Questions & Answers
Chemically, urushiol is a
mixture of eight 3-substituted pyrocatechols. The compound
shown is the C17 diene, an important part of poison-oak’s
Urushiol is a strong reducing
agent. Oxygen in the epidermal layer of the skin transforms
the urushiol to an orthobenzylquinone.
The immune systems of animals
in the last 60 million years have ignored small
metabolically-common molecules, like the six carbon ring of
pyrocatechol. Animal immune systems have concentrated on
foreign molecules larger than 18 carbons, and respond most
briskly to compounds in the 21 to 23 carbon size range.
Septadecylorthobenzylquinone is such a compound; it never
originates in animals, and has 23 carbons. A few
molecules of it can cause a rash!
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