Rosmarinic acid

Rosmarinic acid, C18H16O8, is a natural polyphenol antioxidant carboxylic acid found in many Lamiaceae herbs used commonly as culinary herbs such as rosemary, oregano, sage, thyme and peppermint. Chemically, rosmarinic acid is a dimer of caffeic acid. It is a red-orange powder that is slightly soluble in water, but well soluble is most organic solvents.

Biological importance
Because of the antioxidant activity of Lamiacaea herbs in laboratory test models they have been suggested to have beneficial effects in humans.

Metabolism
Rosmarinic acid is known to undergo metabolism in humans and rats to methylated rosmarinic acid, coumaric acid, ferulic acid and caffeic acid.