Danish scientists at the University of Copenhagen recently published an exciting study on the effects of various plant extracts on the central nervous system. The objective of their experiment was to investigate the activity of these plant extracts on targets relevant to memory and cognitive health. There are multiple factors thought to affect the progression of age-related cognitive decline and memory loss. Two striking cellular/molecular features of these processes are the death of cholinergic neurons (neurons whose neurotransmitter is acetylcholine) and the formation of amyloid plaques in the brain.
Acetylcholinesterase (AChE) is an enzyme in the brain that breaks down acetylcholine. AChE activity turns down the strength of signals sent from cholinergic neurons. In a person who suffers from a loss of cholinergic neurons, blocking AChE activity might help restore the function of the remaining cholinergic neurons by lifting the AChE block on acetylcholine transmission.
Amyloid plaques are abnormal clumps of the protein amyloid beta. These plaques and tangles are thought to be related to the neuronal cell death and subsequent memory loss in aging brains.
The researchers studied ethanolic extracts of 35 plants, including oregano, rosemary, wild olive, clove, lavender, sage, melissa, and spearmint. These plant extracts were tested for their ability to prevent the formation of amyloid plaques using a Thioflavin T fibrillation assay. They were also tested for their ability to inhibit AChE. The researchers discovered that caraway extract in particular “inhibited amyloid beta fibrillation considerably” and that nine other plants, including oregano and thyme, inhibited amyloid beta fibrillation as well, although to a lesser extent. They also found that “five plant extracts from the family Corydalis inhibited the activity of acetylcholinesterase considerably,” and that clove and oregano also had inhibitory effects.
These remarkable results reinforce a growing body of research indicating that plants have amazing potential to support a healthy mind and body. Further research examining the constituents of these extracts will help us understand how the essential oils of these plants might have similar health properties.