Paul Ratcliffe

Structure–activity studies of a novel series of isoxazole-3-carboxamide derivatives as TRPV1 antagonists

Optimisation of a screening hit incorporating both TRPV1 activity and solubility was conducted. Substitution of the isoxazole-3-carboxamide with the bespoke 1S, 3R-3-aminocyclohexanol motif afforded the requisite balance of potency and solubility. Compounds 32 and 40 were found to have antihyperalgesic effects in the rat CFA Hg assay and induce a mechanism based hyperthermia.

Novel Pyridyl Substituted 4,5-Dihydro- (1,2,4)triazolo(4,3‑a)quinolines as Potent and Selective Aldosterone Synthase Inhibitors with Improved in Vitro Metabolic Stability

CYP11B2 inhibition is a promising treatment for diseases caused by excessive aldosterone. To improve the metabolic stability in human liver miscrosomes of previously reported CYP11B2 inhibitors, modifications were performed via a combination of ligand- and structure-based drug design approaches, leading to pyridyl 4,5-dihydro-[1,2,4]triazolo[4,3-a]quinolones. Compound 26 not only exhibited a much longer half-life (t1/2 ≫ 120 min), but also sustained inhibitory potency (IC50 = 4.2 nM) and selectivity over CYP11B1 (SF = 422), CYP17, CYP19, and a panel of hepatic CYP enzymes.

Low brain penetrant CB1 receptor agonists for the treatment of neuropathic pain.

Novel, low brain penetrant, orally bioavailable CB1 receptor agonists were designed starting from a mature lead series of potent brain penetrant CB1 receptor agonists. Increasing the calculated polar surface area was found to be a good strategy for reducing brain penetration whilst retaining drug-like properties. This in silico approach led to the discovery of LBP1, an orally bioavailable, low brain penetrant CB1 receptor agonist with robust activity in rodent models of neuropathic pain and a good preclinical therapeutic profile, which was selected for clinical development.

Design, synthesis, and structure–activity relationships of indole-3-heterocycles as agonists of the CB1 receptor

Novel indole-3-heterocycles were designed and synthesized and found to be potent CB1 receptor agonists. Starting from a microsomally unstable lead 1, a bioisostere approach replacing a piperazine amide was undertaken. This was found to be a good strategy for improving stability both in vitro and in vivo. This led to the discovery of 24, which had an increased duration of action in the mouse tail flick test in comparison to the lead 1.

Discovery of potent, soluble and orally active TRPV1 antagonists. Structure-activity relationships of a series of isoxazoles.

Systematic optimisation of a poorly soluble lead series of isoxazole-3-carboxamides was conducted. Substitution of the 4-position with specific polar functionality afforded the requisite balance of potency, solubility and physicochemical properties. Compound 21a was found to be efficacious in the rat Capsaicin Hargreaves assay following oral administration.

Identification of potent, soluble, and orally active TRPV1 antagonists

Optimization of a water soluble, moderately potent lead series of isoxazole-3-carboxamides was conducted, affording a compound with the requisite balance of potency, solubility and physicochemical properties for in vivo use. Compound 8e was demonstrated to be efficacious in a rat model of inflammatory pain, following oral administration.

Imidazopyridyl compounds as aldosterone synthase inhibitors

The inhibition of aldosterone synthase (CYP11B2) may be an effective treatment of hypertension and heart failure, among other ailments. Previously reported benzimidazole CYP11B2 inhibitors led the way for bioisosteric imidazopyridines that are both potent and selective over CYP11B1.

Design, synthesis and structure–activity relationships of (indo-3-yl) heterocyclic derivatives as agonists of the CB1 receptor. Discovery of a clinical candidate

We report an expansion of the structure-activity relationship (SAR) of a novel series of indole-3-heterocyclic CB1 receptor agonists. Starting from the potent but poorly soluble lead, 1, a rational approach was taken in order to balance solubility, hERG activity and potency while retaining the desired long duration of action within the mouse tail flick test. This led to the discovery of compound 38 which successfully progressed into clinical development.

Discovery of potent and orally bioavailable heterocycle-based cannabinoid CB1 receptor agonists

Novel 3-(1H-indol-3-yl)-1,2,4-oxadiazoles and -thiadiazoles were synthesized and found to be potent CB1 cannabinoid receptor agonists. The oral bioavailability of these compounds could be dramatically improved by optimization studies of the side chains attached to the indole and oxadiazole cores, leading to identification of a CB1 receptor agonist with good oral activity in a range of preclinical models of antinociception and antihyperalgesia.