Potential neuroprotective role of anthocyanins and anthocyanidins mediated by proteasome inhibition

Objective: Recent reports have demonstrated multiple benefits associated with the consumption of blueberries, including decreased vulnerability to oxidative stress, reduced ischemic brain damage, protection of neurons form stroke-induced damage and reversion of age-related changes in brain and behaviour. Regarding the secondary metabolites of berry fruits, anthocyanins count among the main constituents. The present study addresses proteasome inhibition as a possible mechanism by which anthocyanins and their aglycons, the anthocyanidins, may exert health-promoting effects. Methods: HL-60 cells were incubated with test substances and inhibition of the chymotrypsin-like enzyme activity was determined with a chemiluminescent assay. Results: Anthocyanins and their aglycons inhibited proteasome activity in a concentration-dependent manner and achieved IC50 values ranging from 7.8µmol/L for kaempferidinidin and pelargonidin, to 32.4µmol/L for delphinidin. Conclusions: Proteasome inhibitory properties of anthocyanins may contribute to their known anticarcinogenic, antioxidative, anti-inflammatory and neuroprotective activities, rationalizing dietary supplementations with anthocyanins in the prevention and treatment of cancer, stroke and neurodegenerative diseases.