Leaves of the European chestnut tree, rich in ursene and oleanene derivatives, have the power to disarm dangerous staph bacteria without boosting its drug resistance, scientists have found. Rather than killing staph, the botanical extract works by taking away staph's weapons, essentially shutting off the ability of the bacteria to create toxins that cause tissue damage. The research was published in the journal PLOS ONE.
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. MRSA infections lead to everything from mild skin irritations to fatalities. Evolving strains of this "super bug" bacterium pose threats to both hospital patients with compromised immune systems and young, healthy athletes and others who are in close physical contact.
"We've demonstrated in the lab that our extract disarms even the hyper-virulent MRSA strains capable of causing serious infections in healthy athletes," the researchers said. "At the same time, the extract doesn't disturb the normal, healthy bacteria on human skin. It's all about restoring balance."
The researchers steeped chestnut leaves in solvents to extract their chemical ingredients. The work produced an extract of 94 chemicals, of which ursene and oleanene based compounds are the most active.
Tests showed that this extract inhibits the ability of staph bacteria to communicate with one another, a process known as quorum sensing. MRSA uses this quorum-sensing signaling system to manufacture toxins and ramp up its virulence.
A single dose of the extract, at 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 two 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.
The researchers have filed a patent for the discovery of the unique properties of the botanical extract, and they are doing further testing on individual components of the extract to determine if they work best in combination or alone. Their goal is to further refine the extract into a simpler compound that would be eligible for FDA consideration as a therapeutic agent.
Based on material originally posted by Emory Health Sciences.