For nearly three decades, two molecules found in rye pollen sat at the center of a scientific riddle. Researchers had observed them slowing tumor growth in animal tests, but the work stalled because no one could pin down their exact three-dimensional structure. Now chemists at Northwestern University have solved that puzzle, potentially opening a new chapter in cancer drug development.
The molecules, called secalosides A and B, eluded identification despite advanced laboratory techniques. Standard tools like nuclear magnetic resonance spectroscopy could map most of their atoms but stumbled on one critical detail: a key region of the structure existed in two mirror-image versions, and scientists couldn't determine which was correct. The distinction matters enormously. A subtle structural difference can completely change how a molecule behaves inside the body.
Karl A. Scheidt, a chemistry professor at Northwestern's Weinberg College of Arts and Sciences, led the team that cracked the code. Rather than trying to refine existing analytical methods, the researchers took a different path. They synthesized both proposed versions of the molecules from scratch in the laboratory, then compared their creations with natural samples extracted from rye pollen.
Only one version matched the real thing. The team had their answer at last.
The work proved grueling because secalosides contain an unusually strained 10-membered ring at their core, making them extraordinarily difficult to assemble. Scheidt's team solved this by constructing a larger, more flexible ring first, then triggering a chemical reaction that collapsed it into the tightly compressed target structure in a single step. The breakthrough appeared in the Journal of the American Chemical Society.
With the molecular blueprint now confirmed, researchers can finally investigate how these compounds interact with the immune system to fight tumors. That knowledge could guide development of improved synthetic versions tailored for cancer therapy.
Rye pollen extract already sits on health store shelves as a dietary supplement marketed for prostate health, but no pharmaceutical treatment has emerged. The structural mystery was the main barrier. Scheidt noted that preliminary animal studies showed the compounds cleared tumors through an unknown, nontoxic mechanism. That safety profile, combined with the confirmed structure, makes the path forward promising.
The discovery fits into a long tradition of mining nature for drug leads. Morphine comes from opium poppies. Taxol, a key chemotherapy agent, was isolated from Pacific yew trees. Statins, which lower cholesterol, originated in fungi. Scheidt emphasized that natural products often serve as inspiration rather than finished medicines. Chemistry can refine them, making them more stable, orally available, and more precisely targeted.
Scheidt said the team is now seeking collaborators in immunology to help translate the discovery toward clinical use. The study was funded by the National Institute of General Medical Science, the Chemistry of Life Processes Institute Lambert Fellowship, and the National Science Foundation.
Author Jessica Williams: "A three-decade bottleneck broken by old-fashioned synthesis and smart thinking, this is exactly how foundational science fuels drug discovery."
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