How Does Aspirin Work in Plants and Humans?

Millions of people rely on aspirin to treat their headaches, fevers, and other ailments. But most people do not know that the active ingredient in aspirin was first discovered in plants. In humans, the body converts aspirin into a substance called salicylic acid (SA). Plants make SA. They use it to help defend themselves against infection. To discover how SA works in plants, we used powerful methods to identify over two dozen proteins that bind to SA. SA binding changes the activities of these proteins. SA and related compounds also bind to multiple proteins in humans. We discovered several new human proteins that can bind SA. These proteins are associated with very common, devastating human diseases. In addition, we identified several new versions of SA that bind to these proteins more strongly than SA does. As a result, these versions of SA inhibit the disease-associated activities of these proteins better than SA. This gives hope that better aspirin-like drugs can be made.