To realize PDE4 inhibitors with good
developmental potentiality
for the treatment of dementia, structure-based optimizations of lead
compound FCPR03 resulted in novel aminophenylketones 9c and 9H with low nanomolar potency, which displayed
comparable activity to rolipram, satisfactory bioavailability (F% = 36.92 and 42.96% respectively), and good blood–brain
barrier (BBB) permeability switching from the cyclopropyl methoxy
group to the cyclopropyl methylamine and the amide group to the corresponding
ketone. Emetogenicity evaluation on a combined ketamine/xylazine anesthesia
mice alternative model demonstrated that 9H displays
no emetogenicity even at an oral dose of 5 mg/kg. In contrast, rolipram
and roflumilast displayed emetogenicity at an oral dose of 0.5 mg/kg.
In acute toxicological evaluation, 9H showed no obvious
toxicological effect on mice when administered at oral doses below
625 mg/kg. Further investigations revealed that 9H improves
the memory and cognitive impairment of Alzheimer’s disease
(AD) model mice induced by Aβ25–35.