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This paper describes for the first time the synthesis and microbiological assessment of some new β-lactam derivatives containing a 1,8-naphthalimide functional group. These compounds were obtained through a [2 + 2] cyclocondensation (Staudinger reaction) of a ketene derived from 2-(1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl) acetic acid (Alrestatin) and various N-arylimines. The reaction was totally diastereoselective leading exclusively to the formation of trans-β-lactam adducts 3a–l, which were characterized by FT-Infra Red, 1H NMR, 13C NMR, mass spectrometry, elemental analyses, and X-ray crystallography, and then individually evaluated for antibacterial and antimalarial activities. Two of the β-lactams, 3c and 3l, afforded IC50 values of 3 and 5 µM, respectively, against Plasmodium falciparum K1 resistant strain.

A novel series of new 3-spiro monocyclic β-lactams 3a–i have been synthesized in high chemical yields from 9H-xanthene-9-carbonyl chloride 2 as ketene source in the [2+2] cycloaddition (Staudinger reaction) with different aromatic imines. These newly synthesized β-lactams were fully characterized and evaluated for their antimalarial activities against Plasmodium falciparum K14-resistant strain with moderate to excellent EC50 values varying from 8 up to 50 µM.

International audience; Aims: Majority of deaths in children aged under 5 years are due to Plasmodium falciparum malaria. Malaria deaths in children decreased but malaria remains a major killer of children, taking the life of a child every 2 minutes. This study aims to investigate the increasing of the in vitro antiplasmodial activities by mutagenesis techniques using gamma-rays (Cs-137) or sodium azide (NaN3) as utagens. It will allow the importance of mutagenesis use as tools for improvement of secondary metabolites against malaria parasites using chemical or physical mutagens.Study Design: Laboratory experiment tests : identification of plant material, immersion of seeds in SA (sodium azide) solutions or irradiation by Gamma-rays (Cs-137) of P. odontadenius seeds for improvement of secondary metabolites against malaria parasites, in vitro culture of seeds followed by the in situ culturing of plantlets for obtaining material of study, phytochemical screening of Phyllanthus odontadenius aerial parts to determine the change of compounds in comparison to controls, in vitro antiplasmodial tests for the determination of SA concentrations or those of gammarays doses which killing 50% of malaria parasite populations (IC50). Place and Duration of Study: Department of Biotechnology and Molecular Biology, Department of Biochemistry: General Atomic Energy Commission, Regional Nuclear Studies Center of Kinshasa, P.O. Box. 868 Kinshasa XI, Democratic Republic of the Congo (DRC). National Institute of Biomedical Research (NIBR) at Kinshasa/Gombe (DRC). Laboratory of UMR-MD3, Aix-Marseille University, Faculty of Pharmacy/Marseille, France. The experiments were conducted from Junuary - December 2010; August and December 2011 and during May and September 2012 until July 2014.Methodology: Aerial parts of plants M1 and M2 from Gamma-rays irradiation of P. odontadenius seeds or from immersion of P. odontadenius seeds in sodium azide solutions used as biological material for the in vitro antiplasmodial analysis. The in vitro antiplasmodial activities assays on clinical isolates of P. falciparum and on chloroquine-resistante P. falciparum strain K1 was determined using microscopic method, the isotopic micro-test method and using HRP2-based ELISA assay.Results: Gamma-rays (Cs-137) increased (multiplied) the in vitro antiplasmodial activities from 2.48 up to 7.6 in comparison to control. Thus, the in vitro antiplasmodial activities were improved or exceeded from 147.57% up to 660% than those of control plant. SA had increased (multiplied) the in vitro antiplasmodial activities from 1.24 up to 10.15 comparing to the control plants. The antiplasmodial activities in vitro were exceeded compared to the control plants from 24.43% up to 915%. Conclusion: Treatment of P. odontadenius seeds by Gamma-rays or by SA give plants high in vitro antiplasmodial activities. Values of in vitro antiplasmodial activities varried from 1.24 (147.57%) to 10.15 (915%). 125, 150 and 225 Gy of Gamma-rays (Cs-137) for physical mutagenesis and 10.15 and 17.5 M of SA solutions for the chemical mutagenesis could be used for improving in vitro antiplasmodial activities against P. falciparum (clinical isolates of P. falciparum or chloroquine-resistant P. falciparum strain K1). Thus, plants extracts from treated seeds have justified the usefulness of mutagens in plant breeding particularly in the increasing production of secondary metabolite against malaria parasite.

This report describes the preparation of some new β-lactam nanocopolymers. These nanoparticles are synthesized in water by emulsion polymerization of an acrylate β-lactam pre-dissolved in a mixture of co-monomers in the presence of sodium dodecyl sulfate as a surfactant and potassium persulfate as a radical initiator. Dynamic light scattering analysis and electron microscopy images of these emulsions show that the nanoparticles are approximately 30–70 nm in diameter. These compounds have been evaluated for their antimalarial activities against chloroquine-resistant Plasmodium faliparum K1 strain demonstrating IC50 varying from 14 to 50 µM. The interactions between these β-lactam nanocopolymers and the P. falciparum single-stranded DNA-binding proteins have been studied by molecular docking calculations.

A series of novel β-lactams was synthesized from different imines and a special ketene derived from N-endo-5-norbornene-2,3-dicarboxyloylglycine 1 via the [2 + 2] ketene imine cycloaddition. Then, β-lactams 3a–h were treated with 1-azido-4-nitrobenzene 4 to afford β-lactam-triazole hybrids 5a–h. Of the twenty-three β-lactams tested against chloroquine-resistant P. falciparum K14 strain, 3a and 3d showed IC50

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.

This paper describes the synthesis of some new beta-lactam derivatives containing the 1,2,3-triazole moiety. All the compounds were evaluated for their in vitro antimicrobial and antimalarial activities. Moderate to excellent antimalarial activities were encountered. The results showed that compounds 5a, 5c, 5f, 5i exhibited the most potent antimalarial activity with IC50 values of 0.85, < 0.97, < 0.97, 1.81 mu M against chloroquine-resistant P. falciparum K1 strain. A QSAR study highlights the structure-activity relationships that correlate the observed antimalarial activities with changes in the compounds' structural features.

Highly diastereoselective synthesis of some novel benzothiazole-substituted beta-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 beta-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. (C) 2017 Elsevier Masson SAS. All rights reserved.

A new hybrid compound 5 containing a ruthenocene, a 4-aminoquinoline, and a 1,2,4-trioxane within a single molecular structure has been synthesized and evaluated for antimalarial potential. In order to ascertain the role of each component of hybrid 5, its antimalarial activity has been measured against chloroquine-resistant and chloroquine-sensitive strains of Plasmodium falciparum in comparison with those of chloroquine, artemisinin, a ruthenocene-trioxane compound 9 not containing an aminoquinoline, the precursor trioxane ketone 4, and a trioxane dimer 10. Hybrid 5 displays high antimalarial activity, in the mid to low nanomolar IC50 range, and low cytotoxicity toward healthy mammalian cells, which translates into good selectivity indexes. The potency of 5 is consistently higher than those of chloroquine, the parent metal-free trioxane, and compound 9, the structural intermediate featuring a ruthenocene moiety bound to the trioxane but lacking the aminoquinoline. These results validate our hypothesis that it is the combination of the aminoquinoline, the ruthenocenyl moiety, and the trioxane in a single molecule that provides the enhanced antiplasmodial activity, and highlight the concept of hybrid compounds as a strategy that deserves further attention.

Some new mono-, bis-spiro- and dispiro-β-lactams have been synthesized from imines derived from 9H-fluoren-9-one and a ketene derived from 9H-xanthene-9-carboxylic acid or phenoxyacetic acid by a [2+2] cycloaddition reaction in good to excellent yields varying from 45 to 83%. The biological activity of these monocyclic β-lactams was successfully investigated against Plasmodium falciparum K14 resistant strain with excellent EC50 values up to 5 μM.

A new fixed-dose combination of artesunate (AS) plus amodiaquine (AQ) (TRIMALACT) was recently developed for the treatment of uncomplicated falciparum malaria. The originality of this combination lies in its galenic formulation which consists of a three-layer tablet with two layers containing each of the active ingredients, i.e. AS and AQ, and these are separated by a middle layer containing an antioxidant compound. To evaluate the efficacy and tolerability of this combination, adults with uncomplicated malaria received three administrations of two tablets (100:300 mg AS/AQ) in a 24-h interval, in Democratic Republic of Congo. Parasitemia and fever were measured and the plasma levels of parent compounds and metabolites [dihydroartemisinin (DHA) and monodesethylamodiaquine (MdAQ)] were determined by high-performance liquid chromatography. In addition, we determined the prevalence of molecular markers of resistance to chloroquine (CQ) and sulfadoxine/pyrimethamine (SP). The AS/AQ combination TRIMALACT demonstrated a good efficacy resulting in an excellent clinical and parasitological response rate of 100% after correction for PCR results. Treatment regimen was well tolerated. The main disposition parameters to AS+AQ were: for DHA, AUC = 632 +/- 475 ng h/ml and Cmax = 432 +/- 325 ng/ml, and for MdAQ = 14268 +/- 4114 ng h/ml and Cmax = 336 +/- 225 ng/ml (mean +/- standard deviation). Parasite genotyping show high frequencies of molecular SP- and CQ-resistance markers with more 80% of the samples showing more than three mutations linked to SP resistance and 93.48% carrying parasite with the CQ-resistant haplotype. This study shows that the AS/AQ combination TRIMALACT is safe and effective in the treatment of highly drug-resistant falciparum malaria.

The new RuII chloroquine complexes [Ru(η6-arene)(CQ)Cl2] (CQ = chloroquine; arene = p-cymene 1, benzene 2), [Ru(η6-p-cymene)(CQ)(H2O)2][BF4]2 (3), [Ru(η6-p-cymene)(CQ)(en)][PF6]2 (en = ethylenediamine) (4), and [Ru(η6-p-cymene)(η6-CQDP)][BF4]2 (5, CQDP = chloroquine diphosphate) have been synthesized and characterized by use of a combination of NMR and FTIR spectroscopy with DFT calculations. Each complex is formed as a single coordination isomer: in compounds 1–4 chloroquine binds to ruthenium in the η1-N mode through the quinoline nitrogen atom whereas in complex 5 an unprecedented η6 bonding through the carbocyclic ring is observed. Compounds 1, 2, 3, and 5 are active against CQ-resistant (Dd2, K1 and W2) and CQ-sensitive (FcB1, PFB, F32 and 3D7) malaria parasites (Plasmodium falciparum); importantly, the potency of these complexes against resistant parasites is consistently higher than that of the standard drug chloroquine diphosphate. Complexes 1 and 5 also inhibit the growth of colon cancer cells, independently of the p53 status and of liposarcoma tumor cell lines with the latter showing increased sensitivity, especially to complex 1 (IC50 8 µM); this is significant because this type of tumor does not respond to currently employed chemotherapies.

New cis-β-lactams are evaluated for their antimalarial activities against Plasmodium falciparum K14 resistant strain.

Background Artesunate-amodiaquine (AS-AQ) is one of the most widely used artemisinin-based combination therapies (ACTs) to treat uncomplicated Plasmodium falciparum malaria in Africa. We investigated the impact of different dosing strategies on the efficacy of this combination for the treatment of falciparum malaria. Methods Individual patient data from AS-AQ clinical trials were pooled using the WorldWide Antimalarial Resistance Network (WWARN) standardised methodology. Risk factors for treatment failure were identified using a Cox regression model with shared frailty across study sites. Results Forty-three studies representing 9,106 treatments from 1999-2012 were included in the analysis; 4,138 (45.4%) treatments were with a fixed dose combination with an AQ target dose of 30 mg/kg (FDC), 1,293 (14.2%) with a non-fixed dose combination with an AQ target dose of 25 mg/kg (loose NFDC-25), 2,418 (26.6%) with a non-fixed dose combination with an AQ target dose of 30 mg/kg (loose NFDC-30), and the remaining 1,257 (13.8%) with a co-blistered non-fixed dose combination with an AQ target dose of 30 mg/kg (co-blistered NFDC). The median dose of AQ administered was 32.1 mg/kg [IQR: 25.9-38.2], the highest dose being administered to patients treated with co-blistered NFDC (median = 35.3 mg/kg [IQR: 30.6-43.7]) and the lowest to those treated with loose NFDC-25 (median = 25.0 mg/kg [IQR: 22.7-25.0]). Patients treated with FDC received a median dose of 32.4 mg/kg [IQR: 27-39.0]. After adjusting for reinfections, the corrected antimalarial efficacy on day 28 after treatment was similar for co-blistered NFDC (97.9% [95% confidence interval (CI): 97.0-98.8%]) and FDC (98.1% [95% CI: 97.6%-98.5%]; P = 0.799), but significantly lower for the loose NFDC-25 (93.4% [95% CI: 91.9%-94.9%]), and loose NFDC-30 (95.0% [95% CI: 94.1%-95.9%]) (P

International audience; The efficacy of chloroquine, once the drug of choice in the fight against Plasmodium falcipa-rum, 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-amino-quinolines 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 IC 50), markedly superior to chloroquine and comparable to amodiaquine, against chloroquine-sensitive and chloroquine-resistant strains of P. falcipa-rum, 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.

Artesunate (ARS) is a water-soluble artemisinin derivative that is a potential alternative to quinine for the treatment of severe childhood malaria. We studied the pharmacokinetics and bioavailability of ARS given by the intramuscular (i.m.) route in an open crossover study design. Fourteen children were randomized to receive intravenous (i.v.) ARS in a loading dose (2.4 mg/kg of body weight) followed 12 h later by an i.m. dose (1.2 mg/kg) (group I), and 14 children were randomized to receive i.m. ARS (2.4 mg/kg) followed by an i.v. dose of ARS (1.2 mg/kg) (group II). We carried out a two-compartment analysis of ARS and dihydroartemisinin (DHA; the principal antimalarial metabolite) levels in 21 children (groups I and II combined). Absorption of i.m. ARS was rapid, with the maximum concentration of DHA in serum being achieved in less than 1 h in most children (median time to the maximum concentration of drug in serum, 35.1 min; range, 10.8 to 71.9 min). The absolute bioavailability of DHA was a median of 86.4% (range, 11.4 to 462.1%), the median steady-state volume of distribution was 1.3 liters/kg (range, 0.5 to 7.9 liters/kg), and the median clearance was 0.028 liters/kg/min (range, 0.001 to 1.58 liters/kg/min). There were no major adverse events attributable to ARS. Parasite clearance kinetics were comparable between the two treatment groups. These results support the use of i.m. ARS in children with severe malaria.

The effect of double asymmetric induction for the synthesis of new cis-β-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-β-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 β-lactams tested, four showed IC50 ≤ 11 μM.

A novel series of β-lactams bearing an anthraquinone moiety have been synthesized from imines derived from anthraquinone-2-carbaldehyde and ketenes by a [2+2] cycloaddition reaction. The cycloadducts were fully characterized and evaluated for their antimalarial activities against Plasmodium falciparum K14 resistant strain and showed moderate to excellent EC 50 values varying from 9 to 50 μM.

Taxotere (docetaxel) inhibits Plasmodium falciparum erythrocytic development in vitro at nanomolar concentrations, both in chloroquine-sensitive (F32/Tanzania) and chloroquine-resistant (FcB1/Colombia, FcR3/Gambia) strains. The dose-response assays performed on asynchronous cultures during 42 hr showed clear biphasic curves with a plateau from 50 microM to 10 nM and a single sigmoid curve with a concentration inhibiting 50% of growth (IC50) of 3-6 nM observed after a 72-hr incubation. Addition of Taxotere to different stages of FcB1 revealed two types of targets: one type on ring/trophozoite-infected erythrocytes (RBCs), at the micromolar level, and another type on schizont-infected RBCs with Taxotere at micromolar concentrations inhibited the merozoite invasion of erythrocytes and parasite growth. These Taxotere-RBC interactions were stable, at least for 1 day. Pulse experiments of 5 hr with Taxotere efficiently inhibit parasite development regardless of the period of the parasite's erythrocytic life cycle. However, different cellular effects were obtained depending upon periods of drug incubations. The inhibition of P. falciparum development by Taxotere should provide additional strategies to block parasite development.

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 Pf crt and Pf mdr1 genes, the Pf nhe-1 Na + /H + exchanger polymorphism plays a role in decreasing susceptibility. However, conflicting results on the link between the Pf nhe-1 gene and quinine resistance arise from field- and culture-adapted isolates. We tested the association between Pf nhe-1 , Pf crt , and Pf mdr1 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 Pf nhe-1 microsatellite sequence than culture-adapted isolates. In culture-adapted isolates but not in field isolates, mutations in the Pf crt and Pf mdr1 genes, as well as a higher number of DNNND repeats in the Pf nhe-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 Pf nhe-1 gene also harbored mutated Pf crt and Pf mdr1 genes with an apparent cumulative effect on quinine susceptibility. This study supports the involvement of the Pf nhe-1 gene in the modulation of the in vitro quinine response when associated with mutated Pf crt and Pf mdr1 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 Pf nhe-1 polymorphism and quinine susceptibility. However, we do not exclude the possibility that in particular settings, Pf nhe-1 polymorphism can be used as a molecular marker for surveillance of quinine resistance.

Marylin Torrentino-Madamet1, Lionel Almeras2, Christelle Travaillé1, Véronique Sinou1, Matthieu Pophillat3, Maya Belghazi4, Patrick Fourquet3, Yves Jammes5, Daniel Parzy11UMR-MD3, Université de la Méditerranée, Antenne IRBA de Marseille (IMTSSA, Le Pharo), 2Unité de Recherche en Biologie et Epidémiologie Parasitaires, Antenne IRBA de Marseille (IMTSSA, Le Pharo), 3Centre d'Immunologie de Marseille Luminy, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Université de la Méditerranée, 4Centre d'Analyse Protéomique de Marseille, Institut Fédératif de Recherche Jean Roche, Faculté de Médecine Nord, 5UMR-MD2, Physiologie et Physiopathologie en Conditions d'Oxygénations Extrêmes, Institut Fédératif de Recherche Jean Roche, Faculté de Médecine Nord, Marseille, FranceObjectives: 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.Keywords: Plasmodium falciparum, salicylhydroxamic acid, hyperoxia, glycolysis, proteomic

Following our search for antimalarial compounds, novel series of ferrocenic pyrrolo[1,2-a]quinoxaline derivatives 1-2 were synthesized from various substituted nitroanilines and tested for in vitro activity upon the erythrocytic development of Plasmodiumfalciparum strains with different chloroquine-resistance status. The pyrrolo[1,2-a]quinoxalines 1 were prepared in 6-8 steps through a regioselective palladium-catalyzed monoamination by coupling 4-chloropyrrolo[1,2-a]quinoxalines with 1,3-bis(aminopropyl)piperazine or -methylamine using Xantphos as the ligand. The ferrocenic bispyrrolo[1,2-a]quinoxalines 2 were prepared by reductive amination of previously described bispyrrolo[1,2-a]quinoxalines 9 with ferrocene-carboxaldehyde, by treatment with NaHB(OAc)(3). The best results were observed with ferrocenic pyrrolo[1,2-a]quinoxalines linked by a bis(3-aminopropyl)piperazine. Moreover, it was observed that a methoxy group on the pyrrolo[1,2-a]quinoxaline nucleus and no substitution on the terminal N-ferrocenylmethylamine function enhanced the pharmacological activity. Selected compounds 1b, 1f-h, 1l and 2a were tested for their ability to inhibit beta-haematin formation, the synthetic equivalent of hemozoin, by using the HPIA (heme polymerization inhibitory activity) assay. Of the tested compounds, only 2a showed a beta-haematin formation inhibition, but no inhibition of haem polymerization was observed with the other selected ferrocenic monopyrrolo[1,2-a]quinoxaline derivatives 1b, 1f-h and 1l, as the IC(50) values were superior to 10 equivalents.

OBJECTIVES The aim was to study the pharmacokinetic profile of artesunate and its metabolite dihydroartemisinin (DHA) in a pig model. METHODS Thirteen pigs received either intravenous (iv) or intramuscular (im) artesunate (60 mg), with the alternative preparation given 24 h later in an open crossover design. Five of them also received an additional intra-arterial (ia) artesunate dose (60 mg). The plasma concentrations of artesunate and DHA were determined by high-performance liquid chromatography with electrochemical detection. Population modelling was performed with NONMEM, using a two-compartment model. RESULTS Plasma concentration-time profiles were comparable to those observed in humans, with a rapid and biphasic decline for both artesunate and DHA. Following an iv bolus, artesunate had a median maximum plasma concentration (C(max)) of 13.8 microM [interquartile range (IQR), 10.4-22.1 microM], elimination half-life (t(1/2)) = 18 min (IQR, 16-22 min), total plasma clearance (CL) = 5.58 L/h/kg (IQR, 3.31-5.91 L/h/kg) and volume of distribution (V(d)) = 1.85 L/kg (IQR, 1.27-3.20 L/kg). The median C(max) value for DHA was 3.30 microM (IQR, 2.08-5.95 microM), t(1/2) = 26 min (IQR, 23-31 min), CL/Fm = 4.37 L/h/kg (IQR, 3.29-6.87 L/h/kg) and V(d)/Fm = 2.56 L/kg (IQR, 1.93-4.49 L/kg). Artesunate and DHA pharmacokinetic parameters were similar after ia administration. Following im dosing, median artesunate C(max) was 4.81 microM (IQR, 3.74-5.40 microM), t(1/2) = 18 min (IQR, 16-28 min), CL = 4.37 L/h/kg (IQR, 4.13-4.68 L/h/kg) and V(d) = 2.07 L/kg (IQR, 1.83-2.79 L/kg); the bioavailability was 100%. For DHA, median C(max) was 1.43 microM (IQR, 1.00-1.92 microM), t(1/2) = 27 min (IQR, 25-37 min), CL/Fm = 4.68 L/h/kg (IQR, 3.35-6.73 L/h/kg) and V(d)/Fm = 3.31 L/kg (IQR, 2.89-4.27 L/kg). CONCLUSIONS The pharmacokinetic properties of artesunate and DHA in pigs were similar to those reported in humans, suggesting that the swine model is suitable for determining the preclinical pharmacokinetics of artemisinin derivatives.

Artemisinin and its derivatives have been used against malaria in Vietnam since 1991 (4). An increase in clinical artemisinin resistance would be disastrous for malaria treatment. All possible indicators of this potential resistance must be monitored. The sarco/endoplasmic reticulum Ca2+-ATPase ortholog of Plasmodium falciparum (PfATP6) has been suggested to be the target of artemisinins (3). Consequently, the polymorphism of PfATP6 is being monitored by several scientific research teams (2, 6, 7, 9, 10, 15) We report here the genotyping results of PfATP6 from 98 P. falciparum field isolates collected in 2006 to 2007 in South Vietnam. Parasite samples were taken from patients (28.82 ± 12.31 years old) with uncomplicated P. falciparum infections before drug treatment. They were collected in Binh Phuoc and Dak Nong provinces in South Vietnam. Patients did not follow a chemoprophylaxis before sampling. Diagnosis was carried out by microscopic examination and confirmed by real-time PCR as previously described (14). The whole PfATP6 gene was sequenced once in both directions with five primer pairs (adapted from Jambou et al. [7]) and compared to the reference sequence of the 3D7 strain (“PFA0310c” in the genome annotation). We found a total of eight mutations (Table ​(Table1):1): four nonsynonymous (I89T, N463S, N465S, and N683K), three synonymous (N460N, I898I, and C1031C), and one double deletion leading to the loss of two asparagines (Δ463-464). Five of these have not been described previously (N460N, N463S, Δ463-464, N465S, and C1031C). All of the mutations were detected on different isolates, except for I898I, which was found alone or associated with others. Like Mugittu et al. in Tanzania (10) and Zhang et al. in China (15), we did not find either the S769N mutation or the A623E E431K double mutation, associated with reduced susceptibility to artemether (7). Previously, the N683K mutation was only found in Cambodia (2), suggesting that it may be specific to P. falciparum from South-East Asia. However, we did not detect this mutation in the South-East Asiatic strains W2 and Dd2 (both from Indochina, Malaria Research and Reference Reagent Resource Center), IMT-A4 (Vietnam), and IMT-K2 (Cambodia; data not shown). Interestingly, the N460N, N463S, N465S, and N683K mutations and the Δ463-464 double deletion are in a stretch of nine asparagines located in the interspecies variable region of PfATP6, a domain specific for Plasmodium species (8). Consequently, these modifications could be adaptive changes that might alter susceptibility to artemisinins. TABLE 1. Diversity of PfATP6 in P. falciparum samples from Vietnam Cojean et al. found the S769N mutation in an isolate from Africa that was susceptible to dihydroartemisinin (1), while Noedl et al. did not find this mutation in Cambodian samples that were less susceptible to artesunate (11). Consequently, we speculated on whether the correlation between the S769N mutation and the increased artemether 50% inhibitory concentration found in six isolates from French Guyana (7) should be regarded as a local case. Like other investigators, we did not detect any polymorphism in codon 263, described as the key amino acid for the interaction between PfATP6 and artemisinins (13). Mutations observed in our sequences and in those of previous studies (2, 6, 9) could be implicated indirectly in this interaction, in the case of association with artemisinin susceptibility. Considering the development of artemisinin combined therapies and the possible implication of PfATP6 in artemisinin resistance, the molecular variability of this gene should be carefully monitored.

Differentiation of the non-dividing trypomastigote form of Trypanosoma cruzi, the causative agent of Chagas disease, to the dividing amastigote form normally occurs in cytoplasm of infected cells. Here we show that calyculin A. a potent inhibitor of protein phosphatases 1 and 2A, induces at pH 7.5 extracellular transformation of long slender trypomastigotes to round amastigote-like forms which acquire characteristic features observed after the normal differentiation process: repositioning and structural changes of the kinetoplast, release of surface neuraminidase, and expression of amastigote-specific epitopes. Calyculin A inhibits parasite phosphatases and changes in the phosphorylation of specific proteins occur during the transformation process. As an exposure of trypomastigotes to calyculin A concentrations as low as 1 nM and for only 1-2 h is sufficient to induce transformation, the inhibition of calyculin A-sensitive phosphatase(s) appears to play a major role in initiating the trypomastigote differentiation.

The stage-dependent susceptibility of Plasmodium falciparum to a short exposure to docetaxel (Taxotere) was evaluated by subjecting ring-infected, trophozoite-infected, and schizont-infected erythrocytes to a 5-h exposure to various concentrations of the drug. The schizont stage was shown to be the most sensitive stage; an inhibition of more than 60% of parasite development was observed at 10 nM. At this drug concentration, the development of the younger ring and trophozoite forms was unaffected. The in vivo antimalarial activity of docetaxel against the development in blood of old trophozoites of a species that causes malaria in rodents, Plasmodium vinckei petteri, was evaluated in IOPS-OF1 mice. Two tests were performed: the 4-day suppressive test, as described by Peters (W. Peters, p. 145-273, in Chemotherapy, and Drug Resistance in Malaria, vol. 1, 1987), and the effects of a single injection of docetaxel after inoculation of the parasites. A single injection of docetaxel at 40 mg/kg of body weight was sufficient to reduce drastically the level of parasitemia; 90% inhibition of the development of parasites in blood was observed 5 days after drug injection. This program avoided the toxicity observed when mice were treated with four injections of docetaxel. The possibility of using a single bolus of taxoids to treat malaria infections is discussed.