Structural analysis of Gigartina pistillata carrageenans (Gigartinaceae, Rhodophyta)

The chemical structure of carrageenans produced by the gametophytic and tetrasporophytic life cycle phases of Gigartina pistillata has been determined by permethylation analysis, IR and 13C NMR spectroscopies. The chemistry of the galactans varies according to the biological phases of the plant, the gametophytic alga produces heterogeneous κ–ι type carrageenan containing minor amounts of ν-carrabiose. The tetrasporophytic alga synthesizes a complex sulfated galactan composed of λ-, ξ-, π-carrabioses and sulfated carrabioses containing 3-linked galactopyranose 2,6-disulfate. The carrageenan of the gametophytic alga is heterogeneous, of κ–ι type with minor amounts of ν-carrabiose. That of the tetrasporophytic alga is a complex sulfated galactan composed of λ-, ξ-, π-carrabioses and sulfated carrabioses containing 3-linked galactopyranose 2,6-disulfate.