Phytelephas macrocarpa Mannans

Mannans and glucomannans from plant sources all contain linear chains of (1 —> 4)-linked d-D-mannose and /J-D-glucose residues as their main structural features. The only true mannans (that is, polysaccharides containing 95% or more of D-mannose residues) so far examined from land plants are those from vegetable ivory (Phytelephas macrocarpa).90 96 The... 

Mannans, in which mannose units are linked predominantly in j8-d-(1—>4) bonds, are found in the red seaweed Porphyra umbilicalis, in the seed of the tagua palm (Phytelephas macrocarpa) in the form of massive thickening of the cell walls of the endosperm, and in the endosperm of members of the Umbelliferae and of the Compositae (e.g., lettuce seed). 

Mannose (= a-D-Mannopyranose) (hexose monosaccharide) From hydrolysis of Mannans Phytelephas macrocarpa (Arecaceae), Senna obtusfolia (Fabaceae) Sweet (bitter after taste)... 

C18H32O16 504.441 Isol. from the partial acid hydrolysate of ivory-nut mannan Phytelephas macrocarpa). Cryst. (EtOH aq.). 

C18H32O16 504.441 Isol. from the partial acid and enzymic hydrolysates of several mannans e.g. ivory nut (Phytelephas macrocarpa). Palmyra pahn (Borassus flabellifer), galactoman-nans e.g. lucerne (Medicago sativa), seeds of Sesbania aegyptiaca, glucomannans e.g. white spruce (Picea glauca), Larix decidua, jack pine (Pinus banksiana), Bletilla striata and Narcissus tazetta. Isol. from enzymic hydrolysates of brown copra metil, sapwood of Pinus densiflora. Constit. of commercial soybean syrup. Cryst. (EtOH). 

The presence of mannans in the crude cellulose of softwoods has frequently been reported but it is probable that in most of these instances the polysaccharide involved is a glucomannoglycan (see p. 225). A true mannan (ivory nut mannan) forms about 60% of the endosperm of the seed of the tagua palm [Phytelephas macrocarpa) and its X-ray diffraction pattern resembles that of cellulose. The D-mannose units are mainly /S-D-(i -> 4)-linked in a linear molecule. Similar mannans are found in the tubers of some Orchidaceae species (salep mannan) and in the green coffee bean. 

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