The chemistry and immunochemistry of carrageenans from Eucheuma and related algal species

CARRAGEENANS BIOSYNTHESIZED BY CARPOSPOROPHYTES OF RED SEAWEEDS GIGARTINA SKOTTSBERGII (GIGARTINACEAE) AND GYMNOGONGRUS TORULOSUS (PHYLLOPHORACEAE)1

“…Recently, small amounts of lambda structure were found in the system of carrageenans extracted from cystocarpic plants of Gigartina skottsbergii and Gymnogongrus torulosus (Ciancia et al 1993b, 1997, Estevez et al 2001). These results, together with those obtained from seaweeds in which both phases produce only kappa/iota‐carrageenans (DiNinno and McCandless 1978, Bert et al 1989), indicated that the type of carrageenan biosynthesized does not depend on the cell ploidy.…”

“…It has been reported (Gordon‐Mills and McCandless 1975), on the basis of results from histochemical techniques, that the carposporophytes biosynthesized lambda‐carrageenans, in agreement with the diploid character of the phase. This difference between carrageenans biosynthesized by the alternating life stages has not been observed in seaweeds from other families (DiNinno and McCandless 1978, Bert et al 1989).…”

Enzymatic analysis of carrageenans: Structure of carrageenan from Eucheuma nudum

“…Alkali treatment causes a decrease in the resonance peak for C-1 of 3,6-anhydrogalactose (KAI ; 95 .4 ppm relative to C-1 of 3,6-anhydrogalactose-2-sulfate (tAl ; 92 .1 ppm), suggesting that the only precursor form is v-carrageenan. This was also shown by DiNinno & McCandless (1978), who found no galactose-6-sulfate residues . Resonance peaks associated with precursor carrageenan were not clearly resolved in the hot-extracted material, indicating that extraction under mild conditions is a valuable step in determining cryptic features ; however, this does not necessarily apply to carrageenans from all sources .…”

“…Dawes et al (1977) reported that the carrageenan from E. nudum was a `deviant' t-carrageenan . Chemical analysis has also shown the presence of both galactose-2,6-disulfate residues and non-6-sulfated residues (DiNinno & McCandless 1978) . The 13 C-NMR spectrum for the cold-extracted carrageenan shows the presence of several resonance peaks associated with precursor carrageenan (Table 1) .…”

Hybrid (Iota-Nu-Kappa) Carrageenan from Eucheuma nudum (Rhodophyta, Solieriaceae), Identified Using Iota- and Kappa-Carrageenases and 13C-Nuclear Magnetic Resonance Spectroscopy

“…κ-Carrageenan was identified s a minor component in the enzyme resistant fraction after ι-carrageenase degradation. In contrast, previous reports on the carrageenan from E. nudum identified ι-carrageenan s the major component, with v-carrageenan and deviant iota (o)-carrageenan [O-a-D-galactopyranosyl-2-sulfate (!->3)-O--D-galactopyranosyl-4-suIfate (l-»4) present s minor components (Dawes et al 1977, DiNinno andMcCandless 1978]. In the present study, κ-and v-carrageenan were identified s minor components, but -carrageenan was not detected.…”