Figure 3
Source publication
Sulfated flavonoids, a class of polyphenols integral to plant secondary metabolism and chemical defense, exhibit notable pharmacological potential. Seagrasses, marine angiosperms with critical ecological and socioeconomic roles, often accumulate these compounds in high concentrations. However, their complex chemical profiles�including closely relat...
Contexts in source publication
Context 1
... The carbon and proton chemical shifts at positions 3' and 4' exhibited the typical ipso and ortho shifts due to a sulfate group at positions 3' and 4' in compounds 7, 10, and 12 (refer to Table 3). Compounds 7 and 10 showed displacement in 1 H and 13 C NMR of the environment in ring A. This confirms the overall substitution pattern of ring A, which is based on the long-range heteronuclear correlations from the aromatic methine H-8 (δ H 7.29 for 10 and δ H 7.26 for 12) to C-7, C-9, C-6, and C-10 ( Figure 3), with the sulfated group bonded to C-7 (Table 3). However, compound 7 bonds the sulfated group to C-6, and the chemical shift in 1 H and 13 C NMR indicates the overall substitution pattern of ring A. This is based on the long-range heteronuclear correlations from the aromatic methine H-8 (δ H 6.56) to C-7, C-9, C-6, and C-10 ( Table 3. Diagnostic 1 H and 13 C NMR Sulfation Shifts for Flavonoid Sulfates 7, 10, 12, 16-19, 22, 24, 25, and 28 (DMSO-d 6 ); Values Are Expressed in ppm as δ (flavonoid sulfate) -δ (Flavonoid) ...
Context 2
... HR-ESI-MS displayed a quasimolecular ion peak at m/z 397.0230 [ Table 5). The presence of methoxy substituent located at C-3' was confirmed by the long-range heteronuclear correlation between the protons at δ H 3.88 and C-3' (δ C 147.9), as well as through 2D NOESY NMR correlations, which demonstrated the proximity of protons from the methoxy group with the hydrogen-2' belonging to ring B (δ H 7.55) (see Figure 3). The 1 H and COSY data indicated the lack of coupling for ring A. The chemical shift of the aromatic methine (δ H 6.60, δ C 93.8) indicated its location between one oxygen substituent and the quaternary carbon belonging to the heterocyclic ring C, placing this group at C-8, 28 and leaving the phenolic hydroxy groups to be assigned at C-5 and C-7. ...
Context 3
... The shielding of C-5 and C-7 may be due to steric compression exerted by the sulfate group in the C-6 of the aromatic ring. Long-range heteronuclear correlations confirmed ring A's substitution pattern from the aromatic methine H-8 (δ H 6.60) to C-7, C-9, C-6, and C-10 ( Figure 3). This spectroscopic data defines the structure of nodifloretin 6-sulfate (19), as shown in Figure 2. The analysis of the 2D NMR data from the HSQC, HMBC, and NOESY spectra and querying of the SciFinder database confirmed that structure 19 is an undescribed product. ...
Context 4
... chemical shifts in the 1 H and 13 C NMR spectra for the environment in ring C were similar to those observed in compound 19 (Tables 4 and 5). The NOESY correlation between the methoxy hydrogen and H-2' confirms the presence of the methoxy group in position-3' (as shown in Figure 3). The observed long-range heteronuclear correlations also confirm the presence of the methoxy group in position-3' and the general substitution pattern of the B ring in the HMBC spectrum (Figure 3). ...
Context 5
... NOESY correlation between the methoxy hydrogen and H-2' confirms the presence of the methoxy group in position-3' (as shown in Figure 3). The observed long-range heteronuclear correlations also confirm the presence of the methoxy group in position-3' and the general substitution pattern of the B ring in the HMBC spectrum (Figure 3). Additionally, the overall substitution pattern of ring A was confirmed by the long-range heteronuclear correlations from the aromatic methine H-8 (δ H 7.28) to C-7, C-9, C-6, and C-10 ( Figure 3), with the sulfated group bonded to C-7 (Table 3). ...
Context 6
... observed long-range heteronuclear correlations also confirm the presence of the methoxy group in position-3' and the general substitution pattern of the B ring in the HMBC spectrum (Figure 3). Additionally, the overall substitution pattern of ring A was confirmed by the long-range heteronuclear correlations from the aromatic methine H-8 (δ H 7.28) to C-7, C-9, C-6, and C-10 ( Figure 3), with the sulfated group bonded to C-7 (Table 3). These spectroscopic data defined the structure of Figure 2. Analysis of the HSQC, HMBC, and NOESY spectra confirmed the structure of compound 22. ...
Context 7
... HR-ESI-MS displayed a quasi-molecular ion peak at m/z 367.0135 [M + H] Table 4). The presence of the hydroxy substituent was confirmed by the long-range heteronuclear correlations between the phenolic protons H-2'/6' and H-3'/5' at 7.91 and 6.91 ppm with C-4' (δ C 160.9), as illustrated in Figure 3. The 13 C NMR spectrum, in combination with the HSQC spectrum, revealed the presence of a carbonyl (δ C 181.9 (Figure 3), with the sulfated group bonded to C-6 (Table 3). ...
Context 8
... presence of the hydroxy substituent was confirmed by the long-range heteronuclear correlations between the phenolic protons H-2'/6' and H-3'/5' at 7.91 and 6.91 ppm with C-4' (δ C 160.9), as illustrated in Figure 3. The 13 C NMR spectrum, in combination with the HSQC spectrum, revealed the presence of a carbonyl (δ C 181.9 (Figure 3), with the sulfated group bonded to C-6 (Table 3). These spectroscopic data define the structure of scutellarein 6-sulfate (18), as displayed in Figure 2. The analysis of the 2D NMR data from the HSQC and HMBC spectra confirmed that structure 18 is a previously undescribed product, which was also verified by querying the SciFinder database. ...
Context 9
... difference is due to substituting the methoxy group with a hydroxy group at the C-3' carbon of ring B and the lack of the methoxy group signal. The HMBC correlations confirmed the hydroxy group at C-3' (Figure 3). The chemical shifts in the 1 H and 13 C NMR spectra for the environment in ring A were similar to those of compounds 18 and 19 (Tables 3-5). ...
Context 10
... chemical shifts in the 1 H and 13 C NMR spectra for the environment in ring A were similar to those of compounds 18 and 19 (Tables 3-5). This includes the overall substitution pattern of ring A, as evidenced by the long-range heteronuclear correlations from the aromatic methine H-8 (δ H 6.53) to C-7, C-9, C-6, and C-10 with the sulfated group bonded to C-6 ( Figure 3 and Table 3). These spectroscopic data define the structure of 6-hydroxyluteolin 6-sulfate (16), as displayed in Figure 3. ...
Context 11
... includes the overall substitution pattern of ring A, as evidenced by the long-range heteronuclear correlations from the aromatic methine H-8 (δ H 6.53) to C-7, C-9, C-6, and C-10 with the sulfated group bonded to C-6 ( Figure 3 and Table 3). These spectroscopic data define the structure of 6-hydroxyluteolin 6-sulfate (16), as displayed in Figure 3. The structure was confirmed by analyzing the HSQC and HMBC spectra, which confirmed the structure of 16. ...
Context 12
... hydrogenbonded hydroxy group at δ H 12.90 was located at C-5, as confirmed by its HMBC correlations to C-10 (δ C 103.7), C-6 (δ C 98.8), and C-5 (δ C 161.4). The HMBC correlation between the protons at δ H 10.85 to C-8 (δ C 93.9), C-6 (δ C 98.8), and C-7 (δ C 164.13), located in the other hydroxy group was positioned at C-7 (Figure 3 and Tables 4-5). The other aromatic proton belongs to the ABC spin system at 7.44 (1H, d, J = 8.4 Hz), 7.47 (1H, d, J = 2.3 Hz), 7.48 (1H, dd, J = 2.3, 8.4 Hz) related to the B-ring (H-5', H-2' and H-6' respectively) ( Table 5). ...
Context 13
... The chemical shift for carbon in position 4' showed the typical ipso and ortho shifts due to the presence of a sulfate group at position 4' (strong deshielding of H-5', C-5' and C-3'; shielding of C-4') ( Table 3). The HMBC spectrum confirmed the general substitution pattern of the B ring with observed long-range heteronuclear correlations (Figure 3). After NMR analyses, the isolated fraction containing minor amounts of 24 was subjected HR-ESI MS analysis. ...
Context 14
... + due to, desulfation after storage. This spectroscopic data defined the structure of luteolin 4'-sulfate (24), as displayed in Figure 3 previously synthesized by KáňKáň ovaét al. 30 To our knowledge, this compound has not been previously identified as a natural product. ...
Context 15
... negative ESI-MS spectrum displayed a quasimolecular peak [ (Table 3). The aromatic signal reveals an AMX spin system related to ring B. Of the two methoxy groups confirmed by HMBC correlations, one is located in ring B, at position 3', as shown by the correlation between the 1 H signal at 3.75 ppm and C-3' at 147.9 ppm, as well as by 2D NOESY NMR correlations between proton of the methoxy group and the hydrogen-2' (δ H 7.56) (Figure 3 and Tables 4 and 5). The second methoxy in ring A was confirmed at position C-6 by the long-range heteronuclear correlation between the protons at δ H 3.90 and C-3' (δ C 134.1) (Figure 3 and Tables 4 and 5). ...
Context 16
... aromatic signal reveals an AMX spin system related to ring B. Of the two methoxy groups confirmed by HMBC correlations, one is located in ring B, at position 3', as shown by the correlation between the 1 H signal at 3.75 ppm and C-3' at 147.9 ppm, as well as by 2D NOESY NMR correlations between proton of the methoxy group and the hydrogen-2' (δ H 7.56) (Figure 3 and Tables 4 and 5). The second methoxy in ring A was confirmed at position C-6 by the long-range heteronuclear correlation between the protons at δ H 3.90 and C-3' (δ C 134.1) (Figure 3 and Tables 4 and 5). Carbon and proton resonances showed the typical shifts due to the presence of a sulfate group at position 7 (strong deshielding of H-8, C-8, and C-6; Barron et al. 25 ) (Table 3). ...
Context 17
... and proton resonances showed the typical shifts due to the presence of a sulfate group at position 7 (strong deshielding of H-8, C-8, and C-6; Barron et al. 25 ) (Table 3). In addition, the general substitution pattern of the B ring is confirmed by the observed long-range heteronuclear correlations in the HMBC spectrum (Figure 3). These spectroscopic data define the structure of jaceosidin 7-sulfate (28), as shown in Figure 2, which was previously found in P. torreyi, 12 and the maritime growing L. nodif lora. ...
