Rye pollen has been demonstrated to able to slow tumour growth in animal models of cancer. To understand more about this, chemists have determined the 3D structure of the bioactive molecules in rye pollen. The new finding opens the scientific door to exploring how rye pollen inhibits tumour growth.
Thirty years ago, scientists found that a pair of molecules in rye pollen exhibited an unusual ability to slow tumour growth in animal models of cancer. Since then, progress stalled for one seemingly simple reason: No one knew exactly what the molecules looked like.
This has finally been addressed by Northwestern University chemists who have cracked the case. In a new study, the scientists definitively determined the three-dimensional structures of both molecules — secalosides A and B — by building them from scratch.
With the correct blueprint now in hand, scientists can begin to investigate how specific components of pollen from rye — a staple cereal crop grown for its grain — interact with the immune system and whether it could inspire new strategies for cancer treatment.
Nature as inspiration for medicine
Throughout history, researchers, biologists and healthcare workers have looked to nature as an inspiration for new treatments. Some of the most powerful drugs in modern medicine originated not in the lab but in tree bark, microbes and flowers. Morphine, the gold standard for relieving severe pain, is derived from the opium poppy. Taxol, a widely used and effective cancer treatment, was originally isolated from the Pacific yew tree. And statins, which lower cholesterol to prevent heart disease, can trace their origins back to fungi.
Rye pollen could potentially join these ranks. Many consumers around the world already ingest rye pollen extract in supplement form to protect prostate health. But scientists haven’t yet optimized it for use as a pharmaceutical drug. Understanding how it works required knowing the molecules’ precise three-dimensional shape — information that proved elusive.
A molecular mystery
Using traditional techniques, such as advanced nuclear magnetic resonance spectroscopy, scientists could not fully reveal the orientation of the molecules’ key parts. As a result, two competing structural models persisted for decades.
Those two proposed structures had the same atoms, same connections and same overall shape. But a central part of the molecules are mirror images of each other. That subtle distinction can change how the molecule fits into a biological target and determine whether a molecule is biologically active or inert.
Building from scratch
Northwestern team turned to total synthesis, or the step-by-step process of constructing a natural molecule in the laboratory. At their cores, secalosides A and B contain an extremely rare and highly strained feature: a tightly compressed, 10-membered ring that is notoriously difficult to build.
After synthesizing both competing structural versions of the secalosides, the scientists compared them to samples isolated from rye pollen. Only one version matched perfectly, finally revealing the true molecular structure.
The research appears in the Journal of the American Chemical Society, titled “Synthesis and structural confirmation of secalosides A and B”.
