Plant medicines, first formally written about during the Civil War, have properties that allow them to combat drug-resistant infections, researchers have found.
In 1861, the first year of the American Civil War, President Abraham Lincoln instituted a blockade of Confederate ports in the southeast, halting imports and exports, eventually crippling the Confederacy’s economy. The blockade also prevented the import of medicine that was needed in the treatment of Confederate soldiers. Roughly two-thirds of deaths during the war were due to wound infection rather than combat.
To deal with the lack of medicine, the Confederate surgeon general commissioned doctor and medical researcher Francis Porcher to create a guide to the plants native in the southeast that had medicinal properties.
According to Emory University researchers, Porcher relied on the practices of Native Americans and enslaved Africans to build his guide, entitled “Resources of the Southern Fields and Forests,” published in 1863. The researchers concluded that the research likely saved some lives and prevented the amputation of limbs, the prevailing treatment to prevent the spread of infection at the time.
Cassandra Quave, professor of dermatology and human health at Emory University and the senior author on the paper,, decided to revisit the guide in hopes of understanding how traditional medicine worked. The team found evidence to suggest that the compounds found in the plants it studied had properties that combat infection.
After testing three of the plants Porcher wrote about—the white oak, the tulip poplar, and the devil's walking stick—Quave’s team of researchers, which included pathologists and biologists, found the plants had antimicrobial effects on common bacteria that are often the culprits in wound infections, such as Staphylococcus aureus, which is considered the most dangerous form of the common Staph bacteria, Acinetobacter baumannii, and Klebsiella pneumoniae, which can lead to a life-threatening form of pneumonia.
“Plants have evolved this amazing array of chemicals that can serve as defense compounds to protect themselves from pathogens, herbivores, and insects,” said Quave, who’s also trained in medical ethnobotany, the study of plants for medicinal use in various cultures. “There’s this idea in traditional medicines that you can use those same defense compounds as medicines to treat human ailments.”
Traditional antibiotics work by killing bacteria or slowing their growth, which has also led to the rise of drug-resistant bacteria. Quave’s team found that the compounds found in the plants didn’t kill the bacteria, but prevented their spread in other ways, such as inhibiting the bacteria's ability to produce biofilm, which allows bacteria to stick together and to surfaces.
The plant compounds also disrupted the process called quorum-sensing in some cases, which is the release of chemical signals that allow bacteria to coordinate gene expression to create conditions most beneficial to their growth.
In the 1800s, these medicines were only used topically. Quave suggests that the findings could inform new methods and drugs to combat antibiotic-resistant bacteria, but more work needs to be done to understand exactly which compounds are responsible for the effects her team observed.
“I think it’s important to look towards our past to try to understand better how these treatments worked,” Quave said. “We can leverage that historic knowledge to develop better, innovative therapies for the future.”
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