| dc.description.abstract | Hydrolysis of Agave F Hydrolysis of Agave F gave only sugars, indicating that the polysaccharide was a glucan-fructosan in proportions of 92.7% (calculated) glucose and 7.3% (estimated) fructose. Hydrolysate indicates that glucose and fructose are present in the ratio of approximately 12:1.
On the basis of molecular weight and acetate analysis, one would expect the acetate to have a rotation close to that of fructosans.
Fructosans were found to constitute about 7%.
The hydrolysate contained:
• 2,3,4,6-tetra-O-methyl-D-glucose
• tetra-O-methyl-D-fructose
No di-methyl sugar was detected. This would suggest that the Agave polysaccharide is an inulin type and non-reducing.
Using the methanolysis method, five methylated sugars were obtained from hydrolysate of methylated Agave F (Table II). These were tetra-methyl compounds confirmed by methoxyl content and elemental analysis. did not give an accurate idea of the separation of tetramethyl sugars and trimethyl fructose present in these fractions and the probability of fructosans.
The third fraction contained a trimethyl derivative. Fractions a and b corresponded to triacetyl derivatives and were identified as 3,4,6-tri-O-methyl-D-fructose and 2,3,4,6-tetra-O-methyl-D-glucose.
No dimethyl sugar was detected. This would suggest that the agave polysaccharide is an inulin type and non-reducing.
The presence of 3,4,6-tri-O-methyl-D-fructose clearly established the presence of 1,2-linkages between adjacent fructose molecules.
By column chromatography of the hydrolysate of methylated Agave F, five methylated sugars were obtained. Of these, sugars identified were 3,4,6-tri-O-methyl-D-fructose, tetra-O-methyl-D-glucose, and others.
The possibility of a dimethyl glucose was ruled out since no dimethyl sugar was detected after methylation.
Dimethyl fructose derivatives were present, indicating a somewhat branched structure appears less probable because of the lack of response with triphenyl tetrazolium mixture.
3,4,6-tri-O-methyl-fructose and 2,3,4,6-tetra-O-methyl-glucose in the hydrolysates were determined to be present.
The linkages and at least one terminal glucose were established. However, the proportion of the tetramethyl glucose derivative obtained is too high for a simple linear molecule.
This would suggest that the material assumes heterogeneity and that some molecules are more microfructosans with considerably shorter chain lengths.
The solid residue after fractionation indicated a chain length with an approximate molecular weight.
The IR spectra of Agave F and inulin fractions resemble very closely, indicating similarities in structure.
On the basis of the carbohydrate structure, other possibilities appear plausible. | |
