In vitro efficacy of next-generation dihydrotriazines and biguanides against babesiosis and malaria parasites.

Babesia and Plasmodium pathogens, the causative agents of babesiosis and malaria, are vector-borne intraerythrocytic protozoan parasites, posing significant threats to both human and animal health. The widespread resistance exhibited by these pathogens to various classes of antiparasitic drugs underscores the need for the development of novel and more effective therapeutic strategies. Antifolates have long been recognized as attractive antiparasitic drugs as they target the folate pathway, which is essential for the biosynthesis of purines and pyrimidines, and thus is vital for the survival and proliferation of protozoan parasites. More efficacious and safer analogs within this class are needed to overcome challenges due to resistance to commonly used antifolates, such as pyrimethamine, and to address liabilities associated with the dihydrotriazines, WR99210 and JPC-2067. Here, we utilized an in vitro culture condition suitable for the continuous propagation of Babesia duncani, Babesia divergens, Babesia MO1, and Plasmodium falciparum in human erythrocytes to screen a library of 50 dihydrotriazines and 29 biguanides for their efficacy in vitro and compared their potency and therapeutic indices across different species and isolates. We identified nine analogs that inhibit the growth of all species, including the P. falciparum pyrimethamine-resistant strain HB3, with IC50 values below 10 nM, and display excellent in vitro therapeutic indices. These compounds hold substantial promise as lead antifolates for further development as broad-spectrum antiparasitic drugs.

JPC-2997, a new aminomethylphenol with high in vitro and in vivo antimalarial activities against blood stages of Plasmodium.

4-(tert-Butyl)-2-((tert-butylamino)methyl)-6-(6-(trifluoromethyl)pyridin-3-yl)-phenol (JPC-2997) is a new aminomethylphenol compound that is highly active in vitro against the chloroquine-sensitive D6, the chloroquine-resistant W2, and the multidrug-resistant TM90-C2B Plasmodium falciparum lines, with 50% inhibitory concentrations (IC50s) ranging from 7 nM to 34 nM. JPC-2997 is >2,500 times less cytotoxic (IC50s > 35 µM) to human (HepG2 and HEK293) and rodent (BHK) cell lines than the D6 parasite line. In comparison to the chemically related WR-194,965, a drug that had advanced to clinical studies, JPC-2997 was 2-fold more active in vitro against P. falciparum lines and 3-fold less cytotoxic. The compound possesses potent in vivo suppression activity against Plasmodium berghei, with a 50% effective dose (ED50) of 0.5 mg/kg of body weight/day following oral dosing in the Peters 4-day test. The radical curative dose of JPC-2997 was remarkably low, at a total dose of 24 mg/kg, using the modified Thompson test. JPC-2997 was effective in curing three Aotus monkeys infected with a chloroquine- and pyrimethamine-resistant strain of Plasmodium vivax at a dose of 20 mg/kg daily for 3 days. At the doses administered, JPC-2997 appeared to be well tolerated in mice and monkeys. Preliminary studies of JPC-2997 in mice show linear pharmacokinetics over the range 2.5 to 40 mg/kg, a low clearance of 0.22 liters/h/kg, a volume of distribution of 15.6 liters/kg, and an elimination half-life of 49.8 h. The high in vivo potency data and lengthy elimination half-life of JPC-2997 suggest that it is worthy of further preclinical assessment as a partner drug.

Folate pathway disruption leads to critical disruption of methionine derivatives in Mycobacterium tuberculosis.

In this study, we identified antifolates with potent, targeted activity against whole-cell Mycobacterium tuberculosis (MTB). Liquid chromatography-mass spectrometry analysis of antifolate-treated cultures revealed metabolic disruption, including decreased pools of methionine and S-adenosylmethionine. Transcriptomic analysis highlighted altered regulation of genes involved in the biosynthesis and utilization of these two compounds. Supplementation with amino acids or S-adenosylmethionine was sufficient to rescue cultures from antifolate treatment. Instead of the "thymineless death" that characterizes folate pathway inhibition in a wide variety of organisms, these data suggest that MTB is vulnerable to a critical disruption of the reactions centered around S-adenosylmethionione, the activated methyl cycle.

Antibacterial activity of quinoxalines, quinazolines, and 1,5-naphthyridines.

Several phenyl substituted naphthalenes and isoquinolines have been identified as antibacterial agents that inhibit FtsZ-Zing formation. In the present study we evaluated the antibacterial of several phenyl substituted quinoxalines, quinazolines and 1,5-naphthyridines against methicillin-sensitive and methicillin-resistant Staphylococcusaureus and vancomycin-sensitive and vancomycin-resistant Enterococcusfaecalis. Some of the more active compounds against S. aureus were evaluated for their effect on FtsZ protein polymerization. Further studies were also performed to assess their relative bactericidal and bacteriostatic activities. The notable differences observed between nonquaternized and quaternized quinoxaline derivatives suggest that differing mechanisms of action are associated with their antibacterial properties.

Synthesis, biological evaluation, and pharmacokinetic study of prolyl-1-piperazinylacetic acid and prolyl-4-piperidinylacetic acid derivatives as VLA-4 antagonists.

A series of prolyl-1-piperazinylacetic acid and prolyl-4-piperidinylacetic acid derivatives were synthesized and evaluated for their activity as VLA-4 antagonists. Of 22 compounds synthesized, 19 compounds showed potent activity with low nanomolar IC50 values. In addition, the representative compounds 11o and 11p with a hydroxy group in the pyrrolidine ring showed moderate plasma clearance in rats (11o, 30 ml/min/kg and 11p, 21 ml/min/kg) and in dogs (11o, 12 ml/min/kg and 11p, 9 ml/min/kg).

Identified a morpholinyl-4-piperidinylacetic acid derivative as a potent oral active VLA-4 antagonist.

An investigation into the structure-activity relationship of a lead compound, prolyl-5-aminopentanoic acid 4, led to the identification of a novel series of 4-piperidinylacetic acid, 1-piperazinylacetic acid, and 4-aminobenzoic acid derivatives as potent VLA-4 antagonists with low nanomolar IC(50) values. A representative compound morpholinyl-4-piperidinylacetic acid derivative (13d: IC(50)=4.4 nM) showed efficacy in the Ascaris-antigen sensitized murine airway inflammation model by oral administration.

Small molecule biaryl FSH receptor agonists. Part 1: Lead discovery via encoded combinatorial synthesis.

High-throughput screening of two million compounds in 37 distinct encoded combinatorial libraries using FSH receptor transfected cells provided small molecule agonists such as 1 (EC(50)=3 microM) and 2 (EC(50)=3.9 microM), based on which a focused combinatorial library with a total of 31372 compounds was designed, synthesized, and screened to reveal 72 novel biaryl FSH receptor agonists such as 8a-c as well as a unique combinatorial SAR.

Small molecule biaryl FSH receptor agonists. Part 2: Lead optimization via parallel synthesis.

Potent small molecule biaryl diketopiperazine FSH receptor agonists such as 10c (EC(50)=13 nM) and 11f (EC(50)=1.2 nM) were discovered through the design, synthesis and evaluation of three biaryl diketopiperazine optimization libraries with over 300 compounds. These libraries were prepared via solid-phase parallel synthesis using a cyclization-release method.