Evaluation of Blood–Brain Barrier Permeability of Polyphenols, Anthocyanins, and Their Metabolites

Anthocyanins (ACs) are able to protect neurons against β-amyloid-induced neurotoxicity. In this study, we evaluated blood-brain barrier (BBB) permeability of these compounds using a model kit to clarify the mechanism of AC on the brain. Black currant or strawberry AC extract was orally administrated to male Wistar rats. The urine and extirpated brain were collected before and after administration and analyzed quantitatively by liquid chromatography-tandem mass spectrometry. After administration of AC, several phenolic acids were detected in the urine samples. Further, AC and some AC metabolites were found in the brain tissue. BBB permeabilities of these compounds were much lower than the positive control. Epigallocatechin, daidzein, genistein, equol, and nobiletin presented high BBB permeability, whereas apigenin, luteolin, quercetin, and kaempferol showed medium permeability, and epicatechin, rutin, fisetin, resveratrol, and curcumin BBB permeation was neglected. These results suggested that ACs were difficult to cross BBB into the brain and ACs were not directly associated with the prevention of β-amyloid-induced neurotoxicity.