Pyrroloquinolone PDE5 inhibitors with improved pharmaceutical profiles for clinical studies on erectile dysfunction.

We previously reported a series of potent and selective pyrimidinyl pyrroloquinolone PDE5 inhibitors such as 2a for potential use in male erectile dysfunction (MED) (Sui, Z.; Guan, J.; Macielag, M. J.; Jiang, W.; Zhang, S.; Qiu, Y.; Kraft, P., Bhattacharjee, S.; John, T. M.; Craig, E.; Haynes-Johnson, D.; Clancy, J. J. Med. Chem. 2002, 45, 4094-4096). Unfortunately, the low aqueous solubility and poor oral bioavailability rendered them undesirable development candidates. To address this issue, we designed a series of analogues using two approaches: increasing the overall basicity and reducing molecular weight of the lead. Through earlier SAR studies, we discovered that the PDE5 potency of the pyrroloquinolones is insensitive to substitution on the pyrrole nitrogen. Basic functional groups such as pyridines and benzimidazoles were appended via the aromatic ring connected to the pyrrole nitrogen. Several truncated analogues were also designed and synthesized to improve oral absorption. These modifications allowed us to identify analogues with good oral bioavailability in rats, dogs, and monkeys while the high potency against PDE5 and desirable selectivity versus other PDE isozymes were maintained. Compounds R-11e and R-11l were selected as development candidates for MED and other indications.

Synthesis and SAR of tetracyclic pyrroloquinolones as phosphodiesterase 5 inhibitors.

The synthesis of the fused tetracyclic pyrroloquinolones 9a-i in four steps is described. The PDE5 inhibitory activities of these compounds, their selectivities against PDE1, PDE2, PDE3, PDE4 and PDE6, the preclinical pharmacokinetic assessments and the in vivo efficacy in increasing intracavernosal pressure are presented and discussed.

Synthesis and biological activities of novel beta-carbolines as PDE5 inhibitors.

A series of N(2)-furoyl and N(2)pyrimidinyl beta-carbolines was discovered to possess potent inhibitory activity against PDE5. During the synthesis we developed a tandem resin quenching protocol, which allowed us to synthesize large number of target compounds in a rapid fashion. Representative compounds exhibit superior selectivity to sildenafil versus other isozymes of PDEs, and demonstrated in vivo efficacy in increasing introcavernosal pressure in dogs.

Furoyl and benzofuroyl pyrroloquinolones as potent and selective PDE5 inhibitors for treatment of erectile dysfunction.

Synthesis of furoyl and benzofuroyl pyrroloquinolones as potent and selective PDE5 inhibitors was reported. Their in vitro potencies in inhibiting PDE5 and selectivity in inhibiting other PDE isozymes (PDE1-4 and PDE6) were evaluated. Some of these compounds are more potent than sildenafil with better selectivity toward PDE1 and PDE6. Incorporation of solublizing groups resulted in bioavailable analogues. Selected compounds showed in vivo efficacy in anesthetized dog model for penile erection.

Pyrimidinylpyrroloquinolones as highly potent and selective PDE5 inhibitors for treatment of erectile dysfunction.

A series of N-pyrimidinylpyrroloquinolones were discovered as extremely potent and selective PDE5 inhibitors. Representative compounds demonstrated in vivo efficacy in dog erectile dysfunction models and are orally bioavailable.