Wednesday, March 13, 2019
Wisdom Wednesday: Alzheimer's: 'Holy herb' extracts shows promise as future treatment
Yerba santa, a plant with a long history of medicinal use in its native California, contains an active compound that could treat people with Alzheimer's disease one day. This was the conclusion that scientists at the Salk Institute for Biological Studies in La Jolla, CA came to after testing 400 plant extracts with known medicinal properties. Using a new drug-discovery screen, they tested the compounds for their ability to deter the effects of aging on the brain. The initial round of tests yielded several extracts that protected against a type of cell death that occurs in Alzheimer's and other aging-related diseases. Further tests revealed that sterubin, an extract of Eriodictyon californicum, or Yerba santa, was the most able to shield against inflammation and other triggers of brain cell death.
Native tribes of California have long valued Yerba santa, which is the Spanish for "holy herb," very highly as a medicine for respiratory illnesses, fever, infections, bruising, pain, and headaches.
According to a 2018 Alzheimer's Disease International report, dementia affects 50 million people worldwide, two-thirds of whom have Alzheimer's disease. In the U.S., the number of people living with Alzheimer's disease is set to rise from approximately 5.7 million people today to nearly 14 million by 2050.
Although there are some exceptions, Alzheimer's disease most commonly strikes older people, making increasing age the most significant risk factor. The changes to the brain that occur in Alzheimer's disease begin a long time before dementia symptoms, such as memory loss, emerge.
The "prime suspects" behind the changes are toxic plaques of beta-amyloid protein that build up between nerve cells and toxic tangles of tau protein that accumulate inside the cells. Much of the research and development behind treatments for Alzheimer's disease tends to focus on these and other hallmarks and how to stop them. However, as the authors explain in their study paper, because age is "by far" the most significant risk factor for Alzheimer's disease, there must be "a strong rationale for an alternative approach to drug discovery based upon the biology of aging."
The researchers proposed that a screening tool should be able to test for multiple, aging related pathways that kill brain cells "rather than single molecular targets." In previous work, the researchers had used a screening method to identify plant flavonoids that could reduce inflammation and protect nerve cells. From this, they developed a screening tool comprising tests, or assays, that do more than just identify compounds that might protect cells.
They suggest that the new tool can also identify the "target pathways" of these compounds, possibly making them available as new molecular targets for drug developers.
One of the reasons that sterubin stood out was because it showed a strong ability to reduce inflammation in microglia, which are brain cells that provide support to nerve cells. Sterubin also showed an ability to remove iron from cells. Accumulation of iron can lead to a type of nerve cell damage that accompanies aging and that occurs in neurodegenerative conditions.
The investigators now plan to use an animal model to determine sterubin's drug properties and safety levels in animals.
You might know this herb as Bear’s Weed, although it has several other given names. It is very popular on the west coast of the United States where is grows wild. Like Echinacea and Slippery Elm Bark, it has been used by Native Americans for generations.
Holy herb is traditionally used to reduce coughs and congestion as it readily breaks up mucous when the leaf is consumed. The extract, sterubin is already used in several drugs to mask the bad taste of certain medications. Using the extract for new drugs means new patents and potentially large profits. Some of that drug profit is used to underwrite research like this.
There are already commercially prepared sterubin extracts marketed as a treatment to prevent Alzheimer’s disease. I have no clinical experience with Yerba santa, other than its’ use in a few of my herbal combinations. However, it is safe to use on a long term basis. Please avoid use during pregnancy or lactation as there is not enough research to determine its’ safety for an unborn fetus or infant. It also interacts with the prescription drug lithium.