Antineoplastic agents, 88. Pimelea prostrata.

The aerial portion of Pimelea prostrata (Thymelaeaceae) collected in New Zealand was evaluated as a source of substances that inhibit growth of the murine P-388 lymphocytic leukemia (PS). Simplexin (1) and Pimelea factor P2 (2) were found to strongly inhibit growth (ED50 5 X 10(-3) and 8 X 10(-4) micrograms/ml, respectively) of the PS in vitro cell line. The cyclic orthoester (2) was also found to inhibit growth (T/C 132 at 20 micrograms/kg) of the PS in vivo system. Detailed 1H-nmr (at 400 MHz) and 13C-nmr studies combined with fast atom bombardment mass spectral evidence were employed to confirm the structural assignments.