The Nobel Prize in Chemistry for 2026 was awarded on 7 October 2026, to scientists Henri B. Kagan and Kenso Soai, “for the discovery of non-linear effects and autocatalysis in asymmetric organic synthesis.“
Henri B. Kagan is a French chemist and an emeritus professor at the Université Paris-Saclay. Kenso Soai is a Japanese organic chemist and a Professor Emeritus in the Department of Applied Chemistry at Tokyo University of Science.
What did Kagan and Soai discover?
Numerous molecules with identical chemical compositions exist in mirror-image versions of each other. Many classes of biological molecules demonstrate a significant preference for only one handedness, or chirality, of a molecule. For example, proteins in living organisms consist almost completely of “left-handed” amino acids.
The question of how this chemical asymmetry came into existence had long been unanswered by chemists. However, Kagan and Soai uncovered a scientific explanation for how this asymmetry may have emerged.
“Henri Kagan and Kenso Soai have provided a solution to a chemical mystery that is over a century old: how homochirality can emerge spontaneously. The chemical reactions they have developed are spectacular.”
Dr Heiner Linke, Chair of the Nobel Committee for Chemistry
In 1986, Henri Kagan discovered non-linear effects in asymmetric catalysis. In other words, Kagan found that a small imbalance between the mirror-image forms of a catalyst – a substance that speeds up a chemical reaction without being consumed in the process – could yield a much greater imbalance between the mirror-image forms of the resulting molecules, producing a greater excess of one chirality than the other.
Soai then paved the way to the chemists’ pivotal discovery in 1995 by designing the first documented chemical reaction that produces molecules able to catalyse their own formation. This phenomenon is referred to as asymmetric autocatalysis and resulted in a significant imbalance between their mirror-image forms. He successfully engineered this reaction in 2003: a reaction in which one chirality is favoured without requiring a chiral catalyst.
What are the implications of their discovery?
Kagan and Soai’s findings have significant applications in pharmaceutical manufacturing. Producing only one mirror-image form of a molecule used in drugs could prevent harmful side effects.
For instance, the (R)- and (S)-enantiomers of thalidomide were prescribed to pregnant women in the 1950s to treat morning sickness. While the (R)-enantiomer was effective, the (S)-enantiomer was teratogenic, causing severe developmental harm and birth defects. Hence, the findings could help produce only one chirality of a molecule, avoiding potentially harmful side effects.
The discovery also has implications for agriculture. It could enhance the creation of single-enantiomer pesticides and herbicides that effectively target pests or weeds, while minimising the quantity required and toxicity caused by inactive, potentially dangerous mirror-image forms.
However, a large portion of chemists believe further research in this domain to be detrimental for life. There is a difference between manufacturing a molecule and creating a live organism. But breakthroughs in the first, such as these, could increase the probability of the second.
What is mirror life and why is it dangerous?
Mirror-image life – or mirror life – is a field of synthetic biology regarding organisms manufactured from biomolecules that have chiralities opposite to their predetermined biological ones.
Research on mirror life – which was merely a hypothetical concept, prior to the discoveries made by Kagan and Soai – has much more possibilities than before. It could soon be possible to “reverse biology” in ways such as creating right-handed amino acids.
A paper published in Science in late 2024 argues that the chiral opposite of a bacterium could resist bacteriophages: viruses that infect and destroy bacteria. Hence, it could surpass human and animal immune systems and reproduce uncontrolled. This could threaten the health of humans and longevity of ecosystems alike.
A piece by The Economist debates the ethics of this research and, according to the BBC Science Focus Magazine, Professor John Glass has said that “pretty much everyone agrees that creating so-called ‘mirror-life’ is a very, very bad idea.”
Kagan and Soai have not directly contributed to the creation of mirror life. Nonetheless, similar advances in the future might inadvertently lead to a biological crisis.
Research into the chirality of molecules, and how to synthetically control it, has numerous positive implications for fields such as healthcare. But the scientific community must be cautious to contain it, so that it does not become a threat to numerous forms of life.
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