TY - JOUR A1 - Freeman, P A1 - Ritchie, E A1 - Taylor, W T1 - The Constituents of Australian Pimelea spp. I. The Isolation and Structure of the Toxin of Pimelea simplex and P. trichostachya Form B Responsible for St. George Disease of Cattle JF - Australian Journal of Chemistry JO - Aust. J. Chem. Y1 - 1979 VL - 32 IS - 11 SP - 2495 EP - 2506 KW - UR - https://doi.org/10.1071/CH9792495 N2 - Systematic extraction of Pimelea simplex F. Muell., which causes St. George disease of cattle, led to the isolation of the diterpenoid orthoester, simplexin (1), as an active principle. Other toxicsubstances isolated were 12β-acetoxyhuratoxin (10) and the tigliane ester derivative (11) related to mancinellin; huratoxin was found to be present in freshly collected plant material but it could not be separated satisfactorily from simplexin. In addition, loliolide (13) and a mixture of saturated and unsaturated fatty acids were isolated. Simplexin was obtained also from P. trichostachya Lindl. Form B. ER -