J.R. Nunn

Sulphated polysaccharides of the Solieriaceae family : Part I. A polysaccharide from Anatheca dentata

Abstract Hot-water extraction of Anatheca dentata , a red seaweed belonging to the family Solieriaceae , yielded a mixture of polysaccharides. Fractionation of this mixture with Cetavlon gave a glucomannan as minor component and a highly sulphated, major component, which yielded D - and L -galactose, D -xylose, and traces of 3- O -methylgalactose and uronic acid on hydrolysis. Partial hydrolysis of the major component with acid gave 4- O -β- D -galactopyranosyl- L -galactose ( 1 ), 3- O -α- L -galactopyranosyl- D -galactose ( 2 ), 4- O -β- D -galactopyranosyl- D -galactose ( 3 ), O -β- D -galactopyranosyl-(1→4)- O -α- L -galactopyranosyl-(1→3)- D -galactose ( 4 ), and O -β- D -galactopyranosyl-(1→4)- O -α- L -galactopyranosyl-(1→3)- O - D -galactopyranosyl-(1→4)- L -galactose ( 5 ). The results indicate that a substantial part of the molecule has alternating D - and L -galactose residues and α-(1→3)- and β-(1→4)-glycosidic links. However, no role for the excess of D - over L -galactose, or of the xylose, has yet been found.

Sulphated polysaccharides of the grateloupiaceae family : Part VI. A polysaccharides from pachymenia carnosa

Abstract Pachymenia carnosa , a red seaweed of the Grateloupiaceae , yielded a sulphated polysaccharide which, on acid hydrolysis, gave D -galactose, 2- O -methyl- D -galactose, 4- O -methylgalactose, and 6- O -methyl- D -galactose. Partial hydrolysis of the polysaccharide resulted in the isolation and characterisation of 4- O -β- D -galactopyranosyl- D -galactose, 4- O -β- D -galactopyranosyl-2- O -methyl- D -galactose, 3- O -(2- O -methyl- D -galactopyranosyl)- D -galactose, 4- O -(6- O -methyl-β- D -galactopyranosyl)- D -galactose, 2- O -methyl-4- O -(6- O -methyl-β- D -galactopyranosyl)- D -galactose, and a 6- O -methyl-(2- O -methyl- D -galactopyranosyl)- D -galactose. At present, it is not possible to postulate a structure for the polymer.

Sulphated Polysaccharides of the Grateloupiaceae Family Part V1. A Polysaccharide from Aeodes ulvoidea

Abstract Aeodes ulvoidea , a red seaweed of the Grateloupiaceae , yielded a highly sulphated polysaccharide which was shown to contain d -galactose, 4- O -methyl-L-galactose, and 2- O -methyl- d -galactose, together with chromatographic traces of 6- O -methylgalactose, xylose, and mannose. The sulphate was not labile to alkali, but it was largely removed with methanolic hydrogen chloride. Periodate oxidation of the polysaccharide and methylation of the desulphated polymer indicate ( a ) the presence of (1→3)- and (1→4)-glycosidic links in the macromolecule, ( b ) that the 2- O -methyl- d -galactose is either (1→4)= and/or (1→3)-linked, and ( c ) that the 4- O -methyl-L-galactose is probably present only as non-reducing end-group.

Polysaccharides of the red alga Chaetangium erinaceum: Part I. isolation and characterisation of the water-soluble xylan

Abstract Hot-water extraction of the red alga Chaetangium erinaceum yielded a mixture of polysaccharides from which was isolated a xylan. Methylation and partial hydrolysis analysis of the xylan showed it to be a linear molecule with no evidence of branching, and composed exclusively of β-(1→3)- and β-(1→4)-linked d -xylopyranose residues in the ratio of 2:9. Evidence was obtained for regions of adjacent (1→4)-linkages interdispersed with (1→3) linkages, but none for contiguous (1→3)-linkages in the molecule. The following oligosaccharides were isolated from the partial, acid hydrolysate and identified: xylobiose, rhodymenabiose, xylotriose, O -β- d -xylopyranosyl-(1→3)- O -β- d -xylopyranosyl-(1→4)- d -xylose, O -β- d -xylopyranosyl-(1→4)- O -β- d -xylopyranosyl-(1→3)- d -xylose, xylotetraose, and xylopentaose.

A polysaccharide from Aeodes orbitosa

Abstract A highly sulphated, methylated galactan, aeodan, isolated from Aeodes orbitos a was shown to contain d -galactose, 2- O -methyl- d -galactose, and glycerol. It was desulphated with methanolic hydrogen chloride. Both aeodan and desulphated aeodan were studied by periodate oxidation and methylation. In addition, aeodan was subjected to akaline degradation. Evidence is presented for the presence of (1→3)- and (1→4)-glycosidic linkages with sulphate on positions 2 and 6.

The linkage of 4-O-methyl-L-galactose in the sulphated polysaccharide of Aeodes ulvoidea

Abstract Six disaccharides and one trisaccharide, namely, 6- O -β- D -galactopyranosyl- D -galactose, 4- O -β- D -galactopyranosyl- D -galactose, 6- O -(4- O -methyl-α- L -galactopyranosyl)- D -galactose, 3- O -(2- O -methyl-α- D -galactopyranosyl)- D -galactose, 4- O -β- D -galactopyranosyl-2- O -methyl- D -galactose, O -(β- D -galactopyranosyl)-(1→4)- O -[4- O -methyl-α- L -galactopyranosyl-(1→6)]- D -galactose, 2- O -methyl-4- O -(6- O -methyl-β- D -galactopyranosyl)- D -galactose were isolated and characterized from a partial, acid hydrolysate of the sulphated polysaccharide from Aeodes ulvoidea . These results demonstrate, for the first time, the mode of linkage of 4- O -methyl- L -galactose in a red-seaweed polysaccharide.

Investigation of the acetolysis products of the sulphated polysaccharide of Aeodes ulvoidea

Abstract Investigation of the acetolysis products of the sulphated polysaccharide of the seaweed Aeodes ulvoidea led to the isolation and characterization of the following oligosaccharides: 3- O -α- D -galactopyranosyl- D -galactose ( 1 ), 3- O -(2- O -methyl-α- D -galactopyranosyl)- D -galactose ( 2 ), 4- O -β- D -galactopyranosyl-2- O -methyl- L -galactose ( 3 ), 4- O -β- D -galactopyranosyl-2- O -methyl- D -galactose ( 4 ), O -β- D -galactopyranosyl-(1→4)- O -α- D -galactopyranosyl-(1→3)- D -galactose ( 5 ), O -α- D -galactopyranosyl-(1→3)- O -β- D -galactopyranosyl-(1→4)- D -galactose ( 6 ), O -α- D -galactopyranosyl-(1→3)- O -β- D -galactopyranosyl-(1→4)-2- O -methyl- D -galactose ( 7 ), O -(2- O -methyl-α- D -galactopyranosyl)-(1→3)- O -β- D -galactopyranosyl-(1→4)-2- O -methyl- D -galactose ( 10 ), and O -α- D -galactopyranosyl-(1→3)- O -β- D -galactopyranosyl-(1→4)- O -α- D -galactopyranosyl-(1→3)- D -galactose. In addition, the isolation of a tetrasaccharide possessing alternating D - and L -galactose residues demonstrates the hitherto unexpected presence of L -galactose in the polysaccharide. The structure of the polysaccharide is discussed.

Sulphated polysaccharides of the Solieriaceae family : Part II. The acidic components of the polysaccharide from the red alga Anatheca dentata

Abstract Fractionation of a partial, acid hydrolysate of the polysaccharide from the red alga Anatheca dentata yielded 4- O -(α- D -glucopyranosyluronic acid)- L -galactose, 4,6- O -(1-carboxyethylidene)- D -galactose, and 4- O -[4,6- O -(1-carboxyethylidene)-β- D -galactopyranosyl]- L -galactose. A third disaccharide, probably an O -[4,6- O -(1-carboxyethylidene)galactopyranosyl]-galactose, was isolated in too small quantity for full identification. Free pyruvic acid was identified in a total, acid hydrolysate. Treatment with alkaii revealed that only a small part of the sulphate is suitably placed for formation of 3,6-anhydro rings. Periodate oxidation showed the xylose residues to be either (1→4)-linked, (1→2)-linked, and/or present as non-reducing end-groups, and that the xylose residues are free of sulphate. Anatheca dentata polysaccharide is compared with the agars in the light of a recent analysis of the latter 2 , and shown to be surprisingly similar in many respects.

Sulphated polysaccharides of the grateloupiaceae family : Part VII. Investigation of the acetolysis products of a partially desulphated sample of the polysaccharide of pachymenia carnosa☆

Abstract Investigation of the acetolysis products of a partially desulphated sample of the polysaccharide isolated from Pachymenia carnosa led to the isolation and characterization of the following oligosaccharides: 3- O -α- D -galactopyranosyl- D -galactose ( 1 ), 4- O -β- D -galactopyranosyl- D -galactose ( 2 ), 3- O -(2- O -methyl-α- D -galactopyranosyl)- D -galactose ( 3 ), a 4- O -galactopyranosyl-2- O -methylgalactose ( 4 ), 3- O -α- D -galactopyranosyl-6- O -methyl- D -galactose ( 5 ), 4- O -β- D -galactopyranosyl-2- O -methyl- D -galactose ( 6 ), 2- O -methyl-4- O -(6- O -methyl-β- D -galactopyranosyl)- D -galactose ( 14 ), O -β- D -galactopyranosyl-(1→4)- O -α- D -galactopyranosyl-(1→3)- D -galactose ( 8 ), O -α- D -galactopyranosyl-(1→3)- O -β- D -galactopyranosyl-(1→4)- D -galactose ( 9 ), O -β- D -galactopyranosyl-(1→4)- O -α-(2- O -methyl- D -galactopyranosyl)-(1→3)- D -galactose ( 11 ), O -α-(2- O -methyl- D -galactopyranosyl)-(1→3)- O -β- D -galactopyranosyl-(1→4)- D -galactose ( 12 ), O -α- D -galactopyranosyl-(1→3)- O -β- D -galactopyranosyl-(1→4)-2- O -methyl- D -galactose ( 13 ), O -α-(2- O -methyl- D -galactopyranosyl)-(1→3)- O -β- D -galactopyranosyl-(1→4)-2- O -methyl- D -galactose ( 16 ), and O -β- D -galactopyranosyl-(1→4)- O -α- D -galactopyranosyl-(1→3)- O -β- D -galactopyranosyl-(1→4)- D -galactose ( 10 ). In addition, evidence was obtained for the presence of 4- O -(6- O -methyl-β- D -galactopyranosyl)- D -galactose ( 7 ) and O -β- D -galactopyranosyl-(1→4)- O -α- D -galactopyranosyl-(1→3)-6- O -methyl- D -galactose ( 15 ).

Sulphated polysaccharides of the grateloupiaceae family : Part IV. Methylation analysis of phyllymenan and desulphated phyllymenan

Abstract Methylation studies of phyllymenan and desulphated phyllymenan indicate that the D -galactosidic linkages are essentially α-(1→3) and β-(1→4). This information, together with previous data, has led to a partial structure for the polyssacharide.