The effects a drug or chemical compound have on the body depend on how its atoms are arranged in space. Some compounds have a dark twin with the same molecular formula but different 3D structure – and this can have consequences for what they do or don’t do in the body.

The 2026 Nobel Prize in chemistry was awarded to two researchers who developed a chemical process allowing them to create only one of these two twins. Called asymmetric organic synthesis, this discovery meant that chemists developing pharmaceuticals could create one version or the other – for example, only the version of the molecule that benefits the body, not the version that can cause damage.

Consider the tragic story of thalidomide, a morning sickness drug that caused thousands of birth defects and miscarriages. While one form, or isomer, of thalidomide has a sedative effect, the other is thought to cause abnormal physiological development. Because the two versions can convert back and forth in the body, it’s dangerous to take either form of thalidomide while pregnant.

My research has focused on one such compound found in red grapes and peanuts: resveratrol. It has been a scientific mystery why clinical trials on using resveratrol to treat Alzheimer’s disease have had inconsistent results. With the help of the chemical reactions that led to the 2026 Nobel Prize, my team and I discovered that it may be because two different forms were used – while one may help with cognition and memory, the other may be toxic to the nervous system.

Isomers and amino acids

Many drugs have the........

© The Conversation