Sesquiterpenoids with antialgal activity against the common red tide microalgae from marine macroalga Porphyra yezoensis.

Previous studies showed that methanol extracts from Porphyra yezoensis significantly inhibited Karenia mikimitoi and Skeletonema costatum. Five sesquiterpenoids (1-5) were successfully isolated from this marine macroalga through a combination of silica gel column chromatography and repeated preparative thin-layer chromatography in this paper. Their structure was identified as gossonorol (1), 7,10-epoxy-ar-bisabol-11-ol (2), cyclonerodiol (3), cadinol, (4) and 4-cadinen-1-ol (5) on the basis of spectroscopic data.