Characterization of poison oak urushiol.

Procedures are described that were used in the isolation and characterization of urushiol components reported to be the allergenic constituents of poison oak, Toxicodendron diversilobum. Characterization of these components by spectral techniques indicated they are unsaturated congeners of 3-heptadecylcatechol, possessing one, two, or three double bonds in an unbranched C17 side chain. These components are shown to differ from those isolated from poison ivy, Toxicodendron radicans, by a - CH2CH2-unit in the unbranched alkyl side chain.