Two Chemists Win Nobel Prize for Unraveling a Mystery of Molecular ‘Handedness,’ Helping Drugmakers Develop Safer Medications

Many molecules come in two mirrored forms—like left and right hands—but living organisms generally contain only one. However, chemists couldn’t figure out how to make just one version in the lab. Henri Kagan and Kenso Soai share the prize for their work solving the puzzle

Sarah Kuta | Daily Correspondent

October 7, 2026 3:10 p.m.

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Two scientists have been awarded the Nobel Prize in Chemistry for their work untangling a perplexing puzzle about the “handedness” of molecules, allowing drugmakers to develop safer, more precisely targeted medicines. Chemists Henri Kagan of the University of Paris-Sud and Kenso Soai of the Tokyo University of Science were named Nobel laureates on October 7.

“The medicines we have today would not be possible without this chemistry,” Rigoberto Hernandez, president of the American Chemical Society and a chemist at the Johns Hopkins University, tells the Associated Press’ Adithi Ramakrishnan, Kostya Manenkov and Stefanie Dazio.

Kagan and Soai’s award-winning research centers on chirality, which derives from the Greek word for “hand.” Some molecules come in two forms that are mirror images of each other, just like our right and left hands. These mirror images, known as chiral forms, may look similar, but they can behave very differently. The chemical carvone, for instance, can smell like mint or caraway, depending on which version of it you sniff.

However, living organisms usually contain just one version of a molecule. The sugars in our DNA, for example, are right-handed, while most amino acids in your body’s proteins are left-handed. Their mirror-image counterparts, by contrast, are rarely found in nature. This phenomenon is known as homochirality, which derives from the Greek words for “same” and “hand.”

For decades, this chemical asymmetry confounded scientists. How do natural reactions in living organisms produce just one type of a molecule? And why did life’s building blocks evolve a preference for one version or the other?

Deepening the conundrum, they couldn’t replicate this natural asymmetry in the lab. Their experiments produced equal amounts of each version of a molecule—a 50-50 right-handed and left-handed split.

Thanks to Kagan and Soai, as well as numerous scientists who came before them, researchers are now closer to unraveling this mystery.

Their work hinges on catalysts, or substances that can influence chemical reactions without being used up or permanently altered in the process. In 1986, Kagan reported that if an asymmetrical catalyst is introduced to a chemical reaction, it can cause the resulting molecule to be asymmetrical, too, producing more of the right-handed or left-handed version. The effect of the catalyst is nonlinear, meaning that a small imbalance in the catalyst can lead to a much larger imbalance in the handedness of the ensuing molecules.

Soai further tweaked the work and developed chemical reactions that can produce their own asymmetrical catalyst. These “autocatalytic reactions” amplify the imbalance of the ensuing molecule, essentially steering it toward right-handedness or left-handedness. In 2003, he finally published a paper describing a reaction—later dubbed the Soai reaction—in which only one of the mirror images made up the vast majority of the products.

“Their discoveries led to a chemical reaction that spontaneously, without the involvement of other chiral molecules, creates only one mirror image,” said Heiner Linke, chair of the Nobel committee for chemistry and a physicist at Lund University in Sweden, during a livestream of the award announcement. “This is the first time this has happened since the processes that led to the chirality of life billions of years ago.”

Their work doesn’t explain how handedness arose in nature, nor why some molecules are naturally right-handed or left-handed. But it “provides a mechanism by which the problem could be solved,” Matthew Powner, an organic chemist at University College London, tells Nature.

Meanwhile, Kagan and Soai’s research has had major practical implications for pharmacology. Their discoveries have helped drugmakers develop more targeted medicines with fewer side effects, reports STAT’s Annalisa Merelli.

Historically, drugs were often developed as “racemates,” meaning they contained a 50-50 mixture of the left- and right-handed versions of a molecule. While one version of the molecule might produce the desired therapeutic effect, the other might be harmless—or it could interact differently with the body and cause serious side effects.

In recent years, however, pharmacologists have started producing drugs that are primarily one version of the molecule or the other.

“To be able to selectively make handed molecules is absolutely critical, because life is handed, and the world is handed,” Hernandez tells Chemical & Engineering News’ Brianna Barbu. “So, if you can control the handedness of the therapeutic or the molecular system that you put out there, then that can lead to control of its function and its downstream effects.”

Soai was out shopping when he learned of his newly minted Nobel laureate status. “I’m very excited,” he said while calling into the award ceremony. “Of course, this is one of the most exciting days of my life. I’m very glad to share the award with Professor Henri Kagan.”

Members of the Nobel committee and journalists couldn’t immediately reach Kagan. However, his daughter, Veronique Le Deunff, told Reuters’ Marie Mannes, Simon Johnson and Johan Ahlander she was “very happy” for her father, adding that “the ​creativity and originality of his work have opened up new avenues for research.”

The Nobel committees will continue revealing winners of their six award categories this week and early next week. Each award comes with 12 million Swedish kronor (about $1.2 million), which gets split among the laureates.

Sarah Kuta is a writer and editor based in Longmont, Colorado. She covers history, science, travel, food and beverage, sustainability, economics and other topics.