[Isolation and effects on green alga Chlorella pyrenoidosa of algal-inhibiting allelochemicals in the macrophyte, Phragmites communis Tris].

Two fractions of secondary metabolites which inhibited the growth of green alga Chlorella pyrenoidosa, was isolated by several separation techniques from the ethanol extract of the macrophyte, Phragmites communis Tris. The EC50 of the two fractions on C. pyrenoidosa were 0.68 mg/L (the fraction of acidic solvent) and 2.65 mg/L (the fraction of alkaline solvent), respectively. Further purification of the allelochemicals in the acidic solvent by alkaline aluminum oxide column chromatography revealed that this fraction containing inhibiting allelochemicals and stimulating allelochemicals. The inhibiting allelochemicals showed more inhibitory effect and the EC50 was 0.50 mg/L. The result suggests that allelochemicals in P. communis can be used as an algae-inhibitor.