Computational studies suggest urolithin A crosses the blood-brain barrier.
From the article:
Alzheimer’s disease is associated with ß-amyloid (Aß) fibrillation, a process in which amyloid proteins in the brain form clumps. To fight the formation of these fibrils, however, a molecule would have to cross the blood-brain barrier – a series of cell junctions that prevent certain substances from entering the brain. In previous work, the researchers showed that a pomegranate extract has anti-Alzheimer’s effects in animals, but they did not identify the compounds responsible.
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Computational studies found that polyphenols could not cross the blood-brain barrier, but that urolithins could. Urolithins are anti-inflammatory and neuroprotective compounds that are formed when ellagitannins, a type of polyphenol, are metabolized by gut bacteria. The researchers then showed that urolithins reduced Aß fibrillation levels in vitro.