Chestnut leaf extract, rich in ursene and oleanene derivatives, shows that it that blocks Staphlococcus aureus virulence and pathogenesis without detectable resistance. The use of chestnut leaves in traditional folk remedies inspired the research, led by Cassandra Quave, an ethnobotanist at Emory University.
“Rather than killing staph, this botanical extract works by taking away staph’s weapons, essentially shutting off the ability of the bacteria to create toxins that cause tissue damage. In other words, it takes the teeth out of the bacteria’s bite.” The discovery holds potential for new ways to both treat and prevent infections of methicillin-resistant S. aureus, or MRSA, without fueling the growing problem of drug-resistant pathogens.
Antibiotic-resistant bacteria annually cause at least 2 million illnesses and 23,000 deaths in the US, according to the Centers for Disease Control and Prevention. “We’ve demonstrated in the lab that our extract disarms even the hyper-virulent MRSA strains capable of causing serious infections in healthy athletes,” Quave says. “At the same time, the extract doesn’t disturb the normal, healthy bacteria on human skin. It’s all about restoring balance.”
Hundreds of field interviews guided Quave to the European chestnut tree, Castanea sativa in S. Italy. “Local people and healers repeatedly told us how they would make a tea from the leaves of the chestnut tree and wash their skin with it to treat skin infections and inflammations,” Quave says. The researchers steeped chestnut leaves in solvents to extract their chemical ingredients. “You separate the complex mixture of chemicals found in the extract into smaller batches with fewer chemical ingredients, test the results, and keep honing in on the ingredients that are the most active,” Quave explains. The work produced an extract of 94 chemicals, of which ursene and oleanene based compounds are the most active.
>> This extract inhibits the ability of staph bacteria to communicate with one another, ie quorum sensing. MRSA uses this signaling system to manufacture toxins and ramp up its virulence.
“This is more exciting (than monoclonal antibodies) because we’ve shown that with this extract, we can turn off an entire cascade responsible for producing a variety of different toxins.” 50 micrograms cleared up MRSA skin lesions in lab mice, stopping tissue damage and red blood cell damage. The extract does not lose activity, or become resistant, even after 2 weeks of repeated exposure. And tests on human skin cells in a lab dish showed that the botanical extract does not harm the skin cells, or the normal skin micro-flora.
APPS: preventative spray for football pads or other athletic equipment; preventative coatings for medical devices and products such as tampons that offer favorable environments for the growth of MRSA; and as a treatment for MRSA infections, perhaps in combination with antibiotics.
http://www.eurekalert.org/pub_releases/2015-08/ehs-cly081815.php
Emory University’s Cassandra Quave researches the interactions of people and plants — a specialty known as ethnobotany. Credit: Photo by Marco Caputo
Recent Comments