Collaborative Virtual Screening Identifies a 2-Aryl-4-aminoquinazoline Series with Efficacy in an In Vivo Model of Trypanosoma cruzi Infection

Abstract

Probing multiple proprietary pharmaceutical libraries in parallel via virtual screening allowed rapid expansion of the structure-activity relationship (SAR) around hit compounds with moderate efficacy against Trypanosoma cruzi, the causative agent of Chagas Disease. A potency-improving scaffold hop, followed by elaboration of the SAR via design guided by the output of the phenotypic virtual screening efforts, identified two promising hit compounds 54 and 85, which were profiled further in pharmacokinetic studies and in an in vivo model of T. cruzi infection. Compound 85 demonstrated clear reduction of parasitemia in the in vivo setting, confirming the interest in this series of 2-(pyridin-2-yl)quinazolines as potential anti-trypanosome treatments.

Figure 1

Initial hit compound 1 from high-throughput screening (HTS).

Figure 2

Overview of the booster virtual screening process.

Figure 3

Overview of the post-screening design strategy.

Chart 1. Compounds Identified via the Booster Process—Generic Overview of SAR from Booster Only

Scheme 1. Synthesis of Intermediate 27 and Analogue Preparation of Quinazoline Derivatives

Reagents and conditions: (a) HOBT, EDCI, TEA, DMF, rt, 24 h, 85%; (b) 1 N NaOH (aqueous), MeOH, reflux condition, 1 h, 66%; (c) POCl₃, TEA, toluene, reflux condition, overnight, 83%; and (d) amines, n-butanol, 50–110 °C, 12–16 h, or DIEA, solvent (MeCN, DMA or NMP), MW 100–170 °C, 0.5–1 h, 3–98%.

Scheme 2. Core Modification and Analogue Preparation of Pyrrolo[3,2-d]pyrimidine Derivatives

Reagents and conditions: (a) alkyl iodides, Cs₂CO₃, DMF, rt, overnight, 70%; (b) 2-(pyrrolidin-3-yl)pyridine (30), DIEA, THF, rt, 10 h, 71–77%; and (c) (2-pyridine)cyclic-triolborate lithium salt, Pd₂(dba)₃, cuprous chloride, butyl di-1-adamantylphosphine, potassium tert-butoxide, DME, MW 120 °C, 3 h, 19–43%.

Scheme 3. Further Core Modification and Analogue Preparation of Pyrazolopyrimidine and Purine Derivatives

Reagents and conditions: (a) ethyl iodide, K₂CO₃, DMF, rt, 3 h, 70%; (b) iron powder, NH₄Cl, EtOH/H₂O, reflux condition, 2 h, 70%; (c) picolinimidamide (35), DIEA, EtOH, reflux condition, 12 h, 50–93%; (d) POCl₃, toluene, reflux condition, 2 h, 58–87%; (e) 30, n-butanol, 100 °C, overnight, or DIEA, MeCN, MW 120 °C, 2 h, 22–75%; (f) 30, TEA, EtOH, 100 °C, 1 h, or rt, overnight, 27–80%; (g) ethyl iodide, NaH, DMF, rt, 16 h, 37–59%; and (h) 2-(tributylstannyl)pyridine (41), Pd(PPh₃)₄, 1,4-dioxane, reflux condition, 16 h, 11–31%.

Figure 4

Assessment of compound 85 as a treatment for acute-stage Trypanosoma cruzi infections. BALB/c mice (n = 3) at the acute stage of infection (14 days) were treated (50 mg/kg, orally, twice daily) for 5 days. The inset graph shows the total body bioluminescence (sum of ventral and dorsal images) of treated (red) and nontreated (black) mice. The blue bar indicates the treatment period. Gray dotted line represents background + SD.