PI4K is a prophylactic, but not radical curative target in Plasmodium vivax-type malaria parasites

Two Plasmodium PI4 kinase inhibitors, KDU691 and LMV599, were selected for in vivo testing as causal prophylactic and radical cure agents of P. cynomolgi sporozoite infected rhesus macaques, based on their in vitro activity against liver-stages. Animals were infected with P. cynomolgi sporozoites and compounds were dosed orally. Both KDU691 and LMV599 compounds were fully protective when administered prophylactically and the more potent compound LMV599 achieved protection as a single oral 25 mg/kg dose. In contrast, when tested for radical cure, five daily doses of 20 mg/kg of KDU691 or 25 mg/kg of LMV599 did not prevent relapse as all animals experienced a secondary infection due to the reactivation of hypnozoites in the liver. Pharmacokinetic data show that LMV599 achieved plasma exposure that were sufficient to achieve efficacy based on our in vitro data. These findings indicate that Plasmodium PI4K is a potential drug target for malaria prophylaxis but not radical cure. Longer in vitro culture systems will be required to assess compounds activity on established hypnozoites and predict radical cure in vivo

Structure activity relationships of 4-hydroxy-2-pyridones: A novel class of antituberculosis agents

Pyridone 1 was identified from a high-throughput cell-based phenotypic screen against Mycobacterium tuberculosis (Mtb) including multi-drug resistant tuberculosis (MDR-TB) as a novel anti-TB agent and subsequently optimized series using cell-based Mtb assay. Preliminary structure activity relationship on the isobutyl group with higher cycloalkyl groups at 6-position of pyridone ring has enabled us to significant improvement of potency against Mtb. The lead compound 30j, a dimethylcyclohexyl group on the 6-position of the pyridone, displayed desirable in vitro potency against both drug sensitive and multi-drug resistant TB clinical isolates. In addition, 30j displayed favorable oral pharmacokinetic properties and demonstrated in vivo efficacy in mouse model. These results emphasize the importance of 4-hydroxy-2-pyridones as a new chemotype and further optimization of properties to treat MDR-TB

Design, synthesis and biological evaluation of indole-2-carboxamides, a promising class of anti-tuberculosis agents

Indole-2-carboxamides have been identified as a promising class of anti-tuberculosis agents from phenotypic whole cell high-throughput screening against mycobacteria. One of the hits KCD644, an N-cyclohexyl-4,6-dimethyl-1H-indole-2-carboxamide had low µM potency, high in vitro mouse liver microsomal clearance and low aqueous solubility. Structure activity relationship studies revealed that attaching further small alkyl groups to the cyclohexyl ring significantly improved activity against Mycobacterium tuberculosis (Mtb) but reduced aq solubility. Further, chloro, fluoro or cyano substitutions on the 4- and 6-positions of the indole ring and mono or dimethyl substitution on the 4-position of the cyclohexyl ring significantly improved both in vitro and in vivo metabolic stability. KDZ304 and KDZ349, the lead candidates from this study displayed improved in vitro activity compared to the current standard TB drugs. The low aq solubility of compounds in the series could not be mitigated due to the correlation of lipophilicity with potency against Mtb. However, both compounds displayed favorable in vivo pharmacokinetic properties in rodents when dosed in a microemulsion preconcentrate formulation (MEPC). Both KDZ304 and KDZ349 delivered good oral exposure and also demonstrated in vivo efficacy in a mouse model. Thus, indole-2-carboxamides represent a promising new class of anti-TB agents

A Translation Inhibitor That Suppresses Dengue Virus In Vitro and In Vivo▿†

We describe a novel translation inhibitor that has anti-dengue virus (DENV) activity in vitro and in vivo. The inhibitor was identified through a high-throughput screening using a DENV infection assay. The compound contains a benzomorphan core structure. Mode-of-action analysis indicated that the compound inhibits protein translation in a viral RNA sequence-independent manner. Analysis of the stereochemistry demonstrated that only one enantiomer of the racemic compound inhibits viral RNA translation. Medicinal chemistry was performed to eliminate a metabolically labile glucuronidation site of the compound to improve its in vivo stability. Pharmacokinetic analysis showed that upon a single subcutaneous dosing of 25 mg/kg of body weight in mice, plasma levels of the compound reached a Cmax (maximum plasma drug concentration) above the protein-binding-adjusted 90% effective concentration (EC90) value of 0.96 μM. In agreement with the in vivo pharmacokinetic results, treatment of DENV-infected mice with 25 mg/kg of compound once per day reduced peak viremia by about 40-fold. However, mice treated with 75 mg/kg of compound per day exhibited adverse effects. Collectively, our results demonstrate that the benzomorphan compounds inhibit DENV through suppression of RNA translation. The therapeutic window of the current compounds needs to be improved for further development

4-hydroxy-2-pyridones, a novel class of promising direct inhA inhibitors active against tuberculosis.

Multi-drug resistant tuberculosis continues to be a major public health threat, particularly in the developing world. New chemotherapeutic agents are urgently required to combat the TB menace. We identified 4-hydroxy-2-pyridones, a new class of small molecules active against Mtb through phenotypic high-throughput screen. A lead candidate, NITD-916, is a potent bactericidal agent with a promising safety profile. NITD-916 demonstrated a dose dependent efficacy in vivo in acute and established mouse-infection models. Mechanism of-action studies identified the molecular target of NITD-916 as enoyl reductase (InhA), the clinically validated target of isoniazid and ethionamide. ITC and X-ray crystallography revealed that NITD-916 specifically binds to InhA in a NADH-dependent manner and blocks the lipid-substrate binding pocket. The NITD-916 co-crystal structure with InhA has opened-up new avenues for structure-guided rational drug discovery on a phenotypic-screening hit. Isoniazid resistant TB clinical isolates that are most frequently encountered remain fully susceptible to NITD-916, demonstrating the potential use of 4-hydroxy-2-pyridones against MDR-TB

A Cryptosporidium PI(4)K inhibitor is a drug candidate for cryptosporidiosis

The apicomplexan parasite Cryptosporidium is a major cause of infectious diarrhea in children and there are no consistently effective therapies to treat this disease. The search for cryptosporidiosis therapeutics has been hindered by the dearth of models amenable to modern drug discovery approaches. We established a cryptosporidiosis drug discovery screening process built on scalable phenotypic assays and a novel mouse model. We identified pyrazolopyridines as selective ATP-competitive inhibitors of the Cryptosporidium lipid kinase PI(4)K. The pyrazolopyridine KDU731 inhibits Cryptosporidium growth in multiple in vitro assays. In addition, oral treatment with KDU731 results in potent reduction in oocyst shedding in Cryptosporidium infected immunocompromised mice as well as rapid resolution of diarrheal symptoms in the neonatal calf cryptosporidiosis model. Collectively, our results chemically validate the Cryptosporidium lipid kinase PI(4)K as a drug target for the treatment of cryptosporidiosis and support the progression of the drug candidate KDU731 to further preclinical characterization

Design, Synthesis, and Biological Evaluation of Indole-2-carboxamides: A Promising Class of Antituberculosis Agents

Indole-2-carboxamides have been identified as a promising class of antituberculosis agents from phenotypic screening against mycobacteria. One of the hits, indole-2-carboxamide analog (<b>1</b>), had low micromolar potency against Mycobacterium tuberculosis (Mtb), high mouse liver microsomal clearance, and low aqueous solubility. Structure–activity relationship studies revealed that attaching alkyl groups to the cyclohexyl ring significantly improved Mtb activity but reduced solubility. Furthermore, chloro, fluoro, or cyano substitutions on the 4- and 6-positions of the indole ring as well as methyl substitution on the cyclohexyl ring significantly improved metabolic stability. <b>39</b> and <b>41</b>, the lead candidates, displayed improved in vitro activity compared to most of the current standard TB drugs. The low aqueous solubility could not be mitigated because of the positive correlation of lipophilicity with Mtb potency. However, both compounds displayed favorable oral pharmacokinetic properties in rodents and demonstrated in vivo efficacy. Thus, indole-2-carboxamides represent a promising new class of antituberculosis agents

Indolcarboxamide, a promising pre-clinical candidate for the treatment of multi drug resistant tuberculosis

To combat the drug resistance in tuberculosis, new chemotherapeutics active against multi-drug resistant Mycobacterium tuberculosis are urgently needed. We have identified and characterized the indolcarboxamides as a new class of anti-tubercular bactericidal agents. Genetics and lipid profiling studies identified the molecular target of indolcarboxamides as mmpL3, a transporter of TMM, a promiscuous target essential for mycobacterial cell wall biosynthesis. Two lead candidates NITD-304 and NITD-349 showed a significantly potent anti-TB activity against both drug sensitive and multi-drug resistant clinical Mtb isolates. Both compounds displayed favorable pharmacokinetic properties after oral administration in pre-clinical species. NITD-304 and NITD-349 showed no apparent inhibition of major CYP enzymes and are highly efficacious in both acute and chronic TB mouse efficacy models. Furthermore, we have assessed in vitro and in vivo safety profile of both candidates including two weeks exploratory rat toxicology studies. NITD-304 and NITD-349 show the adequate therapeutic index to justify further development for inclusion in the combination therapies for drug sensitive as well as drug resistant TB