Marine red alga Gracilaria verrucosa, a material commonly used to make agar, contains no prostaglandins(PG) in nature. But through physical stimulation, this alga was found to produce remarkable amounts of PG using enzymes and substrates in itself.
PG was produced in the amount of approximately 2g/kg in dry matter with PGE₂ at 90%. PG composition was determined mainly by polyunsaturated fatty acids present in the alga and could be controlled through use of a suitable precursor for each PG.
The data for unialgal culture of G. verrucosa confirmed that this alga produces PG. Various species of other algae belonging to the genus Gracilaria were found to produce PG in small amounts.