RESUMO
BACKGROUND: Anti-malarial resistance in Plasmodium falciparum remains an obstacle for malaria control. Resistance-associated genes were analysed in Brazilian samples over four decades to evaluate the impact of different treatment regimens on the parasite genetic profile. METHODS: Samples were collected on filter paper from patients infected in the Amazon region from 1984 to 2011. DNA was extracted with Chelex® 100 and monoinfection confirmed by PCR. SNPs in the pfcrt, pfmdr1, pfdhfr and pfdhps genes were assessed by PCR-RFLP. The pfmdr1 copy number was estimated using real time quantitative PCR with SYBR® Green. Parasite response was assessed ex vivo with seven concentrations of each anti-malarial. Patients were treated according to Brazilian guidelines: quinine plus tetracycline or mefloquine in period 1 and ACT in period 2. RESULTS: All 96 samples presented the pfcrt 76T mutant throughout the assessed periods. In addition, all isolates showed ex vivo chloroquine resistance. The pfmdr1 86Y was detected in 1.5% of samples in period 1, and in 25% in period 2. All samples presented the pfmdr1 1246Y. The analysis of pfmdr1 copy number showed amplification in 37.3% in period 1 and in 42% in period 2. Mutations in pfdhfr were shown as follows: 51I in all samples in period 1 and in 81.2% in period 2; 59R in 6.4% in period 2. The pfdhfr 108N and the pfdhps 437G were seen in all samples along time; the pfdhps 540E in 93.7% in period 1 and in 75% in period 2. CONCLUSIONS: The 76T mutation associated to chloroquine resistance is still present in the parasite population, although this anti-malarial was withdrawn from the chemotherapy of P. falciparum in Brazil in the mid-1980s. All isolates assayed ex vivo for chloroquine showed resistant phenotype and 76T. No association was observed between pfmdr1 mutations and resistance to quinine, mefloquine and artemisinin derivatives. Additionally, the pfdhfr 108N mutation was detected in all samples throughout the evaluated periods, demonstrating fixation of the mutant allele in the parasite population. Changes in Brazilian national guidelines for the malaria chemotherapy in the last 27 years yielded a discreet genetic impact in the parasite population.
Assuntos
Antimaláricos/farmacologia , Malária Falciparum/parasitologia , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/genética , Proteínas de Protozoários/genética , Brasil , Resistência a Medicamentos/genética , Marcadores Genéticos/genética , Genótipo , Humanos , Malária Falciparum/tratamento farmacológico , Polimorfismo de Nucleotídeo ÚnicoRESUMO
The isolation of bioactive compounds from medicinal plants, based on traditional use or ethnomedical data, is a highly promising potential approach for identifying new and effective antimalarial drug candidates. The purpose of this review was to create a compilation of the phytochemical studies on medicinal plants used to treat malaria in traditional medicine from the Community of Portuguese-Speaking Countries (CPSC): Angola, Brazil, Cape Verde, Guinea-Bissau, Mozambique and São Tomé and Príncipe. In addition, this review aimed to show that there are several medicinal plants popularly used in these countries for which few scientific studies are available. The primary approach compared the antimalarial activity of native species used in each country with its extracts, fractions and isolated substances. In this context, data shown here could be a tool to help researchers from these regions establish a scientific and technical network on the subject for the CPSC where malaria is a public health problem.
Assuntos
Antimaláricos/uso terapêutico , Malária/tratamento farmacológico , Medicina Tradicional , Fitoterapia/métodos , Plantas Medicinais/classificação , Angola , Antimaláricos/classificação , Antimaláricos/isolamento & purificação , Ilhas Atlânticas , Brasil , Cabo Verde , Guiné-Bissau , Humanos , Idioma , MoçambiqueRESUMO
BACKGROUND: Plasmodium falciparum malaria remains a leading health problem in Africa and its control is seriously challenged by drug resistance. Although resistance to the sulphadoxine-pyrimethamine (SP) is widespread, this combination remains an important component of malaria control programmes as intermittent preventive therapy (IPT) for pregnant women and children. In Angola, resistance patterns have been poorly characterized, and IPT has been employed for pregnant women since 2006. The aim of this study was to assess the prevalence of key antifolate resistance mediating polymorphisms in the pfdhfr and pfdhps genes in P. falciparum samples from Angola. METHODS: Plasmodium falciparum samples collected in Luanda, in 2007, were genotyped by amplification and DNA forward and reverse sequencing of the pfdhfr and pfdhps genes. RESULTS: The most prevalent polymorphisms identified were pfdhfr 108N (100%), 51I (93%), 59R (57%) and pfdhps 437G (93%). Resistance-mediating polymorphisms in pfdhps less commonly observed in West Africa were also identified (540E in 10%, 581G in 7% of samples). CONCLUSION: This study documents an important prevalence of 4 P. falciparum polymorphisms that predicts an antifolate resistance in Luanda. Further, some samples presented additional mutations associated to high-level resistance. These results suggest that the use of SP for IPT may no longer be warranted in Angola.
Assuntos
Antimaláricos/farmacologia , Resistência a Medicamentos , Antagonistas do Ácido Fólico/farmacologia , Marcadores Genéticos , Malária Falciparum/parasitologia , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/genética , Adulto , Angola , Criança , Pré-Escolar , Di-Hidropteroato Sintase/genética , Feminino , Frequência do Gene , Genótipo , Humanos , Plasmodium falciparum/isolamento & purificação , Polimorfismo Genético , Gravidez , Proteínas de Protozoários/genética , Análise de Sequência de DNA , Tetra-Hidrofolato Desidrogenase/genéticaRESUMO
OBJECTIVE: To evaluate the in vitro efficacy of artesunate (ATN) and artemether (ATH) against Plasmodium falciparum isolates from the Brazilian Amazon state of Pará and to search for mutations and/or altered copy numbers in the putative resistance-associated pfcrt, pfmdr1 and pfATPase6 genes. METHODS: In vitro efficacy of ATN and ATH was successfully measured in 56 freshly collected P. falciparum isolates, using a conventional WHO microtest with minor modifications. Single nucleotide polymorphisms (SNPs) in the same isolates were inspected using DNA sequencing and/or PCR-RFLP. We used real-time quantitative PCR to assess gene copy numbers. RESULTS: ATN and ATH geometric mean IC(50)s were 0.85 nm, 95% CI (0.55-1.15) and 3.0 nm, 95% CI (1.5-4.5), respectively. There was extremely limited diversity of pfcrt and pfmdr1 genotypes and three SNPs were identified in the pfATPase6 gene: one T to A synonymous mutation at nucleotide 2694 and two non-synonymous (both G to A) mutations at nucleotides 110 and 1916, causing predicted aminoacid shifts of arginine to lysine and of glycine to aspartate, respectively. The previously reported S769N mutation was not detected in any of the isolates inspected. In addition, no gene amplifications were detected in a subset of eight isolates. CONCLUSION: Artemisinin derivatives display satisfactory in vitro activity locally and the pfATPase6 gene is distinct from that reported in French Guiana, suggesting that those haplotypes have not been introduced regionally.
Assuntos
Adenosina Trifosfatases/genética , Antimaláricos/farmacologia , Artemisininas/farmacologia , Malária Falciparum/parasitologia , Plasmodium falciparum/efeitos dos fármacos , Sesquiterpenos/farmacologia , Animais , Artemeter , Artesunato , Brasil/epidemiologia , Resistência a Medicamentos , Dosagem de Genes , Humanos , Malária Falciparum/epidemiologia , Proteínas Associadas à Resistência a Múltiplos Medicamentos/genética , Mutação , Testes de Sensibilidade Parasitária , Plasmodium falciparum/enzimologia , Plasmodium falciparum/genética , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de Restrição , Proteínas de Protozoários/genéticaRESUMO
The frequency and distribution of mutations in Plasmodium falciparum, dihydrofolate reductase and dihydropteroate synthase genes were analyzed, using the polymerase chain reaction and restriction fragment length polymorphism methodology, in infected blood samples from Mozambican children living in Maputo, before and seven days after treatment with sulfadoxine/pyrimethamine (S/P). The results showed the occurrence of point mutations in the genes studied and the presence of combinations of three alleles in dhfr (51Ile, 59Arg and 108Asn) and "quintuple" mutant (dhfr 51Ile, 59Arg, 108Asn and dhps 437Gly, 540Glu). Both of these situations were associated with seven-day therapeutic failure, following treatment with S/P. These findings show the importance of studying S/P resistance in Mozambique, and how molecular markers for antimalarial resistance can provide important data for national malaria control policy.
Assuntos
Antimaláricos/uso terapêutico , Di-Hidropteroato Sintase/genética , Malária Falciparum/parasitologia , Plasmodium falciparum/efeitos dos fármacos , Pirimetamina/uso terapêutico , Sulfadoxina/uso terapêutico , Tetra-Hidrofolato Desidrogenase/genética , Animais , Criança , Pré-Escolar , Combinação de Medicamentos , Resistência a Medicamentos/genética , Humanos , Lactente , Malária Falciparum/tratamento farmacológico , Moçambique , Testes de Sensibilidade Parasitária , Plasmodium falciparum/enzimologia , Plasmodium falciparum/genética , Mutação Puntual , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de RestriçãoRESUMO
Extracts from Holostylis reniformis were tested in vivo against Plasmodium berghei and in vitro against a chloroquine-resistant strain of Plasmodium falciparum. The hexane extract of the roots was the most active, causing 67% reduction of parasitemia in vivo. From this extract, six lignans, including a new (7'R,8S,8'S)-3',4'-methylenedioxy-4,5-dimethoxy-2,7'-cyclolignan-7-one, were isolated and tested in vitro against P. falciparum. The three most active lignans showed 50% inhibitor concentrations of < or =0.32 microM. An evaluation of minimum lethal dose (30%) values showed low toxicity for these lignans in a hepatic cell line (Hep G2A16). Therefore, these compounds are potential candidates for the development of antimalarial drugs.
Assuntos
Antimaláricos/farmacologia , Aristolochiaceae/química , Lignanas/farmacologia , Tetralonas/farmacologia , Animais , Antimaláricos/isolamento & purificação , Linhagem Celular Tumoral , Cromatografia Líquida de Alta Pressão , Dicroísmo Circular , Formazans/metabolismo , Humanos , Concentração Inibidora 50 , Lignanas/química , Camundongos , Conformação Molecular , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Parasitemia/tratamento farmacológico , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/farmacologia , Raízes de Plantas/química , Plasmodium berghei/efeitos dos fármacos , Plasmodium falciparum/efeitos dos fármacos , Espectrofotometria Ultravioleta , Tetralonas/químicaRESUMO
This work aimed to study the T helper type 1/2 (Th1/Th2) cytokine profile in a co-infection murine model of Plasmodium chabaudi chabaudi and Leishmania infantum. Expression of interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) was analyzed, in spleen and liver of C57BL/6 mice, by reverse transcriptase-polymerase chain reaction. High levels of IFN-gamma expression did not prevent the progression of Leishmania in co-infected mice and Leishmania infection did not interfere with the Th1/Th2 switch necessary for Plasmodium control. The presence of IL-4 at day 28 in co-infected mice, essential for Plasmodium elimination, was probably a key factor on the exacerbation of the Leishmania infection.