Inhibitive effects of organic solvent extracts from mangrove plant Bruguiera

Based on allelopathic principles, we used organic solvents to extract the active substances from mangrove plant Bruguieragymnorrhiza, and extracts of hexane phase, ethyl acetate phase, n-butyl alcohol phase and water phase were obtained respectively. Theexperiment was carried out to test the inhibitive effects of these extracts on algae. Measuring the cell density of Phaeocystis globosa, wefound that all of the extracts had significantly inhibitive effects on P. globosa, and the inhibitive effects of extracts of hexane phase andethyl acetate phase were better than those of n-butyl alcohol phase and water phase. The 48h-EC50 of extracts of hexane phase and ethylacetate phase on P. globosa were 14.90 mg/L and 12.18 mg/L ,respectively. The initial algal density (IAD) was considered an importantfactor to influence the inhibitive effects of extracts. The inhibitive rate (IR) was high at low IAD, while it decreased with the increasingof IAD. At a higher IAD, the extracts promoted the growth of P. globosa, rather than inhibited the growth.