The presence of histamine in Cnidosculus oligandrus (Euphorbiaceae).

1) The presence of histamine in prickles and lead and stem tissues of Cnidosculus oligandrus (Mull. Arg) Pax & Hoffm (Euphorbiaceae) is reported. 2) Prickles on stems and leaves have larger amounts of histamine, as determined by the isolated guinea-pig ileum and by fluorimetry of the condensation product of the histamine and ortho-phthalaldehyde (OPT). 3) Additionally, thin-layer chromatography and the increase of vascular permeability bioassay were used to confirm the presence of histamine.