ABSTRACT
Conceptual design and modification of urea moiety in chemotype PF-3845/04457845, the bench marking irreversible inhibitor of fatty acid amide hydrolase (FAAH), led to discovery of a novel nicotinamide-based lead 12a having reversible mechanism of action. Focused SAR around the pyridine heterocycle (Ar) in 12a (Tables 1 and 2) resulted into four shortlisted compounds, (-)-12a, (-)-12i, (-)-12l-m. The required (-)-enantiomers were obtained via diastereomeric resolution of a novel chiral dissymmetric intermediate 15. Based on comparative profile of FAAH potency, metabolic stability in liver microsome, liability of inhibiting major hCYP450 isoforms, rat PK, and brain penetration ability, two SAR optimized compounds, (-)-12l and (-)-12m, were selected for efficacy study in rat model of chemotherapy-induced peripheral neuropathy (CIPN). Both the compounds exhibited dose related antihyperalgesic effects, when treated with 3-30â¯mg/kg po for 7â¯days. The effects at 30â¯mg/kg are comparable to that of PF-04457845 (10â¯mg/kg) and Tramadol (40â¯mg/kg).
Subject(s)
Amidohydrolases/antagonists & inhibitors , Drug Discovery , Enzyme Inhibitors/pharmacology , Hypoglycemic Agents/pharmacology , Neuralgia/drug therapy , Amidohydrolases/metabolism , Animals , Antineoplastic Agents/adverse effects , Disease Models, Animal , Dose-Response Relationship, Drug , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/chemistry , Humans , Hypoglycemic Agents/chemical synthesis , Hypoglycemic Agents/chemistry , Molecular Structure , Neuralgia/metabolism , Rats , Structure-Activity RelationshipABSTRACT
Adenosine A2A receptor (A2AAdoR) antagonism is a nondopaminergic approach to Parkinson's disease treatment that is under development. Earlier we had reported the therapeutic potential of 7-methoxy-4-morpholino-benzothiazole derivatives as A2AAdoR antagonists. We herein described a novel series of [1,2,4]triazolo[5,1-f]purin-2-one derivatives that displays functional antagonism of the A2A receptor with a high degree of selectivity over A1, A2B, and A3 receptors. Compounds from this new scaffold resulted in the discovery of highly potent, selective, stable, and moderate brain penetrating compound 33. Compound 33 endowed with satisfactory in vitro and in vivo pharmacokinetics properties. Compound 33 demonstrated robust oral efficacies in two commonly used models of Parkinson's disease (haloperidol-induced catalepsy and 6-OHDA lesioned rat models) and depression (TST and FST mice models).
