Acyclic diterpenoid from the red alga Gracilaria foliifera

the dichloromethane/methanol extract from the red alga gracilaria foliifera was subjected to a column chromatography which afforded a new (naturally) acyclic diterpenoid 3,7,11,15 tetramethyl-3-hexadec-en-1-ol (1) in addition to two c29 ethylidene steroids fucosterol, (24e)-stigmasta-5,24(28)-diene-3β-ol (2) and isofu-costerol, (24z)-stigmasta-5,24(28)-diene-3β-ol (3) which are reported for the first time from the genus gracilaria. the structures were assigned mainly on the basis of 1h and 13c nmr experiments.