3.2. Spectroscopic Characteristics
The sample of FVP, CHFVP-1, and CHFVP-2 were scanned through ultraviolet spectrum, and the characterization of their absorption spectrum is shown in
Figure 2. It could be found that there was no ultraviolet absorption at 260 and 280 nm, which means that FVP, CHFVP-1, and CHFVP-2 did not contain free protein and nucleic acid.
The infrared spectra of CHFVP-1 and CHFVP-2 at the range of 400–4000 cm
−1 were scanned and are shown in
Figure 3. The two fractions revealed the hydroxyl group (-OH) for the broad and strong absorption peak at around 3400 cm
−1 [
18]. The peaks at 2935 and 2923 cm
−1 indicated the C, H and aliphatic C-H bonds, respectively [
19]. Stretching peaks at 1642 and 1653 cm
−1 corresponded to free carboxyl groups [
20]. The broad absorption bands with intense intensities around 1420–1300 cm
−1 could be owing to stretching vibrations of the C-H bond [
21]. The absorption band at 1000–1200 cm
−1 suggested that the two polysaccharides contained pyranose monomers in their structures [
22]. The absorption bands at 882 and 888 cm
−1 indicated the
β-pyranoside linkage in CHFVP-1 and CHFVP-2 [
23].
3.5. NMR Analysis of CHFVP-1 and CHFVP-2
The NMR spectra of CHFVP-1 are shown in
Figure 5, which were the basis for inferring monosaccharide, glycosidic linkages, and chemical shifts. In
Figure 5a,b, most of the proton and carbon chemical shifts of CHFVP-1 come from the regions ranging from δ 3.0 to 5.50 and δ 60 to 110, respectively, which were the typical chemical shifts of the polysaccharide [
24]. Furthermore, four anomeric proton and carbon chemical shifts at δ 4.53/106.29, δ 5.001/100.79, δ 5.11/105.25, and δ 5.06/104.44 were identified in the
1H NMR,
13C NMR, and HSQC in
Figure 5 and indicated as A, B, C, and D in CHFVP-1.
According to the composition of monosaccharides, methylation results, and literature comparison, the carbon signals at δ 18.52 in the
13C NMR and the proton shift at δ 1.23 in the
1H NMR indicated the existence of terminal-fucose (T-fuc) in CHFVP-1 [
25,
26]. The peak at δ 105.25 indicated the presence of
13C of
α-1,3,6-linked D-mannopyranose units [
27,
28,
29]. The peak at δ 100.79 meant the existence of C1 of the
α-D-galactose [
30]. The signal peak appearing at δ 64.0 suggested the presence of the C-6 galactose in the polysaccharide sugar chain structure [
31]. The peaks in the region of δ 63.83–80.37 indicated the typical shift of carbohydrate. The glycosidic linkage of CHFVP-1 determined by its
1H NMR spectra in the region of δ 4.53–5.11 revealed that there were both
α- and
β-configurations in it [
32].
According to the anomeric chemical shift at δ 4.53/106.29 and literature comparison, the β-configuration of residue A was determined [
33]. From the COSY spectrum (
Figure 5c), the chemical shifts of H2-H6 can be deduced to δ 3.47, δ 3.72, δ 3.96, δ 4.36, and δ 3.76, respectively. The
13C chemical shifts of residue A were obtained from the HSQC spectrum by the chemical shift of
1H (
Figure 5d), and the results are summarized in
Table 4. Furthermore, according to the related literature and the chemical shifts of all
1H and
13C of residue A [
25,
34], residue A should be terminal-β-D-Glc
p.
According to the anomeric chemical shift at δ 5.00/100.79 and literature comparison, the α-configuration of residue B was determined. The other chemical shifts of H-2, H-3, H-4, H-5, H-6 and H-6a at δ 3.89, δ 4.21, δ 4.07, δ 3.79, δ 3.91 and δ 3.70 were found from the cross-peaks in the COSY spectra (
Figure 5c), and the corresponding carbon signals could be attributed to the correlations of C-H signals in the HSQC spectrum (
Figure 5d), which were δ 72.43, δ 71.56, δ 71.21, δ 76.21, and δ 69.45 for C-2, C-3, C-4, C-5, and C-6, respectively. Regarding the complete
1H and
13C chemical shifts of residue B as well as previous work [
35], residue B was →6)-α-D-Gal
p-(1→.
The heterotopic hydrogen and carbon signals of H-1 and C-1 were δ 5.11/105.25. According to the literature, residue C was inferred to be an α-configuration residue. Other signals from H-2 to H-6a were identified from the results of COSY spectrum (
Figure 5c), including H-2 (δ 3.91), H-3 (δ 3.99), H-4 (δ 4.07), H-5 (δ 4.22), and H-6a (δ 4.00). In addition, the matching
13C chemical shifts were C-2 (δ 69.75), C-3 (δ 80.37), C-4 (δ 71.21), C-5 (δ 71.61), and C-6 (δ 74.25) in the HSQC spectrum (
Figure 5d). The chemical shifts of all
1H and
13C of residue C were basically consistent with the literature [
29], which indicated that residue C was →3,6)-α-D-Man
p-(1→.
Based on the terminal
13C and
1H shift at δ5.06/104.44, the α-configuration of the D residue was inferred. In the HSQC spectrum (
Figure 5d), the cross-peak at δ1.23/18.525 indicated the H6/C6 of T-α-L-Fuc
p. The remaining hydrogen chemical shifts of D come from the COSY (
Figure 5c) spectrum, and the
13C chemical shifts associated with it were determined in the HSQC spectrum (
Figure 5d). Compared with the literature, the
1H and
13C chemical shifts for residue D were assigned [
26]. The NMR chemical shifts and significant connectivity are summarized in
Table 4 and
Table 5.
Due to the large molecular weight and viscosity of CHFVP-1 and the wide distribution of branched chains, the NMR data of the sample were incomplete, and only partial sugar residue fragments were inferred. According to the correlation between the peaks of
13C and
1H from the HMBC spectrum (
Figure 5e), the glycosides of the CHFVP-1 residues were linked as follows: AC-1/AH-2; AH-1/DC5; BH-1/DC-5; CC-1/AH-6; CH-1/BC-5/CC-6/3; DH-1/B/C/DC-4; DC-1/AH-2. Hence, considering the aforementioned results, the most probable repeat unit of CHFVP-1 has an →6)-α-D-Galp-(1→ backbone that is branched at O-5 of Gal
p by an →3,6)-α-D-Man
p-(1→attached with T-β-D-Glc
p or T-α-L-Fuc
p side-chains.
CHFVP-2 was analyzed by the same way as that used for CHFVP-1. In
Figure 6, anomeric proton and carbon signals at δ 4.53/105.88 were determined in the
1H and
13C NMR (
Table 6 and
Table 7) and HSQC spectra in
Figure 6 and denoted as A and B in CHFVP-2 [
34]. All the
1H and
13C signals were assigned by
1H/
1H correlation spectroscopy (COSY), heteronuclear single quantum coherence (HSQC), and heteronuclear multiple-bond correlation (HMBC), as shown in
Figure 6, indicating that residue A was T-β-D-Glc
p and B was →6)-β-D-Glc
p-(1→.
The structure of CHFVP-2 was proposed based on the above analysis in the same way used for CHFVP-1, and the possible partial structure of CHFVP-2 information was shown as follows:
→[6)-β-D-Glcp-(1→6)-β-D-Glcp-(1→6)-β-D-Glcp-(1]n→ |
2 | 4 | 5 |
↑ | ↑ | ↑ |
1 | 1 | 1 |
β-D-Glcp | β-D-Glcp | β-D-Glcp |
3.6. Effects of CHFVP-1 and CHFVP-2 on Parameter Coagulation Parameters In Vitro
Four kinds of coagulation kits were used to detect the coagulation activity of polysaccharide components, including APTT, PT, and TT in vitro.
In
Table 8, CHFVP-2 prolonged PT significantly compared with both the blank group (
p < 0.001) and breviscapine group (
p < 0.01), which revealed the extremely significant anticoagulant activity of CHFVP-2. The PT of CHFVP-1 had a slight change but no significant difference. Compared with the blank group, CHFVP-1 significantly shortened APTT, meaning its significant procoagulant activity (
p <0.001). CHFVP-2 also had significant procoagulant activity in terms of APTT (
p <0.01), and the activity was stronger than that of Yunnan Baiyao. Regarding the effect of TT, CHFVP-1 significantly shortened the TT compared with the blank group, (
p < 0.01) which had very significant procoagulant activity, while CHFVP-2 also had certain activity.
Based on the above results, CHFVP-1 significantly shortened APTT and TT (p < 0.01). Thus, CHFVP-1 could activate coagulation factors and promote the condensing of fibrinogen into insoluble fibrin, indicating that CHFVP-1 promoted blood clotting through the endogenous coagulation pathway. CHFVP-2 shortened APTT but increased PT. It is temporarily unable to predict its coagulation activity in vitro.