When people tell Eloy Rodriguez, PhD, that they like what he does because he doesn’t work with chemicals, it makes him pause for a second. “I’m kind of like, ‘What?!’ But I think I understand what they’re telling me. They’re telling me that I don’t work on synthetic chemicals,” he said.
A native of south Texas, Rodriguez is a biochemist, chemical ecologist, and pharmacognosist who has been a member of the American Botanical Council’s (ABC’s) Advisory Board since ABC first established the board in 1996. “I like to believe that I’m a naturalist,” Rodriguez said.
He is the James A. Perkins endowed professor of environmental studies and biochemistry of natural plant medicines and poisons at Cornell University in Ithaca, New York.
Rodriguez has always been interested in botany. “At a young age, I was kind of fascinated with plants,” he said. He grew different composites (i.e., members of the Asteraceae family) around his house because he wanted to make it look more aesthetically appealing.
But he didn’t always know that he would end up doing what he does. In fact, as an undergrad at the University of Texas, he was made a laboratory janitor. “They never were thinking of having me do research. That’s the last thing they thought about, but that’s what happened,” he said. He then pursued a PhD at the university.
His first job was at the University of California at Irvine, where he stayed for 18 years before going to Cornell, where he has been for 21 years.
In the 1980s, Rodriguez and his colleague, Richard Wrangham, PhD, a biological anthropologist at Harvard, coined the term “zoopharmacognosy,” which, put simply, is animal self-medication. Wrangham was studying chimpanzees in Kibaale, Uganda, when he noticed an interesting behavior. The chimpanzees would pluck the leaves of plants in the genus Aspilia (Asteraceae) and swallow them without chewing. Wrangham was perplexed by this behavior and brought it to Rodriguez’s attention. Rodriguez knew that close observation would be necessary before being able to say chemistry played a role in the behavior.
Rodriguez and Wrangham analyzed the plants before they were swallowed by the chimpanzees and then collected them from the feces and analyzed them again. The leaves were still fairly whole since the chimpanzees did not chew them. “Basically we showed that there was a difference.... One of the major compounds was removed,” Rodriguez said. This compound had sulfur in the molecule.
The chimpanzees had symptoms, such as diarrhea, that would indicate the presence of tapeworms, Rodriguez said, and were using the plants for their anthelmintic (anti-parasitic) effects. The chimpanzees would seek out the plants only if they were sick, according to Rodriguez. “Then, after a certain period, [they] would go back to a normal feeding behavior,” he said.
Rodriguez admitted that animal self-medication had been observed perhaps even further back than the 12th century, but this was the first time scientists were able to connect the behavior to the chemistry. He said zoopharmacognosy crosses many disciplines. It combines herbal medicine with behavioral ecology, evolutionary biology, and cultural evolution (animals showing other animals how to use the plants).
“I think that is significant, in my opinion,” he said. “I feel that that’s a very important contribution.”
Rodriguez, in collaboration with colleagues and students, has isolated close to 40 chemicals from plants, and of those, about 30 were new to science, meaning they had never been identified or described.
Now, he and his colleague, Monica Guzman, PhD, a leukemia specialist at Weill Cornell Medical College, are focusing on using some of those chemicals to treat leukemia (“liquid tumors”) and breast cancer (solid tumors).
Rodriguez said he’s concentrating on chemicals from about 40 different, but closely related, species. “I’m a big fan of the Asteraceae, [the] sunflower family. That’s one of my areas of expertise,” Rodriguez said.
He focuses on weeds in the family that are generally considered to be obnoxious. “And the reason they are obnoxious is because they contain these chemicals. That’s what makes them weeds, because they have these nasty chemicals in them. Well, those nasty chemicals are the ones that I go after and try to test them against leukemia,” he said.
His research involves looking at the compounds first from a chemical perspective and then from a biological perspective. In other words, he tries to define what it is about certain chemicals that may make them effective against cancer cells.
“It wasn’t surprising to see that a chemical in a plant that deterred a caterpillar could also be used to treat a cancer cell, because a cancer cell, in many ways, is like a caterpillar. It’s alive. It has enzymes,” he said. So, Rodriguez tries to apply the defense mechanisms of the plants to treat humans.
This also involves trying to identify weak spots in cancer cells. “Is it an enzyme? Is it a certain protein that is important?” he said.
He and Guzman are constantly trying to better understand cancer and why plants, over millions of years, have evolved these molecules that, today, have a certain stereochemistry (i.e., atoms are arranged in a certain way within the molecule).
“We’re talking about millions of years of evolutionary time that have resulted in these molecules that we’re looking at,” Rodriguez said. He is working with a class of compounds called sesquiterpene lactones, which contain 15 carbon atoms. “They come in very different shapes and sizes and potencies,” he said.
“We’re trying to figure out what the structures look like, and that in itself is not easy. That can be a difficult task,” he said.
For now, most of the testing is being done on cancer cell cultures in the lab. The chemicals that have potential will then go on to be tested in animals, and then in humans, though Rodriguez isn’t involved with in vivo studies. Guzman is arranging to have them tested on humans.
Two of the compounds Rodriguez’s students are involved with are called parthenin and tetraneurine.
“Those are sesquiterpene lactones that we feel are already showing some really nice activity against leukemia, and we’re going to be testing them against solid tumors, like breast cancer. So we’re excited,” he said.
He’s also excited because the research involves undergraduate students. “That I think is so important — to get them involved in this kind of research, because herbal medicine and the study of herbs is so important for the health and the diet of people,” he said. “People don’t realize that when they’re eating all these vegetables and fruits that they’re eating zillions of different molecules, which we have no idea what they’re doing, and that’s exciting.”
Some of the compounds that he studies are also found in lettuce, which is also a member of the sunflower family. “People who like wild lettuce are eating sesquiterpene lactones,” he said.
Rodriguez enjoys the collaborative aspect of his work and, even though he loves research first and foremost, he loves teaching too. “I enjoy being with young minds. I really do. They’re great. These kids here at Cornell are really great,” he said.
He likes giving his students an ecology example to illustrate how important plants are to the survival of everything. He tells them there is a plant that makes a certain chemical, and that same chemical shows up in a frog. The frog does not eat that plant and is incapable of producing the chemical. So, how does the frog have a chemistry belonging to a plant that is not part of its diet? “And of course they’re totally confused,” Rodriguez said of his students. “They’re clueless,” he said. Then he tells them that the aphid eats the plant, the ant eats the aphid, and the frog eats the ant. The secondary chemicals are passed from one to the next. Now, what the plant used as defense, the frog uses as defense. “You remove that plant, you remove the chemical defense of the frog, of the ant, of the aphid, and that’s why I think it’s important,” he said.
What he has enjoyed most about his career is getting out in nature with his students, especially in the Amazon, the Taklamakan Desert in China, and the coastal areas of the Caribbean, always in search of plants to study.
Rodriguez said he expects to retire in the next couple years, but wants to continue to educate people about plants and the chemicals they contain. “Because that’s what makes plants so unique — the ability to make secondary metabolites,” he said. “That’s what separates them from animals.”
He said he would definitely encourage young people to get into his field, which today is called metabolomics. “This is more and more exciting, more and more interesting — the more we learn about how small molecules in plants play such an important role in our diet and in our longevity,” he said. Metabolomics requires a love of organic chemistry and natural products, use of nuclear magnetic resonance (NMR) and liquid chromatography-mass spectrometry (LC-MS), and genetic engineering and molecular biology of the many genes involved in the biosynthesis of natural products, according to Rodriguez.
He’s working on two books: one is titled The Evolution of Organic Medicines in Plants in the Americas, which he plans to finish within the next year and a half, and the other, which he plans to finish in the next year, is an untitled memoir aimed at the Latino community.
In his spare time, Rodriguez enjoys reading and making silver jewelry for men. He especially enjoys making turtles with inset stones. He describes his jewelry as “simplistic” and “almost medieval.”
He’s married to his wife Helena M. Viramontes, a fiction writer at Cornell, and has a daughter, Pilar, and son, Eloy Labrada, PhD.
—Connor Yearsley
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