GELIDIUM-SESQUIPEDALE (GELIDIALES, RHODOPHYTA) .1. SOLUBLE POLYMERS

The seaweed Gelidium sesquipedale was extensively extracted with water and the soluble materials fractionated into non-gelling and gelling f ractions. The insoluble material was fractionated into soluble and ins oluble alkaline fractions. The yields were reported and the different fractions were characterized by NMR and IR spectroscopy and chemical c omposition. The successive non-gelling fractions contained in addition to agarose, the biological precursors of agarose and starch/amylose o ligomers. The biological precursors were present mainly in the first e xtraction, the starch/amylose oligomers were predominant in the follow ing extractions. The following four purified fractions: agarose (GF, 4 3%); starch/amylose and biological precursors (NGF, 7%), proteins (ASF , 24-28%) and cellulose (AIF, 8-10%) represented at least 82% of the s tarting dried seaweed.