Kagan and Soai win Chemistry Nobel for mastering molecular mirror images

French scientist Henri B. Kagan and Japanese scientist Kenso Soai won the Nobel Prize in Chemistry on Wednesday for their work on the mirror-image forms of molecules, a breakthrough that has shaped modern medicine and the development of drugs. The Royal Swedish Academy of Sciences announced the award in Stockholm.

Their research showed how chemists can steer reactions to produce the required mirror image of a molecule. The Nobel committee said the achievement solved a problem that had earlier been mastered by no one "other than life itself".

Many molecules exist in forms that resemble each other but are not identical, much like right and left hands. These different versions can have very different properties. One form of the chemical carvone smells like mint, while the other has the scent of caraway, a spice often used in rye bread.

These differences are especially important in medicine because the mirror-image forms of a molecule can behave differently when they interact with other chemicals. Scientists developing drugs need to make sure they get the version that treats illness, not one that could worsen symptoms. "The medicines we have today would not be possible without this chemistry," said Rigoberto Hernandez, president of the American Chemical Society.

In the 1980s, Kagan's work showed that it might be possible to design reactions that produce one form of a molecule over the other. Years later, Soai refined the process and created the first chemical reaction that could efficiently produce only one mirror image of a molecule, now known as the Soai reaction.

"It might be difficult to say that this drug, or that drug, was developed using this," said Peter Somfai, a member of the Nobel Committee for Chemistry. "I would say all of them, because we use this as a tool; we use this as an understanding of how to develop catalysts, how they function." Somfai also said: "This is probably the coolest experiment in organic chemistry."

The importance of mirror images in chemistry is also seen in living systems. DNA twists to the right, and proteins in the human body are made mostly from left-handed building blocks. Chemist Holden Thorp, editor-in-chief of the journal Science, said that understanding these molecular mirror images can help scientists study the chemical architecture of life, apart from aiding the development of medicines and perfumes.

Soai, 76, who is affiliated with the Tokyo University of Science, was shopping at a neighbourhood supermarket when he heard that he had won. "I'm very excited to receive the very nice news," Soai told the Nobel committee and journalists by phone. "Of course, this is one of the most exciting days in my life." Kagan, 95, is affiliated with the Universite Paris-Sud in Orsay, France. Neither university immediately responded to requests for comment from The Associated Press.

Last year, three scientists won the chemistry Nobel for developing new molecular structures that can trap large quantities of gas, laying the groundwork for possible ways to remove greenhouse gases from the atmosphere or collect moisture in desert conditions. This year's Nobel announcements began with the medicine prize on Monday for work that led to a light-based tool to study the brain, while Tuesday's physics prize recognised efforts to explain a rare group of neutrinos.

The literature prize will be announced on Thursday, the peace prize on Friday and the Nobel Memorial Prize in Economic Sciences on Monday. This year's prize money is 12 million Swedish kronor, or about USD 1.2 million. The chemistry award recognised work that made it possible to control molecular mirror images, a tool that now underpins modern chemistry and medicine.

With PTI Inputs

- Ends