Galactan (galactosan) is a polysaccharide consisting of polymerized galactose. In general, galactans in natural sources contain a core of galactose units connected by α(1→3) or α(1→6), with structures containing other monosaccharides as side-chains.
Galactan derived from Anogeissus latifolia is primarily α(1→6), but galactan from acacia trees is primarily α(1→3).
Halymenia durvillei is a red seaweed (algae) that produces a sulfated galactan. Several other algae species also contain galactans. Including Carpopeltis .I.J. Miller and J. Mollion, Evaluation of the structures of galactans from Carpopeltis sp. a member of the Halymeniales in the western Indian Ocean, Bot. Mar., 49 (2006) 79-85
Galactan is found in the side chains of rhamnogalacturonan I (RG-I) and is needed for gel formation in the cell walls of organisms. It was observed there was less of the gelling characteristic (as well as the polymeric chains being more likely to degrade) when fewer galactans were present in the polymeric side chains.
See also Agar Galactooligosaccharide
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