The seaweed extraction was carried out according to the
methods described previously [16,17]. Briefly, G. fisheri was washed
with clean seawater, air-dried, powdered and extracted with
different organic solvents in order of increasing polarity (i.e.,
hexane, chloroform, ethanol and methanol). Powdered seaweed
(30 g) was extracted with 500 ml of each solvent using a Soxhlet
apparatus for 24 h and then the solvent was evaporated in vacuum
(rotator evaporator) at 60 C until a dry residue (extract) was
obtained. The extracts were stored at 20 C.