Walnut extract is made from the fresh green shells of English walnut,
Juglans regia. The aqueous extract has been shown to be particularly
effective as a self-tanning sunscreen agent. Its most important
component is juglone (5-hydroxy-1,4- naphthoquinone), a naphthol
closely related to lawsone (2-hydroxy-1,4- naphthoquinone). Juglone
is known to react with the keratin proteins present in the skin to
form sclerojuglonic compounds. These are colored and have UV
protection properties39