[Studies on the Chemical Constituents from Marine Brown Alga Ishige Okamurai (3)]

Objective: To study the chemical constituents of Ishige okamurai.

Method: Compounds were isolated by Pyricularia oryzae bioassay-guided fractionation method in combination with extraction and partitionation as well as multi-chromatography. Their structures were determined by spectral analysis and chemical evidence.

Result: Seven compounds were obtained and identified as (2S)-1-O-palmitoyl-2-O-(11Z-octadecenoyl)-3-O-beta-D-galacto-pyranosyl glycerol (I), (2S)-1-O-palmitoyl-2-O-myristoyl-3-O-(6-sulfo-alpha-D- quinovopyranosyl) glycerol (II), (2S)-1-O-palmitoyl-2-O-palmitoyl-3-O-(6'-sulfo-alpha-D- quinovopyranosyl) glycerol (III) and (2S)-1-O-palmitoyl-2-O-(11Z-octadecenoyl)-3-O-(6'-sulfo-alpha-D- quinovopyranosyl) glycerol (IV), stearic acid (V), methyl myristate(VI) and palmitic acid (VII).

Conclusion: Compounds I-VI were isolated from the alga for the first time while I, II and IV are new natural products. I-IV showed activity causing morphological abnormality of P. oryzae mycelia.