The Power of Plants in Medicine

A Growing Science: How Plant-Based Research is Elevating Drug Development

Cassandra Quave, PhD, associate professor in the School of Medicine, is a medical ethnobotanist: she studies how people use plants as medicine and isolates specific compounds within plants that have powerful anti-bacterial, anti-fungal, and anti-viral properties. Her extensive library of natural products includes more than 2,000 plant extracts from over 10 years of international research and field work. She collaborates with researchers and communities in the Americas, Europe, Africa and Asia and works toward enhancing research capacity and sharing benefits with her international partners. For example, working with partners in Kosovo, she helped to secure U.S. State Department funds to establish a new microbiology research lab at the University of Prishtina, which local scientists will use to assess the pharmaceutical potential of the rich biodiversity in the country. Through intensive screening and analysis of her chemical library, Quave's current projects and collaborations are producing brilliant results and the future of her research looks even brighter.

New Advances in the Natural Library

According to Quave, her natural products library has two main goals: the first "is to understand how traditional medicines work, which is of great value to the people who have the heritage of using these specific plants. The second goal is looking for new blueprints for compounds that could be useful in a pharmaceutical setting and getting them started on the pipeline towards drug development." Recent discoveries in Quave's library reflect these goals by sourcing compounds from plants used for traditional medicine and identifying how they can improve existing medicines and create more effective drugs.


A large part of Quave's research is finding compounds that inhibit drug resistance in bacteria to combat infections such as MRSA, or methicillin-resistant Staphylococcus aureus. Quave has identified two plant derivatives that treat this resistant strain of bacteria: one compound derives from the Sweet Chestnut plant (Castanea sativa) and the other from the Brazilian pepper tree (Schinus terebinthifolia). Both of these compounds are from plants that have been used historically for inflammatory and infectious skin diseases. The compositions block the bacterial cell signaling, and as a result, block production of virulence factors that are crucial for the progression of the disease process. The MRSA bacteria did not develop resistance to the compounds after repeated exposure, indicating that these compounds can be used as a viable, long-term pathway to treat MRSA.

Cassandra Quave, PhD

There is strong evidence that the same compounds are effective for treating eczema as well, which afflicts up to 30% of the pediatric population. Eczema affects quality of life greatly and with growing prevalence, there has been a recent push to get increased funding to look for alternative treatments. With an increasing prevalence of antimicrobial resistance (AMR), it is critical to stay ahead of the game in developing alternative technologies to have more tools in the toolbox to treat patients.

Both compounds could also be integrated into disinfectant to help keep sports equipment clean, which is a major mechanism for the spread of MRSA. Sports equipment is often full of bacteria, and even the smallest skin abrasion can act as a breeding ground for MRSA. The compounds act on the temporary reservoirs of bacteria within the equipment and inhibit bacterial movement, which could decrease the risk of infection spread. The developments have numerous applications that could benefit individuals across the lifespan with far fewer negative effects than antimicrobial alternatives. Natural product compositions may decrease resistance generation because they are working via numerous mechanisms to inhibit the bacteria rather than a singular mechanism that kills bacteria, which is the function of antimicrobials.

Recently, Quave's lab has isolated a compound from the American Beautyberry, a plant used by Southeastern Native American tribes, that restores the activity of existing antibiotics that treat Staphylococcus aureus infections. Beta-lactam antibiotics are commonly used to treat Staph infections; however, some Staphylococcus aureus bacteria have developed resistance to this class of antibiotics. The restorative properties of the Beautyberry compound could be an integral next step in combatting bacterial resistance by restoring the effectiveness of existing beta-lactam antibiotics.

Another project aimed at combatting bacterial resistance is identifying compounds that modify the behavior of bacteria instead of killing them, which could yield new possibilities for drug development. "One working hypothesis is that by instead of just attacking and slowing their growth or killing them, which we know are major drivers of resistance, if instead we modulate bacterial behavior, that could extend the lifespan of some of these drugs while delaying or evading resistance" says Quave.

Creating Successful Collaborations

Quave collaborates with Julia Kubanek, PhD, a natural products chemist and professor at Georgia Institute of Technology, to analyze complex molecules and study their antibacterial properties. Quave and Kubanek share resources in their labs such as Quave's robotics platform which detects antibacterial activity and Kubanek's technology to determine the structure of complicated molecules. Quave and Kubanek co-authored a publication about the compound PGG (pentagalloylglucose), which inhibits the growth of multi-drug resistant bacteria such as the bacteria Acinetobacter baumannii. Along with their shared passion for pharmacognosy (the study of how plants can be turned into medicinal products), Quave shared, "it's great to collaborate with another strong woman in science – most of my collaborators are men".

In addition to her work with Kubanek, Quave's vast natural library drives cutting edge collaborations with multiple industry partners. These collaborations are mutually beneficial: by adding new protocols and resources to her lab, Quave leads chemical evaluation efforts for compounds that industry partners can use for their product development. "Cassandra is a true innovator in ethnopharmacology, and an exemplar of successful partnerships between academia and industry. Her previous collaborations have added significant value to corporate research programs in nutrition and drug development while also generating funding for further research in her lab," commented Sat Balachander, licensing associate in the Office of Technology Transfer. In the future, she is looking to broaden the scope of her collaborations while keeping the attitude of milestone-driven work that made past projects so successful.

"A lot of my work is driven by my passion for treating infectious disease so I am most excited about those technologies, but I'm very interested in working with industry partners to support drug discovery and innovation not only in the biomedical space but also in the realms of nutraceuticals, cosmeceuticals, and beverage ingredients."

Quave is confident that her work in medical ethnobotany will benefit scientific research and everyday life through more collaborations and projects. "There's a growing acceptance and interest in the scientific community in understanding plant secondary metabolites and their potential in drug discovery. It's very easy for people to dismiss herbs and plants as old wives' tales, but it is very much real science, and I've spent a lot of time trying to build that reputation." As Quave spearheads more innovation to combat bacterial resistance and enhance drug development, that reputation will surely grow stronger.

Techid: 15115, 15078, 19107, 20102

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