A component in blessed thistle, an herb known to promote digestion, may have the potential to repair damaged nerves, investigators have found.
A Mediterranean herb perhaps best known as an ingredient in
Benedictine liqueur, blessed thistle (Cnicus benedictus) has long been used in some parts of the world to promote healthy digestion. Now researchers have uncovered a new and unexpected potential use for the herb: regenerating damaged nerve fibers.
The key is the compound cnicin, a component of the bitter plant, which was shown in a new study to regenerate nerve fibers in both animal models and human cells.
The study, titled “Cnicin promotes functional nerve regeneration,” was recently published in the journal Phytomedicine.
“Remarkably, intravenous administration of cnicin significantly accelerates functional recovery after severe nerve injury in various species, including the anastomosis [surgical reconnection] of severed nerves,” the investigators write of their discovery.
A member of the aster family, blessed thistle is already thought to have anti-inflammatory and anticancer properties,
according to the National Cancer Institute. Taken in extract or as a tea, it is also known as cardin, holy thistle, and St. Benedict’s thistle (it was traditionally cultivated by Benedictine monks), but should not be confused with its cousin
milk thistle, which is used to cleanse the liver and to promote milk production in nursing mothers.
Blessed thistle is commonly used to treat gastrointestinal complaints, university professor Dietmar Fischer, director of the Center for Pharmacology of University Hospital Cologne, Germany, and one of the new cnicin study authors, told The Epoch Times.
However, “I can’t say how well studies have proven this indication,” he added.
Mr. Fischer, along with Mr. Philipp Gobrecht and colleagues, were instead interested in determining whether blessed thistle could be used in a completely new way.
Accelerating Nerve Cell Healing
The key to nerve cell repair is the regeneration of the axon, the part of a nerve cell that carries impulses to other nerves. No drugs currently in clinical use can regenerate axons, according to the researchers who published this new study, but they have isolated an enzyme found in plants of the aster family that can accelerate axon growth.Regeneration must occur soon after nerve injury, according to the researchers, “Although injured axons in the peripheral nervous system usually have a remarkable regenerative capacity, complete functional recovery is often elusive.”
This is because
Schwann cells, which maintain and regenerate axons, promote growth for only about three months. “If reinnervation does not occur within this time frame, the injury often results in lifelong incomplete recovery and the formation of neuromas, which can contribute to the development of neuropathic pain,” they wrote.
A few years ago, Mr. Fischer told The Epoch Times, his group discovered that increased activity of the enzyme GSK3
accelerated the regeneration of axons in injured sciatic nerves.
“Once we had elucidated the underlying mechanism, we were able to search for substances that mimicked this effect. This is how we came across cnicin,” he said.
The substance’s effect on nerve regeneration was a completely new finding, Mr. Fischer added, and this discovery called for further research.
To perform the latest study, the investigators surgically injured the sciatic nerves of mice, rats, and rabbits using protocols that conformed to animal care guidelines. After the surgery, the animals received daily intravenous or oral doses of either cnicin or
parthenolide, a substance found in the
feverfew plant that has been shown to accelerate axon regeneration.
Those animals that received cnicin experienced functional recovery from paralysis and neuropathy that was comparable to those that received parthenolide. This was an important finding because parthenolide has “insufficient oral bioavailability,” explained the investigators, meaning it can be administered only parenterally (by injection or infusion).
Cnicin, however, can be administered orally or intravenously, making it a promising drug for practical treatment of nerve injury.
The researchers also tested the effects of cnicin on donated human retinal cells. They exposed the cells to either cnicin or parthenolide over four days. The cnicin-treated cells “showed significantly longer neurites” than the controls, said Mr. Fischer, demonstrating that cnicin promotes axon growth.
Implications for Human Health
Because this study was performed on animals and human retinal cells from cadavers, practical application in injured patients may be a long way off. However, researchers are confident that they are making progress. Mr. Fischer told The Epoch Times that he and his colleagues are now looking for funding to carry out clinical trials in humans.Although blessed thistle is currently available in capsule form (promoted as a digestive aid), Mr. Fischer said it wouldn’t make sense for people with nerve injury to take it. His group’s previous studies have shown that cnicin is effective for axon growth only within a certain dosage range, which is difficult to determine. Taking too much or too little would be ineffective, he said.
One goal of the human trials he hopes to conduct would be to determine the optimal dosage of cnicin to be effective in the human body.
