Two Deadly Flowers May Hold The Key To New Medicines, Scientists Find

Scientists Finally Mapped How Wolfsbane and Larkspur Build Their Toxic Compounds

Two plants potent enough to cause paralysis in the tiniest doses are also being eyed as sources of new medicine for various ailments like pain, cancer, and malaria. For over 2,000 years, healers have used wolfsbane as both cure and poison. Its garden-flower cousin larkspur makes many of the same compounds. Scientists have now mapped, for the first time, six molecular steps behind them.

Published in the journal Molecular Plant, the findings center on the Aconitum and Delphinium genera, which store these compounds mainly in their roots. Traditional Chinese medicine has used processed wolfsbane root, called “Fuzi,” for at least 2,000 years, and aconitine was first isolated in 1833. Its six interlocking rings have beaten every chemist who has tried to rebuild it since.

“These plants have been used in different forms of medicine throughout the world for thousands of years,” said Garret Miller, co-first author of the paper and now an assistant professor at the University of Michigan-Flint. “We know they interact with our bodies in so many ways, and understanding how to create them can help provide totally new routes of testing.”

Two Labs Chasing the Same Toxin Joined Forces

Michigan State University’s Björn Hamberger had already set his sights on larkspur when he crossed paths with a group chasing the same chemistry in wolfsbane, led by Tomáš Pluskal at the Czech Academy of Sciences, at a conference in Barcelona. The two teams joined forces. “It’s joining up that always leads to the best science,” said Hamberger, the James K. Billman Endowed Professor at MSU.

Cross-Species Gene Comparisons Narrowed 284 Candidates to Six

To figure out how these plants build such compounds, researchers sequenced genetic activity across multiple tissues from Delphinium grandiflorum, Aconitum plicatum, and Aconitum lycoctonum, then added public data from four more Aconitum species, seven species total. “You can imagine a biosynthetic pathway almost as an assembly line,” said Miller, the paper’s co-first author. “If you have ten steps in a row needed to build a finished product, and suddenly one quits, the next steps can’t happen.”

By checking which genes were active in the roots, where these compounds build up, and matching genes across all seven species, researchers narrowed a huge list of candidates to something testable. One group of enzymes started as 284 possibilities in a single species. Cross-species matching cut that to just six.

Testing meant temporarily inserting candidate genes into tobacco plants, a standard method for checking whether a gene triggers an expected reaction. The team confirmed two enzymes that build the molecule’s basic carbon frame, three that add oxygen, and a sixth that threads nitrogen into the structure, the step turning a plain plant chemical into a true alkaloid.

That sixth enzyme, named DAS, was the most surprising find, spotted through gene activity in wolfsbane roots at different growth stages. DAS belongs to a group of proteins nobody had pinned a job to before, though distant relatives turn up in green algae and other plants.

The Nitrogen Surprise at the Heart of Wolfsbane Chemistry

Perhaps the most counterintuitive finding involves how nitrogen, the element that turns an ordinary plant compound into an alkaloid, gets built into the molecule.

Looking at the finished structure of most of these compounds, including aconitine, the nitrogen appears attached through a small chemical piece called ethylamine. That was the obvious guess, and it turned out wrong. When researchers fed the plants tagged versions of both ethylamine and a related building block called ethanolamine, only ethanolamine turned up in the finished products, confirmed by a second experiment using lab-grown plant tissue fed the same tagged molecules for a month. Out of 61 compounds detected, 41 showed signs of ethanolamine and none showed ethylamine, including one signal tentatively identified as aconitine. Ethanolamine already floats around inside plant cells as part of their membranes, and DAS appears to have evolved specifically to grab that everyday molecule and stitch it into the toxin’s structure.

Tobacco Plants Produced a Bioactive Alkaloid Intermediate

Using all six enzymes together, the team rebuilt the pathway in tobacco plants and generated detectable atisinium, a compound previously reported to fight malaria parasites. This covered only the earliest steps and one intermediate, not full-scale manufacturing, but it shows these toxins could someday be grown in engineered organisms rather than dug up from slow-growing roots. “In an ideal scenario, this could eventually help create new drugs inspired by these natural products,” Mutabdžija said.

Researchers also confirmed the six-step process is shared by both genera, meaning the same steps operate in wolfsbane and larkspur despite roughly 27 million years of evolutionary separation. Hundreds of these compounds exist in nature, and a patent application tied to producing them has already been filed by several team members.

“Many of the medicines we use today either come directly from plants or are inspired by plant chemistry,” said Lana Mutabdžija, a graduate student at the Czech Academy of Sciences and co-first author of the paper. For a class of molecules first studied nearly two centuries ago, wolfsbane and larkspur have guarded their manufacturing secrets well. Now, at least for the first crucial steps, scientists finally have the recipe.

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Disclaimer: This article is based on findings from a peer-reviewed study and is intended for general informational purposes. It does not constitute medical advice. Wolfsbane and related plants contain compounds that are acutely toxic and should never be handled, ingested, or self-administered.

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