Abstract

The polysaccharide extracted from Plocamium costatum has been examined by chemical and spectroscopic techniques. Glycosyl linkage analysis of the native polysaccharide revealed a complex sulfated galactan, but the substitution and linkage pattern was not obvious, partly because the 4-linked units are nearly all 3-sulfated and a high proportion of the 3-linked units are 4-sulfated. Glycosyl linkage and ¹³C NMR spectroscopic analysis of a solvolytically desulfated sample, however, confirmed a backbone structure of alternating 3-linked β-D-galactopyranosyl and 4-linked α-galactopyranosyl units as expected for a red algal galactan. The 4-linked galactosyl units, however, are present in both the D- and L-configuration in approximately equal amounts.