Abstract:Compounds P4 and P5 had been isolated from the seeds of Polyalthia plagioneura Diels. The former was identified as howiicin A by the spectral analysis of [ α ]D, IR, 1 H - NMR, 13C-NMR and MS, the latter was characterized as a new monotetrahydrofuran annonaceous acetogenin with C5-OH, which was named plagionicin A.