Chemical contents of stinging trichomes ofCnidoscolus texanus.

Plants known as nettles bear trichomes that deliver a painful sting when touched. Studies of members of the Urticaceae have suggested that their trichomes may contain histamine, acetylcholine, and serotonin. We report investigations using TLC, HPLC, and UV-VIS spectrophotometry to analyze the hair fluids ofCnidoscolus texanus, a member of the Euphorbiaceae, along with standards of known histamine, acetylcholine, and serotonin. Of these, only serotonin was detected in hair extracts. Up to four other compounds were detected and partially characterized, but they have not been identified.