The 2026 Nobel Prize in Chemistry was awarded to Henri Kagan and Kensō Soai for their groundbreaking work on chemical asymmetry, a discovery that holds potential for enhancing the production of pharmaceuticals and other materials.
Chemical asymmetry occurs in chiral molecules, which have two forms that are mirror images of each other, similar to the left and right hands. A notable phenomenon in biology is that living organisms predominantly utilize one of these forms, a concept known as homochirality.
Each form of a chiral molecule, known as an enantiomer, has nearly identical physical properties but can exhibit different behavioral effects. The Nobel Committee illustrated this by likening the situation to a locksmith who can make two mirror-image keys, with only one key fitting a particular lock. Using the wrong key can lead to damage.
This concept presents challenges in drug development, particularly when amino acids or sugars are involved. While one enantiomer may provide the desired therapeutic benefits, its counterpart can lead to adverse side effects. Achieving control over which enantiomer is produced during synthesis has been a persistent challenge for scientists.
The investigation of chiral molecules began with Louis Pasteur, who discovered that two enantiomers reacted differently with bacteria. Since then, researchers have endeavored to replicate homochirality in laboratory settings to pinpoint its spontaneous origins and develop methodologies for controlled chemical reactions. However, initial efforts resulted in equal ratios of the two variants, failing to mimic the natural selectivity.
In the early 20th century, German chemist Willy Marckwald created an asymmetric reaction that tilted the balance slightly towards one enantiomer using a chiral catalyst—substances that promote reactions without being consumed themselves. However, the resulting output was only marginally improved.
Theoretical physicist Charles Frank, in 1953, proposed a model that outlined necessary conditions for achieving homochirality: an asymmetric reaction favoring one version, an amplification of that imbalance, and the self-production of the catalyst during the reaction, known as autocatalysis. This concept implies that a small initial advantage can lead to an accelerated dominance of one variant in the reaction.
This framework inspired Kagan’s research beginning in the early 1980s, wherein he concentrated on refining asymmetric reactions through an in-depth exploration of catalysts. At that time, researchers often employed metal atom catalysts alongside chiral substances, operating under the assumption that an equal mixture of chiral molecules would yield a balanced product.
Kagan and Soai’s discoveries are expected to contribute significantly to the efficiency of drug production moving forward, with further advancements anticipated in the field of chemistry.
