A polysaccharide complex extracted from the agarocytes of algae of the Rhodophyceae. Predominant agar-producing genera are Gelidium, Gracilaria, Acanthopeltis, Ceramium, Pterocladia found in the Pacific and Indian Oceans and Japan Sea. Can be separated into a neutral gelling fraction, agarose, and a sulfated non-gelling fraction, agaropectin: Araki, J. Chem. Soc. Jpn. 58, 1338 (1937). Structure believed to be a complex range of polysaccaride chains having alternating α-(1→3) and β-(1→4) linkages and varying in total charge content; three extremes of structure noted, namely neutral agarose, pyruvated agarose having little sulfation, and a sulfated galactan: Duckworth et al., Carbohydr. Res. 16, 189, 435, 446 (1971) DOI. Reviews: V. J. Chapman, Seaweeds and Their Uses (Pitman Publ., New York, 1952) pp 89-123; Humm, Econ. Bot. 1, 317 (1947); Mori, Adv. Carbohydr. Chem. 8, 317 (1953); Selby, Wynne, in Industrial Gums, R. L. Whistler, Ed. (Academic Press, N.Y., 2nd ed., 1973) pp 29-48.
Cathartic.
Laxative/Cathartic