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Andrew Hemphill - One of the best experts on this subject based on the ideXlab platform.
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Repurposing of an old drug: In vitro and in vivo efficacies of Buparvaquone against Echinococcus multilocularis.
International journal for parasitology. Drugs and drug resistance, 2018Co-Authors: Reto Rufener, Andrew Hemphill, Dominic Ritler, Luca Dick, Laura D'ascoli, Amani Hizem, Timothy N. C. Wells, Britta Lundström-stadelmannAbstract:The metacestode stage of the fox tapeworm Echinococcus multilocularis causes the lethal disease alveolar echinococcosis. Current chemotherapeutic treatment options are based on benzimidazoles (albendazole and mebendazole), which are insufficient and hence alternative drugs are needed. In this study, we screened the 400 compounds of the Medicines for Malaria Venture (MMV) Pathogen Box against E. multilocularis metacestodes. For the screen, we employed the phosphoglucose isomerase (PGI) assay which assesses drug-induced damage on metacestodes, and identified ten new compounds with activity against the parasite. The anti-theilerial drug MMV689480 (Buparvaquone) and MMV671636 (ELQ-400) were the most promising compounds, with an IC50 of 2.87 μM and 0.02 μM respectively against in vitro cultured E. multilocularis metacestodes. Both drugs suggested a therapeutic window based on their cytotoxicity against mammalian cells. Transmission electron microscopy revealed that treatment with Buparvaquone impaired parasite mitochondria early on and additional tests showed that Buparvaquone had a reduced activity under anaerobic conditions. Furthermore, we established a system to assess mitochondrial respiration in isolated E. multilocularis cells in real time using the Seahorse XFp Analyzer and demonstrated inhibition of the cytochrome bc1 complex by Buparvaquone. Mice with secondary alveolar echinococcosis were treated with Buparvaquone (100 mg/kg per dose, three doses per week, four weeks of treatment), but the drug failed to reduce the parasite burden in vivo. Future studies will reveal whether improved formulations of Buparvaquone could increase its effectivity.
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Repurposing of an old drug: In vitro and in vivo efficacies of Buparvaquone against Echinococcus multilocularis
Elsevier, 2018Co-Authors: Reto Rufener, Andrew Hemphill, Dominic Ritler, Luca Dick, Laura D'ascoli, Amani Hizem, Timothy N. C. Wells, Britta Lundström-stadelmannAbstract:The metacestode stage of the fox tapeworm Echinococcus multilocularis causes the lethal disease alveolar echinococcosis. Current chemotherapeutic treatment options are based on benzimidazoles (albendazole and mebendazole), which are insufficient and hence alternative drugs are needed. In this study, we screened the 400 compounds of the Medicines for Malaria Venture (MMV) Pathogen Box against E. multilocularis metacestodes. For the screen, we employed the phosphoglucose isomerase (PGI) assay which assesses drug-induced damage on metacestodes, and identified ten new compounds with activity against the parasite. The anti-theilerial drug MMV689480 (Buparvaquone) and MMV671636 (ELQ-400) were the most promising compounds, with an IC50 of 2.87 μM and 0.02 μM respectively against in vitro cultured E. multilocularis metacestodes. Both drugs suggested a therapeutic window based on their cytotoxicity against mammalian cells. Transmission electron microscopy revealed that treatment with Buparvaquone impaired parasite mitochondria early on and additional tests showed that Buparvaquone had a reduced activity under anaerobic conditions. Furthermore, we established a system to assess mitochondrial respiration in isolated E. multilocularis cells in real time using the Seahorse XFp Analyzer and demonstrated inhibition of the cytochrome bc1 complex by Buparvaquone. Mice with secondary alveolar echinococcosis were treated with Buparvaquone (100 mg/kg per dose, three doses per week, four weeks of treatment), but the drug failed to reduce the parasite burden in vivo. Future studies will reveal whether improved formulations of Buparvaquone could increase its effectivity. Keywords: Pathogen box, MMV671636, MMV689480, Drug screening, Seahorse XFp analyzer, Cytochrome bc1 comple
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Repurposing of antiparasitic drugs: the hydroxy-naphthoquinone Buparvaquone inhibits vertical transmission in the pregnant neosporosis mouse model
Veterinary Research, 2016Co-Authors: Joachim Müller, Richard K. Haynes, Adriana Aguado-martínez, Vera Manser, Ho Ning Wong, Andrew HemphillAbstract:The three anti-malarial drugs artemiside, artemisone, and mefloquine, and the naphthoquinone Buparvaquone known to be active against theileriosis in cattle and Leishmania infections in rodents, were assessed for activity against Neospora caninum infection. All four compounds inhibited the proliferation of N. caninum tachyzoites in vitro with IC_50 in the sub-micromolar range, but artemisone and Buparvaquone were most effective (IC_50 = 3 and 4.9 nM, respectively). However, in a neosporosis mouse model for cerebral infection comprising Balb/c mice experimentally infected with the virulent isolate Nc-Spain7, the three anti-malarial compounds failed to exhibit any activity, since treatment did not reduce the parasite burden in brains and lungs compared to untreated controls. Thus, these compounds were not further evaluated in pregnant mice. On the other hand, Buparvaquone, shown earlier to be effective in reducing the parasite load in the lungs in an acute neosporosis disease model, was further assessed in the pregnant mouse model. Buparvaquone efficiently inhibited vertical transmission in Balb/c mice experimentally infected at day 7 of pregnancy, reduced clinical signs in the pups, but had no effect on cerebral infection in the dams. This demonstrates proof-of-concept that drug repurposing may lead to the discovery of an effective compound against neosporosis that can protect offspring from vertical transmission and disease.
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Buparvaquone is active against neospora caninum in vitro and in experimentally infected mice
International Journal for Parasitology-Drugs and Drug Resistance, 2015Co-Authors: J Muller, Vera Manser, Adriana Aguadomartinez, Vreni Balmer, Pablo Winzer, Dominic Ritler, Isabel Hostettler, David Arranzsolis, Luis Miguel Ortegamora, Andrew HemphillAbstract:The naphthoquinone Buparvaquone is currently the only drug used against theileriosis. Here, the effects of Buparvaquone were investigated in vitro and in an experimental mouse model for Neospora caninum infection. In 4-day proliferation assays, Buparvaquone efficiently inhibited N. caninum tachyzoite replication (IC50 = 4.9 nM; IC100 = 100 nM). However, in the long term tachyzoites adapted and resumed proliferation in the presence of 100 nM Buparvaquone after 20 days of cultivation. Parasiticidal activity was noted after 9 days of culture in 0.5 µM or 6 days in 1 µM Buparvaquone. TEM of N. caninum infected fibroblasts treated with 1 µM Buparvaquone showed that the drug acted rather slowly, and ultrastructural changes were evident only after 3–5 days of treatment, including severe alterations in the parasite cytoplasm, changes in the composition of the parasitophorous vacuole matrix and a diminished integrity of the vacuole membrane. Treatment of N. caninum infected mice with Buparvaquone (100 mg/kg) either by intraperitoneal injection or gavage prevented neosporosis symptoms in 4 out of 6 mice in the intraperitoneally treated group, and in 6 out of 7 mice in the group receiving oral treatment. In the corresponding controls, all 6 mice injected intraperitoneally with corn oil alone died of acute neosporosis, and 4 out of 6 mice died in the orally treated control group. Assessment of infection intensities in the treatment groups showed that, compared to the drug treated groups, the controls showed a significantly higher parasite load in the lungs while cerebral parasite load was higher in the Buparvaquone-treated groups. Thus, although Buparvaquone did not eliminate the parasites infecting the CNS, the drug represents an interesting lead with the potential to eliminate, or at least diminish, fetal infection during pregnancy.
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a quantitative reverse transcriptase pcr assay for the assessment of drug activities against intracellular theileria annulata schizonts
International Journal for Parasitology-Drugs and Drug Resistance, 2014Co-Authors: Isabel Hostettler, Richard K. Haynes, J Muller, Chad E Stephens, Andrew HemphillAbstract:Intracellular schizonts of the apicomplexans Theileria annulata and Theileria parva immortalize bovine leucocytes thereby causing fatal immunoproliferative diseases. Buparvaquone, a hydroxynaphthoquinone related to parvaquone, is the only drug available against Theileria. The drug is only effective at the onset of infection and emerging resistance underlines the need for identifying alternative compounds. Current drug assays employ monitoring of proliferation of infected cells, with apoptosis of the infected host cell as a read-out, but it is often unclear whether active compounds directly impair the viability of the parasite or primarily induce host cell death. We here report on the development of a quantitative reverse transcriptase real time PCR method based on two Theileria genes, tasp and tap104, which are both expressed in schizonts. Upon in vitro treatment of T. annulata infected bovine monocytes with Buparvaquone, TaSP and Tap104 mRNA expression levels significantly decreased in relation to host cell actin already within 4 h of drug exposure, while significant differences in host cell proliferation were detectable only after 48–72 h. TEM revealed marked alterations of the schizont ultrastructure already after 2 h of Buparvaquone treatment, while the host cell remained unaffected. Expression of TaSP and Tap104 proteins showed a marked decrease only after 24 h. Therefore, the analysis of expression levels of mRNA coding for TaSP and Tap104 allows to directly measuring impairment of parasite viability. We subsequently applied this method using a series of compounds affecting different targets in other apicomplexan parasites, and show that monitoring of TaSP- and Tap104 mRNA levels constitutes a suitable tool for anti-theilerial drug development.
Bashir Salim - One of the best experts on this subject based on the ideXlab platform.
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mutations in the tapin1 peptidyl prolyl isomerase gene in theileria annulata parasites isolated in sudan
International Journal for Parasitology-Drugs and Drug Resistance, 2019Co-Authors: Bashir Salim, Elisha Chatanga, Guillaume Jannot, Ehab Mossaad, Ryo Nakao, Jonathan B WeitzmanAbstract:Abstract The tick-borne parasite Theileria annulata is the causative agent of tropical theileriosis or Mediterranean theileriosis. Infection of bovine leukocytes by the obligate intracellular parasites induces proliferative and invasive phenotypes associated with activated signaling pathways. The transformed phenotypes of infected cells are reversible by treatment with the theilericidal drug Buparvaquone. Recent reports of resistance to Buparvaquone in Africa and Asia highlight the need to investigate the mechanisms and prevalence of drug resistance. We screened 67 T. annulata isolates from Sudan to investigate mutations in the T. annulata prolyl isomerase I gene (TaPIN1). The secreted TaPin1 interacts with host proteins to induce pathways driving oncogenic transformation and metabolic reprogramming. We found an Alanine-to-Proline mutation at position 53 (A53P) in the catalytic loop that was previously found in Tunisian drug-resistant samples. This is the first study reporting independent confirmation of the A53P mutation in geographically isolated samples. We found several additional mutations in the predicted N-terminal signal peptide that might affect TaPin1 processing or targeting. We found that many parasites also share mutations in both the TaPIN1 and the cytochrome b genes, suggesting that these two genes represent important biomarkers to follow the spread of resistance in Africa, the Middle East and Asia.
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evidence of multiple point mutations in theileria annulata cytochrome b gene incriminated in Buparvaquone treatment failure
Acta Tropica, 2019Co-Authors: Bashir Salim, Elisha Chatanga, Ryo Nakao, Ehab Mosssad, Hazem Abdo Abubaker, Sondos Amin Alnour, Ken KatakuraAbstract:Abstract Drug resistance is one of the emerging and re-emerging epidemics affecting both veterinary and public health sectors. Buparvaquone provides the most satisfactory means in the treatment of bovine tropical theileriosis. However, recently there has been widespread reports of development of resistance of Theileria annulata to Buparvaquone. To investigate the situation in Sudan where bovine tropical theileriosis is endemic, fifty blood samples from T. annulata-positive cattle. were used for DNA extraction, PCR and cytochrome b gene nucleotide sequencing. Analysis of the two Buparvaquone binding site regions Q01 (130–148) and Q02 (244–266), revealed three non- synonymous mutations at codon 146; alanine (GCT) to threonine (ACT) within the Q01 region across all 50 isolates and the other mutation at codon 129; serine (AGC) to glycine (GGC) in 18 isolates which is very close to the Q01 binding site. However, we documented another mutation at position 227; valine (GTG) to methionine (ATG) close to the close to the Q02 binding site, in three isolates with mutation at codon 129. We concluded that this study has provided evidence of point mutations in the cytochrome b gene of T. annulata that might be associated with Buparvaquone treatment failure in Sudan.
Moez Mhadhbi - One of the best experts on this subject based on the ideXlab platform.
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sequence polymorphism of cytochrome b gene in theileria annulata tunisian isolates and its association with Buparvaquone treatment failure
PLOS ONE, 2015Co-Authors: Melek Chaouch, Kaouthar Ajroud, Mohamed Aziz Darghouth, Moez Mhadhbi, Souha BenabderrazakAbstract:Background Buparvaquone (BW 720C) is the major hydroxynaphtoquinone active against tropical theileriosis (Theileria annulata infection). Previous studies showed that Buparvaquone, similarly to others hydroxynaphtoquinone, probably acts by binding to cytochrome b (cyt b) inhibiting the electron transport chain in the parasite. Several observations suggested that T. annulata is becoming resistant to Buparvaquone in many endemic regions (Tunisia, Turkey and Iran), which may hinder the development of bovine livestock in these areas. Methodology/Principal Findings In the present study we sought to determine whether point mutations in T. annulata cytochrome b gene could be associated to Buparvaquone resistance. A total of 28 clones were studied in this work, 19 of which were obtained from 3 resistant isolates (ST2/12, ST2/13 and ST2/19) collected at different time after treatment, from a field treatment failure and nine clones isolated from 4 sensitive stocks of T. annulata (Beja, Battan, Jed4 and Sousse). The cytochrome b gene was amplified and sequenced. We identified five point mutations at the protein sequences (114, 129, 253, 262 and 347) specific for the clones isolated from resistant stocks. Two of them affecting 68% (13/19) of resistant clones, are present in the drug-binding site Q02 region at the position 253 in three resistant clones and at the position 262 in 11 out of 19 resistant clones. These two mutations substitute a neutral and hydrophobic amino acids by polar and hydrophilic ones which could interfere with the drug binding capabilities. When we compared our sequences to the Iranian ones, the phylogenetic tree analyses show the presence of a geographical sub-structuring in the population of T. annulata. Conclusions/Significance Taken together, our results suggest that the cytochrome b gene may be used as a tool to discriminate between different T. annulata genotypes and also as a genetic marker to characterize resistant isolates of T. annulata.
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in vivo evidence for the resistance of theileria annulata to Buparvaquone
Veterinary Parasitology, 2010Co-Authors: Moez Mhadhbi, Abdelkarim Naouach, Aissa Boumiza, Mohamed Faouzi Chaabani, Souha Benabderazzak, Mohamed Aziz DarghouthAbstract:Abstract The present study describes an outbreak of tropical theileriosis cases refractory to Buparvaquone treatment, which occurred in a small-size dairy farm in Tunisia. Out of seven treated cows, four died in spite of repeated Buparvaquone injections (2.5 and 5 mg kg−1) and the monitoring of the affected cows showed no improvement of the course of the disease with a consistent decrease in the haematocrit, the persistence of fever and an increased parasitaemia after treatment. Ticks were fed on a calf experimentally infected with one isolate established in culture from one of the cases and the resultant infected ticks ground up to generate a supernatant infected with the potentially resistant stock. This was used to experimentally infect three calves, and the clinical observations, post-Buparvaquone treatment, showed an absence of the usual effect of Buparvaquone treatment on the parasite Theileria annulata, such as the rapid decline of schizont index and parasitaemia and a rapid recovery from the disease. These results confirmed for the first time the occurrence of resistance to Buparvaquone in the protozoan T. annulata.
Simon L Croft - One of the best experts on this subject based on the ideXlab platform.
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The activity of hydroxynaphthoquinones against Leishmania donovani
2016Co-Authors: Simon L Croft, J. Hogg, Alan Thomas Hudson, Winston Edward Gutteridge, A. W. RaodauAbstract:activity in vitro against Leishmania donovani amastigotcs in mouse peritonea] macro-phages, with EDy, values of O05, 2-95 and 13-82 (itt, respectively. Fourteen other hydroxynaphthoquinones were tested, of which only S66C80 and 608C86 showed significant activity against amastigotes. Buparvaquone, 250C80 and 56W82 were also highly-active against cultured promastigotes. In a BALB/c mouse model, treatment with 100 mg/kg/day for five days with Buparvaquone, 250C80 and 566C80 (atovaquone) reduced liver amastigote numbers by 60%, 22 % and 30-5%, respectively
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In vivo studies on the antileishmanial activity of Buparvaquone and its prodrugs
The Journal of antimicrobial chemotherapy, 2007Co-Authors: Tracy Garnier, Antti Mäntylä, Tomi Järvinen, Jayne Lawrence, Marc B. Brown, Simon L CroftAbstract:Objectives: The efficacy of different formulations of the naphthoquinone Buparvaquone and two phosphate prodrugs in in vivo models of both visceral and cutaneous leishmaniasis is described. Methods: Several topical formulations of Buparvaquone containing acceptable excipients were tested in vivo against Leishmania major cutaneous lesions in BALB/c mice. In vivo studies against Leishmania donovani investigated whether the prodrugs had improved efficacy when compared with Buparvaquone. Results: Both a hydrous gel and water-in-oil emulsion of Buparvaquone significantly reduced cutaneous parasite burden (P < 0.05, 22 days post-infection) and lesion size, compared with the untreated control (P < 0.0001, 16 days post-infection). The prodrug 3-phosphonooxymethyl-Buparvaquone was formulated into an anhydrous gel and this also significantly reduced parasite burden and lesion size (P < 0.0001, 16 days post-infection). Histology confirmed this efficacy. In the visceral model, both prodrugs were significantly more effective at reducing liver parasite burden than the parent drug, Buparvaquone. Buparvaquone-3-phosphate was shown to be the most effective antileishmanial (P 5 0.0003, 50 mg Buparvaquone molar equivalent/kg/day five times), reducing the liver parasite burden by 34% when compared with the untreated control. Conclusions: The introduction of a topical formulation, such as Buparvaquone (or its prodrug), would be a significant advance for the treatment of simple cutaneous lesions. In particular, the avoidance of the parenteral antimonials would greatly increase patient compliance and reduce treatment costs.
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Topical Buparvaquone formulations for the treatment of cutaneous leishmaniasis.
The Journal of pharmacy and pharmacology, 2007Co-Authors: Tracy Garnier, Antti Mäntylä, Tomi Järvinen, Marc B. Brown, M. Jayne Lawrence, Simon L CroftAbstract:As the part of a study to develop Buparvaquone (BPQ) formulations for the treatment of cutaneous leishmaniasis, the topical delivery of BPQ and one of its prodrugs from a range of formulations was evaluated. In previous studies, BPQ and its prodrugs were shown to be potent antileishmanials in-vitro, with ED50 values in the nanomolar range. 3-Phosphono-oxymethyl-Buparvaquone (3-POM-BPQ) was the most potent antileishmanial and was chosen, together with the parent drug, for further investigation. The ability of the parent and prodrug formulations to cross human and murine skin was tested in-vitro using the Franz diffusion cells. Formulations intended for topical application containing either BPQ or 3-POM-BPQ were developed using excipients that were either acceptable for topical use (GRAS or FDA inactive ingredients) or currently going through the regulatory process. BPQ was shown to penetrate both human epidermal membranes and full thickness BALB/c skin from a range of formulations (gels, emulsions). Similarly, 3-POM-BPQ penetrated full-thickness BALB/c skin from several gel formulations. In-vitro binding studies showed that BPQ bound melanin in a dose-dependent manner and preferably bound to delipidized skin over untreated BALB/c skin (on a weight to weight basis). The results confirm that BPQ and its prodrug 3-POM-BPQ can penetrate the skin from several formulations, making them potentially interesting candidates for further investigation of topical formulations using in-vivo models of cutaneous leishmaniasis.
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Synthesis and antileishmanial activity of novel Buparvaquone oxime derivatives.
Bioorganic & medicinal chemistry, 2004Co-Authors: Antti Mäntylä, Simon L Croft, Jarkko Rautio, Tapio Nevalainen, Jouko Vepsäläinen, Risto O. Juvonen, Howard Kendrick, Tracy Garnier, Tomi JärvinenAbstract:Novel oxime derivatives (2, 3 and 5) of Buparvaquone (1) and O-methyl-Buparvaquone (4) were synthesized and their in vitro activities against Leishmania donovani, the causative agent of visceral leishmaniasis (VL), were determined. Buparvaquone-oxime (2) was also studied as a bioreversible prodrug structure of Buparvaquone (1). Buparvaquone-oxime (2) released Buparvaquone (1) in vitro when it was incubated with induced rat liver microsomes, which suggests that the oxime-structure is a useful prodrug template for developing novel prodrugs of Buparvaquone and other hydroxynaphthoquinones. Moreover, the formation of NO(2)(-) , formed via oxidation of NO, was confirmed during the bioconversion. The release of NO from Buparvaquone-oxime (2) may provide an additional therapeutic effect in the treatment of leishmaniasis. Buparvaquone-oxime (2) and Buparvaquone-O-methyloxime (3) demonstrated moderate activity against amastigotes of the Leishmania species that causes VL. However, the studied oximes (2, 3) most probably did not release Buparvaquone (1) and NO during the present in vitro experiment. Further in vivo studies are needed to verify the biological activity of Buparvaquone-oximes in the treatment of leishmaniasis.
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Synthesis, in Vitro Evaluation, and Antileishmanial Activity of Water-Soluble Prodrugs of Buparvaquone
Journal of medicinal chemistry, 2004Co-Authors: Antti Mäntylä, Simon L Croft, Jarkko Rautio, Tapio Nevalainen, Jouko Vepsäläinen, Tracy Garnier, Ari M. P. Koskinen, Tomi JärvinenAbstract:Water-soluble phosphate prodrugs of Buparvaquone (1), containing a hydroxynaphthoquinone structure, were synthesized and evaluated in vitro for improved topical and oral drug delivery against cutaneous and visceral leishmaniasis. The successful prodrug synthesis involved a strong base; e.g., sodium hydride. Buparvaquone-3-phosphate (4a) and 3-phosphonooxymethyl-Buparvaquone (4b) prodrugs possessed significantly higher aqueous solubilities (>3.5 mg/mL) than the parent drug (
Tomi Järvinen - One of the best experts on this subject based on the ideXlab platform.
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In vivo studies on the antileishmanial activity of Buparvaquone and its prodrugs
The Journal of antimicrobial chemotherapy, 2007Co-Authors: Tracy Garnier, Antti Mäntylä, Tomi Järvinen, Jayne Lawrence, Marc B. Brown, Simon L CroftAbstract:Objectives: The efficacy of different formulations of the naphthoquinone Buparvaquone and two phosphate prodrugs in in vivo models of both visceral and cutaneous leishmaniasis is described. Methods: Several topical formulations of Buparvaquone containing acceptable excipients were tested in vivo against Leishmania major cutaneous lesions in BALB/c mice. In vivo studies against Leishmania donovani investigated whether the prodrugs had improved efficacy when compared with Buparvaquone. Results: Both a hydrous gel and water-in-oil emulsion of Buparvaquone significantly reduced cutaneous parasite burden (P < 0.05, 22 days post-infection) and lesion size, compared with the untreated control (P < 0.0001, 16 days post-infection). The prodrug 3-phosphonooxymethyl-Buparvaquone was formulated into an anhydrous gel and this also significantly reduced parasite burden and lesion size (P < 0.0001, 16 days post-infection). Histology confirmed this efficacy. In the visceral model, both prodrugs were significantly more effective at reducing liver parasite burden than the parent drug, Buparvaquone. Buparvaquone-3-phosphate was shown to be the most effective antileishmanial (P 5 0.0003, 50 mg Buparvaquone molar equivalent/kg/day five times), reducing the liver parasite burden by 34% when compared with the untreated control. Conclusions: The introduction of a topical formulation, such as Buparvaquone (or its prodrug), would be a significant advance for the treatment of simple cutaneous lesions. In particular, the avoidance of the parenteral antimonials would greatly increase patient compliance and reduce treatment costs.
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Topical Buparvaquone formulations for the treatment of cutaneous leishmaniasis.
The Journal of pharmacy and pharmacology, 2007Co-Authors: Tracy Garnier, Antti Mäntylä, Tomi Järvinen, Marc B. Brown, M. Jayne Lawrence, Simon L CroftAbstract:As the part of a study to develop Buparvaquone (BPQ) formulations for the treatment of cutaneous leishmaniasis, the topical delivery of BPQ and one of its prodrugs from a range of formulations was evaluated. In previous studies, BPQ and its prodrugs were shown to be potent antileishmanials in-vitro, with ED50 values in the nanomolar range. 3-Phosphono-oxymethyl-Buparvaquone (3-POM-BPQ) was the most potent antileishmanial and was chosen, together with the parent drug, for further investigation. The ability of the parent and prodrug formulations to cross human and murine skin was tested in-vitro using the Franz diffusion cells. Formulations intended for topical application containing either BPQ or 3-POM-BPQ were developed using excipients that were either acceptable for topical use (GRAS or FDA inactive ingredients) or currently going through the regulatory process. BPQ was shown to penetrate both human epidermal membranes and full thickness BALB/c skin from a range of formulations (gels, emulsions). Similarly, 3-POM-BPQ penetrated full-thickness BALB/c skin from several gel formulations. In-vitro binding studies showed that BPQ bound melanin in a dose-dependent manner and preferably bound to delipidized skin over untreated BALB/c skin (on a weight to weight basis). The results confirm that BPQ and its prodrug 3-POM-BPQ can penetrate the skin from several formulations, making them potentially interesting candidates for further investigation of topical formulations using in-vivo models of cutaneous leishmaniasis.
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Synthesis and antileishmanial activity of novel Buparvaquone oxime derivatives.
Bioorganic & medicinal chemistry, 2004Co-Authors: Antti Mäntylä, Simon L Croft, Jarkko Rautio, Tapio Nevalainen, Jouko Vepsäläinen, Risto O. Juvonen, Howard Kendrick, Tracy Garnier, Tomi JärvinenAbstract:Novel oxime derivatives (2, 3 and 5) of Buparvaquone (1) and O-methyl-Buparvaquone (4) were synthesized and their in vitro activities against Leishmania donovani, the causative agent of visceral leishmaniasis (VL), were determined. Buparvaquone-oxime (2) was also studied as a bioreversible prodrug structure of Buparvaquone (1). Buparvaquone-oxime (2) released Buparvaquone (1) in vitro when it was incubated with induced rat liver microsomes, which suggests that the oxime-structure is a useful prodrug template for developing novel prodrugs of Buparvaquone and other hydroxynaphthoquinones. Moreover, the formation of NO(2)(-) , formed via oxidation of NO, was confirmed during the bioconversion. The release of NO from Buparvaquone-oxime (2) may provide an additional therapeutic effect in the treatment of leishmaniasis. Buparvaquone-oxime (2) and Buparvaquone-O-methyloxime (3) demonstrated moderate activity against amastigotes of the Leishmania species that causes VL. However, the studied oximes (2, 3) most probably did not release Buparvaquone (1) and NO during the present in vitro experiment. Further in vivo studies are needed to verify the biological activity of Buparvaquone-oximes in the treatment of leishmaniasis.
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Design, synthesis and in vitro evaluation of novel water-soluble prodrugs of Buparvaquone
European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences, 2004Co-Authors: Antti Mäntylä, Jarkko Rautio, Tapio Nevalainen, Jouko Vepsäläinen, Pekka Keski-rahkonen, Tomi JärvinenAbstract:Novel water-soluble phosphate prodrugs (2b-5b) of Buparvaquone-oxime (1a) and Buparvaquone-O-methyloxime (1b) were synthesized and evaluated in vitro as potential oral prodrugs against leishmaniasis. Buparvaquone-oxime (1a), and most probably also Buparvaquone-O-methyloxime (1b), released the parent Buparvaquone via a cytochrome P450-catalysed reaction. The prodrugs 2b-5b showed significantly higher aqueous solubilities (>4 mg/ml) than Buparvaquone ( 8 days). Although Buparvaquone-oxime (1a) has been shown to undergo a cytochrome P450-catalysed oxidation in liver microsomes to the parent Buparvaquone and behave as a novel bioreversible prodrug, its usefulness is limited in oral drug delivery due to its poor aqueous solubility, like Buparvaquone itself. Further phosphorylation of an oxime form of Buparvaquone significantly increased water solubility, and this novel approach is therefore useful to improve physicochemical properties of drugs containing a ketone functional group.
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Synthesis, in Vitro Evaluation, and Antileishmanial Activity of Water-Soluble Prodrugs of Buparvaquone
Journal of medicinal chemistry, 2004Co-Authors: Antti Mäntylä, Simon L Croft, Jarkko Rautio, Tapio Nevalainen, Jouko Vepsäläinen, Tracy Garnier, Ari M. P. Koskinen, Tomi JärvinenAbstract:Water-soluble phosphate prodrugs of Buparvaquone (1), containing a hydroxynaphthoquinone structure, were synthesized and evaluated in vitro for improved topical and oral drug delivery against cutaneous and visceral leishmaniasis. The successful prodrug synthesis involved a strong base; e.g., sodium hydride. Buparvaquone-3-phosphate (4a) and 3-phosphonooxymethyl-Buparvaquone (4b) prodrugs possessed significantly higher aqueous solubilities (>3.5 mg/mL) than the parent drug (
