New tigliane and daphnane derivatives from Pimelea prostrata and Pimelea simplex.

From the methanol extract of Pimelea prostrata, prostratin (I) and 2 autoxidation products have been isolated. They are tigliane derivatives and relatively nonirritant on the mouse ear. The irritant pimelea factor P5 (IIa) also with a tigliane skeleton and related to mancinellin (IIb), as well as the irritant diterpene ester pimelea factor P1 (IIa, simplexin) with daphnane skeleton, were found to be present in both P. prostrata and P. simplex. Further the irritant homologue of simplexin, pimela factor IIIb was detected in P. prostrata. Some biogenetic consequences of these findings are discussed.