Hundreds of fatty acids naturally occurring in plant oils, each bearing a similar chemical structure, were discovered and named by scientists through the better portion of the last century.
Discovery of new fatty acids in vegetable oils, biodiesel fuels and other substances slowed, and eventually came to a stop a half-century ago, however.
But then Chunyu Zhang, a former researcher at the University of Nebraska-Lincoln, observed an unusual outcome during a chemical analysis of the oil contained within seeds of the Chinese violet cress.
Testing the violet cress oil using thin-layer chromatography, a technique used to separate compounds through a capillary action taught in high school chemistry classes, Zhang learned the cress oil left a unique signature as it broke down into fatty acids.
Zhang, now a researcher at Huazhong Agricultural University in Wuhan, China, asked his colleague and former boss at UNL for his opinion on the unusual results.
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From the backseat of a car at an airport in China, Edgar Cahoon, the director of UNL's Center for Plant Science Innovation, didn't know quite what to make of Zhang's findings.
"At first, I thought he had made a mistake because it was so different than anything we had ever seen before," Cahoon said, but he agreed to study the Chinese violet cress from his lab on the third floor of the Beadle Center at UNL as a side project.
Five years later, the pair and 11 other researchers from four universities including UNL announced the discovery of two new fatty acids inside the Asian garden plant: Nebraskanic acid and Wuhanic acid, named for the locations of the two leading universities on the project.
Most vegetable oils, including oils made from canola and soybeans, are built from the same five fatty acids, each with 16 to 18 carbon atoms arranged in nearly identical molecular structures.
Nebraskanic and Wuhanic acid, on the other hand, are built from 24 carbon atoms and contain branches connecting to hydrogen and oxygen compounds called hydroxyls, allowing the molecules to stretch.
Cahoon said the "serendipitous" discovery was different than many experiments he's conducted, a happy coincidence the research team noted several times in its article published in the journal "Nature Plants" last month.
"Sometimes when you do research, you know what you're expecting to find," Cahoon said. "You try to prove or disprove a hypothesis. But this wasn't hypothesis-driven, it was curiosity-driven."
Analyzing the oils again using gas chromatography to tease out more details about its fatty acid components, Cahoon modified the experiments, running instruments longer, for example, due to the length of the molecule, and using other techniques to get a better handle on the secrets of the Chinese violet cress.
The team later enlisted the help of researchers at Indiana University-Purdue University Indianapolis, who spent a year using nuclear magnetic resonance to fine-tune each acid's structure.
"Once we could see the structure, we saw it was not like anything that had ever been reported in the literature," Cahoon said.
The unique structure, like a long chain of carbon atoms with branches of hydroxyls, also raised other questions, including how the genetics of the Chinese violet cress helped synthesize the fatty acids, as well as the biochemistry behind its formation, which had not been described in any textbook.
Like a jigsaw puzzle, researchers from different disciplines and different countries collaborated to describe their findings, and prepared a paper for a scientific journal in February 2017.Â
Cahoon said an editor at the journal recommended the team find out the practical use of the discovery and not just answer a biochemical curiosity.
"She wanted to know, 'What good is the oil?'" Cahoon said.
The team guessed the Nebraskanic and Wuhanic fatty acids' unique chain-like structure would make it an ideal candidate for a lubricant, so they asked oil researchers at the University of North Texas to run it through a battery of tests.
The results were promising, even stunning.
Compared to castor oil, which only has one hydroxyl per molecule to Nebraskanic and Wuhanic's two, the violet cress oil reduced friction between metals by 22 percent at a temperature of 77 degrees Fahrenheit.
When the temperature was increased to 212 degrees Fahrenheit, the violet cress oil reduced friction by more than 300 percent compared to the castor oil.
Diana Berman, an assistant professor of materials science and engineering at North Texas, said the molecular structure of the Chinese violet cress seed oil is key to its potential as a lubricant.
"This oil doesn't just have the potential to supplement or replace petroleum-based oil," Berman said. "It can also replace synthetics. It is a renewable solution to a limited-resource problem."
Oil and lubricant companies have taken notice in the new source of fatty acid, Cahoon said.
In the meantime, Cahoon said understanding the unique chemical structure could provide a blueprint for new, longer-lasting or more heat-resistant oil blends in the future.
"If we understand the chemical structure of the oil, we will have nature guiding us in the chemical synthesis of the new lubricants," said Cahoon, "This all started from an observation. It wasn't a planned set of experiments.
"That's how science works sometimes."