The aim of this study was to verify the trypanocidal effectiveness of aqueous, methanolic, and ethanolic extracts of Achyrocline satureioides against Trypanosoma evansi in vitro. A. satureioides extracts, known as macela, were used on trypomastigotes at different concentrations (1, 5, 10, 50, 100, 500, and 1,000 microg/ml) and exposure times (0, 1, 3, 6, and 9 hr). A dose-dependent effect was observed when the 3 extracts were tested. The concentrations of 1, 5, and 10 microg/ml were not able to kill trypomastigotes until 3 hr after exposure, and the highest concentrations (500 and 1,000 microg/ml) were able to kill all trypomastigotes after 1 hr. When the time of exposure was increased up to 9 hr, the concentrations at 50 and 100 microg/ml were 100% effective to 3 extracts. The chemical analysis of the extracts revealed the presence of flavonoids, a trypanocidal compound already described. Based on the results, we can conclude that the A. satureioides extracts exhibit trypanocidal effects.
Achyrocline/chemistry ; Antimalarials/isolation & purification ; Antimalarials/pharmacology ; Cell Survival/drug effects ; Dose-Response Relationship, Drug ; Flavonoids/isolation & purification ; Flavonoids/pharmacology ; Plant Extracts/isolation & purification ; Plant Extracts/pharmacology ; Time Factors ; Trypanosoma/drug effects

The aim of the present study was to investigate antimalarial drug pressure resulting from the clinical use of different antimalarials in Thailand. The phenotypic diversity of the susceptibility profiles of antimalarials, i.e., chloroquine (CQ), quinine (QN), mefloquine (MQ), and artesunate (ARS) in Plasmodium falciparum isolates collected during the period from 1988 to 2003 were studied. P. falciparum isolates from infected patients were collected from the Thai-Cambodian border area at different time periods (1988-1989, 1991-1992, and 2003), during which 3 different patterns of drug use had been implemented: MQ + sulphadoxine (S) + pyrimethamine (P), MQ alone and MQ + ARS, respectively. The in vitro drug susceptibilities were investigated using a method based on the incorporation of [3H] hypoxanthine. A total of 50 isolates were tested for susceptibilities to CQ, QN, MQ, and ARS. Of these isolates, 19, 16, and 15 were adapted during the periods 1988-1989, 1991-1993, and 2003, respectively. P. falciparum isolates collected during the 3 periods were resistant to CQ. Sensitivities to MQ declined from 1988 to 2003. In contrast, the parasite was sensitive to QN, and similar sensitivity profile patterns were observed during the 3 time periods. There was a significantly positive but weak correlation between the IC50 values of CQ and QN, as well as between the IC50 values of QN and MQ. Drug pressure has impact on sensitivity of P. falciparum to MQ. A combination therapy of MQ and ARS is being applied to reduce the parasite resistance, and also increasing the efficacy of the drug.
Animals ; Antimalarials/pharmacology ; Antimalarials/therapeutic use ; Artemisinins/pharmacology ; Artemisinins/therapeutic use ; Chloroquine/pharmacology ; Chloroquine/therapeutic use ; Drug Resistance ; Humans ; Malaria/drug therapy ; Malaria/parasitology ; Mefloquine/pharmacology ; Mefloquine/therapeutic use ; Parasitic Sensitivity Tests/methods ; Plasmodium falciparum/drug effects ; Plasmodium falciparum/isolation & purification ; Quinine/pharmacology ; Quinine/therapeutic use ; Thailand

Pyronaridine and artesunate have been shown to be effective in falciparum malaria treatment. However, pyronaridine is rarely used in Hainan Island clinically, and artesunate is not widely used as a therapeutic agent. Instead, conventional antimalarial drugs, chloroquine and piperaquine, are used, explaining the emergence of chloroquine-resistant Plasmodium falciparum. In this article, we investigated the sensitivity of P. falciparum to antimalarial drugs used in Hainan Island for rational drug therapy. We performed in vivo (28 days) and in vitro tests to determine the sensitivity of P. falciparum to antimalarial drugs. Total 46 patients with falciparum malaria were treated with dihydroartemisinin/piperaquine phosphate (DUO-COTECXIN) and followed up for 28 day. The cure rate was 97.8%. The mean fever clearance time (22.5+/-10.6 hr) and the mean parasite clearance time (27.3+/-12.2 hr) showed no statistical significance with different genders, ages, temperatures, or parasite density (P>0.05). The resistance rates of chloroquine, piperaquine, pyronarididine, and artesunate detected in vitro were 71.9%, 40.6%, 12.5%, and 0%, respectively (P<0.0001). The resistance intensities decreased as follows: chloroquine>piperaquine>pyronarididine>artesunate. The inhibitory dose 50 (IC50) was 3.77x10(-6) mol/L, 2.09x10(-6) mol/L, 0.09x10(-6) mol/L, and 0.05x10(-6) mol/L, and the mean concentrations for complete inhibition (CIMC) of schizont formation were 5.60x10(-6) mol/L, 9.26x10(-6) mol/L, 0.55x10(-6) mol/L, and 0.07x10(-6) mol/L, respectively. Dihydroartemisinin showed a strong therapeutic effect against falciparum malaria with a low toxicity.
Adolescent ; Adult ; Aged ; Antimalarials/pharmacology ; Antimalarials/therapeutic use ; Child ; Child, Preschool ; China ; Female ; Humans ; Inhibitory Concentration 50 ; Malaria, Falciparum/drug therapy ; Malaria, Falciparum/parasitology ; Male ; Middle Aged ; Parasitic Sensitivity Tests ; Plasmodium falciparum/drug effects ; Treatment Outcome ; Young Adult

Artemisinin-based combination therapy (ACT) is currently promoted as a strategy for treating both uncomplicated and severe falciparum malaria, targeting asexual blood-stage Plasmodium falciparum parasites. However, the effect of ACT on sexual-stage parasites remains controversial. To determine the clearance of sexual-stage P. falciparum parasites from 342 uncomplicated, and 217 severe, adult malaria cases, we reviewed and followed peripheral blood sexualstage parasites for 4 wk after starting ACT. All patients presented with both asexual and sexual stage parasites on admission, and were treated with artesunate-mefloquine as the standard regimen. The results showed that all patients were asymptomatic and negative for asexual forms before discharge from hospital. The percentages of uncomplicated malaria patients positive for gametocytes on days 3, 7, 14, 21, and 28 were 41.5, 13.1, 3.8, 2.0, and 2.0%, while the percentages of gametocyte positive severe malaria patients on days 3, 7, 14, 21, and 28 were 33.6, 8.2, 2.7, 0.9, and 0.9%, respectively. Although all patients were negative for asexual parasites by day 7 after completion of the artesunate-mefloquine course, gametocytemia persisted in some patients. Thus, a gametocytocidal drug, e.g., primaquine, may be useful in combination with an artesunate-mefloquine regimen to clear gametocytes, so blocking transmission more effectively than artesunate alone, in malaria transmission areas.
Adolescent ; Adult ; Animals ; Antimalarials/pharmacology ; Antimalarials/therapeutic use ; Artemisinins/pharmacology ; Artemisinins/therapeutic use ; Drug Evaluation ; Drug Therapy, Combination ; Female ; Follow-Up Studies ; Germ Cells/drug effects ; Germ Cells/growth & development ; Humans ; Malaria, Falciparum/drug therapy ; Malaria, Falciparum/parasitology ; Male ; Mefloquine/pharmacology ; Mefloquine/therapeutic use ; Plasmodium falciparum/drug effects ; Plasmodium falciparum/growth & development ; Severity of Illness Index ; Thailand ; Treatment Outcome

The use of sulfadoxine and pyrimethamine (SP) for treatment of vivax malaria is uncommon in most malarious areas, but Plasmodium vivax isolates are exposed to SP because of mixed infections with other Plasmodium species. As P. vivax is the most prevalent species of human malaria parasites in Iran, monitoring of resistance of the parasite against the drug is necessary. In the present study, 50 blood samples of symptomatic patients were collected from 4 separated geographical regions of south-east Iran. Point mutations at residues 57, 58, 61, and 117 were detected by the PCR-RFLP method. Polymorphism at positions 58R, 117N, and 117T of P. vivax dihydrofolate reductase (Pvdhfr) gene has been found in 12%, 34%, and 2% of isolates, respectively. Mutation at residues F57 and T61 was not detected. Five distinct haplotypes of the Pvdhfr gene were demonstrated. The 2 most prevalent haplotypes were F57S58T61S117 (62%) and F57S58T61N117 (24%). Haplotypes with 3 and 4 point mutations were not found. The present study suggested that P. vivax in Iran is under the pressure of SP and the sensitivity level of the parasite to SP is diminishing and this fact must be considered in development of malaria control programs.
Amino Acid Substitution/genetics ; Antimalarials/pharmacology ; Drug Combinations ; Drug Resistance ; Haplotypes ; Humans ; Iran ; Malaria, Vivax/parasitology ; Mutation, Missense ; Plasmodium vivax/enzymology ; Plasmodium vivax/genetics ; Plasmodium vivax/isolation & purification ; Polymorphism, Genetic ; Pyrimethamine/pharmacology ; Sulfadoxine/pharmacology ; Tetrahydrofolate Dehydrogenase/genetics

The parasite Plasmodium falciparum causes severe malaria and is the most dangerous to humans. However, it exhibits resistance to their drugs. Farnesyltransferase has been identified in pathogenic protozoa of the genera Plasmodium and the target of farnesyltransferase includes Ras family. Therefore, the inhibition of farnesyltransferase has been suggested as a new strategy for the treatment of malaria. However, the exact functional mechanism of this agent is still unknown. In addition, the effect of farnesyltransferase inhibitor (FTIs) on mitochondrial level of malaria parasites is not fully understood. In this study, therefore, the effect of a FTI R115777 on the function of mitochondria of P. falciparum was investigated experimentally. As a result, FTI R115777 was found to suppress the infection rate of malaria parasites under in vitro condition. It also reduces the copy number of mtDNA-encoded cytochrome c oxidase III. In addition, the mitochondrial membrane potential (DeltaPsim) and the green fluorescence intensity of MitoTracker were decreased by FTI R115777. Chloroquine and atovaquone were measured by the mtDNA copy number as mitochondrial non-specific or specific inhibitor, respectively. Chloroquine did not affect the copy number of mtDNA-encoded cytochrome c oxidase III, while atovaquone induced to change the mtDNA copy number. These results suggest that FTI R115777 has strong influence on the mitochondrial function of P. falciparum. It may have therapeutic potential for malaria by targeting the mitochondria of parasites.
Antimalarials/pharmacology ; Enzyme Inhibitors/pharmacology ; Farnesyltranstransferase/antagonists & inhibitors ; Farnesyltranstransferase/genetics ; Farnesyltranstransferase/metabolism ; Humans ; Malaria, Falciparum/drug therapy ; Malaria, Falciparum/parasitology ; Mitochondria/drug effects ; Mitochondria/metabolism ; Plasmodium falciparum/drug effects ; Plasmodium falciparum/enzymology ; Plasmodium falciparum/genetics ; Protozoan Proteins/antagonists & inhibitors ; Protozoan Proteins/genetics ; Protozoan Proteins/metabolism ; Quinolones/pharmacology

Resistance of Plasmodium spp. to anti-malarial drugs is the primary obstacle in the fight against malaria, and molecular markers for the drug resistance have been applied as an adjunct in the surveillance of the resistance. In this study, we investigated the prevalence of mutations in pvmdr1, pvcrt-o, pvdhfr, and pvdhps genes in temperate-zone P. vivax parasites from central China. A total of 26 isolates were selected, including 8 which were previously shown to have a lower susceptibility to chloroquine in vitro. For pvmdr1, pvcrt-o, and pvdhps genes, no resistance-conferring mutations were discovered. However, a highly prevalent (69.2%), single-point mutation (S117N) was found in pvdhfr gene. In addition, tandem repeat polymorphisms existed in pvdhfr and pvdhps genes, which warranted further studies in relation to the parasite resistance to antifolate drugs. The study further suggests that P. vivax populations in central China may still be relatively susceptible to chloroquine and sulfadoxine-pyrimethamine.
Antimalarials/pharmacology ; China ; Chloroquine/pharmacology ; DNA, Protozoan/chemistry ; DNA, Protozoan/genetics ; Drug Resistance/genetics ; Folic Acid Antagonists/pharmacology ; Genotype ; Humans ; Malaria, Vivax/epidemiology ; Malaria, Vivax/parasitology ; Plasmodium vivax/drug effects ; Plasmodium vivax/genetics ; Plasmodium vivax/isolation & purification ; Point Mutation ; Polymorphism, Single Nucleotide/genetics ; Prevalence ; Protozoan Proteins/genetics ; Sequence Analysis, DNA ; Tandem Repeat Sequences/genetics

The aim of the study was to explore the possible molecular markers of chloroquine resistance in Plasmodium vivax isolates in Thailand. A total of 30 P. vivax isolates were collected from a malaria endemic area along the Thai-Myanmar border in Mae Sot district of Thailand. Dried blood spot samples were collected for analysis of Pvmdr1 and Pvcrt-o polymorphisms. Blood samples (100 mul) were collected by finger-prick for in vitro chloroquine susceptibility testing by schizont maturation inhibition assay. Based on the cut-off IC50 of 100 nM, 19 (63.3%) isolates were classified as chloroquine resistant P. vivax isolates. Seven non-synonymous mutations and 2 synonymous were identified in Pvmdr1 gene. Y976F and F1076L mutations were detected in 7 (23.3%) and 16 isolates (53.3%), respectively. Analysis of Pvcrt-o gene revealed that all isolates were wild-type. Our results suggest that chloroquine resistance gene is now spreading in this area. Monitoring of chloroquine resistant molecular markers provide a useful tool for future control of P. vivax malaria.
Amino Acid Substitution ; Antimalarials/pharmacology ; Chloroquine/pharmacology ; Drug Resistance ; Humans ; Inhibitory Concentration 50 ; Malaria, Vivax/parasitology ; Membrane Transport Proteins/genetics ; Multidrug Resistance-Associated Proteins/genetics ; Mutation, Missense ; Myanmar ; Parasitic Sensitivity Tests ; Plasmodium vivax/drug effects ; Plasmodium vivax/genetics ; Protozoan Proteins/genetics ; Thailand