The brown seaweed Adenocystis utricularis (family Adenocystaceae, order Ectocarpales
sensu lato) was extracted in parallel with three solvents usually utilized for obtaining
fucoidans: distilled water, 2% calcium chloride solution and diluted hydrochloric
acid (pH 2) solution. In each case, the extraction was effected at room temperature
and then at 70 degrees C. The extraction yields and characteristics of the products
were similar in the three cases, with only minor differences. The analytical features
of the products indicate that two different types of fucoidans are present in this
seaweed. One of them, mostly extracted at room temperature, is composed mainly of
L-fucose, D-galactose and ester sulfate (the 'galactofucan'). The other product (the
'uronofucoidan') is the major component of the extracts obtained at 70 degrees C.
It is composed mainly of fucose, accompanied by other monosaccharides (mostly Man,
but also Glc, Xyl, Rha and Gal), significant amounts of uronic acids and low proportions
of sulfate ester. Fractionation with the cationic detergent cetrimide has allowed
achieving a better separation of the galactofucan and uronofucoidan components. The
galactofucans show a high inhibitory activity against herpes simplex virus 1 and 2,
with no cytotoxicity, whereas the uronofucoidans carry no antiviral activity. Structural
studies on the galactofucan fractions were carried out by methylation analysis, desulfation
and NMR spectroscopy. The fucan constituent is mainly composed of 3-linked alpha-L-fucopyranosyl
backbone, mostly sulfated at C-4, and branched at C-2 with non-sulfated fucofuranosyl
and fucopyranosyl units, and 2-sulfated fucopyranosyl units. The galactan moiety is
more heterogeneous, with predominant D-galactopyranose units linked on C-3 and C-6,
and sulfation mostly on C-4, even in terminal non-reducing units. It may be inferred
that at least some of these galactose units carry the alpha-configuration.