Chemical Modification of the Multitarget Neuroprotective Compound Fisetin

Many factors are implicated in age-related central nervous system (CNS) disorders, making it unlikely that modulating only a single factor will provide effective treatment. Perhaps a better approach is to identify small molecules that have multiple biological activities relevant to the maintenance of brain function. Recently, we identified an orally active, neuroprotective, and cognition-enhancing molecule, the flavonoid fisetin, that is effective in several animal models of CNS disorders. Fisetin has direct antioxidant activity and can also increase the intracellular levels of glutathione (GSH), the major endogenous antioxidant. In addition, fisetin has both neurotrophic and anti-inflammatory activity. However, its relatively high EC50 in cell based assays, low lipophilicity, high topological polar surface area (tPSA), and poor bioavailability suggest that there is room for medicinal chemical improvement. Here we describe a multitiered approach to screening that has allowed us to identify fisetin derivatives with significantly enhanced activity in an in vitro neuroprotection model while at the same time maintaining other key activities.