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The Secret of the Brazilian Pepper Tree

The Brazilian pepper tree, Schinus terebinthifolius, grows throughout the south-eastern US state of Florida, where it’s considered a noxious weed. The pepper tree, which has red berries and green leaves all winter long, is commonly called the ‘Christmas berry’ or ‘Florida holly’. Starting around 1840, people brought the pepper tree from South America to Florida as a decorative garden plant. However, it soon escaped the gardens. It has since spread widely and crowded out many of Florida’s native mangrove and pine trees. Some scientists believe the pepper tree produces a chemical that prevents native trees from growing nearby. Experts in Florida have recommended removing pepper trees to protect native plants.

However, the pepper tree also has a long history of medicinal use. In areas of South America, where the pepper tree grows naturally, people have used its leaves, bark, berries and seeds to treat various maladies, including colds, ulcers and infections. More recently, a research team from Emory University, which is located near Florida, may have discovered yet another promising use for the pepper tree. The team was led by Professor Cassandra Quave, a specialist in ethnobotany. Ethnobotany is the study of how indigenous populations use local plants. Knowing how useful the pepper tree has been to people in South America, she decided to take a closer look at this ‘weed’.

Quave’s research team separated the chemical ingredients within the berries and tested each ingredient against a range of infections. Their experiments confirmed that the pepper tree berries contain a substance that works against certain bacteria. This substance appeared to fight an antibiotic-resistant strain of Staphylococcus aureus. Staphylococcus bacteria cause staph infections, producing symptoms such as skin sores, pneumonia and bone and joint inflammation. Severe staph infections are treated with antibiotic drugs. However, certain Staphylococcus strains, including Staphylococcus aureus, have developed resistance to those drugs. Infections from antibiotic-resistant bacteria are difficult to treat and can be deadly. That makes the pepper tree berry particularly noteworthy.

Quave’s experiments involved giving the pepper berry substance to mice infected with antibiotic-resistant Staphylococcus aureus. This treatment appeared to reduce the formation of boils and other skin sores that infected mice would normally develop. The researchers also found that the berry compound itself caused no harm to the skin. Further, the normal, healthy bacteria present on the skin were not affected. This was all good news.

The researchers then investigated how the berry substance fought Staphylococcus aureus infections in the mice. Rather than killing the bacteria, the berry chemical appeared to prevent individual bacteria cells from communicating with one another. When the communication was blocked, the bacteria did not act as they usually would in a serious infection. Normally, the bacteria cells would produce toxins, or poisons, which damaged the tissues of the infected host. With the berries suppressing the toxins, the mouse’s immune system could fight off the infection. The sores could heal.

Scientists will have to investigate further into the berries’ staph-fighting abilities. Ideally, they’ll be able to develop treatments for human patients. But they face more work ahead before they can determine whether these medicines would work and be safe for people. There’s one step the researchers know won’t be difficult: collecting berries for their experiments. Brazilian pepper trees are easy to find—after all, they grow like weeds!