AUG 25, 2015 05:10 PM PDT

Plant Extract Takes on MRSA

WRITTEN BY: Kerry Evans


It's not your fault! Something went wrong with our formula.
Please begin your experiment again by clicking here.

If this error continues to occur please contact us at

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
MAY 16, 2018
MAY 16, 2018
The Structure of a Bacterial Protein Supercomplex is Revealed
Researchers isolated a supercomplex that acts as a kind of battery and helps generate energy for bacteria....
MAY 22, 2018
MAY 22, 2018
Tiniest House Ever Can Be Built on Strand of Hair
A French robotics team has built a micro-house to demonstrate their new nanotechnology prowess and a system called the μRobotex nanofactory....
MAY 29, 2018
MAY 29, 2018
Early Research Makes Connection Between Liver Tumor Growth Control and Gut Microbiota
Our gut microbiota is unique, but many organisms are shared across populations of people. Early research shows a connection between liver tumors and the control of their growth by microbiota...
JUN 10, 2018
JUN 10, 2018
Killer Antibiotic-resistant Pathogen Isolated in the US
For decades, people have relied on antibiotics to treat microbial infections, but that is changing....
JUL 17, 2018
JUL 17, 2018
Understanding how Microbes Will Accelerate Climate Change
As permafrost starts to thaw out, it's exposing untold numbers of new bacteria, which can spew out methane....
JUL 23, 2018
Genetics & Genomics
JUL 23, 2018
Developing Self-fertilizing Plants
Plants of the future may not need to be fertilized; they might create their own nutrients. That could be a huge relief for the planet....
Loading Comments...