2. Results and Discussion
Phytochemical investigation of the ethanolic extract of
B. suaveolens, prepared from the leaves, yielded four new kaempferol glycosides, while neither of the compounds described by [
7] were isolated in this work. Analysis of the spectroscopic data led to the identification of compounds
1–
4 (
Figure 1).
Figure 1.
Chemical structures of compounds 1–4 isolated from the leaves of Brugmansia suaveolens.
Figure 1.
Chemical structures of compounds 1–4 isolated from the leaves of Brugmansia suaveolens.
The molecular formula of compound
1 was determined as C
26H
28O
15 on the basis of FT-ICR-MS
m/z 603.132636 [M+Na]
+ (calcd.
m/z 603.13204 [M+Na]
+) and ESI-MS
m/z 603.1 [M+Na]
+. The IR spectrum showed the characteristic absorption bands of hydroxyl (3248.2 cm
−1), carbonyl (1652.8 cm
−1), and phenyl groups (1574.4 cm
−1). The
1H-NMR and
13C-NMR spectra (see
Table 1) are similar to those reported by [
7]. The aromatic region of the
1H-NMR spectrum of
1 showed four signals, namely, two broad singlets (δ 6.21 and δ 6.40) for the protons in ring A and two doublets (AA'BB' system) for ring B (δ 6.92 and δ 8.02, both with
J = 8.6 Hz), which are typical for a kaempferol aglycone [
7]. The middle region of the spectrum exhibited two anomeric signals due to the sugar units at δ 5.48 and δ 4.55. The coupling constant of the anomeric proton of the glucose (
J = 7.8 Hz) was in accordance with a β-glycosidic linkage, while the coupling constant of the anomeric proton of the pentose (
J = 3.3 Hz) indicated a α-glycosidic linkage [
8]. Acid hydrolysis of
1 indicated
d-glucose and
l-arabinose, which were compared with an authentic sample by TLC analysis [
9,
10]. A further eleven protons were identified between δ 3.34 and δ 4.21 due to the sugar units [
8]. The structural information concerning the attachment position of the aforementioned moieties was determined based on MS fragmentation and 2D-NMR analysis. The MS fragmentation of
1 showed no [M+H−pentose]
+ fragment, indicating that the pentose is bonded directly to the aglycone, and that the glucose unit is linked as the second sugar moiety [
11,
12]. The HMBC experiment of
1 exhibited a correlation of the anomeric proton H-1'' of α-
l-arabinopyranose (δ 5.48) with C-3 (δ
C3 135.7), indicating the linkage of this sugar with the aglycone moiety. The interglycosidic linkage is shown by the correlation of the H-1''' (δ 4.55) of β-
d-glucopyranose with the C-2'' (δ
C2'' 80.1) of α-
l-arabinopyranose [
13]. Based on the aforementioned spectroscopic data, the structure of
1 was assigned as a kaempferol 3-
O-β-
d-glucopyranosyl-(1'''→2'')-
O-α-
l-arabinopyranoside.
Table 1.
1H-NMR, 13C-NMR, and 2D-NMR spectral data for compounds 1 and 2.
Table 1.
1H-NMR, 13C-NMR, and 2D-NMR spectral data for compounds 1 and 2.
| 1 a | 2 b |
---|
Position | δH (
J in Hz) | δC | COSY | HMBC | δH (
J in Hz) | δC | COSY | HMBC |
---|
2 | | | 158.5 | | | | | 155.9 | | |
3 | | | 135.7 | | | | | 134.3 | | |
4 | | | 179.7 | | | | | 177.7 | | |
5 | | | 161.6 | | | | | 160.2 | | |
6 | 6.21 | Brs | 99.9 | H-8 | C-7,8,10 | 6.44 | Brs | 99.3 | H-8 | C-5,7,8,10 |
7 | | | 166.0 | | | | | 162.9 | | |
8 | 6.40 | Brs | 94.7 | H-6 | C-6,7,9,10 | 6.79 | Brs | 94.6 | H-6 | C-6,7,9,10 |
9 | | | 159.0 | | | | | 156.6 | | |
10 | | | 105.8 | | | | | 105.6 | | |
1' | | | 122.6 | | | | | 120.3 | | |
2' | 8.02 | d (8.6) | 132.4 | H-3' | C-2,4' | 8.10 | d (8.4) | 131.1 | H-3' | C-2,4' |
3' | 6.92 | d (8.6) | 116.5 | H-2' | C-1′,4' | 6.91 | d (8.4) | 115.4 | H-2' | C-1',4' |
4' | | | 163.1 | | | | | 160.2 | | |
5' | 6.92 | d (8.6) | 116.5 | H-6′ | C-1',4' | 6.91 | d (8.4) | 115.4 | H-6' | C-1',4' |
6' | 8.02 | d (8.6) | 132.4 | H-5′ | C-2, 4' | 8.10 | d (8.4) | 131.1 | H-5′ | C-2, 4' |
Ara-O-3 | | | | | | | | | | |
1'' | 5.48 | d (3.3) | 101.3 | H-2'' | C-3 | 5.61 | d (3.1) | 98.9 | H-2'' | C-3 |
2'' | 4.21 | dd (5.4,3.4) | 80.1 | H-1'',3'' | | 4.07 | M | 78.7 | H-1'',3'' | |
3′′ | 3.96 | dd (5.4,6.4) | 71.3 | H-2'',4'' | | 3.86 | M | 68.7 | H-2'',4'' | |
4'' | 3.86 | M | 66.6 | H-3'',5'' | | 3.70 | M | 64.1 | H-3'',5'' | |
5a'' | 3.23 | M | 63.4 | H-4′′ | | 3.07 | M | 61.2 | H-4'' | |
5b′′ | 3.73 | M | | | | 3.51 | brd (11.1) | | | |
Glc-Ara | | | | | | | | | | |
1''' | 4.55 | d (7.8) | 105.4 | H-2''' | C-2'' | 4.37 | d (7.5) | 103.8 | H-2''' | C-2'' |
2''' | 3.25 | brd (7.8) | 75.2 | H-1''',3''' | | 2.97 | M | 73.6 | H-1''',3''' | |
3''' | 3.38 | M | 78.1 | H-2''',4''' | | 3.17 | M | 76.7 | H-2''',4''' | |
4''' | 3.34 | M | 71.4 | H-3''',5''' | | 3.12 | M | 69.7 | H-3''',5''' | |
5''' | 3.36 | M | 78.0 | H-4''', 6''' | | 3.43 | M | 77.1 | H-4''', 6''' | |
6a''' | 3.78–3.82 | M | 62.7 | H-5''' | | 3.43 | brd (11.5) | 60.9 | H-5′′′ | |
6b''' | | | | | | 3.59 | M | | | |
Glc-O-7 | | | | | | | | | | |
1'''' | | | | | | 5.07 | d (7.1) | 99.8 | H-2'''' | C-7 |
2'''' | | | | | | 3.25 | M | 73.1 | H-1'''',3'''' | |
3'''' | | | | | | 3.30 | M | 76.4 | H-2'''',4'''' | |
4'''' | | | | | | 3.17 | M | 69.6 | H-3'''',5'''', | |
5'''' | | | | | | 3.12 | M | 76.8 | H-4'''',6'''' | |
6a'''' | | | | | | 3.70 | M | 60.6 | H-5'''' | |
6b'''' | | | | | | 3.43 | M | | | |
Compound
2 was established as C
32H
38O
20 on the basis of FT-ICR-MS
m/z 765.184176 [M+Na]
+ (calcd.
m/z 765.18486 [M+Na]
+) and ESI-MS
m/z 765.0 [M+Na]
+. The IR spectrum revealed signals of hydroxyl (3365.8 cm
−1), carbonyl (1653.8 cm
−1), and phenyl groups (1605.3 cm
−1). The
1H-NMR and
13C-NMR (see
Table 1) spectra are similar to those of
1. In the middle region of the spectrum, one additional anomeric signal was identified, due to a new sugar unit at δ 5.07. The coupling constant of this anomeric proton (
J = 7.1 Hz) was in accordance with a β-glycosidic linkage. The sugar units of compound
2 were determined as
d-glucose and
l-arabinose by TLC comparison with authentic samples after acid hydrolysis [
9,
10]. As in
1, the HMBC experiment of
2 exhibited correlation between the anomeric proton H-1'' (δ 5.61) and C-3 (δ
C3 134.3), and between H-1'''' (δ 5.07) and C-7 (δ
C7 162.9), indicating, respectively, the linkage of α-
l-arabinopyranose and of β-
d-glucopyranose with the aglycone. Additionally, the interglycosidic linkage is shown by the correlation of the H-1''' (δ 4.37) of another β-
d-glucopyranose with the C-2'' (δ
C2'' 78.7) of α-
l-arabinopyranose [
13]. Therefore, compound
2 was identified as a kaempferol 3-
O-β-
d-glucopyranosyl-(1'''→2'')-
O-α-
l-arabino-pyranoside-7-
O-β-
d-glucopyranoside.
The molecular formula C
41H
44O
23 of compound
3 was deduced based on FT-ICR-MS
m/z 927.215977 [M+Na]
+ (calcd.
m/z 927.21656 [M+Na]
+) and ESI-MS
m/z 927.7 [M+Na]
+. The absorption bands of the hydroxyl (3309.5 cm
−1), carbonyl (1651.9 cm
−1), and phenyl groups (1598.2 cm
−1) were observed in IR analysis. The
1H-NMR and
13C-NMR spectra (see
Table 2) were similar to those of
2, including again three anomeric signals. Acid hydrolysis of
3 suggests
d-glucose and
l-arabinose as sugar moieties, which was confirmed by comparison with authentic samples by TLC analysis [
9,
10]. Additionally, 3 showed two further signals at δ 6.41 and δ 7.81 (both d,
J = 15.8 Hz), which are indicative of olefinic protons of a
trans-caffeoyl group [
14,
15]. The HMBC experiment exhibited correlation between the anomeric proton H-1'' of α-
l-arabinopyranose (δ 6.41) and C-3 (δ
C3 137.0), and between the anomeric proton H-1'''''' (δ 5.78) and C-7 (δ
C7 163.6), showing direct linkages of these sugars moieties with aglycone. The correlation of the H-2'' (δ 5.07) of α-
l-arabinopyranose with the C-1''' (δ
C1''' 106.7) of another β-
d-glucopyranose indicates a linkage between these sugar moieties. The
1H-NMR spectrum of 3 exhibited the downfield shift of the signals corresponding to methylene protons H
2-6''' to δ 4.90–5.03, indicating an acylation at this position [
14]. The HMBC experiment confirmed the linkage of the caffeic acid to C-6''' of β-
d-glucopyranose by a correlation between the H-6
a''' and H-6
b''' (δ 4.90–5.03) of this sugar unit and C=O (δ
C-1'''' 167.4) of the caffeic acid moiety. Based on detailed analysis of the NMR spectra, the structure of compound 3 was determined as a kaempferol 3-
O-β-
d-[6'''-O-(E-caffeoyl)]-glucopyranosyl-(1'''→2'')-
O-α-
l-arabinopyranoside-7-
O-β-
d-glucopyranoside.
Compound
4 was determined as C
41H
44O
23 based on FT-ICR-MS
m/z 927.216170 [M+Na]
+ (calcd.
m/z 927.21656 [M+Na]
+) and ESI-MS
m/z 927.1 [M+Na]
+. The IR spectrum showed bands of hydroxyl (3263.2 cm
−1) and phenyl groups (1586.6 cm
−1). The
1H-NMR and
13C-NMR spectra (see
Table 2) are similar to those of
3. Compound
4 showed again three anomeric signals and also two further signals at δ 6.25 and δ 7.47 (both d,
J = 15.7 Hz), which were assigned to the olefinic protons of a
trans-caffeoyl group [
14,
15]. Acid hydrolysis of
4, followed by TLC comparison with authentic samples, indicated the presence of
d-glucose and
l-arabinose [
9,
10]. The HMBC experiment of
4 exhibited correlation between the anomeric proton H-1'' of α-
l-arabinopyranose (δ 5.58) and C-3 (δ
C3 134.5), and between the anomeric proton H-1'''''' of a β-
d-glucopyranose unit (δ 5.06) and C-7 (δ
C7 162.9), showing the linkages of these sugar units to the kaempferol moiety. The interglycosidic linkage is shown by the correlation of H-1''' (δ 4.68) of another β-
d-glucopyranose with C-2'' (δ
C2'' 78.7) of α-
l-arabinopyranose [
13]. The
1H-NMR spectrum of
4 exhibited also a downfield shift of the signal corresponding to H-2''' at δ 4.60, indicating an acylation at the C-2''' position. The HMBC experiment confirmed the assignment of the caffeic acid moiety to C-2''' of β-
d-glucopyranose by a correlation between the H-2''' (δ 4.60, t,
J = 8.7 Hz) of this sugar unit and the C=O (δ
C-1'''' 165.6) of the caffeic acid moiety.
Table 2.
1H-NMR, 13C-NMR, and 2D-NMR spectral data for compounds 3 and 4.
Table 2.
1H-NMR, 13C-NMR, and 2D-NMR spectral data for compounds 3 and 4.
| 3 c | 4 b | |
---|
Position | δH(
J in Hz) | δC | COSY | HMBC | δH(
J in Hz) | δC | COSY | HMBC | |
---|
2 | | | 157.2 | | | | | 154.4 | | | |
3 | | | 137.0 | | | | | 134.5 | | | |
4 | | | 178.8 | | | | | 177.6 | | | |
5 | | | 161.7 | | | | | 160.5 | | | |
6 | 6.72 | brs | 100.0 | H-8 | C-5,7,8,10 | 6.43 | Brs | 98.7 | H-8 | C-7 | |
7 | | | 163.6 | | | | | 162.9 | | | |
8 | 6.92 | brs | 94.6 | H-6 | C-6,7,9,10 | 6.76 | Brs | 94.0 | H-6 | C-7,10 | |
9 | | | 156.6 | | | | | 155.9 | | | |
10 | | | 106.7 | | | | | 106.0 | | | |
1' | | | 121.8 | | | | | 121.2 | | | |
2' | 8.44 | d (8.6) | 131.8 | H-3' | C-2,4' | 8.06 | d (8.6) | 131.0 | H-3' | C-2 | |
3' | 7.26 | d (8.6) | 116.2 | H-2' | C-1',4' | 6.81 | d (8.6) | 115.4 | H-2' | C-1',4' | |
4' | | | 162.0 | | | | | 160.5 | | | |
5' | 7.26 | d (8.6) | 116.2 | H-6' | C-1',4' | 6.81 | d (8.6) | 115.4 | H-6' | C-1',4' | |
6' | 8.44 | d (8.6) | 131.8 | H-5' | C-2,4' | 8.06 | d (8.6) | 131.0 | H-5' | C-2 | |
Ara-O-3 | | | | | | | | | | | |
1'' | 6.41 | d (5.0) | 100.4 | H-2'' | C-3 | 5.58 | d (3.4) | 98.7 | H-2'' | C-3 | |
2'' | 5.07 | m | 80.7 | H-1'',3'' | | 4.09 | M | 78.7 | H-1'',3'' | | |
3'' | 4.67 | m | 70.9 | H-2'',4'' | | 3.85 | M | 68.6 | H-2'',4'' | | |
4'' | 4.47 | m | 66.0 | H-3'',5'' | | 3.50 | M | 63.7 | H-3'',5'' | | |
5a'' | 4.38 | m | 62.1 | H-4'' | | 3.00 | brd (11.6) | 60.6 | H-4'' | | |
5b'' | 4.56 | brd (11.9) | | | | 3.50 | M | | | | |
Glc-Ara | | | | | | | | | | | |
1''' | 5.28 | d (7.5) | 106.7 | H-2''' | C-2'' | 4.68 | d (7.8) | 101.5 | H-2''' | C-2'' | |
2''' | 4.12 | m | 75.1 | H-1''',3''' | | 4.60 | M | 73.1 | H-1''',3''' | C-1'''' | |
3''' | 4.05 | m | 78.1 | H-2''',4''' | | 3.48 | M | 73.6 | H-2''',4''' | | |
4''' | 4.15 | m | 70.9 | H-3''',5''' | | 3.25 | M | 69.5 | H-3''',5''' | | |
5''' | 4.05 | m | 75.4 | H-4''',6''' | | 3.30 | M | 76.4 | H-4''',6''' | | |
6a''' | 4.90–5.03 | m | 63.9 | H-5''' | C-1'''' | 3.50–3.70 | M | 60.3 | H-5''' | | |
6b''' | | | | | | | | | | | |
Caffeoyl | | | | | | | | | | | |
1'''' | | | 167.4 | | | | | 165.6 | | | |
2'''' | 6.41 | d (15.8) | 114.6 | H-3'''' | C1''''' | 6.25 | d (15.7) | 113.9 | H-3'''' | C1''''' | |
3'''' | 7.81 | d (15.8) | 145.6 | H-2'''' | C-1′′′′, 2''''' | 7.47 | d (15.7) | 145.0 | H-2'''' | C-1'''', 2''''' |
1''''' | | | 126.6 | | | | | 125.4 | | |
2''''' | 7.40 | brs | 115.6 | | C-3'''' | 7.07 | Brs | 114.9 | | C-3'''' |
3''''' | | | 145.6 | | | | | 145.7 | | |
4''''' | | | 147.2 | | | | | 148.7 | | |
5''''' | 7.12 | d (8.0) | 116.3 | H-6''''' | | 6.90 | d (8.6) | 115.8 | H-6''''' | |
6''''' | 6.95 | d (8.0) | 121.8 | H-5''''' | | 6.96 | brd (8.0) | 121.2 | H-5''''' | |
Glc-O-7 | | | | | | | | | | |
1'''''' | 5.78 | d (7.2) | 101.3 | H-2'''''' | C-7 | 5.06 | d (7.4) | 99.8 | H-2'''''' | C-7 |
2'''''' | 4.30 | m | 74.6 | H-1'''''',3'''''' | | 3.20 | M | 72.5 | H-1'''''',3'''''' | |
3'''''' | 4.40 | m | 78.9 | H-2'''''',4'''''' | | 3.28 | M | 76.8 | H-2'''''',4'''''' | |
4'''''' | 4.30 | m | 71.0 | H-3'''''',5'''''' | | 3.25 | M | 69.8 | H-3'''''',5'''''' | |
5'''''' | 4.30 | m | 78.1 | H-4'''''',6'''''' | | 3.40 | M | 77.1 | H-4'''''',6'''''' | |
6a'''''' | 3.71 | m | 63.4 | H-5'''''' | | 3.50-3.70 | M | 60.3 | H-5'''''' | |
6b'''''' | 4.50 | m | | | | | | | | |
Therefore, the structure of 4 was assigned as a kaempferol 3-O-β-d-[2'''-O-(E-caffeoyl)]-glucopyranosyl-(1'''→2'')-O-α-l-arabinopyranoside-7-O-β-d-glucopyranoside.
3. Experimental Section
3.1. General
NMR spectra 1D (1H, 13C, and DEPT-135) and 2D (1H-1H COSY, HSQC, HMBC) were recorded with MeOH-d4, DMSO-d6 or pyridine-d5 on Bruker AMX-600 (600 MHz and 150 MHz) and Bruker AMX-400 (400 MHz and 100 MHz) spectrometers (Bruker BioSpin GmbH, Rheinstetten, Germany). LC-ESI-MS was carried out on an electrospray Finnigan MAT P4000 HPLC-DAD system connected to a Finningan LCQTM Duo ion Trap mass spectrometer (Thermo Electron GmbH, Karlsruhe, Germany). Analytical HPLC was performed with a L-7100 Pump (Merck-HITACHI-LaChrom); UV-Vis detector L7420 (Merck-HITACHI-LaChrom); HPLC D-7000 HSM software with a D7000 data interface. HR-MS (FT-ICR) was performed on a Bruker APEXII (electrospray ionization). The UV spectra were measured in a Hewlett-Packard HP 1090 HPLC-DAD system in MeOH. The IR spectra were obtained on a Perkin Elmer Spectrum One (ATR Technology, Shelton, CT, USA). Sephadex LH-20 (6 × 50 cm) (particle size 25–100 mm, Sigma Chemical Co., Munich, Germany); Thin layer chromatography (TLC) (Silica Gel 60 F254 (0.25 mm) Merck (Darmstadt, Germany); RP-TLC aluminum sheets 20 × 20 cm, RP-18 F254 Merck); Flash chromatography (LaFlash, VWR International, Darmstadt, Germany), RP-18 (25–40 μm) column (5 × 20 cm), with gradient MeOH–H2O (10:90 ➔ 100:0, v/v); Analytical HPLC, LiChrospher RP-18 column (5 × 100 mm; 5 µm), mobile phase (A) MeOH–ACN–FA (95:5:0.1, v/v/v) and (B) gradient of MeOH–ACN–FA (95:5:0.1➔85:15:0.1, v/v/v).
3.2. Plant Material
Leaves of Brugmansia suaveolens were collected in Santa Maria, Rio Grande do Sul, Brazil in January 2008. The plant was identified by botanist Gilberto Zanetti. A voucher specimen was deposited in the herbarium of the Department of Biology at the Federal University of Santa Maria, Brazil, under reference number SMDB12520.
3.3. Extraction and Isolation
The air-dried and powdered leaves (1.087 g) of B. suaveolens were exhaustively extracted with EtOH (7 L, 30 h) in a Soxhlet apparatus. The EtOH extract was concentrated under vacuum at 40 °C and lyophilized to yield 359.94 g, which was treated with MeOH at −20 °C giving a soluble fraction of 344.82 g after solvent removal. Of this extract, 6.18 g was subjected to column chromatography with Sephadex LH-20 and MeOH as mobile phase at a flow rate of 1 mL/min. A total of 300 fractions of 10 mL each were collected and controlled by TLC using silica gel with toluene–MeOH–DEA (8:1:1, v/v/v) and RP-18 with MeOH–H2O (1:1, v/v); Anisaldehyde-H2SO4 was used for detection. Those fractions with a similar profile were combined, yielding 11 fractions (A➔K). Fraction G (80 mg) was chromatographed by RP-18 CC using MeOH–H2O (1:1, v/v) to give five combined sub-fractions (G1.1-G1.5). A sub-fraction G1.2 was fractioned again by RP-18 CC with MeOH–H2O (1:2, v/v) to provide three sub-fractions (G1.2.1-G1.2.3). Sub-fraction G1.2.1 was further purified by HPLC using a gradient of MeOH–ACN–FA (95:5:0.1➔85:15:0.1, v/v/v), yielding compound 2 (10.3 mg). Fraction I (41.1 mg) was chromatographed by RP-18 gel CC using MeOH–H2O (1:1, v/v) to give three combined sub-fractions (I1.1-I1.3). Sub-fraction I1.2.2 was further purified by HPLC using a gradient of MeOH–ACN–FA (95:5:0.1➔85:15:0.1, v/v/v) to afford compound 3 (4.5 mg). Fraction H (100 mg) was separated by flash chromatography RP-18 with gradient MeOH–H2O (10:90 ➔ 100:0, v/v) to give four combined sub-fractions (H1.1-H1.4). Sub-fraction H1.4 (47.8 mg) was further purified by RP-18 CC using MeOH–H2O (1:1, v/v) yielding 3.2 mg of compound 1. Sub-fraction H1.2 (35.2 mg) was applied to HPLC using a gradient of MeOH–ACN–FA (95:5:0.1➔85:15:0.1, v/v/v), affording 11.1 mg of compound 3 and 3.5 mg of compound 4.
3.4. Acid Hydrolysis
An amount of 2 mg per compound
1–
4 was dissolved in EtOH–HCl 10% (10 mL) and refluxed at 80 °C for 2 h. The mixture was diluted in water (10 mL) and extracted with EtOAc (3 × 3 mL). The aglycone and sugar moieties were identified by TLC analysis and compared with authentic samples,
d(+)-glucose,
l(+)-arabinose, and kaempferol used as standards (Sigma-Aldrich, Munich, Germany). Silica gel (Merck), mobile phase for aglycone CHCl
3–EtOAc–MeOH (14:3:3,
v/v/v) detected with AlCl
3, and mobile phase for sugars EtOH 96%–NH
4OH 25%–H
2O (20:1:4,
v/v/v) detected with aniline phthalate [
9,
10].
Kaempferol 3-O-β-d-glucopyranosyl-(1'''→2'')-O-α-l-arabinopyranoside (
1). Yellow amorphous powder. ESI-MS: positive ions m/z (rel. int.): 603.1 [M+Na]
+ (54); 581.0 [M+H]
+ (52); 419.0 [M+H−glucose]
+ (43); 401.1 [M+H−glucose−H
2O]
+ (13); 287.2 [aglycone+H]
+ (100). FT-ICR-MS (ESI): [Measured: 603.132636]
+ (calculated mass for C
26H
28O
15Na
+: 603.13204). UV λ max (nm) MeOH: 265, 346.
1H-NMR,
13C-NMR, COSY, and HMBC:
Table 1.
Kaempferol 3-O-β-d-glucopyranosyl-(1′′′→2′′)-O-α-l-arabinopyranoside-7-O-β-d-glucopyranoside (
2). Yellow amorphous powder. ESI-MS: positive ions m/z (rel. int.): 765.0 [M+Na]
+ (10); 742.8 [M+H]
+ (22); 580.9 [M+H−glucose]
+ (29); 448.8 [M+H−arabinose−glucose]
+ (100); 418.9 [M+H−glucose−glucose]
+ (100); 400.9 [M+H−glucose−glucose−H
2O]
+ (7); 287.1 [aglycone+H]
+ (82). FT-ICR-MS (ESI): [Measured: 765.184176]
+ (calculated mass for C
32H
38O
20Na
+: 765.18486). UV λ max (nm) MeOH: 265, 345.
1H-NMR,
13C-NMR, COSY, and HMBC:
Table 1.
Kaempferol 3-O-β-d-[6′′′-O-(E-caffeoyl)]-glucopyranosyl-(1′′′→2′′)-O-α-l-arabinopyranoside-7-O-β-d-glucopyranoside (
3). Yellow amorphous powder. ESI-MS: positive ions m/z (rel. int.): 927.7 [M+Na]
+ (13); 904.8 [M+H]
+ (74); 742.9 [M+H−caffeic acid]
+ (21); 580.8 [M+H−caffeic acid−glucose]
+ (24); 448.9 [M+H−caffeic acid−arabinose−glucose]
+ (100); 418.8 [M+H−caffeic acid−glucose−glucose]
+ (7); 324.8 [caffeic acid+glucose−H]
+ (8); 287.1 [aglycone+H]
+ (37); 162.9 [caffeic acid−OH]
+ (8). FT-ICR-MS (ESI): [Measured: 927.215977]
+ (calculated mass for C
41H
44O
23Na
+: 927.21656). UV λ max (nm) MeOH: 265, 328.
1H-NMR,
13C-NMR, COSY, and HMBC:
Table 2.
Kaempferol 3-O-β-d-[2′′′-O-(E-caffeoyl)]-glucopyranosyl-(1′′′→2′′)-O-α-l-arabinopyranoside-7-O-β-d-glucopyranoside (
4). Yellow amorphous powder. ESI-MS: positive ions m/z (rel. int.): 927.1 [M+Na]
+ (42); 904.9 [M+H]
+ (26); 742.9 [M+H−caffeic acid]
+ (10); 581.0 [M+H−caffeic acid−glucose]
+ (14); 448.9 [M+H−caffeic acid−arabinose−glucose]
+ (49); 419.1 [M+H−caffeic acid−glucose−glucose]
+ (6); 324.9 [caffeic acid+glucose−H]
+ (25); 287.2 [aglycone+H]
+ (100); 162.9 [caffeic acid−OH]
+ (24). UV λ max (nm) MeOH: 265, 330. FT-ICR-MS (ESI): [Measured: 927.216170]
+ (calculated mass for C
41H
44O
23Na
+: 927.21656).
1H-NMR,
13C-NMR, COSY, and HMBC:
Table 2.