Cassandra Quave

Cures in the Soil

Air Date: December 13, 2021

Emory University medical ethnobotanist Cassandra Quave discusses potential coronavirus cures and her new book “The Plant Hunter: A Scientist’s Quest for Nature's Next Medicines.”


HEFFNER: I’m Alexander Heffner, your host on The Open Mind. I’m delighted to welcome our guest today, Cassandra Quave. Dr. Quave is a medical ethnobotanist whose work is focused on the documentation and analysis of botanical remedies used in the treatment of infectious disease. Dr. Quave is also the author of the recently published “The Plant Hunter: A Scientist’s Quest for Nature’s Next Medicines.” Welcome, Dr. Quave.


QUAVE: Hi, thanks so much for having me on the show.


HEFFNER: You’re welcome. Let me ask you, just to begin with, what separate from the pandemic, which of course I want to ask you about what inspired you to write this book?


QUAVE: Yeah, so we’ve been doing research in my lab for quite some time now looking at infectious disease threats and ways to address these threats through the study of medicinal plants that people all around the world use as medicines to treat everything ranging from headaches, to, you know, much more serious infectious diseases. And so I was inspired to write this book because I think there’s a great hunger for more information around how our herbs work, but also because I thought it would be fun to share my story with the hopes that it would encourage other scientists and especially young women to think about a career in science.


HEFFNER: Please do doctor share that story. Share your story.


QUAVE: Oh my story. Okay. Sure. So I was born in a small rural town in Southwest Florida as a kind of a surprise to my parents when I was born, they discovered that I had a number of congenital skeletal deformities. So I was born missing bones in my legs. Some of the other bones were very short and underdeveloped. And so at the age of three, there was a decision made to amputate my legs that I could then walk with a prosthetic. Unfortunately I acquired a hospital infection. It was a staph infection that just ravaged the tissues and required additional surgeries and cutting back the bone. And so today I walk with a prosthesis and have a very thin layer of scar tissue basically right under the bone. So I can’t run on those, like, you know, bouncy legs, like Olympians do. Just because of that lack of extra padding. I had a number of other issues with my skeletal system ranging from my femur to my hip, to my back. And I had, you know, one, sometimes two surgeries a year until I turned 18. So I’ve been immersed really in medicine, my entire life. And for the longest time I really wanted to fall in the footsteps of my, the people I looked up to, to my heroes, to my doctors that basically rebuilt my body. But in college I became more fascinated with this idea of medicine through different cultural lenses, based on my studies in anthropology. And an opportunity to travel to the Amazon rainforest when I had just turned 21, it really opened my eyes to the potential that nature has as a source of healing compounds. And I’ve been chasing that dream ever since.


HEFFNER: Well, thank you for sharing that. And I encourage our listeners and viewers to check out your book and there it is “The Plant Hunter” and to learn about Cassandra’s story and what motivated her, which is quite inspirational. And I wish you continued progress and good health, always in your ongoing recovery. And I want to ask you now that you’ve had the opportunity to reflect on the treatments and surgeries that you had, were there any that were grounded in plants? I do wonder of the medicines that we take, you alluded to this from the outset, and of the surgeries performed, how many are in effect the result of plants or research of plants?


QUAVE: Yeah, that’s a great question. I mean, I can share a little scene from the book in one of my early chapters when I’m in the Amazon for the second time, and I’m interviewing people in a Yagua indigenous Village, and there’s a gentleman that comes out of the forest carrying this long pole, and it’s a blow gun that he’s handmade himself with nothing but the resources of the forest. And in a little pot, he has something known as curare poison. The curare works basically by immobilizing the prey that you’re hunting, through smooth muscle relaxant effects. And so, here’s something that, that was really developed as a hunting tool in the Amazon, but many years later when it was you know, first studied by scientists is when we came across the compound Tubocurarine, and this agent served as an inspiration that really helped to develop the current kind of regime of anesthetics that we use today during surgery.


So we don’t use tubocurarine today in surgery, but it was one of those early steps. It kind of helped form the foundation of where we went in the future with those surgeries. Other important plant derived medicines that have influenced my life is also, you know, the opium poppy. Now, when we think of the opium poppy today, of course, it’s associated with a lot of horrific effects because of the widespread opioid pandemic and the number of people that unfortunately become addicted to opioids. But the chemicals derived from the opium poppy, the opiates like codine and morphine have revolutionized the way that we’re able to aid people that are in severe pain following surgery, or also at the end of life. And so those are just two examples of plants that I’ve encountered in my studies that have just made huge impacts on the trajectory of medicine as we know it today.


HEFFNER: Your book’s premise fascinated me from the very beginning, because when you see the Musks and the Bezos and their obsession with outer space, you know, it’s depressing to see that it’s not motivated by what would singularly motivate me, and I think you too, which is on the texture of, on the surface we can grasp the texture of never before seen, or smelled, or heard particles. And you know, that would be my motivation and your thesis in effect is we have not really encapsulated the discovery of our own backyard, our own garden of earth, to see, for example, if there are particles or ingredients that could make up a medicine to counteract our global pandemic now, which is the coronavirus pandemic. So how much of your work is motivated by believing that the garden of earth, if you will, is going to facilitate remedies for not only coronaviruses, but cancer and in other diseases that we suffer from?


QUAVE: Oh, you definitely hit right on the premise because I mean, it’s incredible the diversity that we have on earth, and I’m a huge fan of space exploration. I’ll just put that out there. I mean, I was really big into Star Trek as a kid. And the idea of exploring unknown parts of the universe is extremely exciting. But the truth of the matter is that we have a lot of exploration to do here on earth. There are around 374,000 species of plants that are estimated to be on earth and 9 percent of those, at least 9 percent, so that’s around 33,000 are used by people as a form of medicine. And this is something I think we’re a bit disconnected with especially in the U.S. where we view herbal medicine as something that’s maybe fringe or something, that’s kind of, you know, relegated to a supplement.


It’s not our primary mode of healthcare. But around the world, billions of people do turn directly to plants as their major form of healthcare. So keeping that in mind, it’s shocking to me that out of these 33,000, scientists have only really looked in depth at maybe a few hundred of those. I mean, there’s so much space to explore. I’m, I guess one other goal of this book is really to also call others to the field. It’s, my great calling card let’s get together and work on these plants because we’ve already found so many amazing medicines that have revolutionized everything from pain to the treatment of cancer, to the treatment of malaria, by looking deeper into plants. And I think this is a century where we really have to look hard at these species, because at the same time, we’re also facing a biodiversity crisis with the loss of species and we’re facing the language loss crisis, the loss of languages, by the way, also comes a loss of traditional knowledge of how to use these plants. So there’s an urgency to this search and there’s plenty of room for lots of scientists to jump into the fray.


HEFFNER: Why is it the case that they haven’t been investigated? You know, we had the agency to investigate this long before we had microchips and computer processors, right? So what has been the resistance, when did it form, if you will, as resistance to what you describe as a relegation to fringe? Why is that?


QUAVE: I mean, I think there’s a couple of reasons. Number one is, you know, scientists, physicians, and lay people alike have forgotten the history of where our medicines come from. And that’s another goal of the book is to remind people that these are a valuable place to look. But the underlying problem, I think is that it’s difficult to work with these, you know. Nature works in incredibly complex mixtures. It’s very different from our current medical paradigm where you have one drug that’s hitting one pathway in the body or one target in the body. Instead these work by hitting many, many different targets with many different compounds to yield that overall effect. And so that’s fascinating from a scientific viewpoint, but it’s also incredibly difficult to study under our current kind of reductionist paradigms that we operate on in today’s science. But I’m hopeful because I think that there are emerging technologies that are going to allow us to look deeper and deeper into these complex networks. I mean, everything from AI to new bioinformatics platforms to advances in analytical chemistry are going to really start opening up the doors to studying these networks.


HEFFNER: So you think the new technologies will actually galvanize a new interest in studying plants and that we may be able to see elements of those plants that could be helpful in attacking specific diseases?


QUAVE: Absolutely. Absolutely. I think that these new technologies are opening up new ways to sort through the complexities of nature.

HEFFNER: Now you are based at Emory in Georgia. What can you tell us about the landscape there, where you oversee a lab, work with some colleagues on the latest plant discoveries in, and outside of the suburbs of Atlanta and maybe you know, even more broadly through the rural parts of the state, national parks, and forest? So starting in your home base, and then maybe more expansively throughout the south, because you have familiarity with Florida too, and that has certainly a lot of evergreens and Everglades. So, so take us through what plant life is like right now in Atlanta and Georgia more broadly.


QUAVE: Yeah. So I’ll tell you a little bit about how my labs are set up at Emory. So I have a split appointment between the medical school and the college, and I also curate the Emory herbarium. Now, when people think of the word herbarium, they often envision lush tropical greenhouses, but that couldn’t be further from the case. An herbarium is a natural history museum full of dead pressed plants. So these are plants that we collect in the wild and press and preserve, and if cared for properly, they can last five to 600 years or more, based on what we know of the oldest specimens that we have on earth. And so in my labs, we have one lab that’s dedicated towards the study of plant chemistry. So this is where we process our incoming plant specimens; create extracts. So basically pull out the chemistry from whichever tissue we’re studying, like a leaf or fruit or whatnot.


And then the microbiology lab, this is where we assess their activities against everything from pathogenic fungi to bacterial infections. And now we’re also working on SARS-Cov-2, the virus responsible for COVID-19. And we also study, you know, safety toxicity testing in that lab. And we kind of go back and forth between the two groups, because we’re constantly trying to understand which chemicals within those complex mixtures are responsible for the activity that we’re observing in the microbiology lab. Now, stepping out into the field, you know, in the Southeast U.S., we have a lot of plant diversity. We have an ongoing collaboration that is happening in the southern part of the state in Baker County with the Jones Center at Ichauway, which is an ecological research station that was first founded by Robert Woodruff, the former president and CEO of Coca-Cola.


So this is a beautiful 30,000-acre intact habitat of life, long leaf pine that you just don’t see in such a large landmass anymore in the south. And then in Florida, of course, I’m from Southwest Florida near Sarasota, Fort Myers area. And so we’ve done a lot of work in collaboration with large landholders there primarily that are rearing cattle for cattle raising on these lands. And, you know, there’s a lot of conserved land there as well, that, that we’ve been really fortunate to be able to go out and access plants from. And so those local places are great because we can bring out undergraduate students and graduate students, but we also work of course, intensively internationally in the Mediterranean and the Balkans. We’ve done work in, you know, in collaboration with folks in Pakistan, Lebanon, China, South Africa, Egypt, Morocco, Colombia. So we’re really, we really have a global reach with the kind of project that we’re trying to get off the ground.


HEFFNER: That is an excellent overview, but I am curious, and I wonder if our viewers are too, just specifically when it comes to homegrown, if you will homegrown plants, what might be possessed here in the United States that carries those properties that could be medicinal that could provide the medical innovation, are they plants that could well exist in Georgia or in Florida?


QUAVE: Oh absolutely. I mean, just in the past year, we discovered an activity of a compound from the American beautyberry, which is a beautiful plant and fruit right now in the Southeast U.S. has these gorgeous purple fruits. We found a compound that basically restores the activity of beta lactam antibiotics. So these are antibiotics that are very safe and well tolerated, but, you know, we have issues with resistance to these antibiotics. So basically, we were able to find the compounds in the American beautyberry leaves that restore the activity of those antibiotics. And I actually am going to do a little show and tell here. So we have, I’ve been working with Alleles company based in Canada, and they made this beautiful leg cover for my prosthetic leg, and I’ll hold it up so you can see it better. But this is that compound that we found from the American beautyberry. We have other compounds from the blackberry bushes. We’ve worked a lot with chestnut in Europe. So these are just some of the chemical structures and some of the plants that we study. There’s St. John’s wort that we’ve also worked on. So yeah, just, I love, I love the merger between art and science as it’s embodied in this, but that made me think of it because of the clerodane diterpenoids, from the Americas.


HEFFNER: That’s beautiful. Thank you for sharing that. Of the plants that have been deciphered, detected to have medicinal properties, are we able to say with any accuracy, X percent emanate from this continent, you know, either North America or Asia, because you talk about how you’re studying plants from all around the globe. And I just wonder if there’s been any study so far that is at least classifying the likelihood of having medicinal property?

QUAVE: That’s a great question. I mean, when it comes to where to find the most medicinal plants or potentially medicinal plants, I mean, there, there are general figures around the total number of, you know, of drugs that have been either inspired by or derived from plants. But when it comes to places to look, I think there’s this misconception that it must be some far remote place. You know, it’s the most rare orchid, the highest tree, and the rainforest kind of idea, you know, the Sean Connery version of medicine. I love that movie, by the way, that he was in, Medicine Man. But in reality, the medicine plants are all around us. I can walk out into my yard where I have some weeds, you know, there’s plantain growing out in the grass. I’ve got dandelion.


These are examples of medicine. Wo it’s really just knowing what to look for, but it’s also funny hotspots of biodiversity. So some of the places that I focus a lot of my work on are on what are known as the terrestrial hotspots of biodiversity. There are 36 of these in the world, and these are places on earth where you have a high level of endemism. So endemic species are basically species that are only found in that one part of the world, right? So you don’t easily find them in lots of other places. So they’re very rich in biological diversity and remember the chemical diversity can be tied to that biological diversity. So it’s a place where I can look at the most chemicals coming from life in those places. And these also happen to be places that are threatened due to expansion of human populations you know, changes in land practices, land use practices. So these are some of the places that we really try and focus our work because of that great species richness, and also the, the fact that they’re under threat.


HEFFNER: Are any of those 36 places in North America?


QUAVE: Yeah. So we have some, I mean, there, there’s a hotspot of biodiversity here in kind of around the panhandle of Florida and in South Georgia, yeah.


HEFFNER: That’s cool…


QUAVE: There are hotspots and along the kind of the, I believe, along the California coastline going into Oregon as well.


HEFFNER: Yeah. That’s, that’s very cool to know when it comes to any discoveries that can help us overcome the pandemic more quickly. I mean, we know we’re nearly two years into this. COVID is going to be endemic on some level, but we have the intervention now, as we’ve been talking about on the program for some time of a therapeutic, you know, there had always been a focus on the vaccine. And I think we realize now that was absolutely imperative and that is absolutely imperative to have a minimal level of protection. There’s a drug out by Merck that is purports to be a treatment that is not necessarily foolproof. So far, the early experimental stage of use suggests that it could be 50 percent likely to, you know, reduce the severity of your disease. But it’s not guaranteeing that everyone who takes it will then have a 50 percent reduction in the severity of their disease. But I mean, I think that you must have a particular lens into the imperativeness of the therapy in order to ultimately overcome the pandemic because we realize COVID is going to be endemic on some level. So we need not just a vaccine, but we need reliable treatment.


QUAVE: Yeah. Well, I mean, I think the, the drug that you’re talking about by the way was, was first developed at Emory. So this is an Emory innovation, which is really exciting, out of an initiative that really had the foresight to put in the money and scientific expertise for years before this ever happened, to look at, you know, potential therapeutics to address different types of viral illnesses. So I think that in itself is exciting. And, and it’s also, you know, a good example of why consistent, constant, well-supported drug discovery initiatives are so very necessary. We have this bad habit of basically, you know, everyone gets excited about Ebola and there’s money put in Ebola, and then that all goes away or, you know, whatever the current threat of the day is. And what we really need to do is have a constant stream of focused work because the types of scientists that are needed for this work, don’t just develop overnight.


It takes years of training and years of you know, getting the next generation in line, but also of developing the underlying basic science behind that. So that said, yes, we need, we need more drugs like this that can interfere with viral replication. And in this case, you know, it’s getting those kinds of therapies early on. And, you know, early on in your symptoms is very important to, to be effective. So in the lab, we’re working on the search for other steps in that viral replication cycle. We’re looking at what are known as viral entry inhibitors. We have undertaken the largest screen that I know of yet. We haven’t yet published it. So this is still in the hands of one of my graduate students is putting finishing touches. We’re also running additional tests in light of virus right now, but we screened over 2000 extracts from our library of natural products, derived from these plants and have identified three that look somewhat promising.


Again, this is still very early-stage lab studies. We know that it’s safe in human cells. But what’s safe in a cell doesn’t necessarily always translate to what’s safe in an animal or safe in a human or effective in an animal or effective in a human. So I’m very cautious with how we communicate these findings as they come out, because, you know, the difference between something like this drug that’s being developed by Merck versus something that I’ve published showing is that people can go and grab these plants and start self-treating. And we have to be very careful about what we communicate because there have been some plants that are actually quite deadly that have been communicated in the press, during the course of the pandemic, which actually spoke out against because of the toxicity concerns. And so, I mean, that’s, there’s a balance there, if that makes sense.


HEFFNER: Yeah, absolutely. And as we close here, Cassandra, to be clear, the Merck pill does not derive from plants.


QUAVE: No it’s not. That’s a very separate, that’s a very separate study.


HEFFNER: So those are lab created devices basically.


QUAVE: Right.


HEFFNER: But that’s, that’s the last question I want to ask you. We, we know and, and Kevin Esvelt at MIT who we hosted on the podcast talks about information hazards. When is discovery actually going to injure society as opposed to help and knowing that we still, and maybe never will know, we still don’t know and may never know the origin of COVID-19 and whether it was a lab accident or whether it was from the natural environment? What are your last words of wisdom on this question of, of human discovery and to the extent that there is a limit to what we ought to want to discover, because that discovery may become hazardous to us?


QUAVE: I mean, I think, I think it comes down to scientific rigor, right. and responsibility over, over, how you undertake your science. It just, as I, as I mentioned, you know, there, there are, you have to have very clear communication with the public about the meaning of your scientific results. I think that’s really critical. You hear all the time, you know, a new study will come out that says, oh, chocolate’s great for your heart health. Well, perhaps some element of the chemicals in chocolate is good for your heart health, but it doesn’t mean that you should start just, you know, eating a ton of candy bars that is not good for your heart health. So I think that there’s a great responsibility both, you know, in the arms of the media, but also in the scientists that engage with the media to be very clear in communication around scientific findings, because we don’t want people to leap to the wrong decisions and make bad choices for their health.


HEFFNER: Dr. Cassandra Quave of Emory University, thank you so much for,


QUAVE: Thank you.


HEFFNER: And author of “The Plant Hunter.” Do check it out. Thank you so much for your time today, Cassandra.


QUAVE: Thank you.


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