AUG 25, 2015 05:10 PM PDT

Plant Extract Takes on MRSA

WRITTEN BY: Kerry Evans
Cassandra Quave, Ph.D., has built a career on the medicinal properties of plants.  The Emory University ethnobotanist is particularly interested in plant extracts that could be used to treat bacterial infections. Quave and University of Iowa microbiologist Alexander Horswill, Ph.D., identified chemicals from chestnut leaves (Castanea sativa) that decrease toxin production by methicillin-resistant Staphylococcus aureus (MRSA). 

Chestnut leaf extracts attenuate MRSA.
The team distilled chemicals from the chestnut leaves and identified 94 compounds that were active against the bacteria.  The chemicals, derivatives of ursene and oleanene, disrupt the agr pathway, a key quorum sensing pathway the bacteria use to communicate with each other and produce virulence factors such as toxins.  They published their findings in the journal PLOS ONE.

“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 chestnut extract works by antagonizing the S. aureus “accessory gene regulator” (agr) system.  This system regulates virulence factor production through the quorum sensing molecule AIP.  An excess of AIP signals the bacteria to produce virulence factors such as toxins.

The extract cleared MRSA skin lesions in mice without affecting healthy tissue or normal skin flora.  Importantly, the bacteria did not become resistant to the extract, even after long-term exposure.

An obvious drawback is that these extracts do not actually kill the bacteria, they only attenuate virulence.  This means that antibiotics would need to be used in conjunction with the extracts, an obvious roadblock when treating antibiotic-resistant bacteria.

Despite this shortcoming, Quave is hopeful.  “We now have a mixture that works”, she says, “our goal is to further refine it into a simpler compound that would be eligible for FDA consideration as a therapeutic agent”.



Sources: PLOS ONE, Science Daily
About the Author
  • Kerry received a doctorate in microbiology from the University of Arkansas for Medical Sciences.
You May Also Like
OCT 17, 2019
Microbiology
OCT 17, 2019
Some Microbes Can't be Washed off of Apples
There may be tangible benefits to selecting organic fruits....
OCT 17, 2019
Microbiology
OCT 17, 2019
Cigarette Smoke can Increase the Pathogenicity of Microbes
Strains of MRSA can become more resistant to antibiotics when exposed to cigarette smoke....
OCT 17, 2019
Earth & The Environment
OCT 17, 2019
The methane-eating microorganisms in the ocean
New research published in the journal Limnology and Oceanography reveals part of the mystery behind a one million square kilometer patch of ocean in the Pa...
OCT 17, 2019
Health & Medicine
OCT 17, 2019
Honey As An Antibacterial Against Methicillin-Resistant Staphylococcus Aureus
Honey has been used for its medicinal properties for thousands of years to treat wound infections, gastrointestinal ailments, and burns. Because of th...
OCT 17, 2019
Microbiology
OCT 17, 2019
Dengue Virus Changes According to the Temperature
Four related types of dengue virus are common in at least 100 countries and threaten around three billion people....
OCT 17, 2019
Microbiology
OCT 17, 2019
Bacterial Enzyme Strips Inflammatory Carbohydrate From Meat
Humans don't make a carbohydrate called Neu5Gc, but most mammals, including cows, do....
Loading Comments...