## 3 Results and Discussion
### Structural Characterization of JSP
#### 3.2.3 NMR Investigations
The signals at \(\delta\) 103.8/4.41 and correlation of \(\delta\) 4.70/3.60 in the COSY were assigned to the \(\rightarrow\)3-\(\beta\)-p-Gal\(p\)-(1,4)-\(\alpha\)-t-Gal\(p\)-(1\(\rightarrow\) substituted units (Figure 4), while the signals at \(\delta\) 102.8/4.70 in \({}^{13}\)C- and \({}^{1}\)H-NMR, respectively, were attributed to the anomeric carbon and proton of \(\rightarrow\)3-\(\beta\)-p-Gal\(p\)-(1,4)-3,\(\delta\)-\(\alpha\)-t-AnGal\(p\)-(1\(\rightarrow\) residues, confirming the main backbone structure of JSP [3; 48]. The signals at \(\delta\) 101.09/5.07 ppm and correlation of \(\delta\) 5.07/3.34 (H-1/H-2) in the COSY spectrum (Figure 4) were assigned to the anomeric proton of \(\alpha\)-(1,4)-\(\iota\)-Gal\(p\) residues substituted at the \(O\)-3, mainly by sulfate groups and rarely with methoxy groups [48]. This assignment (at \(\delta\) 101.09/5.07 ppm) was already made to the 3-\(O\)-methyl-\(\alpha\)-\(\iota\)-Gal\(p\) unit [3], but, in this case, a sulfate group appeared to be present at this position compared to the JDP spectrum. Two signals at \(\delta\) 5.42 ppm (Figure 2A) and 99.10 ppm (Figure 3A) could be assigned to the \(\alpha\)-Glc residues in the floridean starch. These assignments were supported by other reports [2; 3] and were in accordance with the monosaccharides composition (see Section 3.2.2). The resonances at \(\delta\) 97.7/5.34 and 98.7/5.18 ppm were mainly affected by 3,6-An-\(\alpha\)-\(\iota\)-Gal\(p\) (2-\(\mathrm{SO}_{3}\)\({}^{-}\)) and 3,6-An-\(\alpha\)-\(\iota\)-Gal\(p\) (2-\(\mathrm{O}\)-methyl ether), while the signals at \(\delta\) 98.9/5.49 ppm were assigned to the H-1 of 2-\(O\)-methyl-\(\alpha\)-\(\iota\)-Gal\(p\) residues [3; 19]. The \(\alpha\)-\(\iota\)-Gal\(p\) and 3-Me-\(\alpha\)-\(\iota\)-Gal\(p\) residues were identified at \(\delta\) 5.24 ppm and \(\delta\) 101.5 ppm and the signals at around \(\delta\) 100.22/5.56 ppm were ascribed to the \(\alpha\)-(1,4)-linked \(\iota\)-Gal\(p\) (2-\(\mathrm{SO}_{3}\)\({}^{-}\)) residues [19]. It was possible to assign the \({}^{13}\)C- and \({}^{1}\)H-NMR chemical shifts, corresponding to the \(\beta\)-p-xylosyl units, as \(\delta\) 104.3/4.49  
Figure 3: \({}^{13}\)C-NMR spectra at 300 MHz of (**A**) JSP and (**B**) JDP fractions. The analyses were recorded at 40 g/L in D\({}_{2}\)O solution at 60 \({}^{\circ}\)C.  
(C-1/H-1), 76.07/3.24 (C-2/H-2), 73.47/3.53 (C-3/H-3), 70.86/3.64 (C-4/H-4), 65.56/3.34 (C-5/H-5) and 8 3.89 (H-5) ppm [3, 19]. The \({}^{1}\)H/\({}^{1}\)H correlations of \(\delta\) 5.07/3.38 could be attributed to the H-1/H-6 of \(\beta\)-(1,3)-6-Me-d-Gal\(p\) units linked to \(\alpha\)-(1,4)-d-Gal\(p\)-(1\(\rightarrow\) in the NOESY spectrum (Figure 5) [19, 48]. Overall, all other attributes were consistent with the \({}^{1}\)H-\({}^{1}\)H COSY and NOESY spectra obtained for the JSP fraction (Figure 5). To conclude, these analyses showed that JSP presents a new and complex polysaccharide structure compared to other xylogalactans of corallinans reported in the literature. Further analyses are needed (enzymatic hydrolysis, etc.) to better apprehend the full structure of JSP. Figure 4: 2D \({}^{1}\)H–\({}^{1}\)H COSY NMR correlation spectra of the JSP fraction. The analyses were recorded at 40 g/L in D\({}_{2}\)O solution at 60 \({}^{\circ}\)C.  
Figure 5: 2D \({}^{1}\)H–\({}^{1}\)H NOESY NMR correlation spectra of JSP fraction. The analyses were recorded at 40 g/L in D\({}_{2}\)O solution at 60 \({}^{\circ}\)C.