Acylated flavonol glycosides from Sedum aizoon

Article abstract of DOI:10.1007/s10600-012-0150-3

A new acylated flavonol glycoside (1) and a known compound (2) have been isolated from the whole plant of Sedum aizoon L. Their structures have been established as quercetin 3-O-[β-D-(2?-O-(E)-feruloyl)-xylopyranosyl] -(1→6)-β-D-glucopyranoside (1) and rutin (2) by means of spectroscopic analysis and chemical methods.

Full text of DOI:10.1007/s10600-012-0150-3

Chemistry of Natural Compounds, Vol. 48, No. 1, March, 2012 [Russian original No. 1, January–February, 2012]
ACYLATED FLAVONOL GLYCOSIDES FROM Sedum aizoon
1
2*
2
Qiu-Yan Luo, Wei-Lin Li, and Li-Qiang Wu
UDC 547.972
A new acylated flavonol glycoside (1) and a known compound (2) have been isolated from the whole plant of
Sedum aizoon L. Their structures have been established as quercetin 3-O-[ꢀ-D-(2ꢁꢁꢁ-O-(E)-feruloyl)-
xylopyranosyl]-(1ꢂ6)-ꢀ-D-glucopyranoside (1) and rutin (2) by means of spectroscopic analysis and chemical
methods.
Keywords: Sedum aizoon, acylated flavonol glycosides, quercetin 3-O-[ꢀ-D-(2ꢁꢁꢁ-O-(E)-feruloyl)-xylopyranosyl]-
(1ꢂ6)-ꢀ-D-glucopyranoside.
Sedum aizoon L. is an endemic plant. It is useful for tranquilization, arresting bleeding, and relieving stasis, and as a
decoction for counteracting toxicity. The plant has been used to treat pain or trauma and various hemorrhage and palpitation
conditions [1, 2]. There are about 150 Sedum species distributed in China.
The phytochemical constituents of Sedum species, a large genus of the family Crassulaceae, have been extensively
reported [3–6]. In our research on this plant, repeated column chromatographic separation of BuOH fractions of the MeOH
extract resulted in the isolation of a new flavonol glycoside (1), as well as a known flavonol glycoside (2), whose structure was
determined to be rutin (2) [7] by comparing its spectroscopic data with those in the literature.
Compound 1 (see structure in Fig. 1) was isolated as a yellowish amorphous powder. The HR-ESI-MS showed a
+
quasi-molecular ion peak at m/z 773.1929 [M + H] (calcd for 773.1937), corresponding to the molecular formula of
C H O . The IR spectrum indicated the presence of hydroxyl groups, an ester carbonyl group, and an aromatic ring.
36 36 19
+
+
Positive ESI-MS/MS of 1 showed a quasi-molecular ion [M + H] at m/z 773.2 and fragment ions at m/z 641.2 [M + H – 132]
and 479.2 [M + H – 132 – 162] , indicating the loss of pentosyl and hexosyl moieties from the quasi-molecular ion. The
molecular weight of the aglycone was m/z 302. Its H NMR spectrum showed the presence of one chelated hydroxyl group
+
1
(13.04, s, 5-OH), three ABX protons belonging to a 3,4-disubstituted phenyl group (ꢃ 7.60, 1H, d, J = 1.8 Hz, H-2ꢁ; 6.89,
1H, d, J = 8.0 Hz, H-5ꢁ; 7.56, 1H, dd, J = 1.8, 8.0 Hz, H-6ꢁ), two protons typical of a 5,7-disubstituted ring A (ꢃ 6.45, 6.84,
each 1H, d, J = 2.0, H-8 and H-6), and two anomeric protons representing two glycosyl units (ꢃ 5.15, d, J = 7.5 Hz and 4.43,
13
d, J =7.5). These data, together with those of C NMR spectroscopy, indicated the presence of a quercetin [8] and two
glycosyl units [9]. After acid hydrolysis, quercetin was obtained as the aglycone. Glucose and xylose moieties were determined
1
via acid hydrolysis and comparing with standard D-glucose and D-xylose. From the H NMR spectrum, the coupling constant
of Glc H-1ꢁꢁ (J = 7.5 Hz) and Xyl H-1ꢁꢁꢁ (J = 7.5 Hz) suggested a ꢀ-anomeric configuration for the glucose and xylose. The
cross-peak between C-3 and H-1ꢁꢁ in the HMBC spectrum established the linkage point at quercetin and the glucosyl moiety.
13
From the C NMR spectral data, the C-6ꢁꢁ (Glc) was shifted downfield at ꢃ 68.9, indicating that glycosylation was at this
unit. In the HMBC spectrum, the cross-peak between C-6ꢁꢁ (Glc) and H-1ꢁꢁꢁ (Xyl) established the linkage point between the
two sugar moieties (Fig. 1). The presence of the feruloyl moiety was deduced from the ABX spin system at ꢃ 6.63 (1H, d,
J = 8.0 Hz, H-5ꢁꢁꢁꢁ), 6.91 (1H, dd, J = 1.8, 8.0 Hz, H-6ꢁꢁꢁꢁ), and 7.14 (1H, d, J = 1.8 Hz, H-2ꢁꢁꢁꢁ). The E-configuration of the
double bond was confirmed by the large coupling constant of the coupled olefinic protons at ꢃ 7.33 (1H, d, J = 15.9 Hz, H-7ꢁꢁꢁꢁ)
and 6.27 (1H, d, J = 15.9 Hz, H-8ꢁꢁꢁꢁ). The methoxy group at ꢃ 3.85 (3H, s, OCH ) was determined at C-3ꢁꢁꢁꢁ of the feruloyl,
3
which was evidenced by the cross-peaks of the O-methyl hydrogens to C-3ꢁꢁꢁꢁ (ꢃ 147.9) in the HMBC spectrum (Fig. 1).
1) Department of Gynecology and Obstetrics, the Third Affiliated Hospital to Xinxiang Medical University, Xinxiang
453003, P. R. China; 2) Department of Medicinal Chemistry, Pharmacy College of Xinxiang Medical University, Xinxiang
453003, P. R. China, fax: +86 373 302 98 79, e-mail: liweilin2002@163.com. Published in Khimiya Prirodnykh Soedinenii,
No. 1, pp. 26–28, January–February, 2012. Original article submitted December 25, 2010.
0009-3130/12/4801-0023 02012 Springer Science+Business Media, Inc.
23

1
13
TABLE 1. H NMR and C NMR Chemical Shifts of 1 (DMSO-d , ꢃ, ppm, J/Hz)
6
C atom
C atom
Xyl
ꢃH
ꢃC
ꢃH
ꢃC
2
3
4
5
6
7
8
9
10
1ꢁ
157.8
136.4
179.5
162.5
99.8
163.1
94.5
157.6
107.9
122.6
117.4
145.8
149.2
115.1
123.0
102.7
73.7
4.43 (d, J = 7.5)
4.62 (dd, J = 9.0, 9.0)
3.30 m
3.40 m
3.76 (dd, J = 12.0, 2.0)
3.04 (dd, J = 12.0, 4.0)
104.7
73.5
74.6
69.8
65.8
1
2
3
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
6.45 (d, J = 2.0)
6.84 (d, J = 2.0)
4ꢁꢁꢁ
5 a
ꢁꢁꢁ
5 b
ꢁꢁꢁ
-Feruloyl
trans
125.5
110.7
147.9
145.3
115.3
123.4
144.6
115.3
168.7
56.2
1
ꢁꢁꢁꢁ
2ꢁꢁꢁꢁ
7.14 (d, J = 1.8)
7.60 (d, J = 1.8)
2
3
4
ꢁ
ꢁ
ꢁ
3
4
5
ꢁꢁꢁꢁ
ꢁꢁꢁꢁ
ꢁꢁꢁꢁ
6.63 (d, J = 8.0)
6.91 (dd, J = 8.0, 1.8)
7.33 (d, J = 15.9)
6.27 (d, J = 15.9)
6.89 (d, J = 8.0)
7.56 (dd, J = 8.0, 1.8)
5ꢁ
6ꢁꢁꢁꢁ
6
ꢁ
7
8
9
ꢁꢁꢁꢁ
ꢁꢁꢁꢁ
ꢁꢁꢁꢁ
3- -Glc
O
1ꢁꢁ
2ꢁꢁ
5.15 (d, J = 7.5)
3.34 m
77.4
70.3
76.2
68.9
3.85 s
OMe
3
4
5
ꢁꢁ
ꢁꢁ
ꢁꢁ
3.30 m
3.10 m
3.58 m
6 a
ꢁꢁ
3.96 (dd, J = 12.2, 3.0)
3.62 (dd, J = 12.2, 5.0)
6 b
ꢁꢁ
OH
OH
4'
HO
O
1'
3
1
O
O
O
6''
O
OH
OH
4
5
OH
O
2'''
OH 1'''
O
OH
O
1''
HO
HO
9''''
7''''
1''''
4''''
3''''
H CO
3
1
Fig. 1. Key HMBC correlations of compound 1.
The connection of the xylopyranosyl group through C-2ꢁꢁꢁ to the carbonyl group of trans-feruloyl at C-9ꢁꢁꢁꢁ was determined by
the HMBC correlations, where the cross-peaks of H-2ꢁꢁꢁ (ꢃ 4.62) to C-9ꢁꢁꢁꢁ (ꢃ 168.7) were presented. Thus, the structure of 1
was elucidated to be quercetin 3-O-[ꢀ-D-(2ꢁꢁꢁ-O-(E)-feruloyl)-xylopyranosyl]-(1ꢂ6)-ꢀ-D-glucopyranoside.
EXPERIMENTAL
General Experimental Procedures. Melting points were determined on an XT-4 digital melting-point apparatus
with a binocular microscope and are uncorrected. UV and IR spectra were recorded respectively with a Jasco V-650
spectrophotometer and an FTS-40 infrared spectrometer with KBr pellets. HR-ESI-MS was measured on an Agilent 6520
1
13
Accurate-Mass Q-TOF LC/MS system. H NMR (400 MHz) spectra were recorded on Bruker-400 spectrometer. C NMR
(100 MHz) and HMBC spectra were run on a Bruker-400 spectrometer with TMS as internal standard. Silica gel (Qingdao
Marine Chemical Factory, 200–300 mesh) and Sephadex LH-20 (Pharmacia) and RP-18 (Merck, 40–60 ꢄm) were used for
column chromatography (CC). Reversed-phase HPLC separations were performed on a Shimadzu LC-6A system, detected by
a UV detector at 254 nm and equipped with a YMC semipreparative C column (10 ꢄm, 10 ꢅ 250 mm) running with a flow
18
24

rate of 4 mL/min. Precoated plates of silica gel GF and silica gel RP-18 F (Merck) were used for TLC, and spots were
254
254
detected under UV light or by heating after spraying with 98% H SO –EtOH (10:90, v/v).
2
4
Plant Material. The plant S. aizoon was collected from Taihang Mountain, Henan province, P. R. China, in September
2007 and identified by Prof. Chen-Ming Dong, Henan College of Traditional Chinese Medicine. A voucher specimen
(No. 200798) had been deposited at the Herbarium of the Pharmacy College of Xinxiang Medical University.
Isolation. The dry whole plant tissue of Sedum aizoon L. (4.5 kg) was macerated at room temperature with MeOH for
48 h four times (4 ꢅ 10 L, 7 day) and filtered. The combined methanolic extract was concentrated in vacuo to yield a crude
extract (350 g), which was dissolved in water (2.0 L) and then partitioned with petroleum ether, EtOAc, and n-BuOH successively.
The petroleum ether layer was evaporated to give 25.4 g residue; the EtOAc fraction yielded 95.4 g, and the n-BuOH fraction
yielded 230 g. The n-BuOH fraction was passed over a D macroporous resin CC (1 kg) eluted with a gradient of aqueous
101
EtOH (0, 30, 60, 80, 95, v/v) to yield five fractions (1–5). Fraction 3 (11.3 g) was subjected to reversed-phase silica gel CC and
eluted with a gradient of aqueous MeOH (0, 30, 45, 60, 75, 95, v/v) to give six fractions (3.1–3.6), Fraction 3.2 (890 mg) was
subjected to Sephadex LH-20 CC (eluted with MeOH) and preparative HPLC (60% aqueous MeOH, 4 mL/min) to yield
compound 1 (7.8 mg); fraction 3.3 (1.35 g) was also purified by Sephadex LH-20 CC (eluted with MeOH) to give compound
2 (10 mg).
20
Compound 1. Yellowish amorphous powder (MeOH), mp 201.3–202.1ꢆC. [ꢇ] –62ꢆ (c 0.2, MeOH). UV (MeOH,
D
–1
ꢈ
, nm): 256, 268, 328. IR (KBr, ꢉ, cm ): 3434 (br), 2918, 1696, 1654, 1605, 1510, 1445, 1359, 1263, 1067, 812, and 595.
For H NMR and C NMR data, see Table 1. ESI-MS m/z: 773.19 [M + H] , 795.18 [M + Na] ; HR-ESI-MS m/z: 773.1929
max
1
13
+
+
+
[M + H] (calcd for C H O , 773.1937).
36 36 19
Acid Hydrolysis of Compound 1. A solution of compound 1 (2.0 mg) in 1 M HCl (1.0 mL) was heated under reflux
for 3 h. After cooling, the reaction mixture was extracted with EtOAc, and the residues from the organic phase were identified
as quercetin and ferulic acid by comparative TLC [Si gel, CHCl –MeOH (8:2)] with authentic samples available in our
3
laboratory. The aqueous phase was concentrated, and the sugar was identified as D-glucose and D-xylose by TLC [Si gel,
BuOH–AcOH–H O (3:1:1)] with a standard sample (Merck).
2
+
1
Compound 2. Yellow amorphous powder, mp 185–188ꢆC. ESI-MS (m/z): 611 [M + H] . H NMR (400 MHz,
acetone-d , ꢃ, ppm, J/Hz): 12.58 (1H, s, 5-OH), 7.54 (1H, d, J = 1.8, H-2ꢁ), 7.52 (1H, dd, J = 8.4, 1.8, H-6ꢁ), 6.84 (1H, d, J = 8.4,
6
H-5ꢁ), 6.37 (1H, d, J = 1.5, H-8), 6.18 (1H, d, J = 1.5, H-6), 5.34 (1H, d, J = 7.2, H-1ꢁꢁ), 4.37 (1H, d, J = 1.6, H-1ꢁꢁꢁ), 0.98 (3H,
d, J = 6.0, H-6ꢁꢁꢁ).
ACKNOWLEDGMENT
This research was supported by the Foundation for High Academic Talents of Xinxiang Medical University, P. R.
China (No. 05SSKYQD).
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