Fumaric acid

Fumaric acid is a chemical substance that occurs in various plants. It also occurs as a by-product at various times in the human body. In chemistry it is used for food preservation. It is known as E 297. Usually it replaces citric acid. In medicine, it is used to treat various diseases of the skin, such as Psoriasis. 
Albert Szent-Györgyi was awarded the Nobel Prize for Chemistry in 1937 because of his work on Fumaric acid.