1
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Flaherty S, Strauch P, Maktabi M, Pybus BS, Reichard G, Walker LA, Rochford R. Mechanisms of 8-aminoquinoline induced haemolytic toxicity in a G6PDd humanized mouse model. J Cell Mol Med 2022; 26:3675-3686. [PMID: 35665597 PMCID: PMC9258708 DOI: 10.1111/jcmm.17362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 03/29/2022] [Accepted: 04/05/2022] [Indexed: 11/29/2022] Open
Abstract
Primaquine (PQ) and Tafenoquine (TQ) are clinically important 8‐aminoquinolines (8‐AQ) used for radical cure treatment of P. vivax infection, known to target hepatic hypnozoites. 8‐AQs can trigger haemolytic anaemia in individuals with glucose‐6‐phosphate dehydrogenase deficiency (G6PDd), yet the mechanisms of haemolytic toxicity remain unknown. To address this issue, we used a humanized mouse model known to predict haemolytic toxicity responses in G6PDd human red blood cells (huRBCs). To evaluate the markers of eryptosis, huRBCs were isolated from mice 24–48 h post‐treatment and analysed for effects on phosphatidylserine (PS), intracellular reactive oxygen species (ROS) and autofluorescence. Urinalysis was performed to evaluate the occurrence of intravascular and extravascular haemolysis. Spleen and liver tissue harvested at 24 h and 5–7 days post‐treatment were stained for the presence of CD169+ macrophages, F4/80+ macrophages, Ter119+ mouse RBCs, glycophorin A+ huRBCs and murine reticulocytes (muRetics). G6PDd‐huRBCs from PQ/TQ treated mice showed increased markers for eryptosis as early as 24 h post‐treatment. This coincided with an early rise in levels of muRetics. Urinalysis revealed concurrent intravascular and extravascular haemolysis in response to PQ/TQ. Splenic CD169+ macrophages, present in all groups at day 1 post‐dosing were eliminated by days 5–7 in PQ/TQ treated mice only, while liver F4/80 macrophages and iron deposits increased. Collectively, our data suggest 8‐AQ treated G6PDd‐huRBCs have early physiological responses to treatment, including increased markers for eryptosis indicative of oxidative stress, resulting in extramedullary haematopoiesis and loss of splenic CD169+ macrophages, prompting the liver to act as the primary site of clearance.
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Affiliation(s)
- Siobhan Flaherty
- Department of Immunology and Microbiology, The University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Pamela Strauch
- Department of Immunology and Microbiology, The University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Mahdi Maktabi
- Department of Immunology and Microbiology, The University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Brandon S Pybus
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland, USA
| | - Gregory Reichard
- Department of Drug Discovery, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland, USA
| | - Larry A Walker
- National Center for Natural Products Research and Department of Biomolecular Sciences, School of Pharmacy, The University of Mississippi, University, Mississippi, USA
| | - Rosemary Rochford
- Department of Immunology and Microbiology, The University of Colorado School of Medicine, Aurora, Colorado, USA
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2
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Kavishe RA, Koenderink JB, Alifrangis M. Oxidative stress in malaria and artemisinin combination therapy: Pros and Cons. FEBS J 2017; 284:2579-2591. [DOI: 10.1111/febs.14097] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 04/05/2017] [Accepted: 04/28/2017] [Indexed: 12/13/2022]
Affiliation(s)
- Reginald A. Kavishe
- Department of Biochemistry & Molecular Biology; Faculty of Medicine; Kilimanjaro Christian Medical University College; Moshi Tanzania
| | - Jan B. Koenderink
- Department of Pharmacology and Toxicology; Radboud Institute for Molecular Life Sciences; Radboud University Medical Center; Nijmegen The Netherlands
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3
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Age, Weight, and CYP2D6 Genotype Are Major Determinants of Primaquine Pharmacokinetics in African Children. Antimicrob Agents Chemother 2017; 61:AAC.02590-16. [PMID: 28289025 PMCID: PMC5404566 DOI: 10.1128/aac.02590-16] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 03/06/2017] [Indexed: 12/22/2022] Open
Abstract
Low-dose primaquine is recommended to prevent Plasmodium falciparum malaria transmission in areas threatened by artemisinin resistance and areas aiming for malaria elimination. Community treatment campaigns with artemisinin-based combination therapy in combination with the gametocytocidal primaquine dose target all age groups, but no studies thus far have assessed the pharmacokinetics of this gametocytocidal drug in African children. We recruited 40 children participating in a primaquine efficacy trial in Burkina Faso to study primaquine pharmacokinetics. These children received artemether-lumefantrine and either a 0.25- or a 0.40-mg/kg primaquine dose. Seven blood samples were collected from each participant for primaquine and carboxy-primaquine plasma levels determinations: one sample was collected before primaquine administration and six after primaquine administration according to partially overlapping sampling schedules. Physiological population pharmacokinetic modeling was used to assess the impact of weight, age, and CYP2D6 genotype on primaquine and carboxy-primaquine pharmacokinetics. Despite linear weight normalized dosing, the areas under the plasma concentration-time curves and the peak concentrations for both primaquine and carboxy-primaquine increased with age and body weight. Children who were CYP2D6 poor metabolizers had higher levels of the parent compound, indicating a lower primaquine CYP2D6-mediated metabolism. Our data indicate that primaquine and carboxy-primaquine pharmacokinetics are influenced by age, weight, and CYP2D6 genotype and suggest that dosing strategies may have to be reconsidered to maximize the transmission-blocking properties of primaquine. (This study has been registered at ClinicalTrials.gov under registration no. NCT01935882.)
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4
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Leang R, Khu NH, Mukaka M, Debackere M, Tripura R, Kheang ST, Chy S, Kak N, Buchy P, Tarantola A, Menard D, Roca-Felterer A, Fairhurst RM, Kheng S, Muth S, Ngak S, Dondorp AM, White NJ, Taylor WRJ. An optimised age-based dosing regimen for single low-dose primaquine for blocking malaria transmission in Cambodia. BMC Med 2016; 14:171. [PMID: 27784313 PMCID: PMC5081959 DOI: 10.1186/s12916-016-0701-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 09/20/2016] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND In 2012, the World Health Organization recommended the addition of single low-dose primaquine (SLDPQ, 0.25 mg base/kg body weight) to artemisinin combination therapies to block the transmission of Plasmodium falciparum without testing for glucose-6-phosphate dehydrogenase deficiency. The targeted group was non-pregnant patients aged ≥ 1 year (later changed to ≥ 6 months) with acute uncomplicated falciparum malaria, primarily in countries with artemisinin-resistant P. falciparum (ARPf). No dosing regimen was suggested, leaving malaria control programmes and clinicians in limbo. Therefore, we designed a user-friendly, age-based SLDPQ regimen for Cambodia, the country most affected by ARPf. METHODS By reviewing primaquine's pharmacology, we defined a therapeutic dose range of 0.15-0.38 mg base/kg (9-22.5 mg in a 60-kg adult) for a therapeutic index of 2.5. Primaquine doses (1-20 mg) were tested using a modelled, anthropometric database of 28,138 Cambodian individuals (22,772 healthy, 4119 with malaria and 1247 with other infections); age distributions were: 0.5-4 years (20.0 %, n = 5640), 5-12 years (9.1 %, n = 2559), 13-17 years (9.1 %, n = 2550), and ≥ 18 years (61.8 %, n = 17,389). Optimal age-dosing groups were selected according to calculated mg base/kg doses and proportions of individuals receiving a therapeutic dose. RESULTS Four age-dosing bands were defined: (1) 0.5-4 years, (2) 5-9 years, (3) 10-14 years, and (4) ≥15 years to receive 2.5, 5, 7.5, and 15 mg of primaquine base, resulting in therapeutic doses in 97.4 % (5494/5640), 90.5 % (1511/1669), 97.7 % (1473/1508), and 95.7 % (18,489/19,321) of individuals, respectively. Corresponding median (1st-99th centiles) mg base/kg doses of primaquine were (1) 0.23 (0.15-0.38), (2) 0.29 (0.18-0.45), (3) 0.27 (0.15-0.39), and (4) 0.29 (0.20-0.42). CONCLUSIONS This age-based SLDPQ regimen could contribute substantially to malaria elimination and requires urgent evaluation in Cambodia and other countries with similar anthropometric characteristics. It guides primaquine manufacturers on suitable tablet strengths and doses for paediatric-friendly formulations. Development of similar age-based dosing recommendations for Africa is needed.
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Affiliation(s)
- Rithea Leang
- National Center for Parasitology, Entomology and Malaria Control, Corner St. 92, Trapeng Svay Village, Sangkat Phnom Penh, Thmei, Khan Sen Sok, Phnom Penh, Cambodia
| | - Naw Htee Khu
- Mahidol Oxford Tropical Medicine Research Unit (MORU), 420/6 Rajvithi Road, Rajthevee, Bangkok, 10400, Thailand
| | - Mavuto Mukaka
- Mahidol Oxford Tropical Medicine Research Unit (MORU), 420/6 Rajvithi Road, Rajthevee, Bangkok, 10400, Thailand.,Oxford Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research Building, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford, OX3 7FZ, UK
| | - Mark Debackere
- MSF Belgium Cambodia Malaria Program, #19, Street 388, Sangkat Tuol Svay Prey, Khan Chamkarmon, PO Box 1933, Phnom Penh, Cambodia
| | - Rupam Tripura
- Mahidol Oxford Tropical Medicine Research Unit (MORU), 420/6 Rajvithi Road, Rajthevee, Bangkok, 10400, Thailand
| | - Soy Ty Kheang
- University Research Co., LLC, MK Building, House #10 (2nd floor), St. 214, Chey Chumneas, Daun Penh, Phnom Penh, Cambodia
| | - Say Chy
- University Research Co., LLC, MK Building, House #10 (2nd floor), St. 214, Chey Chumneas, Daun Penh, Phnom Penh, Cambodia
| | - Neeraj Kak
- University Research Co., LLC Washington DC: 7200 Wisconsin Ave, Bethesda, MD, 20814, USA
| | - Philippe Buchy
- Institut Pasteur du Cambodge, 5 Monivong Boulevard, PO Box 983, Phnom Penh, 12201, Cambodia
| | - Arnaud Tarantola
- Institut Pasteur du Cambodge, 5 Monivong Boulevard, PO Box 983, Phnom Penh, 12201, Cambodia
| | - Didier Menard
- Institut Pasteur du Cambodge, 5 Monivong Boulevard, PO Box 983, Phnom Penh, 12201, Cambodia
| | - Arantxa Roca-Felterer
- Malaria Consortium, House #91 Street 95, Boeung Trabek, Chamkar Morn, Phnom Penh, Cambodia
| | - Rick M Fairhurst
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, 20852, USA
| | - Sim Kheng
- National Center for Parasitology, Entomology and Malaria Control, Corner St. 92, Trapeng Svay Village, Sangkat Phnom Penh, Thmei, Khan Sen Sok, Phnom Penh, Cambodia
| | - Sinoun Muth
- National Center for Parasitology, Entomology and Malaria Control, Corner St. 92, Trapeng Svay Village, Sangkat Phnom Penh, Thmei, Khan Sen Sok, Phnom Penh, Cambodia
| | - Song Ngak
- FHI 360 Cambodia Office, #03, Street 330 Boeung Keng Kang III Khan Chamkamon, PO Box: 2586, Phnom Penh, Cambodia
| | - Arjen M Dondorp
- Mahidol Oxford Tropical Medicine Research Unit (MORU), 420/6 Rajvithi Road, Rajthevee, Bangkok, 10400, Thailand.,Oxford Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research Building, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford, OX3 7FZ, UK
| | - Nicholas J White
- Mahidol Oxford Tropical Medicine Research Unit (MORU), 420/6 Rajvithi Road, Rajthevee, Bangkok, 10400, Thailand.,Oxford Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research Building, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford, OX3 7FZ, UK
| | - Walter Robert John Taylor
- Mahidol Oxford Tropical Medicine Research Unit (MORU), 420/6 Rajvithi Road, Rajthevee, Bangkok, 10400, Thailand. .,Oxford Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research Building, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford, OX3 7FZ, UK. .,Centre de Médecine Humanitaire, Hôpitaux Universitaires de Genève, Genève, Switzerland.
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5
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Ding Y, Liu H, Tekwani BL, Nanayakkara NPD, Khan IA, Walker LA, Doerksen RJ. Methemoglobinemia Hemotoxicity of Some Antimalarial 8-Aminoquinoline Analogues and Their Hydroxylated Derivatives: Density Functional Theory Computation of Ionization Potentials. Chem Res Toxicol 2016; 29:1132-41. [DOI: 10.1021/acs.chemrestox.6b00063] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Yuanqing Ding
- National Center for Natural Products Research,
Research Institute
of Pharmaceutical Science, and ‡Department of BioMolecular Sciences, School
of Pharmacy, University of Mississippi, University, Mississippi 38677, United States
| | - Haining Liu
- National Center for Natural Products Research,
Research Institute
of Pharmaceutical Science, and ‡Department of BioMolecular Sciences, School
of Pharmacy, University of Mississippi, University, Mississippi 38677, United States
| | - Babu L. Tekwani
- National Center for Natural Products Research,
Research Institute
of Pharmaceutical Science, and ‡Department of BioMolecular Sciences, School
of Pharmacy, University of Mississippi, University, Mississippi 38677, United States
| | - N. P. Dhammika Nanayakkara
- National Center for Natural Products Research,
Research Institute
of Pharmaceutical Science, and ‡Department of BioMolecular Sciences, School
of Pharmacy, University of Mississippi, University, Mississippi 38677, United States
| | - Ikhlas A. Khan
- National Center for Natural Products Research,
Research Institute
of Pharmaceutical Science, and ‡Department of BioMolecular Sciences, School
of Pharmacy, University of Mississippi, University, Mississippi 38677, United States
| | - Larry A. Walker
- National Center for Natural Products Research,
Research Institute
of Pharmaceutical Science, and ‡Department of BioMolecular Sciences, School
of Pharmacy, University of Mississippi, University, Mississippi 38677, United States
| | - Robert J. Doerksen
- National Center for Natural Products Research,
Research Institute
of Pharmaceutical Science, and ‡Department of BioMolecular Sciences, School
of Pharmacy, University of Mississippi, University, Mississippi 38677, United States
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6
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Murce E, Cuya-Guizado TR, Padilla-Chavarria HI, França TCC, Pimentel AS. Structure-based de novo design, molecular docking and molecular dynamics of primaquine analogues acting as quinone reductase II inhibitors. J Mol Graph Model 2015; 62:235-244. [PMID: 26521207 DOI: 10.1016/j.jmgm.2015.10.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 09/29/2015] [Accepted: 10/01/2015] [Indexed: 10/22/2022]
Abstract
Primaquine is a traditional antimalarial drug with low parasitic resistance and generally good acceptance at higher doses, which has been used for over 60 years in malaria treatment. However, several limitations related to its hematotoxicity have been reported. It is believed that this toxicity comes from the hydroxylation of the C-5 and C-6 positions of its 8-aminoquinoline ring before binding to the molecular target: the quinone reductase II (NQO2) human protein. In this study we propose primaquine derivatives, with substitution at position C-6 of the 8-aminoquinoline ring, planned to have better binding to NQO2, compared to primaquine, but with a reduced toxicity related to the C-5 position being possible to be oxidized. On this sense the proposed analogues were suggested in order to reduce or inhibit hydroxylation and further oxidation to hemotoxic metabolites. Five C-6 substituted primaquine analogues were selected by de novo design and further submitted to docking and molecular dynamics simulations. Our results suggest that all analogues bind better to NQO2 than primaquine and may become better antimalarials. However, the analogues 3 and 4 are predicted to have a better activity/toxicity balance.
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Affiliation(s)
- Erika Murce
- Departamento de Química, Pontifícia Universidade Católica do Rio de Janeiro, RJ 22453-900, Brazil
| | - Teobaldo Ricardo Cuya-Guizado
- Laboratory of Molecular Modeling Applied to the Chemical and Biological Defense (LMCBD), Military Institute of Engineering, 22290-270 Rio de Janeiro, RJ, Brazil
| | | | - Tanos Celmar Costa França
- Laboratory of Molecular Modeling Applied to the Chemical and Biological Defense (LMCBD), Military Institute of Engineering, 22290-270 Rio de Janeiro, RJ, Brazil; Center for Basic and Applied Research, Faculty of Informatics and Management, University of Hradec Králové, Hradec Králové, Czech Republic
| | - Andre Silva Pimentel
- Departamento de Química, Pontifícia Universidade Católica do Rio de Janeiro, RJ 22453-900, Brazil.
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7
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Liu H, Ding Y, Walker LA, Doerksen RJ. Computational Study on the Effect of Exocyclic Substituents on the Ionization Potential of Primaquine: Insights into the Design of Primaquine-Based Antimalarial Drugs with Less Methemoglobin Generation. Chem Res Toxicol 2015; 28:169-74. [PMID: 25222923 PMCID: PMC4332040 DOI: 10.1021/tx500230t] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
The effect of an
exocyclic substituent on the ionization potential
of primaquine, an important antimalarial drug, was investigated using
density functional theory methods. It was found that an electron-donating
group (EDG) makes the ionization potential decrease. In contrast,
an electron-withdrawing group (EWG) makes the ionization potential
increase. Among all the exocyclic positions, a substituent at the
5- or 7-position has the largest effect. This can be explained by
the contribution of the atomic orbitals at those positions to the
highest occupied molecular orbital (HOMO). In addition, a substituent
at the N8-position has a considerably large effect on the ionization
potential because this atom makes the second largest contribution
to the HOMO. These findings have potential implications for the design
of less hemotoxic antimalarial drugs. We suggest that it is worth
considering placement of an EWG at the 5-, 7-, or N8-positions of
primaquine in future drug discovery attempts.
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Affiliation(s)
- Haining Liu
- Department of BioMolecular Sciences and ‡the National Center for Natural Products Research, School of Pharmacy, University of Mississippi , University, Mississippi 38677, United States
| | - Yuanqing Ding
- Department of BioMolecular Sciences and ‡the National Center for Natural Products Research, School of Pharmacy, University of Mississippi , University, Mississippi 38677, United States
| | - Larry A Walker
- Department of BioMolecular Sciences and ‡the National Center for Natural Products Research, School of Pharmacy, University of Mississippi , University, Mississippi 38677, United States
| | - Robert J Doerksen
- Department of BioMolecular Sciences and ‡the National Center for Natural Products Research, School of Pharmacy, University of Mississippi , University, Mississippi 38677, United States
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8
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Fasinu PS, Tekwani BL, Nanayakkara NPD, Avula B, Herath HMTB, Wang YH, Adelli VR, Elsohly MA, Khan SI, Khan IA, Pybus BS, Marcsisin SR, Reichard GA, McChesney JD, Walker LA. Enantioselective metabolism of primaquine by human CYP2D6. Malar J 2014; 13:507. [PMID: 25518709 PMCID: PMC4301821 DOI: 10.1186/1475-2875-13-507] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 12/11/2014] [Indexed: 11/15/2022] Open
Abstract
Background Primaquine, currently the only approved drug for the treatment and radical cure of Plasmodium vivax malaria, is still used as a racemic mixture. Clinical use of primaquine has been limited due to haemolytic toxicity in individuals with genetic deficiency in glucose-6-phosphate dehydrogenase. Earlier studies have linked its therapeutic effects to CYP2D6-generated metabolites. The aim of the current study was to investigate the differential generation of the CYP2D6 metabolites by racemic primaquine and its individual enantiomers. Methods Stable isotope 13C-labelled primaquine and its two enantiomers were incubated with recombinant cytochrome-P450 supersomes containing CYP2D6 under optimized conditions. Metabolite identification and time-point quantitative analysis were performed using LC-MS/MS. UHPLC retention time, twin peaks with a mass difference of 6, MS-MS fragmentation pattern, and relative peak area with respect to parent compound were used for phenotyping and quantitative analysis of metabolites. Results The rate of metabolism of (+)-(S)-primaquine was significantly higher (50% depletion of 20 μM in 120 min) compared to (−)-(R)-primaquine (30% depletion) when incubated with CYP2D6. The estimated Vmax (μmol/min/mg) were 0.75, 0.98 and 0.42, with Km (μM) of 24.2, 33.1 and 21.6 for (±)-primaquine, (+)-primaquine and (−)-primaquine, respectively. Three stable mono-hydroxylated metabolites, namely, 2-, 3- and 4-hydroxyprimaquine (2-OH-PQ, 3-OH-PQ, and 4-OH-PQ), were identified and quantified. 2-OH-PQ was preferentially formed from (+)-primaquine in a ratio of 4:1 compared to (−)-primaquine. The racemic (±)-primaquine showed a pattern similar to the (−)-primaquine; 2-OH-PQ accounted for about 15–17% of total CYP2D6-mediated conversion of (+)-primaquine. In contrast, 4-OH-PQ was preferentially formed with (−)-primaquine (5:1), accounting for 22% of the total (−)-primaquine conversion. 3-OH-PQ was generated from both enantiomers and racemate. 5-hydroxyprimaquine was unstable. Its orthoquinone degradation product (twice as abundant in (+)-primaquine compared to (−)-primaquine) was identified and accounted for 18–20% of the CYP2D6-mediated conversion of (+)-primaquine. Other minor metabolites included dihydroxyprimaquine species, two quinone-imine products of dihydroxylated primaquine, and a primaquine terminal alcohol with variable generation from the individual enantiomers. Conclusion The metabolism of primaquine by human CYP2D6 and the generation of its metabolites display enantio-selectivity regarding formation of hydroxylated product profiles. This may partly explain differential pharmacologic and toxicologic properties of primaquine enantiomers.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | - Larry A Walker
- The National Center for Natural Products Research, University of Mississippi, University, MS 38677, USA.
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9
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Ding Y, Liu H, Nanayakkara NPD, Khan IA, Tekwani BL, Walker LA, Doerksen RJ. Hydroxylated derivatives of NPC1161: theoretical insights into their potential toxicity and the feasibility and regioselectivity of their formation. J Phys Chem A 2014; 118:5501-7. [PMID: 24956138 PMCID: PMC4216223 DOI: 10.1021/jp502612t] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
For antimalarial 8-aminoquinoline
(8-AQ) drugs, the ionization
potential (energy required to remove an electron) of their putative
metabolites has been proposed to be correlated in part to their hemotoxicity
potential. NPC1161 is a developmental candidate as an 8-AQ antimalarial
drug. In this work, the ionization potentials (IPs) of the S-NPC1161 (NPC1161a) hydroxylated derivatives, which are
possible metabolites derived from action of endogenous cytochrome
P450 (CYP450) enzymes, were calculated at the B3LYP-SCRF(PCM)/6-311++G**//B3LYP/6-31G**
level in water. The derivative hydroxylated at N1′ (8-amino)
was found to have the smallest IP of ∼430 kJ/mol, predicting
that it would be the most hemotoxic. The calculated IPs of the derivatives
hydroxylated at the C2 and C7 positions were ∼475 and ∼478
kJ/mol, respectively, whereas the calculated IPs of those hydroxylated
at all other possible positions were between 480 and 490 kJ/mol. The
homolytic bond dissociation energies (HBDEs) of all C–H/N–H
bonds in NPC1161a were also calculated. The smaller HBDEs of the C–H/N–H
bonds on the 8-amino side chain suggest that these positions are more
easily hydroxylated compared to other sites. Molecular orbital analysis
implies that the N1′ position should be the most reactive center
when NPC1161 approaches the heme in CYP450.
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Affiliation(s)
- Yuanqing Ding
- National Center for Natural Products Research, Research Institute of Pharmaceutical Science, ‡Department of Medicinal Chemistry, §Department of Pharmacognosy, and ∥Department of Pharmacology, School of Pharmacy, University of Mississippi , University, Mississippi 38677, United States
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10
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Liu H, Tekwani BL, Nanayakkara NPD, Walker LA, Doerksen RJ. Methemoglobin generation by 8-aminoquinolines: effect of substitution at 5-position of primaquine. Chem Res Toxicol 2013; 26:1801-9. [PMID: 24224488 DOI: 10.1021/tx400067a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Currently, the only clinically approved antimalarial drug to treat relapsing malaria is primaquine (PQ), yet PQ administration can cause life-threatening hemolytic anemia in some patients. In our efforts to understand the connection between PQ and methemoglobin formation, the effect of 5-substituted primaquine derivatives on the basicity of hemoglobin-bound O2 was investigated using various computational methods, including quantum mechanics/molecular mechanics (QM/MM) calculations, molecular dynamics simulations and density functional theory calculations, to determine the geometries, relative energies, spin densities, proton affinities and ionization potentials of various PQ derivatives and PQ···hemoglobin complexes. We found that the protein environment and solvent do not change our previously proposed methemoglobin formation mechanism that 5-hydroxyprimaquine donates an electron to O2, facilitating its conversion to H2O2 and generating methemoglobin. Because of 5-hydroxyprimaquine's ability to lose an electron by this mechanism, we then used different substituents at primaquine's 5-position and found that an electron-withdrawing group (EWG) increases the ionization potential of the corresponding derivative. As a result, the EWG-substituted derivatives make the hemoglobin-bound O2 less basic, because of their weaker electron-donating ability. These derivatives hence are predicted to have a lower propensity to generate methemoglobin, which can inform future design of less hemotoxic antimalarial drugs. We also carried out experimental measurement of methemoglobin formation for some of the 5-substituted derivatives.
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Affiliation(s)
- Haining Liu
- Department of Medicinal Chemistry, ‡National Center for Natural Products Research, and §Department of Pharmacology, University of Mississippi , University, Mississippi 38677, United States
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11
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Humanized mouse model of glucose 6-phosphate dehydrogenase deficiency for in vivo assessment of hemolytic toxicity. Proc Natl Acad Sci U S A 2013; 110:17486-91. [PMID: 24101478 DOI: 10.1073/pnas.1310402110] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Individuals with glucose 6-phosphate dehydrogenase (G6PD) deficiency are at risk for the development of hemolytic anemia when given 8-aminoquinolines (8-AQs), an important class of antimalarial/antiinfective therapeutics. However, there is no suitable animal model that can predict the clinical hemolytic potential of drugs. We developed and validated a human (hu)RBC-SCID mouse model by giving nonobese diabetic/SCID mice daily transfusions of huRBCs from G6PD-deficient donors. Treatment of SCID mice engrafted with G6PD-deficient huRBCs with primaquine, an 8-AQ, resulted in a dose-dependent selective loss of huRBCs. To validate the specificity of this model, we tested known nonhemolytic antimalarial drugs: mefloquine, chloroquine, doxycycline, and pyrimethamine. No significant loss of G6PD-deficient huRBCs was observed. Treatment with drugs known to cause hemolytic toxicity (pamaquine, sitamaquine, tafenoquine, and dapsone) resulted in loss of G6PD-deficient huRBCs comparable to primaquine. This mouse model provides an important tool to test drugs for their potential to cause hemolytic toxicity in G6PD-deficient populations.
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Pybus BS, Marcsisin SR, Jin X, Deye G, Sousa JC, Li Q, Caridha D, Zeng Q, Reichard GA, Ockenhouse C, Bennett J, Walker LA, Ohrt C, Melendez V. The metabolism of primaquine to its active metabolite is dependent on CYP 2D6. Malar J 2013; 12:212. [PMID: 23782898 PMCID: PMC3689079 DOI: 10.1186/1475-2875-12-212] [Citation(s) in RCA: 138] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 06/13/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The efficacy of the 8-aminoquinoline (8AQ) drug primaquine (PQ) has been historically linked to CYP-mediated metabolism. Although to date no clear evidence exists in the literature that unambiguously assigns the metabolic pathway or specific metabolites necessary for activity, recent literature suggests a role for CYP 2D6 in the generation of redox active metabolites. METHODS In the present study, the specific CYP 2D6 inhibitor paroxetine was used to assess its effects on the production of specific phenolic metabolites thought to be involved in PQ efficacy. Further, PQ causal prophylactic (developing liver stage) efficacy against Plasmodium berghei in CYP 2D knockout mice was assessed in comparison with a normal C57 background and with humanized CYP 2D6 mice to determine the direct effects of CYP 2D6 metabolism on PQ activity. RESULTS PQ exhibited no activity at 20 or 40 mg/kg in CYP 2D knockout mice, compared to 5/5 cures in normal mice at 20 mg/kg. The activity against developing liver stages was partially restored in humanized CYP 2D6 mice. CONCLUSIONS These results unambiguously demonstrate that metabolism of PQ by CYP 2D6 is essential for anti-malarial causal prophylaxis efficacy.
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Howes RE, Battle KE, Satyagraha AW, Baird JK, Hay SI. G6PD deficiency: global distribution, genetic variants and primaquine therapy. ADVANCES IN PARASITOLOGY 2013; 81:133-201. [PMID: 23384623 DOI: 10.1016/b978-0-12-407826-0.00004-7] [Citation(s) in RCA: 155] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Glucose-6-phosphate dehydrogenase (G6PD) is a potentially pathogenic inherited enzyme abnormality and, similar to other human red blood cell polymorphisms, is particularly prevalent in historically malaria endemic countries. The spatial extent of Plasmodium vivax malaria overlaps widely with that of G6PD deficiency; unfortunately the only drug licensed for the radical cure and relapse prevention of P. vivax, primaquine, can trigger severe haemolytic anaemia in G6PD deficient individuals. This chapter reviews the past and current data on this unique pharmacogenetic association, which is becoming increasingly important as several nations now consider strategies to eliminate malaria transmission rather than control its clinical burden. G6PD deficiency is a highly variable disorder, in terms of spatial heterogeneity in prevalence and molecular variants, as well as its interactions with P. vivax and primaquine. Consideration of factors including aspects of basic physiology, diagnosis, and clinical triggers of primaquine-induced haemolysis is required to assess the risks and benefits of applying primaquine in various geographic and demographic settings. Given that haemolytically toxic antirelapse drugs will likely be the only therapeutic options for the coming decade, it is clear that we need to understand in depth G6PD deficiency and primaquine-induced haemolysis to determine safe and effective therapeutic strategies to overcome this hurdle and achieve malaria elimination.
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Thuita JK, Wang MZ, Kagira JM, Denton CL, Paine MF, Mdachi RE, Murilla GA, Ching S, Boykin DW, Tidwell RR, Hall JE, Brun R. Pharmacology of DB844, an orally active aza analogue of pafuramidine, in a monkey model of second stage human African trypanosomiasis. PLoS Negl Trop Dis 2012; 6:e1734. [PMID: 22848769 PMCID: PMC3404106 DOI: 10.1371/journal.pntd.0001734] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Accepted: 06/04/2012] [Indexed: 11/18/2022] Open
Abstract
Novel drugs to treat human African trypanosomiasis (HAT) are still urgently needed despite the recent addition of nifurtimox-eflornithine combination therapy (NECT) to WHO Model Lists of Essential Medicines against second stage HAT, where parasites have invaded the central nervous system (CNS). The pharmacology of a potential orally available lead compound, N-methoxy-6-{5-[4-(N-methoxyamidino) phenyl]-furan-2-yl}-nicotinamidine (DB844), was evaluated in a vervet monkey model of second stage HAT, following promising results in mice. DB844 was administered orally to vervet monkeys, beginning 28 days post infection (DPI) with Trypanosoma brucei rhodesiense KETRI 2537. DB844 was absorbed and converted to the active metabolite 6-[5-(4-phenylamidinophenyl)-furanyl-2-yl]-nicotinamide (DB820), exhibiting plasma C(max) values of 430 and 190 nM for DB844 and DB820, respectively, after the 14th dose at 6 mg/kg qd. A 100-fold reduction in blood trypanosome counts was observed within 24 h of the third dose and, at the end of treatment evaluation performed four days post the last drug dose, trypanosomes were not detected in the blood or cerebrospinal fluid of any monkey. However, some animals relapsed during the 300 days of post treatment monitoring, resulting in a cure rate of 3/8 (37.5%) and 3/7 (42.9%) for the 5 mg/kg×10 days and the 6 mg/kg×14 days dose regimens respectively. These DB844 efficacy data were an improvement compared with pentamidine and pafuramidine both of which were previously shown to be non-curative in this model of CNS stage HAT. These data show that synthesis of novel diamidines with improved activity against CNS-stage HAT was possible.
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Affiliation(s)
- John K. Thuita
- Trypanosomiasis Research Centre, Kenya Agricultural Research Institute (TRC-KARI), Kikuyu, Kenya
| | - Michael Z. Wang
- Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, Kansas, United States of America
| | - John M. Kagira
- Trypanosomiasis Research Centre, Kenya Agricultural Research Institute (TRC-KARI), Kikuyu, Kenya
| | - Cathrine L. Denton
- Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Mary F. Paine
- Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Raymond E. Mdachi
- Trypanosomiasis Research Centre, Kenya Agricultural Research Institute (TRC-KARI), Kikuyu, Kenya
| | - Grace A. Murilla
- Trypanosomiasis Research Centre, Kenya Agricultural Research Institute (TRC-KARI), Kikuyu, Kenya
| | - Shelley Ching
- SVC Associates, Inc., Apex, North Carolina, United States of America
| | - David W. Boykin
- Chemistry Department, Georgia State University, Atlanta, Georgia, United States of America
| | - Richard R. Tidwell
- Pathology Department, School of Medicine, University of North Carolina at Chapel Hill, North Carolina, United States of America
| | - James E. Hall
- Pathology Department, School of Medicine, University of North Carolina at Chapel Hill, North Carolina, United States of America
| | - Reto Brun
- Swiss Tropical and Public Health Institute and University of Basel, Basel, Switzerland
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Abstract
The DEAH helicase RHAU (alias DHX36, G4R1) is the only helicase shown to have G-quadruplex (G4)-RNA resolvase activity and the major source of G4-DNA resolvase activity. Previous report showed RHAU mRNA expression to be elevated in human lymphoid and CD34(+) BM cells, suggesting a potential role in hematopoiesis. Here, we generated a conditional knockout of the RHAU gene in mice. Germ line deletion of RHAU led to embryonic lethality. We then targeted the RHAU gene specifically in the hematopoiesis system, using a Cre-inducible system in which an optimized variant of Cre recombinase was expressed under the control of the Vav1 promoter. RHAU deletion in hematopoietic system caused hemolytic anemia and differentiation defect at the proerythroblast stage. The partial differentiation block of proerythroblasts was because of a proliferation defect. Transcriptome analysis of RHAU knockout proerythroblasts showed that a statistically significant portion of the deregulated genes contain G4 motifs in their promoters. This suggests that RHAU may play a role in the regulation of gene expression that relies on its G4 resolvase activity.
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Ganesan S, Chaurasiya ND, Sahu R, Walker LA, Tekwani BL. Understanding the mechanisms for metabolism-linked hemolytic toxicity of primaquine against glucose 6-phosphate dehydrogenase deficient human erythrocytes: evaluation of eryptotic pathway. Toxicology 2012; 294:54-60. [PMID: 22330256 DOI: 10.1016/j.tox.2012.01.015] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Revised: 01/25/2012] [Accepted: 01/30/2012] [Indexed: 01/10/2023]
Abstract
Therapeutic utility of primaquine, an 8-aminoquinoline antimalarial drug, has been limited due to its hemolytic toxicity in population with glucose 6-phosphate dehydrogenase deficiency. Recent investigations at our lab have shown that the metabolites generated through cytochrome P(450)-dependent metabolic reactions are responsible for hemotoxic effects of primaquine, which could be monitored with accumulation of methemoglobin and increased oxidative stress. The molecular markers for succeeding cascade of events associated with early clearance of the erythrocytes from the circulation were evaluated for understanding the mechanism for hemolytic toxicity of primaquine. Primaquine alone though did not induce noticeable methemoglobin accumulation, but produced significant oxidative stress, which was higher in G6PD-deficient than in normal erythrocytes. Primaquine, presumably through redox active hemotoxic metabolites generated in situ in human liver microsomal metabolism-linked assay, induced a dose-dependent methemoglobin accumulation and oxidative stress, which were almost similar in normal and G6PD-deficient erythrocytes. Primaquine alone or in presence of pooled human liver microsomes neither produced significant effect on intraerythrocytic calcium levels nor affected the phosphatidyl serine asymmetry of the normal and G6PD-deficient human erythrocytes as monitored flowcytometrically with Annexin V binding assay. The studies suggest that eryptosis mechanisms are not involved in accelerated removal of erythrocytes due to hemolytic toxicity of primaquine.
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Affiliation(s)
- Shobana Ganesan
- National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, MS 38677, United States
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17
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Liu H, Walker LA, Doerksen RJ. DFT study on the radical anions formed by primaquine and its derivatives. Chem Res Toxicol 2011; 24:1476-85. [PMID: 21699254 DOI: 10.1021/tx200094v] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The electron affinities (EA) of the 8-aminoquinoline antimalarial drug primaquine and several of its metabolites were studied using the density functional theory method. We first considered six substituents at the 5-position, -CH(3), -OH, -OCH(3), -Ph, -OPh, and -CHO. We found that in the gas phase the adiabatic EAs are similar to that of the parent primaquine for the -CH(3), -OH, and -OCH(3) substituents. In contrast, the -Ph, -OPh, and -CHO substituents all markedly increase the adiabatic EA. However, only the -CHO substituted compound is predicted to form a stable covalently bound radical anion in the gas phase due to its significant positive vertical EA relative to that of the parent primaquine. In addition, when the 8-position is substituted by the N-hydroxyl group or a quinone-imine structure is formed, the electron capture ability is significantly increased. In aqueous solution, all these molecules have significantly larger adiabatic EAs than in the gas phase. In addition, all of the vertical EAs are positive in aqueous solution. The implications of these findings for contributing to our mechanistic understanding of the red cell toxicity of 8-aminoquinoline compounds are further discussed.
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Affiliation(s)
- Haining Liu
- Department of Medicinal Chemistry, University of Mississippi, Mississippi 38677, USA
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Noh JY, Park JS, Lim KM, Kim K, Bae ON, Chung SM, Shin S, Chung JH. A naphthoquinone derivative can induce anemia through phosphatidylserine exposure-mediated erythrophagocytosis. J Pharmacol Exp Ther 2010; 333:414-20. [PMID: 20164298 DOI: 10.1124/jpet.109.164608] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
A naphthoquinone derivative, beta-lapachone (betaL; 3,4-dihydro-2,2-dimethyl-2H-naphthol[1,2-b]pyran-5,6-dione), is receiving huge attention for its potent therapeutic effects against various diseases. However, during the preclinical safety evaluation, repeated oral treatment of betaL in rats induced anemia, i.e., a significantly decreased erythrocyte count. In this study, in an effort to elucidate the mechanism underlying the betaL-induced anemia, we investigated the effects of betaL on erythrocytes with freshly isolated human erythrocytes in vitro and rat in vivo. betaL did not induce erythrocyte hemolysis, indicating that direct hemotoxicity was not involved in betaL-associated anemia. Meanwhile, phosphatidylserine (PS) exposure along with spherocytic shape change and microvesicle generation, important factors in the facilitation of erythrophagocytosis, were increased significantly by betaL. The PS exposure on erythrocytes was from betaL-induced reactive oxygen species generation and subsequent depletion of reduced glutathione and protein thiol, which culminated in the modified activities of phospholipid translocases, i.e., inhibition of flippase and activation of scramblase. It is important to note that coincubation of macrophage with betaL-treated erythrocyte in vitro showed increased erythrophagocytosis, demonstrating that the removal of erythrocyte by macrophage can be facilitated by betaL-induced PS exposure. In good accordance with these in vitro results, after oral administration of betaL in rats, increased PS exposure and depletion of glutathione were observed along with enhanced splenic sequestration of erythrocytes. In conclusion, these results suggest that betaL-induced anemia might be mediated through the PS exposure and subsequent erythrophagocytosis, providing novel insight into the drug-induced anemia.
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Affiliation(s)
- Ji-Yoon Noh
- College of Pharmacy, Seoul National University, Seoul, Korea
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Wells TNC, Burrows JN, Baird JK. Targeting the hypnozoite reservoir of Plasmodium vivax: the hidden obstacle to malaria elimination. Trends Parasitol 2010; 26:145-51. [PMID: 20133198 DOI: 10.1016/j.pt.2009.12.005] [Citation(s) in RCA: 206] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2009] [Revised: 11/17/2009] [Accepted: 12/21/2009] [Indexed: 02/03/2023]
Abstract
Plasmodium vivax is the major species of malaria parasite outside Africa. It is especially problematic in that the infection can relapse in the absence of mosquitoes by activation of dormant hypnozoites in the liver. Medicines that target the erythrocytic stages of Plasmodium falciparum are also active against P. vivax, except where these have been compromised by resistance. However, the only clinical therapy against relapse of vivax malaria is the 8-aminoquinoline, primaquine. This molecule has the drawback of causing haemolysis in genetically sensitive patients and requires 14 days of treatment. New, safer and more-easily administered drugs are urgently needed, and this is a crucial gap in the broader malaria-elimination agenda. New developments in cell biology are starting to open ways to the next generation of drugs against hypnozoites. This search is urgent, given the time needed to develop a new medication.
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Ganesan S, Tekwani BL, Sahu R, Tripathi LM, Walker LA. Cytochrome P(450)-dependent toxic effects of primaquine on human erythrocytes. Toxicol Appl Pharmacol 2009; 241:14-22. [PMID: 19616568 DOI: 10.1016/j.taap.2009.07.012] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2009] [Revised: 07/09/2009] [Accepted: 07/09/2009] [Indexed: 02/02/2023]
Abstract
Primaquine, an 8-aminoquinoline, is the drug of choice for radical cure of relapsing malaria. Use of primaquine is limited due to its hemotoxicity, particularly in populations with glucose-6-phosphate dehydrogenase deficiency [G6PD(-)]. Biotransformation appears to be central to the anti-infective and hematological toxicities of primaquine, but the mechanisms are still not well understood. Metabolic studies with primaquine have been hampered due to the reactive nature of potential hemotoxic metabolites. An in vitro metabolism-linked hemotoxicity assay has been developed. Co-incubation of the drug with normal or G6PD(-) erythrocytes, microsomes or recombinant cytochrome P(450) (CYP) isoforms has allowed in situ generation of potential hemotoxic metabolite(s), which interact with the erythrocytes to generate hemotoxicity. Methemoglobin formation, real-time generation of reactive oxygen intermediates (ROIs) and depletion of reactive thiols were monitored as multiple biochemical end points for hemotoxicity. Primaquine alone did not produce any hemotoxicity, while a robust increase was observed in methemoglobin formation and generation of ROIs by primaquine in the presence of human or mouse liver microsomes. Multiple CYP isoforms (CYP2E1, CYP2B6, CYP1A2, CYP2D6 and CYP3A4) variably contributed to the hemotoxicity of primaquine. This was further confirmed by significant inhibition of primaquine hemotoxicity by the selective CYP inhibitors, namely thiotepa (CYP2B6), fluoxetine (CYP2D6) and troleandomycin (CYP3A4). Primaquine caused similar methemoglobin formation in G6PD(-) and normal human erythrocytes. However, G6PD(-) erythrocytes suffered higher oxidative stress and depletion of thiols than normal erythrocytes due to primaquine toxicity. The results provide significant insights regarding CYP isoforms contributing to hemotoxicity and may be useful in controlling toxicity of primaquine to increase its therapeutic utility.
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Affiliation(s)
- Shobana Ganesan
- National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University MS 38677, USA
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