New Flavanol Glucosides from Abacopteris aspera (Presl) Ching

Article abstract of DOI:10.1002/hlca.201400135

Three new flavanol glycosides, 1-3, and eight known compounds, 4-11, were isolated from a MeOH extract of the fern Abacopteris aspera (Presl) Ching. Their structures were elucidated on the basis of extensive spectroscopic analysis, including HSQC, HMBC, ¹H,¹H-COSY, and NOESY experiments, acid hydrolysis, and by the comparison of their NMR data with those of related compounds.

Full text of DOI:10.1002/hlca.201400135

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Helvetica Chimica Acta – Vol. 98 (2015)
New Flavanol Glucosides from Abacopteris aspera (Presl) Ching
by Zhen Fana)1), Jing Jinb)1), Chaozhan Linc), Chenchen Zhuc), Tao Yanga), Bao Yanga),
Jinping Zhua), and Zhongxiang Zhao*a)
a) School of Chinese Materia Medica, Guangzhou University of Chinese Medicine, Guangzhou 510006,
P. R. China (phone: þ 86-20-39358325; fax: þ 86-2-39358253; e-mail: zzx37@163.com)
b) School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou 510275, P. R. China
c) Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, Guangzhou 510405,
P. R. China
Three new flavanol glycosides, 1 – 3, and eight known compounds, 4 – 11, were isolated from a MeOH
extract of the fern Abacopteris aspera (Presl) Ching. Their structures were elucidated on the basis of
extensive spectroscopic analysis, including HSQC, HMBC, 1H,1H-COSY, and NOESYexperiments, acid
hydrolysis, and by the comparison of their NMR data with those of related compounds.
Introduction. – The fern Abacopteris aspera (Presl) Ching (Thelypteridaceae
family) is widely distributed in the south of China and other tropical regions [1]. The
plant has been used in Chinese medicine to relieve redness, heat, and swelling of sore
throat caused by acute and chronic pharyngitis [2][3]. Previous phytochemical
investigations on the genus Abacopteris revealed the occurrence of rare flavan-4-ols, 3-
deoxyanthocyanins, and C-methylflavonoids [4 – 16], among which flavan-4-ols are
considered as the main characteristic constituents. Recently, several pharmacological
features of flavan-4-ols have been studied, which include cytotoxic, anti-inflammation,
hypolipidemic potential, and vascular protective activities [10][17 – 19]. There are no
previous reports on the constituents and biological properties of this medicinal plant. A
phytochemical investigation of the whole plants of A. aspera was thus performed as a
part of our continuous search for new or bioactive compounds from Abacopteris
species. Herein, we report the isolation and structure elucidation of three new flavanol
glycosides, 1 – 3, and eight known compounds, 4 – 11 (Fig. 1) from A. aspera.
Results and Discussion. – Air-dried whole plants of A. aspera were extracted with
MeOH to give a residue, which was suspended in H2O and extracted sequentially with
petroleum ether (PE), AcOEt, and BuOH. The BuOH and AcOEt extracts were then
subjected to column chromatography on silica gel, octadecyl silica (ODS), Sephadex
LH-20, and macroporous resin, and to semi-preparative HPLC, to afford eleven
compounds, 1 – 11. The structures of the new compounds 1 – 3 were determined by
extensive spectroscopic analyses, including HSQC, HMBC, 1H,1H-COSY, and NOESY
techniques, and acid hydrolysis.
1
)
These authors contributed equally to this work.
ꢀ 2015 Verlag Helvetica Chimica Acta AG, Zꢁrich

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Fig. 1. Structures of compounds 1 – 11
Compound 1, white amorphous powder, had the molecular formula C30H38O15 as
deduced from its 13C-NMR and HR-ESI-TOF-MS data (m/z 661.2070 ([M þ Na]þ)).
The IR spectrum showed absorptions due to OH (3421 cmꢀ1) and phenyl (1614,
1519 cmꢀ1) groups. The 1H-NMR spectrum showed characteristic signals of a Me group
(d(H) 2.70 (s)), a MeO group (d(H) 3.71 (s)), two anomeric H-atoms (d(H) 5.62 (d,
J ¼ 8.4, 1 H) and 5.49 (d, J ¼ 7.2, 1 H)), and four aromatic H-atoms (as two doublets at
d(H) 7.36 (d, J ¼ 8.8, 2 H) and 7.01 (d, J ¼ 8.8, 2 H)), suggesting a para-substituted
phenyl group (Table). The 13C-NMR data of 1 analyzed with the aid of the DEPT and
HSQC spectra revealed the presence of two Me, four sp3 CH2, four sp2 CH, and twelve
1
sp3 CH groups, and eight sp2 quaternary C-atoms (Table). The H- and 13C-NMR
signals (Table) of 1 were completely assigned by a combination of HSQC, HMBC, and
1H,1H-COSY experiments (Fig. 2). According to the 1H,1H-COSY and HSQC spectra,
the substructure, ꢀCHꢀCH2ꢀCHꢀ was deduced from the correlation CH2(3) (d(H)
2.33 and 2.05)/HꢀC(2) (d(H) 4.99) and HꢀC(4) (d(H) 5.21) (Fig. 2). In the HMBC
spectrum, correlations (Fig. 2) HꢀC(4)/C(5) (d(C) 151.9), C(9) (d(C) 154.7), and
C(10) (d(C) 109.8); CH2(11) (d(H) 5.51 and 5.18)/C(5), C(6) (d(C) 121.7), and C(7)
(d(C) 156.3); and MeꢀC(8) (d(H) 2.70)/C(7), C(8) (d(C) 117.2), and C(9) indicated
the presence of a 5,7-disubstituted 6-methylene-8-methylchromane ring. Additionally,
correlations HꢀC(2) (d(H) 4.99)/C(1’) (d(C) 133.6) and C(2’,6’) (d(C) 128.7);

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Table. 1H- and 13C-NMR Data (400 and 100 MHz; (D5)pyridine) of 1 – 3. d in ppm, J in Hz.
Position
1
2
3
d(H)
d(C)
d(H)
d(C)
d(H)
d(C)
2
3
4.99 (br. d, J ¼ 11.6)
2.33 (br. d, J ¼ 14.4),
2.05 (ddd, J ¼ 3.2,
11.6, 14.4)
74.7 5.75 (br. d, J ¼ 11.6)
73.8 5.59 (dd, J ¼ 2.4, 12.0)
38.3 2.42 (dt, J ¼ 2.4, 14.0),
1.88 (ddd, J ¼ 2.4,
12.0, 14.0)
73.7
34.9
37.5 2.42 (br. d, J ¼ 13.6),
1.90 (ddd, J ¼ 3.2,
11.6, 13.6)
4
5
6
7
8
9
10
11
5.21 (d, J ¼ 3.2)
66.2 5.53 (d, J ¼ 3.2)
58.8 5.70 (t, J ¼ 2.4)
67.9
156.1
118.4
157.6
116.9
155.6
112.9
66.7
151.9
155.0
121.7
156.3
117.2
154.7
118.1
157.5
117.4
155.1
109.8
117.4
5.51 (br. d, J ¼ 11.2),
5.18 (br. d, J ¼ 11.2)
55.3 5.48 (d, J ¼ 9.2),
65.2 5.37 (d, J ¼ 9.6),
5.31 (d, J ¼ 9.6)
3.69 (s)
11.1 2.60 (s)
58.1 3.66 (s)
135.1
128.5 7.45 (d, J ¼ 8.8)
114.9 7.04 (d, J ¼ 8.8)
160.3
5.44 (d, J ¼ 9.2)
MeOꢀC(4)
56.5
11.1
58.7
134.9
128.5
114.9
160.4
55.7
MeꢀC(8)
2.70 (s)
10.5 2.65 (s)
3.69 (s)
133.6
128.7 7.50 (d, J ¼ 8.8)
114.8 7.04 (d, J ¼ 8.8)
160.5
MeOꢀC(11)
1’
2’,6’
3’,5
4’
7.36 (d, J ¼ 8.8)
7.01 (d, J ¼ 8.8)
MeOꢀC(4’) 3.71 (s)
5-O-Glc
55.8 3.70 (s)
55.7 3.71 (s)
1’’
2’’
3’’
4’’
5’’
6’’
5.62 (d, J ¼ 8.4)
101.6 5.94 (d, J ¼ 6.8)
79.0 4.35 – 4.38 (m)
76.6 4.28 – 4.30 (m)
72.6 4.33 – 4.36 (m)
76.4 4.02 – 4.05 (m)
63.7 4.45 (dd, J ¼ 2.4,
8.8),
106.9 5.67 (d, J ¼ 7.6)
76.1 4.37 – 4.40 (m)
79.1 4.30 – 4.32 (m)
71.9 4.33 – 4.36 (m)
79.4 4.07 – 4.11 (m)
62.5 4.38 – 4.41 (m),
4.30 – 4.33 (m)
107.8
76.9
79.4
72.3
79.1
63.3
3.90 – 3.93 (m)
4.29 – 4.32 (m)
4.18 (t, J ¼ 9.2)
3.91 – 3.94 (m)
4.45 (dd, J ¼ 2.8,
12.0),
4.25 – 4.28(m)
4.37 – 4.39(m)
7-O-Glc
1’’’
2’’’
3’’’
4’’’
5.49 (d, J ¼ 7.2)
4.38 – 4.40 (m)
4.30 – 4.33 (m)
4.06 – 4.08 (m)
4.07 – 4.10 (m)
4.51 (br. d, J ¼ 11.2),
4.33 – 4.36 (m)
106.6 5.54 (d, J ¼ 7.2)
76.4 4.32 – 4.35 (m)
78.8 4.34 – 4.37 (m)
71.5 4.28 – 4.30 (m)
80.1 3.93 – 3.96 (m)
62.8 4.46 (dd, J ¼ 2.4,
11.2),
107.1 5.66 (d, J ¼ 7.2)
76.5 4.32 – 4.35 (m)
78.8 4.33 – 4.35 (m)
72.4 4.24 (t, J ¼ 9.2)
78.9 3.86 – 3.89 (m)
63.6 4.58 (dd, J ¼ 2.4,
11.2),
106.9
76.4
78.7
72.5
78.8
63.8
5’’’
6’’’
4.29 – 4.32 (m)
4.33 – 4.36 (m)
HꢀC(2’,6’)/C(2) (d(C) 74.7) revealed that the para-substituted phenyl group was
attached to C(2) of the chromane ring. From these data and by comparison with the
spectra of flavan-4-ol-type glycosides previously isolated from Abacopteris plants
[7 – 9], compound 1 could be assigned as a flavan-4-ol-type glycoside with two sugar
units. Analysis of the NMR data of the sugar units (Table) suggested that the two sugars

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Fig. 2. Key HMBCs (H ! C) and 1H,1H-COSY (—) correlations of compounds 1 – 3
were both b-d-glucoses, which was confirmed by acid hydrolysis and GC analysis of the
thiazolidine derivative.
As observed in the HMBC spectrum (Fig. 2), the anomeric HꢀC(1’’) (d(H) 5.62)
correlated with C(5) (d(C) 151.9), and HꢀC(1’’’) (d(H) 5.49) with C(7) (d(C) 156.3),
indicating that two b-d-glucoses were connected with C(5) and C(7), respectively.
In addition, correlations HꢀC(2’’) (d(H) 3.90 – 3.93)/C(4) (d(C) 66.2), and HꢀC(4)
(d(H) 5.21)/C(2’’) (d(C) 79.0) evidenced that C(2’’) was linked to C(4) through
a O-bridge. The position of the MeO group at C(4’) was deduced from the HMBC d(H)
3.71 (MeOꢀC(4’))/d(C) 160.5 (C(4’)). Comparison of the above NMR spectroscopic
data of 1 with those of the co-occurring compound 8 (abacopterin I [9]) disclosed that
1 had a very similar structure, except for the disappearance of a Me group and the
appearance of a new O-bearing CH2 group resonating at d(C) 55.3 (CH2(11)). The
presence of the CH2(6)ꢀO group was confirmed by the HMBC CH2(11)/C(5), C(6),
and C(7).

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To establish the configurations at C(2) and C(4), the chemical shifts and coupling
constants of HꢀC(2), CH2(3), and HꢀC(4), and CD spectrum were examined in detail.
The coupling constants of HꢀC(2) (br. d, J ¼ 11.6) and HꢀC(4) (d, J ¼ 3.2) suggested
that HꢀC(2) and HꢀC(4) were trans-configurated [9], and this was supported by the
NOESY spectrum, in which no cross-peak HꢀC(2)/HꢀC(4) was observed. In the CD
spectrum, a positive Cotton effect at 283 nm was observed, which was very close to that
of abacopterin I (8) [9], indicating (4R)-configuration at C(4). On the basis of these
evidences, the absolute configurations at C(2) and C(4) were established as (2S) and
(4R). Thus, the structure of 1 was finally elucidated as 1,2-O-[(2S,4R)-7-(b-d-
glucopyranosyloxy)-3,4-dihydro-6-(hydroxymethyl)-2-(4-methoxyphenyl)-8-methyl-2H-
1-benzopyran-5,4-diyl] b-d-glucopyranose.
Compound 2 was obtained as white needles (MeOH), and its molecular formula,
C31H42O16, was deduced from its HR-ESI-TOF-MS (m/z 693.2358 ([M þ Na]þ; calc.
693.2371)) and 13C-NMR spectra. The IR spectrum displayed absorption bands for OH
(3423 cmꢀ1) and phenyl (1601, 1516 cmꢀ1) groups. The 1H-NMR spectrum of 2
exhibited a pair of A2B2-type signals (d(H) 7.50, 7.04 (2d, J ¼ 8.8, 2 H each), attributed
to a para-substituted phenyl group, and signals of one Me group (d(H) 2.65 (s)), two
MeO groups (d(H) 3.70 (s) and d(H) 3.69 (s)), and two anomeric H-atoms (d(H) 5.94
(d, J ¼ 6.8, 1 H) and 5.54 (d, J ¼ 7.2, 1 H)), suggesting two sugar moieties (Table). The
13C-NMR spectrum (Table) analyzed with the aid of the DEPT and HSQC spectra
further supported these results. On acid hydrolysis of 2, only d-glucose was detected by
GC. The b-pyranosyl configuration of the glycosidic bonds was deduced from the
coupling constants of the anomeric H-atoms and the 13C-NMR data of the sugars
(Table). From the above mentioned evidence, in conjunction with biogenetic
considerations, 2 was considered to be a flavan-4-ol-type glycoside.
1
The H- and 13C-NMR data of 2 were very similar to those of triphyllin A [5],
except for the appearance of a MeO signal in the spectra of 2. This was confirmed by
analyses of the 2D-NMR data of 2. The HMBCs (Fig. 2) CH2(11) (d(H) 5.48 and 5.44)/
C(6) (d(C) 118.1), and MeOꢀC(11) (d(H) 3.69)/C(11) (d(C) 65.2) suggested that a
MeO-carrying CH2 group was attached to C(6). Two b-d-glucoses were attached to
C(5) and C(7) respectively, and the position of the Me group was determined to be at
C(8), as judged by the HMBCs HꢀC(1’’) (d(H) 5.94)/C(5) (d(C) 155.0); HꢀC(1’’’)
(d(H) 5.54)/C(7) (d(C) 157.5); and MeꢀC(8) (d(H) 2.65)/C(8) (d(C) 117.4).
In the CD spectrum of 2, a negative Cotton effect at 225 nm, and positive Cotton
effects at 238 and 280 nm were observed, which were quite comparable to those of
triphyllin A [8]. The signals of HꢀC(2) (br. d, J ¼ 11.6), CH2(3) (br. d, J ¼ 13.6; ddd,
J ¼ 3.2, 11.6, 13.6), and HꢀC(4) (d, J ¼ 3.2) were also consistent with those of triphyllin
A. These evidences implied that 2 had the same configuration (2S,4R) as triphyllin A.
Therefore, the structure of 2 was deduced to be (2S,4R)-5-(b-d-glucopyranosyloxy)-
3,4-dihydro-4-hydroxy-6-(methoxymethyl)-2-(4-methoxyphenyl)-8-methyl-2H-1-ben-
zopyran-7-yl b-d-Glucopyranoside.
Compound 3 was obtained as white amorphous powder (MeOH) with the
molecular formula of C32H44O16 as deduced from its HR-ESI-TOF-MS (m/z 707.2532
([M þ Na]þ; calc. 707.2527)) and 13C-NMR data. The IR spectrum indicated the
1
presence of OH (3405 cmꢀ1), and phenyl (1599, 1516 cmꢀ1) groups. The H- and
13C-NMR data of 3 (Table) were very similar to those of 2, evidencing the presence of a

Helvetica Chimica Acta – Vol. 98 (2015)
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MeO group instead of a OH group at C(4). The HMBC (Fig. 2) MeOꢀC(4) (d(H)
3.69)/C(4) (d(C) 67.9) indicated that the MeO group was located at C(4). The
configurations at C(2) and C(4) were determined as (2S) and (4R) by comparing the
coupling constants of key H-atoms, and, CD and NOESY data of 3 with those of 2.
Thus, 3 was identified as (2S,4R)-5-(b-d-glucopyranosyloxy)-3,4-dihydro-4-methoxy-6-
(methoxymethyl)-2-(4-methoxyphenyl)-8-methyl-2H-1-benzopyran-7-yl b-d-glucopyr-
anoside.
The known compounds abacopterin C (4) [8], 6’’-O-acteyltriphyllin A (5) [12],
eruberin B (6) [5], triphyllin A (7) [5], abacopterin I (8) [9], hesperitin (9) [20],
7-hydroxy-4’-methoxy-6,8-dimethylanthocyanidin 5-O-b-d-glucopyranoside (10) [4]
[15], and rel-(2R,3R)-6-(2-carboxyethenyl)-3-(3,4-dihydroxyphenyl)-2-carboxy-1,4-
benzodioxin (caffeicin B; 11) [13][14] were identified by comparison of their
spectroscopic data with those reported in the literature. Compound 9 was found for
the first time from the genus Abacopteris.
This work was supported by the Special Funds from Central Finance of China in Support of the
Development of Local Colleges and Universities (Educational finance Grant No. 276 (2014)).
Experimental Part
General. TLC: Silica gel GF254 pre-coated plates (Qindao Marine Chemical Co., Ltd.). Column
chromatography (CC): silica gel (SiO2, 100 – 200, 200 – 300, 300 – 400 mesh; Qindao Marine Chemical
Co., Ltd.), Sephadex LH-20 (25 – 100 mm; Fluka BioChemika), CHP resin (Mitsubishi Chemical
Holdings), and ODS gel (230 – 400 mesh; Fluka BioChemika). Semi-prep. HPLC: CE2000 liquid
chromatograph with a UV detector (DaLian Elite Analytical Instruments Co., Ltd.) and a Kromasil 100-5
C18 column (250 mm ꢁ 4.6 mm, 5 mm). GC: Shimadzu GC-2010 plus gas chromatograph; cap. column
(30 m ꢁ 0.25 mm ꢁ 0.25 mm, RTX-WAX); detection, FID; temp. for injector, 2308, and for detector, 2508;
N2 as carrier gas; temp. for the oven, 2208. M.p.: X4 micro-melting-point apparatus. Optical rotations:
Autopol IV automatic polarimeter. Circular dichroism (CD) and UV spectra: Chirascan spectropo-
larimeter; lmax (log e) in nm. IR Spectra: Nicolet Nexus 300 FT-IR spectrometer; KBr disk; ˜n in cmꢀ1
.
NMR Spectra: Bruker DRX-400 AV400 instrument; at 400 (1H) and 100 MHz (13C); (D5)pyridine,
CDCl3, or (D6)DMSO as solvent; d in ppm rel. to Me4Si as internal standard, J in Hz. HR-ESI-TOF-MS:
Acquity UPLC-Q-Tof Micro MS spectrometer; in m/z.
Plant Material. Whole plants of A. aspera were collected in Ruyuan County, Guangdong Province of
China in January 2009, and identified by C. Z. (Institute of Clinical Pharmacology, Guangzhou
University of Chinese Medicine). A voucher specimen (XYJ2009-01) has been deposited with School of
Chinese Materia Medica, Guangzhou University of Chinese Medicine.
Extraction and Isolation. The air-dried whole plants of A. aspera (1.05 kg) were pulverized and
extracted with MeOH (2 l ꢁ 5) at r.t. for a week. The MeOH extract was concentrated under reduced
pressure to leave a residue (150 g), which was suspended in H2O (700 ml) and then partitioned with
petroleum ether (PE; 3 ꢁ 700 ml), AcOEt (3 ꢁ 700 ml), and BuOH (5 ꢁ 700 ml) sequentially. The
BuOH extract (80 g) was subjected to CC (CHP resin; MeOH/H2O 30 :70 ! 95 :5) to give Frs. A1 – A6.
Fr. A1 (4.5 g) was dissolved under heating in 60% aq. MeOH and allowed to reach saturation, and then
crystallized at r.t. to give 7 (3.2 g). Fr. A2 (5.0 g) was separated by CC (ODS; MeOH/H2O 35 :65 !
50 :50) to afford six subfractions, Frs. A2.1 – A2.6, and Fr. A3 (4.1 g) was subjected to CC (Sephadex
LH-20; MeOH/H2O 60 :40 ! 75 :25) to yield four subfractions Frs. A3.1 – A3.4. Fr. A2.4 (1.5 g) was
purified by CC (SiO2; CHCl3/MeOH/H2O 6 :1:0.1) to yield 8 (947 mg). Fr. A3.2 (2.5 g) was separated by
CC (ODS; MeOH/H2O 30 :70 ! 60 :40) to give eight subfractions, Frs. A3.2.1 – A3.2.8, then Fr. A3.2.2
(0.2 g) was further purified by CC (SiO2; CHCl3/MeOH/H2O 5 :1:0.1) to yield 2 (36 mg), and Fr. A3.2.5
(1.6 g) was further purified by recrystallization from MeOH/H2O 90 :10 to give 5 (46 mg). Frs. A3.2.6 and

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Helvetica Chimica Acta – Vol. 98 (2015)
A2.2 were combined (1.3 g) and purified by CC (SiO2; CHCl3/MeOH/H2O 5 :1:0.1) to yield 6 (382 mg),
and its subfractions mainly containing 3 was further purified by repeated semi-prep. HPLC (Kromasil
100-5 C18; MeOH/H2O 1:1) to afford 3 (130 mg). Frs. A3.2.8 and A2.6 were combined (0.4 g) and
dissolved in MeOH. A red solid precipitated during evaporation of the solvent at r.t., which was filtered
to yield 10 (23 mg), and the filtrate was further separated by CC (SiO2; CHCl3/MeOH/H2O 7:1:0.05 !
5 :1:0.1) to furnish 1 (57 mg).
The AcOEt extract (20 g) was subjected to CC (SiO2; CHCl3/MeOH 50 :1 ! 2 :1) to give Frs. B1 –
B13. Fr. B1 (1.2 g) was separated by CC (Sephadex LH-20; CHCl3/MeOH 1:1), followed by a further CC
(SiO2; PE/acetone 2 :1) to yield 9 (148 mg). Fr. B6 (1.1 g) was purified by CC (Sephadex LH-20; CHCl3/
MeOH 1:1) to afford 4 (26 mg). Fr. B8 (0.5 g) was subjected to CC (Sephadex LH-20; CHCl3/MeOH
1:1), followed by a further CC (ODS; MeOH/H2O/HCOOH 4 :6 :0.1), and finally purified by CC
(Sephadex LH-20; MeOH) to yield 11 (140 mg).
Acidic Hydrolysis. Each compound (2 mg) was hydrolyzed with 9% HCl (2 ml) at 908 for 5 h. After
cooling, the mixture was filtered, and then the filtrate was dried under vacuum at low temp. The residues
were converted to thiazolidine derivatives for GC analysis as described in [8].
1,2-O-[(2S,4R)-7-(b-d-Glucopyranosyloxy)-3,4-dihydro-6-(hydroxymethyl)-2-(4-methoxyphenyl)-
8-methyl-2H-1-benzopyran-5,4-diyl] b-d-Glucopyranose; 1). White amorphous powder (MeOH).
[a]1D5 ¼ þ69 (c ¼ 0.145, MeOH). CD (MeOH): 225 (ꢀ0.47), 236 (þ0.12), 283 (þ0.42). UV (MeOH):
210 (3.99), 226 (3.63), 274 (2.59), 281 (2.59). IR (KBr): 3421, 2918, 1614, 1519, 1459, 1384, 1245, 1153,
1072, 806. 1H- and 13C-NMR: see the Table. HR-ESI-TOF-MS: 661.2070 ([M þ Na]þ, C30H38NaO1þ5 ; calc.
661.2108).
(2S,4R)-5-(b-d-Glucopyranosyloxy)-3,4-dihydro-4-hydroxy-6-(methoxymethyl)-2-(4-methoxyphen-
yl)-8-methyl-2H-1-benzopyran-7-yl b-d-Glucopyranoside (2). White needles (MeOH). M.p. 177 – 1808.
[a]1D5 ¼ þ20 (c ¼ 0.193, MeOH). CD (MeOH): 225 (ꢀ1.30), 238 (þ0.27), 280 (þ0.29). UV (MeOH):
209 (4.16), 215 (3.92), 227 (3.71), 274 (2.67), 281 (2.63). IR (KBr): 3423, 2925, 1601, 1516, 1458, 1385,
1249, 1158, 1076, 838. 1H- and 13C-NMR: see the Table. HR-ESI-TOF-MS: 693.2358 ([M þ Na]þ,
C31H42NaOþ16 ; calc. 693.2371).
(2S,4R)-5-(b-d-Glucopyranosyloxy)-3,4-dihydro-4-methoxy-6-(methoxymethyl)-2-(4-methoxyphen-
yl)-8-methyl-2H-1-benzopyran-7-yl b-d-Glucopyranoside (3). White amorphous powder (MeOH).
[a]1D5 ¼ ꢀ11 (c ¼ 0.200, MeOH). CD (MeOH): 214 (ꢀ2.43), 238 (þ1.81), 279 (þ0.23). UV (MeOH):
210 (4.18), 226 (3.75), 275 (2.75), 281 (2.73). IR (KBr): 3405, 2926, 1599, 1516, 1456, 1385, 1250, 1154,
1073, 833. 1H- and 13C-NMR: see the Table. HR-ESI-TOF-MS: 707.2532 ([M þ Na]þ, C32H44NaO1þ6 ; calc.
707.2527).
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Received April 16, 2014