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1.
Chem Biodivers ; 21(2): e202301745, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38192127

ABSTRACT

Many people around the world suffer from malaria, especially in tropical or subtropical regions. While malaria medications have shown success in treating malaria, there is still a problem with resistance to these drugs. Herein, we designed and synthesized some structurally novel benzotriazole-ß-lactams using 2-(1H-benzo[d][1,2,3]triazol-1-yl)acetic acid as a key intermediate. To synthesize the target molecules, the ketene-imine cycloaddition reaction was employed. First, The reaction of 1H-benzo[d][1,2,3]triazole with 2-bromoacetic acid in aqueous sodium hydroxide yielded 2-(1H-benzo[d][1,2,3]triazol-1-yl)acetic acid. Then, the treatment of 2-(1H-benzo[d][1,2,3]triazol-1-yl)acetic acid with tosyl chloride, triethyl amine, and Schiff base provided new ß-lactams in good to moderate yields.The formation of all cycloadducts was confirmed by elemental analysis, FT-IR, NMR and mass spectral data. Moreover, X-ray crystallography was used to determine the relative stereochemistry of 4a compound. The in vitro antimalarial activity test was conducted for each compound against P. falciparum K1. The IC50 values ranged from 5.56 to 25.65 µM. A cytotoxicity profile of the compounds at 200 µM final concentration revealed suitable selectivity of the compounds for malaria treatment. Furthermore, the docking study was carried out for each compound into the P. falciparum dihydrofolate reductase enzyme (PfDHFR) binding site to analyze their possible binding orientation in the active site.


Subject(s)
Antimalarials , Malaria , Humans , Antimalarials/chemistry , Molecular Docking Simulation , beta-Lactams/pharmacology , beta-Lactams/chemistry , Spectroscopy, Fourier Transform Infrared , Triazoles/chemistry , Acetates , Structure-Activity Relationship
2.
Antibiotics (Basel) ; 11(1)2022 Jan 12.
Article in English | MEDLINE | ID: mdl-35052971

ABSTRACT

A series of oleanolic acid derivatives holding oxo- or 3-N-polyamino-3-deoxy-substituents at C3 as well as carboxamide function at C17 with different long chain polyamines have been synthesized and evaluated for antimicrobial activities. Almost all series presented good to moderate activity against Gram-positive S. aureus, S. faecalis and B. cereus bacteria with minimum inhibitory concentration (MIC) values from 3.125 to 200 µg/mL. Moreover, compounds possess important antimicrobial activities against Gram-negative E. coli, P. aeruginosa, S. enterica, and EA289 bacteria with MICs ranging from 6.25 to 200 µg/mL. The testing of ability to restore antibiotic activity of doxycycline and erythromycin at a 2 µg/mL concentration in a synergistic assay showed that oleanonic acid conjugate with spermine spacered through propargylamide led to a moderate improvement in terms of antimicrobial activities of the different selected combinations against both P. aeruginosa and E. coli. The study of mechanism of action of the lead conjugate 2i presenting a N-methyl norspermidine moiety showed the effect of disruption of the outer bacterial membrane of P. aeruginosa PA01 cells. Computational ADMET profiling renders this compound as a suitable starting point for pharmacokinetic optimization. These results give confidence to the successful outcome of bioconjugation of polyamines and oleanane-type triterpenoids in the development of antimicrobial agents.

3.
Int J Mol Sci ; 22(4)2021 Feb 19.
Article in English | MEDLINE | ID: mdl-33669790

ABSTRACT

In the search for an effective strategy to overcome antimicrobial resistance, a series of new morpholine-containing 5-arylideneimidazolones differing within either the amine moiety or at position five of imidazolones was explored as potential antibiotic adjuvants against Gram-positive and Gram-negative bacteria. Compounds (7-23) were tested for oxacillin adjuvant properties in the Methicillin-susceptible S. aureus (MSSA) strain ATCC 25923 and Methicillin-resistant S. aureus MRSA 19449. Compounds 14-16 were tested additionally in combination with various antibiotics. Molecular modelling was performed to assess potential mechanism of action. Microdilution and real-time efflux (RTE) assays were carried out in strains of K. aerogenes to determine the potential of compounds 7-23 to block the multidrug efflux pump AcrAB-TolC. Drug-like properties were determined experimentally. Two compounds (10, 15) containing non-condensed aromatic rings, significantly reduced oxacillin MICs in MRSA 19449, while 15 additionally enhanced the effectiveness of ampicillin. Results of molecular modelling confirmed the interaction with the allosteric site of PBP2a as a probable MDR-reversing mechanism. In RTE, the compounds inhibited AcrAB-TolC even to 90% (19). The 4-phenylbenzylidene derivative (15) demonstrated significant MDR-reversal "dual action" for ß-lactam antibiotics in MRSA and inhibited AcrAB-TolC in K. aerogenes. 15 displayed also satisfied solubility and safety towards CYP3A4 in vitro.


Subject(s)
Anti-Bacterial Agents/pharmacology , Drug Resistance, Multiple, Bacterial/genetics , Imidazoles/pharmacology , Morpholines/pharmacology , Allosteric Site , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Bacteria/drug effects , Crystallography, X-Ray , Drug Evaluation, Preclinical , Drug Interactions , Drug Resistance, Multiple, Bacterial/drug effects , Hydrogen Bonding , Hydrogen-Ion Concentration , Imidazoles/chemical synthesis , Imidazoles/chemistry , Ligands , Microbial Sensitivity Tests , Molecular Conformation , Molecular Docking Simulation , Morpholines/chemical synthesis , Morpholines/chemistry , Solubility , Structure-Activity Relationship , Water
4.
Iran J Pharm Res ; 18(2): 596-606, 2019.
Article in English | MEDLINE | ID: mdl-31531044

ABSTRACT

Fifteen novel ß-lactams bearing N-ethyl tert-butyl carbamate group 5a-o and fifteen N-(2- aminoethyl) ß-lactams 6a-o were synthesized by [2+2] ketene-imine cycloaddition reaction (Staudinger). The cycloaddition reaction was found to be totally diastereoselective leading exclusively to theformation of cis-ß-lactam derivatives. These newly synthesized ß-lactams were evaluated for their antimalarial activity against p. falciparum K14 resistant strain and showed good to excellent EC50 values. Of the thirty ß-lactams tested, 5 h, 6a and 6c showed IC50 < 20 µM while 5b, 5c, 5e, 5f, 5g, 5i, 5j, 6d, 6g and 6h exhibited IC50 <50 . Compounds 5c, 5h, and 5q-t were examined for their anticancer properties against K562 Leukemia cell line and 5s showed the best activity. Compounds 3a-j, 5a-o, 6a-o, were tested against S. aureus , E. coli, C. albicans and showed no activity below 125 µg/mL.

5.
Infect Immun ; 87(11)2019 11.
Article in English | MEDLINE | ID: mdl-31405958

ABSTRACT

The level of human group IIA secreted phospholipase A2 (hGIIA sPLA2) is increased in the plasma of malaria patients, but its role is unknown. In parasite culture with normal plasma, hGIIA is inactive against Plasmodium falciparum, contrasting with hGIIF, hGV, and hGX sPLA2s, which readily hydrolyze plasma lipoproteins, release nonesterified fatty acids (NEFAs), and inhibit parasite growth. Here, we revisited the anti-Plasmodium activity of hGIIA under conditions closer to those of malaria physiopathology where lipoproteins are oxidized. In parasite culture containing oxidized lipoproteins, hGIIA sPLA2 was inhibitory, with a 50% inhibitory concentration value of 150.0 ± 40.8 nM, in accordance with its capacity to release NEFAs from oxidized particles. With oxidized lipoproteins, hGIIF, hGV, and hGX sPLA2s were also more potent, by 4.6-, 2.1-, and 1.9-fold, respectively. Using specific immunoassays, we found that hGIIA sPLA2 is increased in plasma from 41 patients with malaria over levels for healthy donors (median [interquartile range], 1.6 [0.7 to 3.4] nM versus 0.0 [0.0 to 0.1] nM, respectively; P < 0.0001). Other sPLA2s were not detected. Malaria plasma, but not normal plasma, contains oxidized lipoproteins and was inhibitory to P. falciparum when spiked with hGIIA sPLA2 Injection of recombinant hGIIA into mice infected with P. chabaudi reduced the peak of parasitemia, and this was effective only when the level of plasma peroxidation was increased during infection. In conclusion, we propose that malaria-induced oxidation of lipoproteins converts these into a preferential substrate for hGIIA sPLA2, promoting its parasite-killing effect. This mechanism may contribute to host defense against P. falciparum in malaria where high levels of hGIIA are observed.


Subject(s)
Antimalarials/pharmacology , Group II Phospholipases A2/pharmacology , Lipoproteins/metabolism , Plasmodium chabaudi/drug effects , Plasmodium falciparum/drug effects , Adolescent , Adult , Female , Humans , Malaria, Falciparum/epidemiology , Malaria, Falciparum/parasitology , Male , Middle Aged , Oxidation-Reduction , Vietnam/epidemiology , Young Adult
6.
Iran J Pharm Res ; 18(1): 34-48, 2019.
Article in English | MEDLINE | ID: mdl-31089342

ABSTRACT

Some new ß-lactams bearing biologically important morpholine ring have been synthesized by acylation of amino ß-lactams in the presence of morpholine-4-carbonyl chloride. These novel ß-lactams were prepared under mild reaction conditions without any solvent in short reaction times. Their biological activities have been examined against microbial agents such as Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and fungi such as Candida albicans (C. albicans) and Candida glabrata (C. glabrata). They have been also tested against Plasmodium falciparum K14 resistant strain and showed moderate to good IC50 values.

7.
Acta Trop ; 190: 183-192, 2019 Feb.
Article in English | MEDLINE | ID: mdl-30439344

ABSTRACT

Malaria is highly endemic in Umphang Valley, a district in the western edge of Tak Province, along the boundary with Kayin State of Myanmar. Although there are high indigenous malaria cases in this area every year, nothing about malaria vectors and their transmission role have been investigated before this study. The objective of this work is to characterize the Anopheles species diversity and trophic behavior of malaria vectors in the transmission area of Umphang Valley. Females of Anopheles mosquitoes were collected every two months during a two-year period. Mosquito collections were using standard collection technique, indoor and outdoor human landing collections and outdoor cattle bait collection. Anopheles mosquitoes were identified using morphological characters and multiplex AS-PCR assay for the identification of sibling species within groups and complexes present. From a total of 16,468 Anopheles females, 2723 specimens (16.54%) were collected from humans and 13,745 specimens (83.46%) were captured from cattle. From human landing collections, 2447 specimens (89.86%) of Anopheles minimus were obtained, followed by 119 Anopheles peditaeniatus (4.37%), 62 Anopheles maculatus (2.28%), 17 Anopheles dirus (0.6%), 15 Anopheles aconitus (0.5%) and 6 Anopheles sawadwongporni (0.2%) respectively. Seven putative malaria vectors, including An. minimus, An. dirus, An. baimaii, An. sawadwongporni, An. maculatus, An. pseudowillmori and An. aconitus were documented from this study and trophic behavior of each respective species were observed. Such information is definitely crucial for defining the vector capacity of each single species and for designing appropriate vector prevention and control strategies against target vector species.


Subject(s)
Anopheles/physiology , Endemic Diseases , Feeding Behavior , Malaria/epidemiology , Mosquito Vectors/physiology , Animals , Anopheles/classification , Cattle , Female , Humans , Malaria/transmission , Multiplex Polymerase Chain Reaction , Thailand/epidemiology
8.
Drug Dev Res ; 80(1): 133-137, 2019 02.
Article in English | MEDLINE | ID: mdl-30499121

ABSTRACT

A structure-activity relationship study of active molecules against chloroquine-resistant Plasmodium falciparum K1 strain is reported. Structurally simplified analogues of antiplasmodial active alkaloids presented similar levels of activity as their corresponding natural products extracted from Guiera senegalensis and Mitragyna inermis with IC50 values on chloroquine-resistant P. falciparum K1 strain of up to 10.6 µM for spirooxindoles and 13.8 µM for ß-carbolines. The identification of such simpler and cheaper structural analogues is crucial to efficiently study these natural products' action mode as well as developing new cures against malaria.


Subject(s)
Antimalarials/pharmacology , Carbolines/pharmacology , Drug Design , Oxindoles/pharmacology , Plasmodium falciparum/drug effects , Antimalarials/chemistry , Carbolines/chemistry , Cells, Cultured , Humans , Oxindoles/chemistry , Plasmodium falciparum/physiology
9.
J Antimicrob Chemother ; 73(10): 2704-2715, 2018 10 01.
Article in English | MEDLINE | ID: mdl-30053021

ABSTRACT

Background: In 2005, the Democratic Republic of the Congo (DRC) switched to artesunate/amodiaquine as the first-line antimalarial in response to increasing sulfadoxine/pyrimethamine resistance and adopted intermittent preventive treatment using sulfadoxine/pyrimethamine in pregnancy. Objectives: To determine the prevalence of molecular markers of sulfadoxine/pyrimethamine resistance in southwestern DRC 10 years after the new policy was instituted. Methods: From March 2014 to December 2015, blood samples were collected from symptomatic patients presenting to outpatient centres in urban and rural areas. A total of 2030 confirmed Plasmodium falciparum isolates were genotyped at codons associated with sulfadoxine/pyrimethamine resistance. Results: The prevalence of pfdhfr-N51I, C59R and S108N and pfdhps-A437G mutations was consistently high; the prevalence of the pfdhps-K540E mutation was low but increased since its first report in 2008 in the same region, reaching 17.6% by 2015. The pfdhps-A581G mutation increased from ∼4.5% in 2014 to ∼14.0% in 2015 at urban sites while in rural areas it remained low (∼4.0%). The mutations pfdhfr-I164L and pfdhps-A613S were detected for the first time in DRC. Also, 11 (0.8%) isolates revealed the presence of the newly described pfdhps-I431V mutation. Combining pfdhfr and pfdhps alleles, quintuple and sextuple mutations were observed, with the emergence of septuple (IRNI/IAGEGA)- and octuple (IRNI/VAGKGS)-mutant genotypes. Conclusions: Intermittent preventive treatment using sulfadoxine/pyrimethamine during pregnancy remains warranted in southwestern DRC. However, the expansion of pfdhps-K540E mutation and emergence of mutants that cause higher levels of sulfadoxine/pyrimethamine resistance is concerning and may present a challenge for future preventive interventions in the country.


Subject(s)
Antimalarials/pharmacology , Drug Resistance, Multiple/genetics , Plasmodium falciparum/drug effects , Protozoan Proteins/genetics , Pyrimethamine/pharmacology , Sulfadoxine/pharmacology , Tetrahydrofolate Dehydrogenase/genetics , Adolescent , Adult , Alleles , Ambulatory Care Facilities/statistics & numerical data , Child , Child, Preschool , Democratic Republic of the Congo , Female , Genotype , Humans , Malaria, Falciparum/blood , Malaria, Falciparum/drug therapy , Male , Mutation , Polymorphism, Genetic , Prevalence , Young Adult
10.
Eur J Med Chem ; 143: 283-291, 2018 Jan 01.
Article in English | MEDLINE | ID: mdl-29197733

ABSTRACT

Highly diastereoselective synthesis of some novel benzothiazole-substituted ß-lactam hybrids was achieved starting from (benzo[d]thiazol-2-yl)phenol as an available precursor. This is the first time (benzo[d]thiazol-2-yl)phenoxyacetic acid has been used as ketene source in synthesizing monocyclic 2-azetidinones. These compounds were evaluated for their antimicrobial activities against a large panel of Gram-positive and Gram-negative bacterial strains and moderate activities were encountered. Antimalarial data revealed that adding methoxyphenyl or ethoxyphenyl group on the ß-lactam ring makes compounds that are more potent. Moreover, hemolytic activity and mammalian cell toxicity survey of the compounds showed their potential as a medicine.


Subject(s)
Anti-Bacterial Agents/pharmacology , Antifungal Agents/pharmacology , Antimalarials/pharmacology , Benzothiazoles/pharmacology , beta-Lactams/pharmacology , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Anti-Infective Agents , Antifungal Agents/chemical synthesis , Antifungal Agents/chemistry , Antimalarials/chemical synthesis , Antimalarials/chemistry , Bacteria/drug effects , Bacteria/growth & development , Benzothiazoles/chemical synthesis , Benzothiazoles/chemistry , Cell Survival/drug effects , Dose-Response Relationship, Drug , Fungi/drug effects , Fungi/growth & development , Hep G2 Cells , Humans , Molecular Structure , Plasmodium falciparum/drug effects , Stereoisomerism , Structure-Activity Relationship , beta-Lactams/chemical synthesis , beta-Lactams/chemistry
11.
PLoS One ; 10(10): e0140878, 2015.
Article in English | MEDLINE | ID: mdl-26473363

ABSTRACT

The efficacy of chloroquine, once the drug of choice in the fight against Plasmodium falciparum, is now severely limited due to widespread resistance. Amodiaquine is one of the most potent antimalarial 4-aminoquinolines known and remains effective against chloroquine-resistant parasites, but toxicity issues linked to a quinone-imine metabolite limit its clinical use. In search of new compounds able to retain the antimalarial activity of amodiaquine while circumventing quinone-imine metabolite toxicity, we have synthesized five 4-aminoquinolines that feature rings lacking hydroxyl groups in the side chain of the molecules and are thus incapable of generating toxic quinone-imines. The new compounds displayed high in vitro potency (low nanomolar IC50), markedly superior to chloroquine and comparable to amodiaquine, against chloroquine-sensitive and chloroquine-resistant strains of P. falciparum, accompanied by low toxicity to L6 rat fibroblasts and MRC5 human lung cells, and metabolic stability comparable or higher than that of amodiaquine. Computational studies indicate a unique mode of binding of compound 4 to heme through the HOMO located on a biphenyl moeity, which may partly explain the high antiplasmodial activity observed for this compound.


Subject(s)
Chloroquine , Drug Resistance/drug effects , Models, Chemical , Plasmodium falciparum/metabolism , Animals , Antimalarials/chemical synthesis , Antimalarials/chemistry , Antimalarials/pharmacokinetics , Antimalarials/pharmacology , Cell Line , Chloroquine/chemistry , Chloroquine/pharmacokinetics , Chloroquine/pharmacology , Humans , Rats
12.
Anal Bioanal Chem ; 407(25): 7823-30, 2015 Oct.
Article in English | MEDLINE | ID: mdl-26280205

ABSTRACT

Despite significant progress in prevention and therapy, malaria is still one of the world's leading major diseases due to its high morbidity and mortality. Recommended treatments by the World Health Organization include the use of artemisinin and artemisinin derivative-based combination therapies. To allow efficient patient monitoring during antimalarial therapy without the use of expensive apparatus, we developed a sensitive direct chemiluminescent enzyme immunoassay for the determination of dihydroartemisinin in biological fluids. To produce specific antibodies against dihydroartemisinin (DHA), a synthetic DHA derivative was coupled to bovine serum albumin as the immunogen. In parallel, a new, rapid, and efficient procedure to covalently link glycoprotein to all amine-containing molecules has been established and the enzyme tracer was prepared by chemically coupling the DHA derivative in combination with SBP rather than the more commonly used HRP. It allowed us to develop, after optimization of the luminescent reagent, a sensitive and stable luminescent EIA, with a LLOQ of 90 pg mL(-1). This assay compares favorably with the most efficient HPLC methods previously reported with a LLOQ close to 1 ng mL(-1) and shows good precision and efficiency since recovery from human plasma spiked with DHA ranged between 91 and 103%, with coefficients of variation of <13%. To date, no immunoassay for DHA has been applied to plasma analysis and this EIA should be very useful in all clinical laboratories for rapid and cost-effective analysis.


Subject(s)
Antimalarials/blood , Artemisinins/blood , Drug Monitoring/methods , Immunoenzyme Techniques/methods , Animals , Humans , Limit of Detection , Luminescent Measurements/methods , Peroxidase/chemistry , Rabbits , Glycine max/enzymology
13.
Malar J ; 14: 279, 2015 Jul 17.
Article in English | MEDLINE | ID: mdl-26185098

ABSTRACT

This meeting report presents the outcomes of a workshop held in Bangkok on December 1st 2014, where the following challenges were discussed: the threat of resistance to artemisinin and artemisinin-based combination therapy in the Greater Mekong Sub-region (GMS) and in Africa; access to treatment for most at risk and hard to reach population; insecticide resistance, residual and outdoors transmission. The role of operational research and the interactions between research institutions, National Malaria Control Programmes, Civil Society Organizations, and of financial and technical partners to address those challenges and to accelerate translation of research into policies and programmes were debated. The threat and the emergency of the artemisinin resistance spread and independent emergence in the GMS was intensely debated as it is now close to the border of India. The need for key messages, based on scientific evidence and information available and disseminated without delay, was highlighted as crucial for an effective and urgent response.


Subject(s)
Global Health , Health Policy , Malaria/prevention & control , Africa , Education , Humans , India , Insecticide Resistance , Operations Research , Thailand , World Health Organization
14.
Eur J Med Chem ; 87: 364-71, 2014 Nov 24.
Article in English | MEDLINE | ID: mdl-25282260

ABSTRACT

The effect of double asymmetric induction for the synthesis of new cis-ß-lactams by [2 + 2] cycloaddition reactions of chiral imines with a chiral ketene was investigated. The cycloaddition reaction was found to be totally diastereoselective leading exclusively to the formation of the cis-ß-lactam derivatives. The newly synthesized cycloadducts were evaluated for their antimalarial activities against Plasmodium falciparum K14 resistant strain with moderate to excellent IC50 values varying from 8 to 50 µM. Of the fifteen ß-lactams tested, four showed IC50 ≤ 11 µM.


Subject(s)
Antimalarials/chemistry , Antimalarials/pharmacology , Cycloaddition Reaction , Ethylenes/chemistry , Imines/chemistry , Ketones/chemistry , beta-Lactams/chemistry , beta-Lactams/pharmacology , Antimalarials/chemical synthesis , Chemistry Techniques, Synthetic , Inhibitory Concentration 50 , Plasmodium falciparum/drug effects , Stereoisomerism , Structure-Activity Relationship , beta-Lactams/chemical synthesis
15.
Parasit Vectors ; 7: 316, 2014 Jul 09.
Article in English | MEDLINE | ID: mdl-25008314

ABSTRACT

BACKGROUND: Human malaria is still a burden in Dak Nong and Binh Phuoc Provinces in south-central Vietnam that border Cambodia. Several Anopheles species that transmit human malarial Plasmodium may also transmit Wuchereria bancrofti, the nematode that causes Bancroftian lymphatic filariasis. The objective of this study was to investigate the role of Anopheles species in the transmission of these two pathogens in the two highly malaria endemic provinces of Vietnam. METHODS: Anopheles mosquitoes were collected in Dak Nong and Binh Phuoc Provinces in November and December of 2010 and 2011. Human landing catches, paired collections on human and buffalo, and resting captures were made with mouth aspirators. Collections were also made with light traps. Morphological and PCR-based methods were used to identify the species. Real-time PCR was used to detect Plasmodium species and W. bancrofti in individual mosquitoes. RESULTS: Twenty-four Anopheles species were identified among 797 captured mosquitoes. Anopheles dirus was found in both provinces and was the predominant species in Binh Phuoc Province; An. maculatus was the most prevalent species in Dak Nong Province. Anopheles minimus was collected only in Binh Phuoc Province. Some specimens of An. minimus and An. pampanai were misidentified based on morphology. Four specimens of An. scanloni were identified, and this is the first report of this species of the Dirus Complex in Vietnam. Two females, one An. dirus and one An. pampanai, collected in Binh Phuoc Province were infected with P. vivax, for an overall infection rate of 0.41% (2/486): 0.28% for An. dirus (1/361) and 20% for An. pampanai (1/5). No mosquitoes were found to be infected with P. falciparum, P. knowlesi or W. bancrofti in either province. CONCLUSION: A diversity of Anopheles species occurs in Dak Nong and Binh Phuoc Provinces of Vietnam, several of which are considered to be actual and potential vectors of malarial protozoa and microfilariae. It is highly likely that two of the species, An. dirus and An. pampanai, are active in malaria transmission based on the detection of P. vivax in females of these species. This is the first report of An. scanloni in Vietnam.


Subject(s)
Anopheles/classification , Malaria/epidemiology , Animal Distribution , Animals , Female , Humans , Insect Vectors/classification , Insect Vectors/physiology , Malaria/transmission , Plasmodium/classification , Plasmodium/isolation & purification , Species Specificity , Vietnam/epidemiology , Wuchereria bancrofti/isolation & purification
16.
Antimicrob Agents Chemother ; 57(7): 3121-30, 2013 Jul.
Article in English | MEDLINE | ID: mdl-23612201

ABSTRACT

Assessment of in vitro susceptibility is a fundamental component of antimalarial surveillance studies, but wide variations in the measurement of parasite growth and the calculation of inhibitory constants make comparisons of data from different laboratories difficult. Here we describe a Web-based, high-throughput in vitro analysis and reporting tool (IVART) generating inhibitory constants for large data sets. Fourteen primary data sets examining laboratory-determined susceptibility to artemisinin derivatives and artemisinin combination therapy partner drugs were collated from 11 laboratories. Drug concentrations associated with half-maximal inhibition of growth (IC50s) were determined by a modified sigmoid Emax model-fitting algorithm, allowing standardized analysis of 7,350 concentration-inhibition assays involving 1,592 isolates. Examination of concentration-inhibition data revealed evidence of apparent paradoxical growth at high concentrations of nonartemisinin drugs, supporting amendment of the method for calculating the maximal drug effect in each assay. Criteria for defining more-reliable IC50s based on estimated confidence intervals and growth ratios improved correlation coefficients for the drug pairs mefloquine-quinine and chloroquine-desethylamodiaquine in 9 of 11 and 8 of 8 data sets, respectively. Further analysis showed that maximal drug inhibition was higher for artemisinins than for other drugs, particularly in ELISA (enzyme-linked immunosorbent assay)-based assays, a finding consistent with the earlier onset of action of these drugs in the parasite life cycle. This is the first high-throughput analytical approach to apply consistent constraints and reliability criteria to large, diverse antimalarial susceptibility data sets. The data also illustrate the distinct biological properties of artemisinins and underline the need to apply more sensitive approaches to assessing in vitro susceptibility to these drugs.


Subject(s)
Antimalarials/pharmacology , Artemisinins/pharmacology , Malaria, Falciparum/drug therapy , Plasmodium falciparum/drug effects , Amodiaquine/analogs & derivatives , Amodiaquine/pharmacology , Automation, Laboratory , Chloroquine/pharmacology , Drug Resistance , Drug Therapy, Combination , High-Throughput Screening Assays , Internet , Malaria, Falciparum/parasitology , Mefloquine/pharmacology , Parasitic Sensitivity Tests , Quinine/pharmacology
17.
Antimicrob Agents Chemother ; 55(12): 5834-41, 2011 Dec.
Article in English | MEDLINE | ID: mdl-21947391

ABSTRACT

Plasmodium falciparum isolates with decreased susceptibility to quinine are increasingly being found in malaria patients. Mechanisms involved in this resistance are not yet understood. Several studies claim that alongside mutations in the Pfcrt and Pfmdr1 genes, the Pfnhe-1 Na(+)/H(+) exchanger polymorphism plays a role in decreasing susceptibility. However, conflicting results on the link between the Pfnhe-1 gene and quinine resistance arise from field- and culture-adapted isolates. We tested the association between Pfnhe-1, Pfcrt, and Pfmdr1 polymorphisms in field- and culture-adapted isolates from various countries with their in vitro susceptibility to quinine. Field isolates presented a higher diversity of the Pfnhe-1 microsatellite sequence than culture-adapted isolates. In culture-adapted isolates but not in field isolates, mutations in the Pfcrt and Pfmdr1 genes, as well as a higher number of DNNND repeats in the Pfnhe-1 gene, were associated with a higher 50% inhibitory concentration (IC(50)) of quinine. Furthermore, most of the culture-adapted isolates with more than one DNNND repeat in the Pfnhe-1 gene also harbored mutated Pfcrt and Pfmdr1 genes with an apparent cumulative effect on quinine susceptibility. This study supports the involvement of the Pfnhe-1 gene in the modulation of the in vitro quinine response when associated with mutated Pfcrt and Pfmdr1 genes. Culture adaptation could be responsible for selection of specific haplotypes of these three genes. Methods used for drug testing might thus influence the association between Pfnhe-1 polymorphism and quinine susceptibility. However, we do not exclude the possibility that in particular settings, Pfnhe-1 polymorphism can be used as a molecular marker for surveillance of quinine resistance.


Subject(s)
Antimalarials/pharmacology , Drug Resistance/genetics , Plasmodium falciparum/drug effects , Polymorphism, Genetic/genetics , Quinine/pharmacology , Sodium-Hydrogen Exchangers/genetics , Animals , Culture Media , Humans , Inhibitory Concentration 50 , Membrane Transport Proteins/genetics , Molecular Sequence Data , Multidrug Resistance-Associated Proteins/genetics , Parasitic Sensitivity Tests , Plasmodium falciparum/genetics , Plasmodium falciparum/growth & development , Plasmodium falciparum/isolation & purification , Protozoan Proteins/genetics , Sequence Analysis, DNA
18.
Malar J ; 10: 164, 2011 Jun 14.
Article in English | MEDLINE | ID: mdl-21669011

ABSTRACT

BACKGROUND: The Plasmodium falciparum NA+/H+ exchanger (pfnhe1, gene PF13_0019) has recently been proposed to influence quinine (QN) susceptibility. However, its contribution to QN resistance seems to vary geographically depending on the genetic background of the parasites. Here, the role of this gene was investigated in in vitro QN susceptibility of isolates from Viet Nam. METHOD: Ninety-eight isolates were obtained from three different regions of the Binh Phuoc and Dak Nong bordering Cambodia provinces during 2006-2008. Among these, 79 were identified as monoclonal infection and were genotyped at the microsatellite pfnhe1 ms4760 locus and in vitro QN sensitivity data were obtained for 51 isolates. Parasite growth was assessed in the field using the HRP2 immunodetection assay. RESULTS: Significant associations were found between polymorphisms at pfnhe1 microsatellite ms4760 and susceptibility to QN. Isolates with two or more DNNND exhibited much lower susceptibility to QN than those harbouring zero or one DNNND repeats (median IC(50) of 682 nM versus median IC(50) of 300 nM; p = 0.0146) while isolates with one NHNDNHNNDDD repeat presented significantly reduced QN susceptibility than those who had two (median IC(50) of 704 nM versus median IC(50) of 375 nM; p < 0.01). These QNR associated genotype features were mainly due to the over representation of profile 7 among isolates (76.5%). The majority of parasites had pfcrt76T and wild-type pfmdr1 (> 95%) thus preventing analysis of associations with these mutations. Interestingly, area with the highest median QN IC(50) showed also the highest percentage of isolates carrying the pfnhe1 haplotype 7. CONCLUSIONS: The haplotype 7 which is the typical Asian profile is likely well-adapted to high drug pressure in this area and may constitute a good genetic marker to evaluate the dissemination of QNR in this part of the world.


Subject(s)
Antimalarials/pharmacology , Drug Resistance , Malaria, Falciparum/parasitology , Plasmodium falciparum/drug effects , Polymorphism, Genetic , Quinine/pharmacology , Sodium-Hydrogen Exchangers/genetics , Gene Frequency , Haplotypes , Humans , Parasitic Sensitivity Tests , Plasmodium falciparum/genetics , Plasmodium falciparum/isolation & purification , Vietnam
19.
Res Rep Trop Med ; 2: 109-119, 2011.
Article in English | MEDLINE | ID: mdl-30881184

ABSTRACT

OBJECTIVES: Although human respiratory metabolism is characterized by the mitochondrial electron transport chain, some organisms present a "branched respiratory chain." This branched pathway includes both a classical and an alternative respiratory chain. The latter involves an alternative oxidase. Though the Plasmodium falciparum alternative oxidase is not yet identified, a specific inhibitor of this enzyme, salicylhydroxamic acid (SHAM), showed a drug effect on P. falciparum respiratory function using oxygen consumption measurements. The present study aimed to highlight the metabolic pathways that are affected in P. falciparum following SHAM exposure. DESIGN: A proteomic approach was used to analyze the P. falciparum proteome and determine the metabolic pathways altered following SHAM treatment. To evaluate the SHAM effect on parasite growth, the phenotypic alterations of P. falciparum after SHAM or/and hyperoxia exposure were observed. RESULTS: After SHAM exposure, 26 proteins were significantly deregulated using a fluorescent two dimensional-differential gel electrophoresis. Among these deregulated proteins, some were particularly involved in energetic metabolism. And the combinatory effect of SHAM/hyperoxia seems deleterious for the growth of P. falciparum. CONCLUSION: Our results indicated that SHAM appears to activate glycolysis and decrease stress defense systems. These data provide a better understanding of parasite biology.

20.
J Sep Sci ; 33(12): 1863-9, 2010 Jun.
Article in English | MEDLINE | ID: mdl-20437411

ABSTRACT

In Africa, Mitragyna inermis (Willd.) O. Kuntze (Rubiaceae) is commonly used in traditional medicine to treat malaria. Antimalarial activity is mostly due to the hydromethanolic extract of M. inermis leaves and especially to the main alkaloids, uncarine D and isorhynchophilline. In the present study, we describe for the first time an HPLC method for the simultaneous quantification of uncarine D and isorhynchophylline in biological matrices. SPE was used to extract the components and the internal standard naphthalene from human and pig plasma samples. Chromatographic separation was performed on a C-18 reversed column at a flow rate of 1 mL/min, using methanol-phosphate buffer (10:90, pH 7), as a mobile phase. Good linearity was observed over the concentration ranges of 0.0662-3.31 microg/mL for uncarine D and 0.0476-2.38 microg/mL for isorynchophylline. The precision was less than 12% and the accuracy was from 86 to 107% without any discrepancy between the two species. Uncarine D and isorhynchophylline recoveries were over 80%. These results allowed the quantification of both uncarine D and isorhynchophylline in pig plasma after intravenous administration of M. inermis extract.


Subject(s)
Alkaloids/analysis , Chromatography, High Pressure Liquid/methods , Mitragyna/chemistry , Alkaloids/blood , Alkaloids/pharmacokinetics , Animals , Humans , Limit of Detection , Quality Control , Reference Standards , Reproducibility of Results , Swine
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