TheREnantiomer of the Antitubercular Drug PA-824 as a Potential Oral Treatment for Visceral Leishmaniasis

ABSTRACTThe novel nitroimidazopyran agent (S)-PA-824 has potent antibacterial activity againstMycobacterium tuberculosisin vitroandin vivoand is currently in phase II clinical trials for tuberculosis (TB). In contrast toM. tuberculosis, where (R)-PA-824 is inactive, we report here that both enantiomers of PA-824 show potent parasiticidal activity againstLeishmania donovani, the causative agent of visceral leishmaniasis (VL). In leishmania-infected macrophages, (R)-PA-824 is 6-fold more active than (S)-PA-824. Both des-nitro analogues are inactive, underlining the importance of the nitro group in the mechanism of action. Although thein vitroandin vivopharmacological profiles of the two enantiomers are similar, (R)-PA-824 is more efficacious in the murine model of VL, with >99% suppression of parasite burden when administered orally at 100 mg kg of body weight−1, twice daily for 5 days. InM. tuberculosis, (S)-PA-824 is a prodrug that is activated by a deazaflavin-dependent nitroreductase (Ddn), an enzyme which is absent inLeishmaniaspp. Unlike the case with nifurtimox and fexinidazole, transgenic parasites overexpressing the leishmania nitroreductase are not hypersensitive to either (R)-PA-824 or (S)-PA-824, indicating that this enzyme is not the primary target of these compounds. Drug combination studiesin vitroindicate that fexinidazole and (R)-PA-824 are additive whereas (S)-PA-824 and (R)-PA-824 show mild antagonistic behavior. Thus, (R)-PA-824 is a promising candidate for late lead optimization for VL and may have potential for future use in combination therapy with fexinidazole, currently in phase II clinical trials against VL.

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Antileishmanial Efficacy and Pharmacokinetics of DB766-Azole Combinations

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01129-17 ◽

2017 ◽

Vol 62 (1) ◽

Cited By ~ 4

Author(s):

April C. Joice ◽

Sihyung Yang ◽

Abdelbasset A. Farahat ◽

Heidi Meeds ◽

Mei Feng ◽

...

Keyword(s):

Visceral Leishmaniasis ◽

Leishmania Donovani ◽

Treatment Strategies ◽

Parasite Burden ◽

Pharmacokinetic Analysis ◽

Content Type ◽

New Treatment ◽

Almost All

ABSTRACT Given the limitations of current antileishmanial drugs and the utility of oral combination therapy for other infections, developing an oral combination against visceral leishmaniasis should be a high priority. In vitro combination studies with DB766 and antifungal azoles against intracellular Leishmania donovani showed that posaconazole and ketoconazole, but not fluconazole, enhanced DB766 potency. Pharmacokinetic analysis of DB766-azole combinations in uninfected Swiss Webster mice revealed that DB766 exposure was increased by higher posaconazole and ketoconazole doses, while DB766 decreased ketoconazole exposure. In L. donovani-infected BALB/c mice, DB766-posaconazole combinations given orally for 5 days were more effective than DB766 or posaconazole alone. For example, 81% ± 1% (means ± standard errors) inhibition of liver parasite burden was observed for 37.5 mg/kg of body weight DB766 plus 15 mg/kg posaconazole, while 37.5 mg/kg DB766 and 15 mg/kg posaconazole administered as monotherapy gave 40% ± 5% and 21% ± 3% inhibition, respectively. Combination index (CI) analysis indicated that synergy or moderate synergy was observed in six of nine combined dose groups, while the other three were nearly additive. Liver concentrations of DB766 and posaconazole increased in almost all combination groups compared to monotherapy groups, although many increases were not statistically significant. For DB766-ketoconazole combinations evaluated in this model, two were antagonistic, one displayed synergy, and one was nearly additive. These data indicate that the efficacy of DB766-posaconazole and DB766-ketoconazole combinations in vivo is influenced in part by the pharmacokinetics of the combination, and that the former combination deserves further consideration in developing new treatment strategies against visceral leishmaniasis.

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Novel Arylimidamides for Treatment of Visceral Leishmaniasis

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00250-10 ◽

2010 ◽

Vol 54 (6) ◽

pp. 2507-2516 ◽

Cited By ~ 44

Author(s):

Michael Zhuo Wang ◽

Xiaohua Zhu ◽

Anuradha Srivastava ◽

Qiang Liu ◽

J. Mark Sweat ◽

...

Keyword(s):

Visceral Leishmaniasis ◽

Leishmania Donovani ◽

Leishmania Major ◽

Oral Treatment ◽

Antileishmanial Activity ◽

Repeat Dose ◽

Lead Discovery ◽

Preclinical Development

ABSTRACT Arylimidamides (AIAs) represent a new class of molecules that exhibit potent antileishmanial activity (50% inhibitory concentration [IC50], <1 μM) against both Leishmania donovani axenic amastigotes and intracellular Leishmania, the causative agent for human visceral leishmaniasis (VL). A systematic lead discovery program was employed to characterize in vitro and in vivo antileishmanial activities, pharmacokinetics, mutagenicities, and toxicities of two novel AIAs, DB745 and DB766. They were exceptionally active (IC50 ≤ 0.12 μM) against intracellular L. donovani, Leishmania amazonensis, and Leishmania major and did not exhibit mutagenicity in an Ames screen. DB745 and DB766, given orally, produced a dose-dependent inhibition of liver parasitemia in two efficacy models, L. donovani-infected mice and hamsters. Most notably, DB766 (100 mg/kg of body weight/day for 5 days) reduced liver parasitemia in mice and hamsters by 71% and 89%, respectively. Marked reduction of parasitemia in the spleen (79%) and bone marrow (92%) of hamsters was also observed. Furthermore, these compounds distributed to target tissues (liver and spleen) and had a moderate oral bioavailability (up to 25%), a large volume of distribution, and an elimination half-life ranging from 1 to 2 days in mice. In a repeat-dose toxicity study of mice, there was no indication of liver or kidney toxicity for DB766 from serum chemistries, although mild hepatic cell eosinophilia, hypertrophy, and fatty changes were noted. These results demonstrated that arylimidamides are a promising class of molecules that possess good antileishmanial activity and desirable pharmacokinetics and should be considered for further preclinical development as an oral treatment for VL.

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Nanotized Curcumin and Miltefosine, a Potential Combination for Treatment of Experimental Visceral Leishmaniasis

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01169-16 ◽

2016 ◽

Vol 61 (3) ◽

Cited By ~ 27

Author(s):

Brajendra Tiwari ◽

Richa Pahuja ◽

Pradeep Kumar ◽

Srikanta Kumar Rath ◽

Kailash Chand Gupta ◽

...

Keyword(s):

Visceral Leishmaniasis ◽

Leishmania Donovani ◽

Oral Drug ◽

Hamster Model ◽

Content Type ◽

Leishmanicidal Activity ◽

Traditional Indian Medicine ◽

Indian Medicine

ABSTRACT Leishmaniasis chemotherapy remains very challenging due to high cost of the drug and its associated toxicity and drug resistance, which develops over a period of time. Combination therapies (CT) are now in use to treat many diseases, such as cancer and malaria, since it is more effective and affordable than monotherapy. CT are believed to represent a new explorable strategy for leishmaniasis, a neglected tropical disease caused by the obligate intracellular parasite Leishmania. In the present study, we investigated the effect of a combination of a traditional Indian medicine (ayurveda), a natural product curcumin and miltefosine, the only oral drug for visceral leishmaniasis (VL) using a Leishmania donovani-hamster model. We developed an oral nanoparticle-based formulation of curcumin. Nanoformulation of curcumin alone exhibited significant leishmanicidal activity both in vitro and in vivo. In combination with miltefosine, it exhibited a synergistic effect on both promastigotes and amastigotes under in vitro conditions. The combination of these two agents also demonstrated increased in vivo leishmanicidal activity accompanied by increased production of toxic reactive oxygen/nitrogen metabolites and enhanced phagocytic activity. The combination also exhibited increased lymphocyte proliferation. The present study thus establishes the possible use of nanocurcumin as an adjunct to antileishmanial chemotherapy.

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Discovery of Safe and Orally Effective 4-Aminoquinaldine Analogues as Apoptotic Inducers with Activity against Experimental Visceral Leishmaniasis

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00700-11 ◽

2011 ◽

Vol 56 (1) ◽

pp. 432-445 ◽

Cited By ~ 17

Author(s):

Partha Palit ◽

Abhijit Hazra ◽

Arindam Maity ◽

R. S. K. Vijayan ◽

Prabu Manoharan ◽

...

Keyword(s):

Visceral Leishmaniasis ◽

Oral Delivery ◽

Leishmania Donovani ◽

Reactive Oxygen Species Generation ◽

Oral Route ◽

Apoptotic Pathway ◽

Content Type ◽

Lead Compounds

ABSTRACTNovel antileishmanials are urgently required to overcome emergence of drug resistance, cytotoxic effects, and difficulties in oral delivery. Toward this, we investigated a series of novel 4-aminoquinaldine derivatives, a new class of molecules, as potential antileishmanials. 4-Aminoquinaldine derivatives presented inhibitory effects onL. donovanipromastigotes and amastigotes (50% inhibitory concentration range, 0.94 to 127 μM). Of these, PP-9 and PP-10 were the most effectivein vitroand demonstrated strong efficaciesin vivothrough the intraperitoneal route. They were also found to be effective against both sodium antimony gluconate-sensitive and -resistantLeishmania donovanistrains in BALB/c mice when treated orally, resulting in more than 95% protection. Investigation of their mode of action revealed that killing by PP-10 involved moderate inhibition of dihydrofolate reductase and elicitation of the apoptotic cascade. Our studies implicate that PP-10 augments reactive oxygen species generation, evidenced from decreased glutathione levels and increased lipid peroxidation. Subsequent disruption ofLeishmaniapromastigote mitochondrial membrane potential and activation of cytosolic proteases initiated the apoptotic pathway, resulting in DNA fragmentation and parasite death. Our results demonstrate that PP-9 and PP-10 are promising lead compounds with the potential for treating visceral leishmaniasis (VL) through the oral route.

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Immunoadjuvant Chemotherapy of Visceral Leishmaniasis in Hamsters Using Amphotericin B-Encapsulated Nanoemulsion Template-Based Chitosan Nanocapsules

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01984-12 ◽

2013 ◽

Vol 57 (4) ◽

pp. 1714-1722 ◽

Cited By ~ 61

Author(s):

Shalini Asthana ◽

Anil K. Jaiswal ◽

Pramod K. Gupta ◽

Vivek K. Pawar ◽

Anuradha Dube ◽

...

Keyword(s):

Visceral Leishmaniasis ◽

Amphotericin B ◽

Leishmania Donovani ◽

Transforming Growth Factor ◽

Treatment Options ◽

Interleukin 12 ◽

Necrosis Factor Alpha ◽

Content Type

ABSTRACTThe accessible treatment options for life-threatening neglected visceral leishmaniasis (VL) disease have problems with efficacy, stability, adverse effects, and cost, making treatment a complex issue. Here we formulated nanometric amphotericin B (AmB)-encapsulated chitosan nanocapsules (CNC-AmB) using a polymer deposition technique mediated by nanoemulsion template fabrication. CNC-AmB exhibited good steric stabilityin vitro, where the chitosan content was found to be efficient at preventing destabilization in the presence of protein and Ca2+. A toxicity study on the model cell line J774A and erythrocytes revealed that CNC-AmB was less toxic than commercialized AmB formulations such as Fungizone and AmBisome. The results ofin vitro(macrophage-amastigote system; 50% inhibitory concentration [IC50], 0.19 ± 0.04 μg AmB/ml) andin vivo(Leishmania donovani-infected hamsters; 86.1% ± 2.08% parasite inhibition) experiments in conjunction with effective internalization by macrophages illustrated the efficacy of CNC-AmB at augmenting antileishmanial properties. Quantitative mRNA analysis by real-time PCR (RT-PCR) showed that the improved effect was synergized with the upregulation of tumor necrosis factor alpha (TNF-α), interleukin-12 (IL-12), and inducible nitric oxide synthase and with the downregulation of transforming growth factor β (TGF-β), IL-10, and IL-4. These research findings suggest that a cost-effective CNC-AmB immunoadjuvant chemotherapeutic delivery system could be a viable alternative to the current high-cost commercial lipid-based formulations.

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The anti-tubercular drug delamanid as a potential oral treatment for visceral leishmaniasis

eLife ◽

10.7554/elife.09744 ◽

2016 ◽

Vol 5 ◽

Cited By ~ 41

Author(s):

Stephen Patterson ◽

Susan Wyllie ◽

Suzanne Norval ◽

Laste Stojanovski ◽

Frederick RC Simeons ◽

...

Keyword(s):

Visceral Leishmaniasis ◽

Dose Response ◽

Leishmania Donovani ◽

Oral Treatment ◽

Cost Effective ◽

Resistant Tuberculosis ◽

Multi Drug Resistant Tuberculosis ◽

Effective Drugs

There is an urgent requirement for safe, oral and cost-effective drugs for the treatment of visceral leishmaniasis (VL). We report that delamanid (OPC-67683), an approved drug for multi-drug resistant tuberculosis, is a potent inhibitor of Leishmania donovani both in vitro and in vivo. Twice-daily oral dosing of delamanid at 30 mg kg-1 for 5 days resulted in sterile cures in a mouse model of VL. Treatment with lower doses revealed a U-shaped (hormetic) dose-response curve with greater parasite suppression at 1 mg kg-1 than at 3 mg kg-1 (5 or 10 day dosing). Dosing delamanid for 10 days confirmed the hormetic dose-response and improved the efficacy at all doses investigated. Mechanistic studies reveal that delamanid is rapidly metabolised by parasites via an enzyme, distinct from the nitroreductase that activates fexinidazole. Delamanid has the potential to be repurposed as a much-needed oral therapy for VL.

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Antileishmanial Activities of Stearylamine-Bearing Liposomes

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.44.6.1739-1742.2000 ◽

2000 ◽

Vol 44 (6) ◽

pp. 1739-1742 ◽

Cited By ~ 37

Author(s):

Tuhina Dey ◽

Khairul Anam ◽

Farhat Afrin ◽

Nahid Ali

Keyword(s):

Single Dose ◽

Visceral Leishmaniasis ◽

Leishmania Donovani ◽

Therapeutic Potential ◽

Parasite Burden ◽

Intracellular Amastigotes ◽

Antileishmanial Activities

ABSTRACT Here we report the activity of liposomes comprising egg phosphatidylcholine (PC) and stearylamine (SA) against Leishmania donovani parasites. Both promastigotes and intracellular amastigotes in vitro and in vivo were susceptible to SA-PC liposomes. A single dose of 55 mg of SA-PC liposomes/animal could significantly reduce the hepatic parasite burden by 85 and 68% against recent and established experimental visceral leishmaniasis, respectively, suggesting their strong therapeutic potential.

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PREPARATION AND CHARACTERIZATION OF ANDROGRAPHOLIDE NANOPARTICLES FOR VISCERAL LEISHMANIASIS CHEMOTHERAPY: IN VITRO AND IN VIVO EVALUATIONS

International Journal of Pharmacy and Pharmaceutical Sciences ◽

10.22159/ijpps.2016v8i12.14773 ◽

2016 ◽

Vol 8 (12) ◽

pp. 102

Author(s):

Pallab Ghosh ◽

Subhasish Mondal ◽

Tanmoy Bera

Keyword(s):

Visceral Leishmaniasis ◽

Leishmania Donovani ◽

Parasite Burden ◽

Plga Nanoparticles ◽

Antileishmanial Activity ◽

Infection Model ◽

Vitamin E Tpgs ◽

Polyethylene Glycol 1000

Objective: To overcome low physiological solubility, poor bioavailability, the short plasma half-life of andrographolide (AG), a delivery system based on poly (D, L-lactide-co-glycolide) (PLGA) nanoparticles (NPs) were developed to increase the efficiency of AG against visceral leishmaniasis (VL). Methods: Andrographolide-PLGA nanoparticles (AGnp) were prepared with Pgp efflux inhibitor vitamin E TPGS (D-α-tocopheryl polyethylene glycol 1000 succinate) by emulsion solvent evaporation method and characterized. Antileishmanial activity was evaluated using in vitro and in vivo VL infection model. Results: The particle size of AGnp was found to be171.4±11.5 nm with an encapsulation efficiency of 81%. The AGnp reduced AG cellular toxicity, retained it's in vitro antileishmanial activity and lead to a reduction (99.9%) of parasite burden in the Leishmania donovani infected spleen and liver. AGnp was more active in infected mice liver at low dose than in spleen. Therapeutic indexes (TI) were 6.9-fold greater in AG and 68-fold in AGnp compared to amphotericin B (AmB) when evaluated in L. donovani infected spleen. Conclusion: Incorporation of AG in PLGA nanoparticles, provided controlled and improved in vivo performance against VL

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TCP1γ Subunit Is Indispensable for Growth and Infectivity of Leishmania donovani

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00669-20 ◽

2020 ◽

Vol 64 (8) ◽

Cited By ~ 1

Author(s):

Shailendra Yadav ◽

Jitendra Kuldeep ◽

Mohammad I. Siddiqi ◽

Neena Goyal

Keyword(s):

Cell Cycle Progression ◽

Leishmania Donovani ◽

Gene Replacement ◽

Titration Calorimetry ◽

Content Type ◽

T Complex ◽

Complex Protein ◽

Oligomeric Complex

ABSTRACT T-complex protein-1 (TCP1) is a ubiquitous group II chaperonin and is known to fold various proteins, such as actin and tubulin. In Leishmania donovani, the γ subunit of TCP1 (LdTCP1γ) has been cloned and characterized. It forms a high-molecular-weight homo-oligomeric complex that performs ATP-dependent protein folding. In the present study, we evaluated the essentiality of the LdTCP1γ gene. Gene replacement studies indicated that LdTCP1γ is essential for parasite survival. The LdTCP1γ single-allele-replacement mutants exhibited slowed growth and decreased infectivity in mouse macrophages compared to the growth and infectivity of the wild-type parasites. Modulation of LdTCP1γ expression in promastigotes also modulated cell cycle progression. Suramin, an antitrypanosomal drug, not only inhibited the luciferase refolding activity of the recombinant LdTCP1γ (rLdTCP1γ) homo-oligomeric complex but also exhibited potential antileishmanial efficacy both in vitro and in vivo. The interaction of suramin and LdTCP1γ was further validated by isothermal titration calorimetry. The study suggests LdTCP1γ as a potential drug target and also provides a framework for the development of a new class of drugs.

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Transcriptomic Signatures Predict Regulators of Drug Synergy and Clinical Regimen Efficacy against Tuberculosis

mBio ◽

10.1128/mbio.02627-19 ◽

2019 ◽

Vol 10 (6) ◽

Cited By ~ 6

Author(s):

Shuyi Ma ◽

Suraj Jaipalli ◽

Jonah Larkins-Ford ◽

Jenny Lohmiller ◽

Bree B. Aldridge ◽

...

Keyword(s):

Clinical Trials ◽

Computational Model ◽

Drug Combinations ◽

Broth Culture ◽

Multiple Drug ◽

Content Type ◽

Drug Synergy ◽

Drug Regimens

ABSTRACT The rapid spread of multidrug-resistant strains has created a pressing need for new drug regimens to treat tuberculosis (TB), which kills 1.8 million people each year. Identifying new regimens has been challenging due to the slow growth of the pathogen Mycobacterium tuberculosis (MTB), coupled with the large number of possible drug combinations. Here we present a computational model (INDIGO-MTB) that identified synergistic regimens featuring existing and emerging anti-TB drugs after screening in silico more than 1 million potential drug combinations using MTB drug transcriptomic profiles. INDIGO-MTB further predicted the gene Rv1353c as a key transcriptional regulator of multiple drug interactions, and we confirmed experimentally that Rv1353c upregulation reduces the antagonism of the bedaquiline-streptomycin combination. A retrospective analysis of 57 clinical trials of TB regimens using INDIGO-MTB revealed that synergistic combinations were significantly more efficacious than antagonistic combinations (P value = 1 × 10−4) based on the percentage of patients with negative sputum cultures after 8 weeks of treatment. Our study establishes a framework for rapid assessment of TB drug combinations and is also applicable to other bacterial pathogens. IMPORTANCE Multidrug combination therapy is an important strategy for treating tuberculosis, the world’s deadliest bacterial infection. Long treatment durations and growing rates of drug resistance have created an urgent need for new approaches to prioritize effective drug regimens. Hence, we developed a computational model called INDIGO-MTB that identifies synergistic drug regimens from an immense set of possible drug combinations using the pathogen response transcriptome elicited by individual drugs. Although the underlying input data for INDIGO-MTB was generated under in vitro broth culture conditions, the predictions from INDIGO-MTB correlated significantly with in vivo drug regimen efficacy from clinical trials. INDIGO-MTB also identified the transcription factor Rv1353c as a regulator of multiple drug interaction outcomes, which could be targeted for rationally enhancing drug synergy.

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