French and Japanese chemists win Nobel for cracking mirror molecule mystery

Two scientists who unlocked the secret behind mirror image molecules, a discovery that transformed how life saving medicines are made, have been named winners of the 2026 Nobel Prize in Chemistry.

Henri Kagan of France, 95, and Kenso Soai of Japan, 76, were honored for their work on asymmetric reactions, which allow chemists to create only one version of a molecule that exists in two mirror image forms. The Royal Swedish Academy of Sciences announced the award on Wednesday, October 7, in Stockholm.

Soai said he was out shopping when the call came through.

“This is the most exciting day in my life, I am very glad to share this prize with professor Henri Kagan,”

he told the Nobel press conference by phone. The committee was still trying to reach Kagan to give him the news.

The chemistry prize is the third of this year's Nobels, following the medicine and physics awards announced earlier in the week.

Why do mirror image molecules matter?

Many molecules essential to life come in two forms that are mirror images of each other, much like left and right hands. But living organisms almost always use just one version, a puzzle chemists call homochirality, from the Greek word for hand. The mystery had stumped scientists for more than a century.

Kagan and Soai showed how chemical reactions can be pushed to favor a single mirror image. That matters greatly for drug manufacturing, because the two forms can have very different effects on the human body.

“The left-handed version of the drug can have one effect, and the right-handed version can have another effect, and then we need methods for selectively preparing them,”

said Peter Somfai, a member of the Nobel Committee for Chemistry.

“In developing such methods the findings of this year's laureates are important. They provided powerful tools for that.”

Building on the work of Louis Pasteur

The story begins with Louis Pasteur, the 19th century French chemist who died before the first Nobel Prizes were handed out. While studying tartaric acid, a compound used in winemaking, Pasteur noticed that bacteria would ferment only one of its two forms, the one naturally found in grapes. The other form remained untouched.

That observation proved that some substances exist in two versions with different properties, sometimes with harmful health effects. But how to create the right version of a chiral substance remained unsolved until Kagan and Soai developed asymmetric reactions that produce an excess of one form.

The tragic case of thalidomide shows why this matters. In the early 1960s, thousands of children were born with severe birth defects after their mothers took the sedative. Researchers later realized that it was the mirror image of the active substance that caused the harm.

What does the Nobel Prize include?

The prizes were established in the will of Alfred Nobel, the Swedish inventor and businessman who made his fortune from dynamite and other explosives. They have been awarded since 1901, with some interruptions during the world wars. The economics prize was added later, funded by the Swedish central bank.

While chemistry laureates sometimes get less attention than their counterparts in physics, literature, or peace, the field has recognized many pivotal discoveries, including nuclear fission and genetic sequencing techniques.

Last year's chemistry prize went to Susumu Kitagawa, Richard Robson, and Omar Yaghi for developing metal organic frameworks, molecular structures that could help tackle climate change and water shortages.

The laureates will receive their medals from Sweden's King Carl XVI Gustaf at a ceremony in Stockholm on December 10, the anniversary of Alfred Nobel's death. The awards are followed by a lavish banquet at Stockholm City Hall. The winners share 12 million Swedish crowns, about $1.2 million, along with the prestige of winning one of the world's most celebrated science awards.

The peace prize, the only Nobel not presented in Sweden, is awarded separately in Oslo.

This article is based on a report from Rappler. Photo: Nobel Prize Outreach.