Amyloid-beta is a toxic protein that aggregates (clumps together) and forms plaques in the brain with age. Amyloid-beta aggregation is associated with Alzheimer’s disease, a progressive neurodegenerative disease that causes dementia. Findings from a recent study suggest that defensive compounds present in plants protect against amyloid-beta aggregation in an animal model of Alzheimer’s disease.

Plants produce vast arsenals of defensive compounds to protect them from pathogenic attack and herbivore consumption. Evidence suggests that these compounds exert protective effects in humans, reducing the risk of many acute and chronic diseases. Scientists have identified thousands of plant defensive compounds that may benefit human health; perhaps the best known of these include sulforaphane, curcumin, and resveratrol.

The study investigators performed an in vitro assay to gauge the capacity of nine plant defensive compounds (five flavones and four [tyrosols])https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6571782/) to prevent amyloid-beta aggregation. They found that two of the flavone compounds, scutellarein and baicalein (which are found in plants in the mint family), reduced amyloid-beta aggregation as much as 90 percent, and two of the tyrosol compounds, hydroxytyrosol and hydroxytyrosol acetate (which are found in olives and olive oil), reduced aggregation as much as 100 percent. Then the investigators gave hydroxytyrosol to worms that tend to develop a condition like Alzheimer’s disease and found that the compound reduced amyloid-beta aggregation in the worms' brains by 43 percent.

These findings demonstrate that plant defensive compounds scutellarein, baicalein, hydroxytyrosol, and hydroxytyrosol acetate inhibit amyloid-beta aggregation and show promise as candidates to prevent and/or treat Alzheimer’s disease. Evidence indicates that sulforaphane shows similar promise, as it impairs amyloid-beta production and improves learning and memory

• Link to study abstract.