Flavonoid Permeability across the Blood-Brain Barrier
The blood-brain barrier (BBB) is mainly formed by brain capillary endothelial cells, however other cell types such as pericytes, astrocytes and neuronal cells also play an important role . Brain capillary endothelial cells differ from peripheral endothelial cells as brain endothelial cells have tight junctions which prevent paracellular transport of small and large water-soluble compounds from blood to the brain . Transcellular transport is further limited due to low vesicular transport and high metabolic activity. Altogether, the BBB functions as a physical and metabolic barrier . A prerequisite for CNS activity is therefore that flavonoids and their conjugates are able to traverse the BBB and enter the CNS.
Cognition and Neurodegeneration
Evidence is mounting that flavonoids have effect on memory, cognition and neurodegeneration. Although many of the studies in this field have been performed with flavonoid-rich fruits, both these studies and studies with isolated flavonoids indicate that flavonoids have potential to protect neurons against injury induced by neurotoxins and neuroinflammation, a potential to activate synaptic signalling and an ability to improve cerebrovascular blood flow, as has recently been reviewed .
Flavonoids and the CNS
Received: 22 December 2010; in revised form: 21 January 2011 / Accepted: 26 January 2011 /
Published: 10 February 2011