In the 1940s and ’50s, insecticides were so harsh, their toxicity to humans so misunderstood, that farmers were spraying DDT and heavy metals like lead and arsenic on their orchards.
In the years since, such sprays have been banned and pesticides have become far less poisonous, but the demand is still toward ever-greener pest control.
Now a chemist at the College of William and Mary in Williamsburg is looking into whether certain natural alkaloids found in rye and fescue grasses — alkaloids with the ability to defend against insects and some herbivores — could one day produce a next-generation pesticide that’s harmless to humans.
“If you forage sheep on some of these grasses, they don’t appear to show any effects — they live, they’re healthy,” said Jonathan Scheerer, associate professor. “If you put cattle on some of these, it’s the same sort of environment — there isn’t any observed effects.
“So in this lab,” he said, “I’m trying to make these things and understand them and get a little bit into the weeds of what are these molecules really doing. Because it is sort of an interesting natural pest control paradigm that just isn’t very well understood.”
Parasitic fungi
The alkaloids aren’t produced by the grasses themselves, but by parasitic fungi that live on them. The two species have evolved a symbiotic relationship: The fungus takes nutrients from its grass host, while the grass allows it because the fungus produces alkaloid molecules that are toxic to the insects that want to eat it.
It’s those alkaloids that Scheerer and his students are figuring out how to synthesize and study in the lab, “to learn a little bit more about the currency that’s being exchanged.”
There’s much more work to be done, Scheerer said, to confirm that the alkaloids are nontoxic to humans even in larger doses — “The dose makes the poison, right?” — and plenty of hurdles to scale such work up to a commercial product one day.
But, Scheerer said, “I wouldn’t see it out of the realm of possibility that something like this could show up in sort of an organic agricultural setting in a decade or two.”
Molecular architects
Simply put, alkaloids are molecules that contain nitrogen. They’re naturally occurring chemical compounds produced by a wide variety of organisms, from bacteria to plants to animals.
Drink coffee? Eat chocolate? Caffeine from coffee and cocoa plants is an alkaloid. Smoke tobacco? Nicotine from the tobacco plant is an alkaloid, too.
And they have the same evolutionary underpinnings as the ryes and fescues with their fungi: Caffeine and nicotine help the plant survive because they’re toxic to many hungry pests.
But a great many alkaloids also have beneficial effects, particularly for humans, and in fact have become workhorses among pharmaceuticals — quinine to treat malaria, for instance, morphine to treat pain, penicillin and tetracycline to treat infection, and omacetaxine mepesuccinate to treat leukemia.
“They’ve had an amazing impact on human health,” Scheerer said. “You can look at essentially the Top 200 most-prescribed medicines in the world and 95 percent of them are alkaloids.”
Other alkaloids, of course, like strychnine, can be deadly.
But it’s their potential to cure human diseases that drew Jonathan Perkins, a 24-year-old graduate student from Roanoke, to work on organic synthesis in Scheerer’s lab.
On Friday, Perkins was busy with flasks and heat, running a reaction — boiling a solvent to condense it down to try to form a specific chemical bond.
“I feel like synthesis is a puzzle,” Perkins said. “You start with some idea of something that you want, and then you want to take different things and put it together and make it. And a lot of times it’s something that no one’s ever done before.”
Science and art
For Scheerer, who earned a doctorate from Harvard University in 2006 and was a postdoctoral research fellow at Johns Hopkins University, organic synthesis is both a science and an art.
“A lot of people would say it’s like a molecular architect — you’re building things the same way someone would build things with Legos,” he said.
Perkins said he’s aiming for a Ph.D. in chemistry, and one day would like to work in the pharmaceuticals industry, building cures for human diseases.
“I always try to look for the far-reaching goal — maybe someday this molecule will help someone in some way,” Perkins said.
A top honor
In recognition of his work in the lab and the classroom, Scheerer was just awarded a 2015 Henry Dreyfus Teacher-Scholar Award, considered a top honor for chemistry professors.
It’s presented by the Camille and Henry Dreyfus Foundation, a nonprofit group devoted to advancing the chemical sciences, and comes with a $60,000 grant. The award “supports the research and teaching careers of talented young faculty in the chemical sciences at undergraduate institutions,” according to the foundation.
Scheerer said he plans to use the money to help fund research and educational travel for his students.
Dietrich can be reached by phone at 757-247-7892.
Online
For more information about Dr. Jonathan Scheerer and his research, go to wmpeople.wm.edu/site/page/jrscheerer.
