Brain-Penetrant TetrahydronaphthaleneThromboxaneA2-Prostanoid (TP) Receptor Antagonists as Prototype Therapeuticsfor Alzheimer’s Disease

摘要

A hallmark pathological feature of the Alzheimer’s disease (AD) brain is the presence of senile plaques, which comprise amyloid β (Aβ) peptides that are derived from the amyloid precursor protein (APP). The plaque-containing AD brain is thought to be under oxidative stress, as evidenced by increased lipid oxidation products that include isoprostane-F2αIII (iPF2αIII). IPF2αIII can bind to and activate the thromboxane A2-prostanoid (TP) receptor, and TP receptor activation causes increased Aβ production through enhancement of APP mRNA stability. Moreover, TP receptor antagonists have been shown to block iPF2αIII-induced increases of Aβ secretion. Thus, the TP receptor may be a potential drug target for AD therapy. However, here we show that existing TP receptor antagonists have poor blood-brain barrier (BBB) permeability, likely due to the presence of a carboxylic acid moiety that is believed to be important for receptor interaction, but which may hamper passive diffusion acrossthe BBB. We now report selected analogues of a known tetrahydronaphthaleneTP receptor antagonist, wherein the carboxylic acid moiety has beenreplaced by heterocyclic bioisosteres. These heterocyclic analoguesretained relatively high affinity for the mouse and human TP receptors,and, unlike the parent carboxylic acid compound, several examplesfreely diffused across the BBB into the brain upon administrationto mice. These results reveal that brain-penetrant tetrahydronaphthaleneTP receptor antagonists can be developed by substituting the carboxylicacid moiety with a suitable nonacidic bioisostere. Compounds of thistype hold promise as potential lead structures to develop drug candidatesfor the treatment of AD.