Spectra alginic acid

Figure 14.33. Structures of guluronic acid and mannuronic acid and the 100-MHz l3C spectrum of alginic acid. (From ref. 8. Reprinted with permission of Elsevier Science S.A.)...

Infra red spectra of the non-modified and modified seaweed polysaccharides were recorded in KBr on a Perkin-Elmer Spectrum GX, FT-IR System (USA). G NMR spectra were recorded on a Bruker Avance-II 500 spectrometer, Switzerland, at 125 MHz. The parent polysaccharide and their modified products were dissolved in D2O (40 mg/ml) and the spectra were recorded at 70°C with 5000 accumulations, pulse duration 5.9 ps, acquisition time 1.2059 s and relaxation delay 6 ps using DMSO as internal standard (ca. 8 39.5). The NMR of alginic acid and otolidine was carried out at 70 and at room temperature and were dissolving in NaOH/D20 and MeOH/D20, respectively. 

From the products obtained by treatment of a dilute solution of sodium alginate with an extract of the liver of abalone (a mollusc) was isolated a crystalline disaccharide which gave D-mannuronic acid on hydrolysis and showed the spectrum of an a,/3-unsaturated acid. If the assumption is made that no transglycosylation had occurred, the structure of this compound must be that of 4-0-(4-deoxy-a-L-er2/[Pg.115]

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