Algicidal activity of glycerolipids from brown alga Ishige sinicola toward red tide microalgae

Bioassay-guided fractionation of a methanol extract of the brown alga, Ishige sinicola, led to the isolation of five algicidal compounds. Their structures were determined to be α-monoglycerides of eicosa-5Z,8Z,11Z, 14Ztetraenoic (arachidonic) acid, octadeca-6Z,9Z,12Z,15Ztetraenoic acid, linoleic acid and oleic acid, and 1-O-palmitoyl-3-O-(6-sulfo-α-D- quinovopyranosyl)-sn-glycerol on the basis of spectroscopic data and a comparison with the data in the literature. These glycerolipids showed moderate-to-high cell lysis activity against the red tide microalgal species, Heterosigma akashiwo, Karenia mikimotoi and Alexandrium catenella, at a concentration of 20μg/mL.