CARRAGEENANS FROM THE TETRASPORIC STAGES OF GIGARTINA-CLAVIFERA AND GIGARTINA-ALVEATA (GIGARTINACEAE, RHODOPHYTA)

Modern chemical and spectroscopic techniques have been used to charact erise the polysaccharides extracted from the tetrasporic life stages o f Gigartina clavifera and Gigartina alveata. Both are predominantly ze ta-carrageenans. About one in six of the 3-linked residues in both pol ysaccharides also have a pyruvate acetal group at the 4- and 6-positio ns. In addition, a similar proportion of the 4-linked units of each po lysaccharide are devoid of sulfate groups, whilst more have sulfate es ters on both 0-2 and 0-6. Some of the 3-linked units contain a sulfate at the 6-position in addition to that at 0-2. The polysaccharide from tetrasporophytic G. alveata also contains a small but significant num ber of 3,6-anhydrogalactosyl units, most of which are naturally sulfat ed at the 2-position.