Native to South America, the Brazilian peppertree is an evergreen shrub that has become an unwelcome visitor in parts of the United States, but some researchers are fascinated by the potential that lurks in the berries of these trees.

The invasive plant has taken over areas of Hawaii, Florida, Texas and California where it forms dense thickets, choking native vegetation. Sometimes the trees can grow as high as 30 feet tall, frustrating residents who say the plant pest causes them to suffer from swollen eyes, itchy rashes and breathing problems.

But where they see a pest, Cassandra Quave sees a cure. A medical ethnobotanist at Atlanta's Emory University, Quave and her team found that an extract from those berries prevents the hard-to-treat bacterium MRSA from forming skin lesions in mice. Although that particular study hasn't been published yet, Quave's work with other plants and their potential has been far-reaching.

In 2015, she researched how extract from the leaves of the European chestnut tree could shut down staph infections, including even the dangerous resistant MRSA strains. MRSA infections can lead to everything from minor skin irritations to death.

"We've identified a family of compounds from this plant that have an interesting medicinal mechanism," Quave said, when the study was released. "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."

What is ethnobotany?

Turmeric's leaves(Curcuma longa) Turmeric (Curcuma longa) was long prized in Asian traditional medicine and now modern research is learning more about its antifungal properties and other health benefits. (Photo: Skyprayer2005/Shutterstock)

As more and more bacteria are becoming resistant to antibiotics, researchers are looking to older remedies to find new medicines. Ethnobotany studies the relationships between plants and people. Medical ethnobotanists like Quave look to plants as sources for medicine, and often search for solutions to battle the highly evolving, drug-impervious bugs.

Of course, studying the relationship between plants and people is hardly new.

“Wherever humans have lived, they have used nature's resources for medicine," Quave tells MNN. "In some cases, knowledge of which plants to use is passed down orally, from generation to generation between healers to their apprentices. In other cases, it is also recorded in the written record and taught in a more formal setting."

Ayurveda, traditional Chinese medicine, European herbalism, Native American medical traditions and Jamu, a traditional medicine in Indonesia, are all traditional forms of plant-based medicine, Quave says. Their practices are full of details including plant names and the parts of plants used, as well as the best time to harvest, preparation and administration techniques, and on what diseases the plant extracts are most effective.

"The details embedded in traditional knowledge of medicinal plants can give biologists and chemists important clues into the chemistry and potential bioactivity of different species," Quave says.

A brief history of antibiotics

Antibiotics and similar medications (both called antimicrobial agents) have been used since the 1940s to treat infectious diseases. The drugs have been incredibly successful in saving lives. However, the drugs have been prescribed so much and for such a long period of time that the targeted organisms have adapted and the drugs have become much less effective, according to the Centers for Disease Control and Prevention.

Resistance can happen for many reasons, says the CDC.

  • Up to 50 percent of the time antibiotics are prescribed, the drugs are not needed or the dosing or duration is incorrect.
  • The germs that can be found contaminating food can become resistant due to the use of antibiotics in people, as well as in animals used for food.
  • Once resistant strains develop, they often can spread easily from person to person.

Each year in the U.S., 2 million people or more become infected with antibiotic-resistant bacteria and at least 23,000 people die annually due to those infections, the CDC reports.

Quave Research Group The Quave Research Group at Emory University takes the ethnobotanical approach to discovering new drugs. Cassandra Quave is the woman in the crook of tree. (Photo: Quave Research Group)

The story of the chestnut tree

In the case of Quave's work with chestnut leaves, it was the result of years of research she and her colleagues had done, looking into the traditional remedies of rural people in Southern Italy and other parts of the Mediterranean. She conducted hundreds of interviews, which led her to the European chestnut tree, Castanea sativa.

"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.

Emory researchers collected leaves and spent hours extracting 94 chemical ingredients. Their tests showed that the extract they created cleared up MRSA skin lesions in lab mice, stopped tissue damage and red blood cell damage. In addition, the extract doesn't become resistant, even after repeated exposure.

Emory has applied for a patent for the extract. Potential uses include a preventative spray for athletic equipment, a preventative coatings for medical devices, and as a treatment for MRSA infections, possibly in conjunction with antibiotics.

"It's easy to dismiss traditional remedies as old wives' tales, just because they don't attack and kill pathogens," Quave says. "But there are many more ways to help cure infections, and we need to focus on them in the era of drug-resistant bacteria."

Mary Jo DiLonardo covers a wide range of topics focused on nature, health, science and anything that helps make the world a better place.

Will the next antibiotic breakthrough come from these humble plants?
Researchers turn to the ancient remedies of plants to find new medical cures.