Design, synthesis, and enzymatic characterization of quinazoline-based CYP1A2 inhibitors.

Cytochrome P450 isozyme 1A2 (CYP1A2) is one main xenobiotic metabolizing enzyme in humans. It has been associated with the bioactivation of procarcinogens, including 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), a tobacco specific and potent pulmonary carcinogen. This work describes the computational design and in-silico screening of potential CYP1A2 inhibitors, their chemical synthesis, and enzymatic characterization with the ultimate aim of assessing their potential as cancer chemopreventive agents. To achieve this, a combined classifiers model was used to screen a library of quinazoline-based molecules against known CYP1A2 inhibitors, non-inhibitors, and substrates to predict which quinazoline candidates had a better probability as an inhibitor. Compounds with high probability of CYP1A2 inhibition were further computationally evaluated via Glide docking. Candidates predicted to have selectivity and high binding affinity for CYP1A2 were synthesized and assayed for their enzymatic inhibition of CYP1A2, leading to the discovery of novel and potent quinazoline-based CYP1A2 inhibitors.

Design and synthesis of selective CYP1B1 inhibitor via dearomatization of α-naphthoflavone.

Selective cytochrome P450 (CYP) 1B1 inhibition has potential as an anticancer strategy that is unrepresented in the current clinical arena. For development of a selective inhibitor, we focused on the complexity caused by sp3-hybridized carbons and synthesized a series of benzo[h]chromone derivatives linked to a non-aromatic B-ring using α-naphthoflavone (ANF) as the lead compound. Ring structure comparison suggested compound 37 as a suitable cyclohexyl-core with improved solubility. Structural evolution of 37 produced the azide-containing cis-49a, which had good properties in three important respects: (1) selectivity for CYP1B1 over CYP1A1 and CYP1A2 (120-times and 150-times, respectively), (2) greater inhibitory potency of >2 times that of ANF, and (3) improved solubility. The corresponding aromatic B-ring compound 59a showed low selectivity and poor solubility. To elucidate the binding mode, we performed X-ray crystal structure analysis, which revealed the interaction mode and explained the subtype selectivity of cis-49a.

Scaffold Hopping and Optimization of Maleimide Based Porcupine Inhibitors.

Porcupine is an O-acyltransferase that regulates Wnt secretion. Inhibiting porcupine may block the Wnt pathway which is often dysregulated in various cancers. Consequently porcupine inhibitors are thought to be promising oncology therapeutics. A high throughput screen against porcupine revealed several potent hits that were confirmed to be Wnt pathway inhibitors in secondary assays. We developed a pharmacophore model and used the putative bioactive conformation of a xanthine inhibitor for scaffold hopping. The resulting maleimide scaffold was optimized to subnanomolar potency while retaining good physical druglike properties. A preclinical development candidate was selected for which extensive in vitro and in vivo profiling is reported.

Discovery and Optimization of Chromeno[2,3-c]pyrrol-9(2H)-ones as Novel Selective and Orally Bioavailable Phosphodiesterase 5 Inhibitors for the Treatment of Pulmonary Arterial Hypertension.

Phosphodiesterase 5 (PDE5) inhibitors have been used as clinical agents to treat erectile dysfunction and pulmonary arterial hypertension (PAH). Herein, we detail the discovery of a novel series of chromeno[2,3-c]pyrrol-9(2H)-one derivatives as selective and orally bioavailable inhibitors against phosphodiesterase 5. Medicinal chemistry optimization resulted in 2, which exhibits a desirable inhibitory potency of 5.6 nM with remarkable selectivity as well as excellent pharmacokinetic properties and an oral bioavailability of 63.4%. In addition, oral administration of 2 at a dose of 5.0 mg/kg caused better pharmacodynamics effects on both mPAP (mean pulmonary artery pressure) and RVHI (index of right ventricle hypertrophy) than sildenafil citrate at a dose of 10.0 mg/kg. These activities along with its reasonable druglike properties, such as human liver microsomal stability, cytochrome inhibition, hERG inhibition, and pharmacological safety, indicate that 2 is a potential candidate for the treatment of PAH.