chemistry, novel targets could be identified followed by drug development for drug resistant strains providing wide ranges of novel targets in the development of new therapy. The new approaches and targets mentioned in the manuscript provide a basis for the development of new unique strategies for antimalarial therapy with limited off-target effects in the near future.


Assuntos
Antimaláricos/farmacologia , Malária/tratamento farmacológico , Plasmodium falciparum/efeitos dos fármacos , Animais , Antimaláricos/química , Humanos , Testes de Sensibilidade Parasitária
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA