POLYSACCHARIDES FROM ALGAE .51. PARTIAL R EDUCTIVE HYDROLYSIS OF SULFATED GALACTAN FROM RED ALGA LAURENCIA-CORONOPUS J AG (RHODOPHYTA, RHODOMELACEAE)

The structure of the agarlike sulfated galactan from the epiphytic red alga Laurencia coronopus was elucidated by partial reductive hydrolys is. In the presence of borane-4-methylmorpholine complex, the acid-lab ile glycosidic linkages of 3,6-anhydrogalactose residues of the polysa ccharide are hydrolyzed with the simultaneous reduction of these resid ues, thus precluding their further acidic degradation. The main produc ts of this hydrolysis were 3,6-anhydro-4-O-beta-D-galactopyranosyl-L-d ulcitol (agarobiitol), its 6-O-methyl derivative, agarobiitol 6-sulfat e, and some higher oligosaccharides. These products were structurally analyzed by composition, mass spectrometry, and NMR.