The 2026 Nobel Prize in Chemistry was awarded to Henri Kagan and Kenso Soai for research into chemical reactions that selectively produce one desired form of a mirror-image molecule. Even when molecules have the same formula and bonds, different arrangements of their atoms in space can lead to different therapeutic effects or risks in the body. The research has drawn attention because it shows the importance of distinguishing between the two forms when making medicines and examining which one produces the desired effect.

Background and context

Some molecules exist in two mirror-image forms that cannot be superimposed on each other. Such molecules are called chiral compounds (compounds with mirror-image forms that cannot be superimposed on each other). Just as the left and right hands are mirror images that cannot be superimposed, molecules can have the same atoms and bonds but different spatial arrangements.

Biological targets and enzymes can bind differently to molecules with particular shapes. So a drug’s different mirror-image forms cannot be assumed to act the same way in the body just because they have the same molecular formula. Asymmetric organic synthesis has enabled chemists to make the desired one of the two mirror-image forms.

In 1986, Kagan demonstrated a nonlinear effect in which mixing catalysts with different mirror-image forms produced more of one form of the product. In 2003, Soai presented a reaction that selectively produces only one mirror-image form, based on autocatalysis, in which the product of a reaction promotes the formation of more of the same form. The two studies expanded the chemical tools available to produce mirror-image molecules in a desired form, connecting this work to drug development.

What this news means

Distinguishing between molecular forms in drug development is about more than structural analysis. One form may be beneficial in treatment, while the other may have a weaker effect or be harmful. Technology that selectively synthesizes a particular form can be important in designing drug candidates and verifying which form was used in testing. However, whether a specific drug is safe and effective for people must be assessed separately on the basis of clinical evidence for that drug.

The case of thalidomide illustrates the risk. According to the article, one isomer has a sedative effect, while the other is believed to cause abnormal physiological development. The article explains that because the two forms can convert into each other in the body, taking either form during pregnancy is dangerous. Therefore, the chemical ability to produce only one form and the conclusion that taking only that form is safe are not the same thing.

Resveratrol is an example of how this distinction may also matter when interpreting clinical trial results. The author’s research team has studied resveratrol, a compound found in red grapes and peanuts. According to the article, the possibility that different forms were used may help explain the mixed results of clinical trials of resveratrol for treating Alzheimer’s disease. In experiments with mouse neurons, the cis form increased TyrRS levels, while high concentrations of the trans form depleted TyrRS and caused neuronal damage.

For example, readers comparing results from Alzheimer’s disease-related trials should look not only at whether the results were positive or negative, but also at which form of resveratrol was used. However, the cell experiment findings presented in the article are not enough to conclude that the same effects occur in people. The article does not specify exactly how the different forms were used in each clinical trial.

What is known and what remains unknown

What is known

  • The 2026 Nobel Prize in Chemistry was awarded to Henri Kagan and Kenso Soai for research on selectively producing mirror-image molecules.
  • Some compounds can produce different effects in the body depending on their spatial structure, even when they have the same molecular formula.
  • The article explains that the two forms of thalidomide can convert into each other in the body, making either form dangerous during pregnancy.
  • In experiments with mouse neurons, the cis form of resveratrol increased TyrRS levels, while high concentrations of the trans form depleted TyrRS and caused neuronal damage.
  • The research team said it also observed depleted TyrRS levels in the brains of Alzheimer’s disease patients with elevated tyrosine levels.

What remains unknown

  • The article provided does not establish whether the cis and trans forms of resveratrol have different effects in people with Alzheimer’s disease, as confirmed in clinical studies.
  • It has not been established how the two forms were used in each clinical trial or how any differences affected the results.
  • The article alone cannot establish whether the depletion of TyrRS observed in patients’ brains causes Alzheimer’s disease or occurs alongside the disease process.

What readers should check

  • When comparing research findings on drugs or health-related compounds, readers can check whether the form and concentration of the molecule used in the study are specified.
  • It is important to distinguish between findings from cell or mouse experiments and results from clinical trials involving people.
  • Readers should bear in mind the warning that taking thalidomide during pregnancy is dangerous in either form. Whether to take a particular drug should not be decided on the basis of the chemical principles discussed in the article alone; readers should check the drug’s instructions and consult a healthcare professional.

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