Multitargeted drug development: Discovery and profiling of dihydroxy substituted 1-aza-9-oxafluorenes as lead compounds targeting Alzheimer disease relevant kinases

Alzheimer disease (AD) turned out to be a multifactorial process leading to neuronal decay. So far merely single target structures which attribute to the AD progression have been considered to develop specific drugs. However, such drug developments have been disappointing in clinical stages. Multitargeting of more than one target structure determines recent studies of developing novel lead compounds. Protein kinases have been identified to contribute to the neuronal decay with CDK1, GSK-3β and CDK5/p25 being involved in a pathological tau protein hyperphosphorylation. We discovered novel lead structures of the dihydroxy-1-aza-9-oxafluorene type with nanomolar activities against CDK1, GSK-3β and CDK5/p25. Structure-activity relationships (SAR) of the protein kinase inhibition are discussed within our first compound series. One nanomolar active compound profiled as selective protein kinase inhibitor. Bioanalysis of a harmless cellular toxicity and of the inhibition of tau protein phosphorylation qualifies the compound for further studies.