Henri Kagan of France and Kenso Soai of Japan have been awarded the 2026 Nobel Prize in Chemistry for their groundbreaking research on molecular asymmetry, known as chirality, which plays a critical role in biological processes and pharmaceutical development. The Royal Swedish Academy of Sciences announced the joint award on Wednesday in Stockholm, with the laureates sharing a prize of 12 million Swedish kronor (approximately £900,000).
Chirality refers to the property of some molecules to exist in two mirror-image forms that cannot be superimposed on each other, much like human left and right hands. These chiral molecules include amino acids and sugars fundamental to life. However, living organisms predominantly use only one type of mirror image, a phenomenon called homochirality. Understanding how chemical reactions favor one mirror form over the other has been a longstanding puzzle in chemistry.
Henri Kagan, a 95-year-old professor emeritus at Université Paris-Sud, began investigating this asymmetry in the 1960s. His key contribution in 1986 demonstrated that a slight imbalance in a catalyst's handedness could create a greater excess of one chiral product than previously thought possible. Kenso Soai, 76, professor emeritus at Tokyo University of Science, advanced this concept by developing a reaction characterized by autocatalysis, where the molecules produced act to catalyze the formation of more molecules of the same handedness. In 2003, Soai succeeded in demonstrating a reaction that generated predominantly one mirror-image form, effectively reproducing the molecular one-handedness observed in living systems.
The ability to control molecular chirality has significant practical implications, particularly in medicine. Many drugs interact differently with biological targets depending on their chirality; one enantiomer (mirror form) can be therapeutic, while the other might be less effective or even harmful. A notable example is thalidomide, a drug used in the late 1950s and early 1960s to alleviate morning sickness, which caused severe birth defects due to its racemic mixture containing harmful mirror-image molecules.
The Nobel Committee described the laureates’ chemical reactions as “spectacular” and emphasized their role in enabling chemists to selectively produce chiral molecules, a critical step for pharmaceutical manufacturing and other chemical industries. The committee chair, Heiner Linke, highlighted that their work solved a “chemical mystery that is over a century old,” tracing back to Louis Pasteur’s discovery of molecular asymmetry in 1848.
Kenso Soai expressed pride in the recognition and underscored the fundamental importance of chirality for understanding the origins of life and the function of amino acids. Henri Kagan, though not immediately reachable following the announcement, has previously described his work as driven by curiosity and the desire to make unexpected yet practical discoveries.
The laureates will receive their medals and diplomas at a formal ceremony in Stockholm on December 10, the anniversary of Alfred Nobel’s death. Their discoveries are expected to continue influencing research in molecular chemistry, synthetic development, and the design of more effective and safer drugs.