In order to identify these allelochemicals of ethyl acetate extracts from Portulacaceae and seeds, the chemical components of the extracts were analyzed by gas chromatography-mass spectrometry (GC-MS). The algal inhibitory effects of the extracts were determined by bioassays using Microcystis aeruginosa. 15 kinds of compounds, including fatty acid, ester, ketone, sterol were obtained and 8 identified fatty acids and N-phenyl-2-Naphthalenamine were found to be significantly active against some harmful algae. The inhibitory ratios of the ethyl ac...