Pathogenomic in silico approach identifies NSP-A and Fe-IIISBP as possible drug targets in Neisseria Meningitidis MC58 and development of pharmacophores as novel therapeutic candidates.

Meningitis creates a life-threatening clinical crisis. Moreover, the administered antibiotics result into multi-drug resistance, thereby necessitating development of alternative therapeutic strategies. This study aimed at identifying novel-drug targets in Neisseria meningitidis and therapeutic molecules which can be exploited for the treatment of meningitis. Novel targets were identified by applying a pathogenomic approach involving protein data-set mining, subtractive channel analysis and subsequent qualitative analysis comprising of in silico pharmacokinetics, molecular docking and pharmacophore generation. Pathogenomic studies revealed Neisserial Surface Protein A (NSP-A) and Iron-III-Substrate Binding Protein (Fe-IIISBP) as potential targets. Two pharmacophore models comprising of 2-(biaryl) carbapenems, efavirenz, praziquantel and pyrimethamine for NSP-A and 2-(biaryl) carbapenems, trimipramine and pyrimethamine for Fe-IIISBP, showed successful docking, followed drug-likeness criteria and generated pharmacophore model with a score of 8.08 and 8.818, respectively, which had further been docked to the target stably. Thus, our study identifies NSP-A and Fe-IIISBP as novel targets in Neisseria meningitidis for which 2-(biaryl) carbapenems, efavirenz, praziquantel, trimipramine and pyrimethamine may be employed for effective treatment of meningitis.

Glycyrrhizin-Assisted Transport of Praziquantel Anthelmintic Drug through the Lipid Membrane: An Experiment and MD Simulation.

Praziquantel (PZQ) is one of the most widespread anthelmintic drugs. However, the frequent insufficient application of PZQ after oral administration is associated with its low solubility, penetration rate, and bioavailability. In the present study, the permeation of PZQ through a 1,2-dioleoyl- sn-glycero-3-phosphocholine (DOPC) membrane was investigated to probe glycyrrhizin-assisted transport. Glycyrrhizin (or glycyrrhizic acid, GA), a natural saponin, shows the ability to enhance the therapeutic activity of various drugs when it is used as a drug delivery system. However, the molecular mechanism of this effect is still under debate. In the present study, the transport rate was measured experimentally by a parallel artificial membrane permeation assay (PAMPA) and molecular dynamics (MD) simulation with DOPC lipid bilayers. The formation of the noncovalent supramolecular complex of PZQ with disodium salt of GA (Na2GA) in an aqueous solution was proved by the NMR relaxation technique. PAMPA experiments show a strong increase in the amount of the penetrating praziquantel molecules in comparison with a saturated aqueous solution of pure drug used as a control. MD simulation of PZQ penetration through the bilayer demonstrates an increase in permeability into the membrane in the presence of a glycyrrhizin molecule. A decrease in the free energy barrier in the middle of the lipid bilayer was obtained, associated with the hydrogen bond between PZQ and GA. Also, GA reduces the local bilayer surface resistance to penetration of PZQ by rearranging the surface lipid headgroups. This study clarifies the mechanism of increasing the drug's bioavailability in the presence of glycyrrhizin.

The effect of ketoconazole on praziquantel pharmacokinetics and the role of CYP3A4 in the formation of X-OH-praziquantel and not 4-OH-praziquantel.

AIM: The study sought to determine the effect of ketoconazole (KTZ) on the pharmacokinetics of praziquantel (PZQ) and on the formation of its major hydroxylated metabolites, cis- and trans-4-OH-PZQ, and X-OH-PZQ in healthy subjects. METHODS: Two treatments were evaluated by single-dose PK studies; the reference treatment was a 20 mg/kg dose of praziquantel given alone. The test treatment was a 20 mg/kg dose of praziquantel given in combination with 200 mg of ketoconazole. The study had a balanced and randomised cross-over design. Serial blood samples were collected between 0 and 12 h after each drug administration. PZQ, and cis- and trans-4-OH-PZQ and X-OH-PZQ concentrations in plasma were determined by LC-MS. A non-compartmental approach was used for pharmacokinetic analysis. Data were analysed using ANOVA and assessment of the 90% confidence interval of the geometric means of the log-transformed PK parameters obtained for each treatment. RESULTS: The pharmacokinetics of PZQ following the two treatments, PZQ alone and PZQ + KTZ, were not equivalent based on the assessment of the 90% CI of the geometric mean ratios of the AUC and Cmax (α = 0.05). The geometric mean ratios of the AUC and Cmax were found to be 176.8% and 227% respectively. The 90% CI of the AUC and Cmax were found to be 129.8%-239.8% and 151.4%-341.4% respectively. The AUC of PZQ was increased by 75% with KTZ co-administration (3516 vs 6172 ng h/ml) (p < 0.01). Meanwhile, the mean AUC of trans-4-OH-PZQ increased by 67% (61,749 ng h/ml vs 103,105 ng h/ml) (p < 0.01). X-OH-PZQ levels were reduced by about 57% (semi-quantified as 7311 ng h/ml vs 3109 ng h/ml by using trans-4-OH as standards) (p < 0.01) with KTZ co-administration. CONCLUSIONS: The relative bioavailability of praziquantel was increased by concomitant KTZ administration. KTZ preferentially inhibited the formation of X-OH-PZQ rather than 4-OH-PZQ, confirming in vitro data which implicates CYP3A4 in the formation of X-OH-PZQ rather than 4-OH-PZQ. The 4-hydroxylation of PZQ was shown to be the major metabolic pathway of PZQ, as evidenced by larger quantities of 4-OH-PZQ produced, thus explaining the modest albeit significant effect of ketoconazole on PZQ pharmacokinetics.

Characterizing the Biochemical Response to Schistosoma mansoni Infection and Treatment with Praziquantel in Preschool and School Aged Children.

Schistosomiasis is a widespread chronic neglected tropical disease prevalent mostly in children in under-resourced rural areas. Its pathological effects have been clinically characterized, yet the molecular-level effects are understudied. In this study, the biochemical effects of Schistosoma mansoni infection and praziquantel treatment were studied in 130 preschool aged and 159 school aged infected children and 11 noninfected children in Azaguié, Côte d'Ivoire. Urine samples were collected prior to receiving 20, 40, or 60 mg/kg of praziquantel or a placebo, as well as 24 h post-treatment, and at the 3-week follow up. Urinary metabolic phenotypes were measured using 1H NMR spectroscopy, and metabolic variation associated with S. mansoni infection and praziquantel administration was identified using multivariate statistical techniques. Discriminatory metabolic signatures were detected between heavily infected and noninfected children at baseline as well as according to the dose of praziquantel administered 24 h post treatment. These signatures were primarily associated with the metabolic activity of the gut microbiota, gut health and growth biomarkers and energy and liver metabolism. These analyses provide insights into the metabolic phenotype of schistosomiasis and treatment with praziquantel in two important demographics.

Praziquantel for Schistosomiasis: Single-Drug Metabolism Revisited, Mode of Action, and Resistance.

Schistosomiasis, a major neglected tropical disease, affects more than 250 million people worldwide. Treatment of schistosomiasis has relied on the anthelmintic drug praziquantel (PZQ) for more than a generation. PZQ is the drug of choice for the treatment of schistosomiasis; it is effective against all major forms of schistosomiasis, although it is less active against juvenile than mature parasites. A pyrazino-isoquinoline derivative, PZQ is not considered to be toxic and generally causes few or transient, mild side effects. Increasingly, mass drug administration targeting populations in sub-Saharan Africa where schistosomiasis is endemic has led to the appearance of reduced efficacy of PZQ, which portends the selection of drug-resistant forms of these pathogens. The synthesis of improved derivatives of PZQ is attracting attention, e.g., in the (i) synthesis of drug analogues, (ii) rational design of pharmacophores, and (iii) discovery of new compounds from large-scale screening programs. This article reviews reports from the 1970s to the present on the metabolism and mechanism of action of PZQ and its derivatives against schistosomes.

Design and optimization of thermosensitive nanoemulsion hydrogel for sustained-release of praziquantel.

OBJECTIVE: This work aimed to develop an alternative sustained-release thermosensitive praziquantel-loaded nanoemulsion (PZQ-NE) hydrogel for better schistosomiasis treatment. SIGNIFICANCE: PZQ-NE-dispersed chitosan/glycerol 2-phosphate disodium/HPMC (NE/CS/ß-GP/HMPC) hydrogel was successfully prepared to improve bioavailability of PZQ. METHODS: Solubility tests and pseudo-ternary phase diagrams were applied to screen optimal oils, surfactants and co-surfactants of NE. The hydrogels were characterized for gelling time, surface exudates, rheological properties and in vitro drug release. Formulation optimization of NE/CS/ß-GP/HMPC hydrogel was conducted by Box-Behnken experimental design combined with response surface methodology. In vitro cytotoxicity of hydrogel was studied by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide method. The sustained-release property of PZQ in NE and optimized hydrogel was evaluated by pharmacokinetic study in rabbits. RESULTS: The formulation of PZQ-NE consisted of mass ratio of 12.5% capryol 90 containing PZQ (160 mg/g), 40% cremophor RH 40/tween 20 and transcutol HP (S/CoS = 2:1), 47.5% deionized water. PZQ releasing from NE/CS/ß-GP/HMPC hydrogels was best fitted to Higuchi model and governed by diffusion. Rheological investigation evidenced the themosensitive gelation of different hydrogel systems and their gel-like character at 37 °C. The optimized hydrogel formulation consisted of HPMC solution (103.69 mg/g), 3.03% (w/v) chitosan and 14.1% (w/v) ß-GP showed no cytotoxicity when the addition of NE was no more than 100 mg/g. Pharmacokinetic parameters indicated that NE/CS/ß-GP/HMPC hydrogel can significantly slow down drug elimination, prolong mean residence time and improve bioavailability of PZQ. CONCLUSIONS: NE/CS/ß-GP/HMPC hydrogel possessed sustained-release property and could be an alternative antischistosomal drug delivery system with improved therapeutic effect.

Praziquantel - 50 Years of Research.

Investigations on praziquantel (PZQ) started fifty years ago by a cooperation between Bayer AG and Merck KGaA. Until today PZQ is the drug of choice for schistosomiasis in human medicine and used in many combinations with antinematode drugs in veterinary medicine. The Sm.TRPMPZQ , a Ca2+ -permeable transient receptor potential (TRP) channel, has been discovered as primary target of PZQ during the last decade. Furthermore, there is a short overview of routes of large-scale synthesis of racemic and pure (R)-PZQ. Until now racemic PZQ is used in veterinary and human medicine. In 2012 the Pediatric Praziquantel Consortium started PZQ chemistry and process development of pure (R)-PZQ for human application. It is hoped that (R)-PZQ will become available for pediatric use soon. The knowledge of the binding pocket of PZQ in Sm.TRPMPZQ allows to design synthesis of PZQ-derivatives of the next generation for a target-site directed screening. A similar screening should also be started for Fasciola hepatica TRPMPZQ .

Human umbilical cord blood mesenchymal stem cells as a potential therapy for schistosomal hepatic fibrosis: an experimental study.

The objective of our study was to assess the effect of human umbilical cord blood (HUCB) mesenchymal stem cells (MSCs) transplantation on schistosomal hepatic fibrosis in mice. The study animals were divided into three groups. Group I is a control group, where the mice were infected with Schistosoma mansoni cercariae and remained untreated. The mice of the other two groups were infected and treated with either praziquantel (Group II) or HUCB-MSCs (Group III). Liver function tests, as well as histopathological evaluation of liver fibrosis using hematoxylin and eosin and Masson's trichrome stains, were performed. Additionally, an immunohistochemical study was carried out using anti-glial fibrillary acidic protein (GFAP) in hepatic stellate cells. Compared to the control group, the treated (praziquantel and MSCs) groups showed a substantial improvement, with a significant difference regarding the histopathological evaluation of liver fibrosis in the MSCs-treated group. In conclusion, MSCs could be a promising and efficient cell therapy for liver fibrosis.

Simultaneous determination of praziquantel and its main metabolites in the tissues of black goats and their residue depletion.

Praziquantel (PZQ) is a pyrazino-isoquinoline compound with broad spectrum of activity against parasitic trematodes and cestodes, and a key veterinary drug in the parasitic disease control field. However, PZQ residues caused by non-conforming or excessive use in food-producing animals may pose a serious threat to human health. Herein, a simple, sensitive and reproducible LC-MS/MS method was developed for the simultaneous determination of praziquantel and trans- and cis-4-hydroxypraziquantel in black goat tissues to guide the reasonable use of PZQ. The mean recoveries for three target analytes were 71.2 ∼ 117.6%, and the limits of quantification were 1.0 µg/kg. Twenty-five healthy black goats were administered a single dose of praziquantel tablets at a dose of 35 mg/kg of body weight for residue elimination study, The results revealed that praziquantel and 4-hydroxypraziquantel were rapidly depleted in goat tissues and the elimination half-lives did not exceed 1 day in all tissues except for muscle and lung. It provides guidance for the establishment of maximum residue limit of praziquantel in goat.

Praziquantel: An update on the mechanism of its action against schistosomiasis and new therapeutic perspectives.

Praziquantel (PZQ) is the drug of choice for the treatment of all forms of schistosomiasis, although its mechanisms of action are not completely understood. PZQ acts largely on adult worms. This narrative literature review describes what is known about the mechanisms of action of PZQ against schistosomes from in vitro and in vivo studies and highlights the molecular targets in parasites and immune responses induced in definitive hosts by this drug. Moreover, new therapeutic uses of PZQ are discussed. Studies have demonstrated that in addition to impacting voltage-operated Ca2 + channels, PZQ may interact with other schistosome molecules, such as myosin regulatory light chain, glutathione S-transferase, and transient receptor potential channels. Following PZQ administration, increased T regulatory type 1 (Tr1) cell differentiation and decreased inflammation were observed, indicating that PZQ promotes immunoregulatory pathways. Although PZQ is widely used in mass drug administration schemes, the existence of resistant parasites has not been proven; however, it is a concern that should be constantly investigated in human populations. In addition, we discuss studies that evaluate health applications of PZQ (other than helminth infection), such as its effect in cancer therapy and its adjuvant action in vaccines against viruses.

Schistosome TRPML channels play a role in neuromuscular activity and tegumental integrity.

Schistosomiasis is a neglected tropical disease caused by parasitic flatworms of the genus Schistosoma. Mono-therapeutic treatment of this disease with the drug praziquantel, presents challenges such as inactivity against immature worms and inability to prevent reinfection. Importantly, ion channels are important targets for many current anthelmintics. Transient receptor potential (TRP) channels are important mediators of sensory signals with marked effects on cellular functions and signaling pathways. TRPML channels are a class of Ca2+-permeable TRP channels expressed on endolysosomal membranes. They regulate lysosomal function and trafficking, among other functions. Schistosoma mansoni is predicted to have a single TRPML gene (SmTRPML) with two splice variants differing by 12 amino acids. This study focuses on exploring the physiological properties of SmTRPML channels to better understand their role in schistosomes. In mammalian cells expressing SmTRPML, TRPML activators elicit a rise in intracellular Ca2+. In these cells, SmTRPML localizes both to lysosomes and the plasma membrane. These same TRPML activators elicit an increase in adult worm motility that is dependent on SmTRPML expression, indicating a role for these channels in parasite neuromuscular activity. Suppression of SmTRPML in adult worms, or exposure of adult worms to TRPML inhibitors, results in tegumental vacuolations, balloon-like surface exudates, and membrane blebbing, similar to that found following TRPML loss in other organisms. Together, these findings indicate that SmTRPML may regulate the function of the schistosome endolysosomal system. Further, the role of SmTRPML in neuromuscular activity and in parasite tegumental integrity establishes this channel as a candidate anti-schistosome drug target.

Mechanism of praziquantel action at a parasitic flatworm ion channel.

Praziquantel (PZQ) is an essential medicine for treating parasitic flatworm infections such as schistosomiasis, which afflicts over 250 million people. However, PZQ is not universally effective, lacking activity against liver flukes of the Fasciola genus. The reason for this insensitivity is unclear, as the mechanism of PZQ action is unknown. Here, we use ligand- and target-based methods to demonstrate that PZQ activates a transient receptor potential melastatin ion channel (TRPMPZQ) in schistosomes by engaging a hydrophobic ligand binding pocket within the voltage sensor­like domain of the channel to cause calcium entry and worm paralysis. PZQ activates TRPMPZQ homologs in other PZQ-sensitive flukes, but not Fasciola hepatica. However, a single amino acid change in the F. hepatica TRPMPZQ binding pocket, to mimic schistosome TRPMPZQ, confers PZQ sensitivity. After decades of clinical use, the molecular basis of PZQ action at a druggable TRP channel is resolved.

Investigation on the uptake of ciprofloxacin, chloramphenicol and praziquantel by button mushrooms.

Button mushrooms are widely produced edible basidiomycetes. Commercially, they are cultivated on substrates containing fermented horse manure and chicken feces. Since pharmacologically active substances (PAS) might be introduced into the food chain via animal treatment, their residues may be present in manure used for mushroom growth. Previous studies in plants have demonstrated an uptake of PAS from the agricultural environment. The present study was performed to investigate the presence of PAS in button mushrooms. For analysis, a multi-analyte method for the detection of 21 selected PAS using liquid chromatography tandem-mass spectrometry was developed, successfully validated and applied to commercially available button mushrooms. Traces of chloramphenicol were detected in two of 20 samples. Additionally, in a mushroom cultivation experiment an uptake of ciprofloxacin, chloramphenicol and praziquantel was conducted. Throughout the whole experiment, praziquantel was present in quantifiable amounts in mushrooms and in high quantities in soil.

Selective Depletion of Chiral 4-Hydroxypraziquantel Metabolites in Three Types of Aquaculture Fish by LC-MS/MS.

The rise of aquaculture has necessitated the use of antibiotics and other agents in these densely populated and often closed environments. An enantioselective depletion study of four chiral 4-hydroxypraziquantel metabolites (4-OH-PZQ) in perch, tilapia, and ricefield-eel muscles was done using a simple, sensitive, and reliable liquid-chromatography-tandem-mass-spectrometry (LC-MS/MS) method. These metabolites result from the uptake of the drug praziquantel (PZQ), which is used in aquaculture. A novel strategy of using a C18 short column in tandem with a chiral hydroxypropyl-ß-cyclodextrin superficially porous particle (CDShell-RSP) column produced the optimal separation for both the enantiomers and diastereoisomers of 4-OH-PZQ. The method was linear over the concentration range of 1-250 µg L-1 ( r2 ≥ 0.99) for R- trans-4-OH-PZQ, S- trans-4-OH-PZQ, R- cis-4-OH-PZQ, and S- cis-4-OH-PZQ. The average recoveries of four analytes at three spiked levels of 1, 10, and 100 µg kg-1 ranged from 84.2 to 93.1%, and the intraday and interday relative standard deviations were less than 7.9%. The limits of quantification of the four 4-OH-PZQ metabolites in perch-, tilapia-, and ricefield-eel-muscle matrices were 1.0 µg kg-1. The method was utilized to monitor the depletion of trans- and cis-4-OH-PZQ enantiomers in perch, tilapia, and ricefield-eel muscle following oral administration (medicine bath for ricefield eel). Species-specific differences in the PZQ metabolism of isomers were observed. In addition, new metabolites of PZQ were observed: 3-hydroxypraziquantel diastereomers.

Identification of degradation products of praziquantel during the mechanochemical activation.

Praziquantel (PZQ) is an inexpensive, low toxicity BCS II class anthelmintic drug used for the treatment of neglected tropical diseases. In earlier papers a mechanochemical activation has been used to induce physical transformations on the drug which would ameliorate its solubility and hence its bioavailability and a systematic study of the effects of varying temperature, frequency and time of milling on drug melting enthalpy and drug recovery was given. In this communication, the focus is on the degradation products that are formed during this mechanical treatment of Praziquantel. In the cogrinding process with povidone and crospovidone several degradation products are formed. Different degradation products are formed, which depend on the type of polymer rather than the process conditions. Two of the most prominent degradation products were identified and their structure proposed on the basis of information obtained from GC-MS, UPLC-MS and 1H NMR techniques.

The tegumental allergen-like proteins of Schistosoma mansoni: A biochemical study of SmTAL4-TAL13.

Schistosoma mansoni, like other trematodes, expresses a number of unusual calcium binding proteins which consist of an EF-hand domain joined to a dynein light chain-like (DLC-like) domain by a flexible linker. These proteins have been implicated in host immune responses and drug binding. Three members of this protein family from S. mansoni (SmTAL1, SmTAL2 and SmTAL3) have been well characterised biochemically. Here we characterise the remaining family members from this species (SmTAL4-13). All of these proteins form homodimers and all except SmTAL5 bind to calcium and manganese ions. SmTAL9, 10 and 11 also bind to magnesium ions. The antischistosomal drug, praziquantel interacts with SmTAL4, 5 and 8. Some family members also bind to calmodulin antagonists such as chlorpromazine and trifluoperazine. Molecular modelling suggests that all ten proteins adopt similar overall folds with the EF-hand and DLC-like domains folding discretely. Bioinformatics analyses suggest that the proteins may fall into two main categories: (i) those which bind calcium ions reversibly at the second EF-hand and may play a role in signalling (SmTAL1, 2, 8 and 12) and (ii) those which bind calcium ions at the first EF-hand and may play either signalling or structural roles (SmTAL7, 9, 10 and 13). The remaining proteins include those which do not bind calcium ions (SmTAL3 and 5) and three other proteins (SmTAL4, 6 and 11). The roles of these proteins are less clear, but they may also have structural roles.

Praziquantel binds Schistosoma mansoni adult worm actin.

Praziquantel (PZQ) is widely used for the treatment of schistosomiasis. It induces worm muscle contractions and tegumental disruption, followed by exposure of parasite surface membrane antigens to the host immunological defence mechanisms. It may be assumed that PZQ, like cholesterol, is too hydrophobic to traverse the schistosome outer lipid bilayers by passive diffusion and probably requires binding to a surface membrane protein carrier for distribution throughout the worm. However, the PZQ binding site on the schistosome surface and the precise mechanism of action are not yet known. The Claisen condensation reaction was used to bind PZQ on cellulose acetate membranes. Triton-insoluble surface membrane antigens of Schistosoma mansoni adult worms were allowed to bind to the PZQ column. The identity of the bound molecules was examined by amino acid microsequencing and immunogenicity in outbred and inbred mice. The PZQ column was found to bind molecules of 45 kDa selectively from the Triton-insoluble surface membrane antigens of S. mansoni adult worms. Amino acid microsequencing revealed that the 45 kDa species consist predominantly of schistosome actin. This finding was supported by the poor immunogenicity of the 45 kDa molecules in outbred and inbred mice. PZQ was also shown to bind bovine actin but not bovine serum albumin. However, pre-incubation with bovine actin did not impair the effect of PZQ on adult worms in vitro. The study represents an attempt to understand how PZQ distributes across schistosome outer lipid bilayers.

Drug-transporter mediated interactions between anthelminthic and antiretroviral drugs across the Caco-2 cell monolayers.

BACKGROUND: Drug interactions between antiretroviral drugs (ARVs) and anthelminthic drugs, ivermectin (IVM) and praziquantel (PZQ) were assessed by investigating their permeation through the Caco-2 cell monolayers in a transwell. The impact of anthelminthics on the transport of ARVs was determined by assessing the apical to basolateral (AP → BL) [passive] and basolateral to apical (BL → AP) [efflux] directions alone, and in presence of an anthelminthic. The reverse was conducted for the assessment of the influence of ARVs on anthelminthics. METHODS: Samples from the AP and BL compartments were taken at 60, 120, 180 and 240 min and quantified either by HPLC or radiolabeled assay using a liquid scintillating counter for the respective drugs. Transepithelial resistance (TEER) was used to assess the integrity of the monolayers. The amount of compound transported per second (apparent permeability, Papp) was calculated for both AP to BL (PappAtoB), and BL to AP (PappBtoA) movements. Samples collected after 60 min were used to determine the efflux ratio (ER), quotient of secretory permeability and absorptive permeability (PappBL-AP/PappAP-BL). The reverse, (PappAP-BL/PappBL-AP) constituted the uptake ratio. The impact of SQV, EFV and NVP on the transport of both IVM and PZQ were investigated. The effect of LPV on the transport of IVM was also determined. The influence of IVM on the transport of SQV, NVP, LPV and EFV; as well as the effect PZQ on the transport of SQV of was also investigated, and a two-tailed p value of <0.05 was considered significant. RESULTS: IVM significantly inhibited the efflux transport (BL → AP movement) of LPV (ER; 6.7 vs. 0.8, p = 0.0038) and SQV (ER; 3.1 vs. 1.2 p = 0.00328); and increased the efflux transport of EFV (ER; 0.7 vs. 0.9, p = 0.031) suggesting the possibility of drug transporter mediated interactions between the two drugs. NVP increased the efflux transport of IVM (ER; 0.8 vs. 1.8, p = 0.0094). CONCLUSIONS: The study provides in vitro evidence of potential interactions between IVM, an anthelminthic drug with antiretroviral drugs; LPV, SQV, NVP and EFV. Further investigations should be conducted to investigate the possibility of in vivo interactions.

Study of praziquantel phytoremediation and transformation and its removal in constructed wetland.

Accumulation and/or degradation of Praziquantel (PZQ) in plants were determined using Phragmites australis, both suspension cultures and in vitro cultivated plants. In case of initial PZQ concentration 20mgL-1, 90% was removed from liquid media within 21days. The accumulated PZQ was partly metabolized, twenty one compounds being identified, products of both Phase I and II of detoxification metabolism. Laboratory results were confirmed in real scale using the constructed wetland (CW), where PZQ (500mg in total) was completely removed until the first purification pond. This result offers a promising possibility to use CW for PZQ removal from agricultural as well as domestic waste-waters.

In vitro and in vivo activity of R- and S- praziquantel enantiomers and the main human metabolite trans-4-hydroxy-praziquantel against Schistosoma haematobium.

BACKGROUND: Praziquantel (PZQ) is the mainstay of schistosomiasis control and has been successfully used for decades. However, its mechanism of action is not fully understood. While the majority of studies have been conducted on Schistosoma mansoni, it is not known which enantiomer, R- or S-praziquantel (R-/S-PZQ), is responsible for the activity on Schistosoma haematobium. METHODS: In vitro and in vivo studies were conducted to evaluate the activity of R- and S-PZQ, racemic PZQ and the main human metabolite, namely trans-4-OH-PZQ, on S. haematobium. IC50 values on adult S. haematobium were determined in vitro. Dose-response relationship studies were performed in golden Syrian hamsters, harbouring a chronic S. haematobium infection. RESULTS: R-PZQ displayed the highest activity against adult worms in vitro, revealing an IC50 of 0.007 µg/ml at 4 h and 0.01 µg/ml at 72 h. In contrast, S-PZQ was 501× less active (eudysmic ratio at 4 h), with an IC50 of 3.51 and 3.40 µg/ml (4 and 72 h, respectively). Racemic PZQ and trans-4-OH-PZQ resulted in an IC50 of 0.03 µg/ml and 1.47 µg/ml both at 4 and 72 h, respectively. In vivo, R-PZQ was the most potent drug with worm burden reductions (WBRs) of 98.5, 75.6 and 73.3% at 125.0, 62.5 and 31.0 mg/kg, respectively. A single oral dose of 250.0 mg/kg PZQ resulted in a WBR of 99.3%. S-PZQ was highly active in vivo at 250.0 and 500.0 mg/kg with WBRs of 83.0 and 94.1%, respectively. The lowest tested dose of S-PZQ, 125.0 mg/kg, showed moderate activity (WBR of 46.7%). The calculated ED50 for R- and S-PZQ were 24.7 and 127.6 mg/kg, respectively, with a corresponding eudysmic ratio of 5.17. CONCLUSION: Our data support the theory of R-PZQ driving the antischistosomal activity. Interestingly, also S-PZQ proved to possess a significant activity towards S. haematobium, particularly in vivo.