Dr Cassandra L Quave Assistant Professor of Dermatology and Human Health, Emory University, USA
The Brazilian Peppertree (Schinus terebinthifolia Raddi) is a large shrub or small dioecious tree, native to Brazil, Paraguay and Argentina (1). It can also be found in over 20 subtropical countries and is considered to be an invasive species in the southeastern United States, particularly in Florida where it has colonized most of the state (2).
Peppertree is included in the Brazilian Pharmacopoeia and has served as a staple in Brazilian traditional medicine (3). Almost all parts of the plant, including leaves, bark, fruit, seeds and resin have been used to treat a variety of ailments (4). In particular, it has been used traditionally for its antiseptic and anti-inflammatory qualities in the treatment of wounds and ulcers, bruises, hemoptysis, diarrhoea, chills, tumours and arthritis, as well as urinary and respiratory infections (3, 5).
Although the bright red fruits have a long history of use as an ingredient in a balm to treat wounds and ulcers, little was reported in the literature concerning the activity of the fruits. Thus, we endeavoured to investigate the efficacy and safety of S. terebinthifolia fruits for treating S. aureus infections, which are frequently implicated as a major pathogen found in infected wounds and ulcers.
Interestingly, we found that fruit extracts did not inhibit bacterial growth, but rather interfered with the capacity of the bacteria to communicate with one another using a chemical signaling system known as quorum sensing (6). Through blocking communication, these plant compounds “tricked” the bacteria into behaving like they were alone even when surrounded by millions of their peers. This is important because bacteria behave differently when they are in a group setting; as a group, S. aureus cells coordinate production of large amounts of toxins that are secreted into the host. In turn, these toxins act to destroy host tissues, attack the immune system and aid the bacteria in spreading to other parts of the body. By blocking bacterial communication, these peppertree compounds effectively disarm the bacteria, rendering them harmless and more vulnerable to clearance by the host immune system. The full text of the article reporting these findings is available via open access at Scientific Reports.
Dr Cassandra L Quave is an Assistant Professor of Dermatology and Human Health at Emory University. She has interests in medical ethnobotany, antimicrobial resistance and drug discovery. Her work has been profiled in the New York Times Magazine and National Geographic Channel and featured by numerous international media outlets, including the The Washington Post, The Telegraph and CBS News. For more information, visit her website: http://etnobotanica.us
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6. Muhs A. et al. Virulence inhibitors from Brazilian Peppertree block quorum sensing and abate dermonecrosis in skin infection models. Scientific Reports 7, 42275, doi:10.1038/srep42275 http://www.nature.com/articles/srep42275#supplementary-information (2017).