Glycosides from the root of Iodes cirrhosa

Article abstract of DOI:10.1021/np7007329

Seven new neolignan glycosides (1-7), two arylglycerol glycosides (8, 9), and 18 known glycosides have been isolated from an ethanolic extract of the root of Iodes cirrhosa. Their structures including absolute configurations were determined by spectroscop

Full text of DOI:10.1021/np7007329

J. Nat. Prod. 2008, 71, 647–654
647
Glycosides from the Root of Iodes cirrhosa
Maoluo Gan, Yanling Zhang, Sheng Lin, Mingtao Liu, Weixia Song, Jiachen Zi, Yongchun Yang, Xiaona Fan, Jiangong Shi,*
Jinfeng Hu, Jiandong Sun, and Naihong Chen*
Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College (Key Laboratory of BioactiVe
Substances and Resources Utilization of Chinese Herbal Medicine, Ministry of Education), Beijing 100050, People’s Republic of China
ReceiVed December 18, 2007
Seven new neolignan glycosides (1–7), two arylglycerol glycosides (8, 9), and 18 known glycosides have been isolated
from an ethanolic extract of the root of Iodes cirrhosa. Their structures including absolute configurations were determined
by spectroscopic and chemical methods. Based on analysis of the NMR data of threo and erythro 8–4′-oxyneolignans
and arylglycerols in different solvents, the validity of J7,8 and ∆δC8-C7 values to distinguish threo and erythro derivatives
was discussed. In the in Vitro assays, compound 4 and liriodendrin (17) both showed activity against glutamate-induced
PC12 cell damage at 10-5 M.
Iodes (Icacinaceae) species are woody climber plants, widely
distributed in southeastern Asia, especially in southern China. Iodes
cirrhosa Turcz. is one of several Iodes species used in traditional
Chinese medicine. Extracts of the root and stem are reported to
improve general blood circulation and are used for treatment of
inflammatory and rheumatic diseases.1 There have been no previous
reports concerning the secondary metabolites from this genus. As
part of a program to assess the chemical and biological diversity
of traditional Chinese medicines,2,3 an ethanolic extract of the root
of I. cirrhosa has been investigated. We describe herein isolation
and structural elucidation of seven new neolignan glycosides (1–7),
two new arylglycerol glycosides (8, 9), and 18 known glycosides.
Compounds 1–3 are unusual 8–4′-oxyneolignan glycosides with a
glycosyloxy group at C-3′, while 7 is an unusual dihydro[b]ben-
zofuran neolignan glycoside with an aromatic ring at C-8′. Since
the assignment of some of the erythro and threo 8–4′-oxyneolignan
and arylglycerol derivatives is ambiguous in the literature,4–9 the
validity of J7,8 and ∆δC8-C7 values to distinguish threo and erythro
8–4′-oxyneolignan and arylglycerol derivatives is discussed on the
basis of NMR data of threo and erythro 8–4′-oxyneolignans and
arylglycerols in different solvents. Some in Vitro bioassays are also
reported.
gave a positive optical rotation, [R] +47.2, indicating that it was
D-glucose.10 The 13C NMR and DEPT spectra of 1 showed carbon
signals corresponding to the above units (Table 2). The presence
of four oxygen-bearing aromatic carbons (δ > 145 ppm) in the
13C NMR spectrum, in combination with the chemical shifts and
coupling patterns of the protons of the two aromatic rings in the
1H NMR spectrum and the molecular composition, suggested that
1 was a 8–4′-oxyneolignan ꢀ-D-glucopyranoside with one phenolic
OH and one aromatic methoxy groups. However, the spectroscopic
data of 1 were different from those of related known compounds.11–13
1
Extensive analysis of HMQC and H-1H COSY spectra of 1
provided unambiguous assignments of proton and carbon signals
in the NMR spectra. In the HMBC spectrum of 1, long-range
correlations from H-7 to C-1, C-2, C-6, C-8, and C-9 and from
H-7′ to C-1′, C-2′, C-6′, C-8′, and C-9′ (Figure S1, Supporting
Information), in combination with chemical shifts and coupling
patterns, confirmed the presence of 3,4-disubstituted phenylglyc-
eryloxy and 3′,4′-disubstituted trans-phenylpropenoxy units. HMBC
correlations of C-3 with H-2, H-5, and the methoxy protons and of
C-4 with H-2 and H-6 proved that the methoxy was located at C-3.
Correlations of C-3′ with H-2′, H-5′, and the anomeric proton and
of C-4′ with H-2′ and H-6′, and the chemical shift of C-3′, indicated
that the glucose was attached at C-3′. This conclusion was supported
by NOE enhancements of H-7′, H-8′, and H-1′′ by irradiation of
H-2′ in the NOE difference experiment (Figure S1, Supporting
Information). Although a correlation from H-8 to C-4′ was not
observed in the HMBC spectrum of 1, NOE enhancements of H-2,
H-6, and H-5′ by irradiation of H-8 indicated a connection between
C-8 and C-4′ in 1.
The stereochemistry of 1 was elucidated by a comprehensive
analysis of the NMR and CD data of 1, 1a, and the acetonide 1b.
The 1H NMR spectra of 1a and 1b (Table S1, Supporting
Information) showed J7,8 values of 4.2 and 9.0 Hz, respectively.
This suggested that 1 possessed an erythro relative configura-
tion.11,12,14–18 The CD spectra of 1 and 1a showed negative Cotton
effects at 233 and 236 nm (Figures S2 and S3, Supporting
Information), respectively, indicating 8R configuration for these
compounds.18,19 Thus, 1 was determined to be (-)-(7S,8R,7′E)-
4,7,9,3′,9′-pentahydroxy-3-methoxy-8–4′-oxyneolign-7′-ene-3′-O-
ꢀ-D-glucopyranoside.
Results and Discussion
Compound 1 was obtained as an amorphous solid, and the
presence of OH (3358 cm-1) and aromatic (1602 and 1509 cm-1
)
groups were indicated by its IR spectrum. The positive mode ESIMS
of 1 gave a quasi-molecular ion peak at m/z 547 [M + Na]+, and
the molecular formula C25H32O12 was indicated by HRFABMS at
1
m/z 547.1801. The H NMR of 1 in DMSO-d6 showed signals
attributed to two 1,3,4-trisubstituted aromatic rings at δ 6.97 (H-
2), 6.68 (H-5), and 6.80 (H-6), and 7.19 (H-2′), 6.89 (H-5′), and
6.93 (H-6′), together with signals attributed to an aromatic methoxy
at δ 3.72 and an exchangeable phenolic OH proton at δ 8.80 (OH-
4). A trans-arylpropenoxy unit was indicated by signals at δ 6.41
(H-7′), 6.21 (H-8′), and 4.06 (H2-9′). Meanwhile, an arylglyceryloxy
unit was indicated by signals of a vicinal coupling system attributed
to two oxymethines at δ 4.69 (H-7) and 4.27 (H-8) and an
oxymethylene at δ 3.63 (H-9a) and 3.51 (H-9b). A doublet
assignable to an anomeric proton at δ 4.79, partially overlapped
signals attributed to oxymethylene and oxymethine protons between
δ 3.13 and 3.70, and exchangeable OH protons between δ 4.50
and 5.35 suggested that there was a ꢀ-glycosyl moiety in 1.
Enzymatic hydrolysis of 1 produced 1a and a sugar. The sugar
Compound 2 was obtained as an amorphous powder, and the
molecular formula C25H34O12 was indicated by HRESIMS at m/z
549.1963 [M + Na]+. The UV, IR, and NMR spectroscopic data
of 2 indicated that it was a diastereomer of (7R,8R)-4,7,9,9′-
tetrahydroxy-3-methoxy-8-O-4′-neolignan-3′-O-ꢀ-D-glucopyrano-
side,15 which was confirmed by the HMBC experiment of 2.
Hydrolysis of 2 with ꢀ-glucosidase librated 2a and D-glucose. The
* To whom correspondence should be addressed. Tel: 86-10-83154789.
Fax: 86-10-63017757. E-mail: shijg@imm.ac.cn.
10.1021/np7007329 CCC: $40.75
2008 American Chemical Society and American Society of Pharmacognosy
Published on Web 03/08/2008

648 Journal of Natural Products, 2008, Vol. 71, No. 4
Gan et al.

Glycosides from the Root of Iodes cirrhosa
Journal of Natural Products, 2008, Vol. 71, No. 4 649
a
13
Table 2.
C NMR Data for Compounds 1-7
C-9′. The J7,8 (3.6 Hz) of 4a in CDCl3 (Table S1) suggested that 4
had an erythro-configuration. In the CD spectra of 4 and 4a, a
positive Cotton effect at 238 nm (Figures S2 and S3) suggested
that they both had an 8S configuration. Consequently, 4 was
determined to be (-)-(7R,8S)-4,7,9,3′,9′-pentahydroxy-3-methoxy-
8–4′-oxyneolignan-9′-O-ꢀ-D-glucopyranoside.
The NMR data of 5 (Tables 1 and 2) were in good agreement
with those of (-)-(7R,8R)-4,7,9,9′-tetrahydroxy-3,3′-dimethoxy-8-
O-4′-neolignan-9′-O-ꢀ-D-glucopyranoside.15 However, the optical
rotation and CD data of 5 and its aglycone 5a (Figures S2 and S3)
were opposite of that reported. Therefore, the structure of 5 was
assigned as (+)-(7S,8S)-4,7,9,9′-tetrahydroxy-3,3′-dimethoxy-8–4′-
oxyneolignan-9′-O-ꢀ-D-glucopyranoside. This was supported by the
1H NMR data of 5a and its acetonide 5b in CDCl3, which displayed
J7,8 values of 8.4 and ∼0.0 Hz (Table S2), respectively.
no.
1
2
3
4
5
6
7b
1
2
3
4
5
6
7
8
9
1′
2′
3′
4′
5′
6′
132.9 133.0 132.7 132.7 133.0
111.2 111.2 111.0 111.4 111.0
147.1 147.0 147.1 147.1 147.0
145.5 145.4 145.5 145.6 145.4
114.8 114.8 114.8 114.8 114.6
119.6 119.6 119.3 119.4 119.0
69.1 135.6
80.5 110.2
62.0 148.9
146.1
115.3
117.8
86.5
53.5
71.4
85.6
59.9
71.3
85.9
59.8
71.6
86.4
59.6
71.8
87.0
60.2
71.0
84.8
60.1
63.4
131.0 136.0 132.4 136.5 134.8 129.6 138.4
115.3 117.9 108.0 116.5 112.9 112.7 110.8
148.4 148.2 151.2 149.7 149.5 151.9 142.8
147.9 146.4 135.4 144.9 146.4 151.9 145.9
118.5 118.8 153.0 119.3 116.0 117.2 127.6
120.8 122.3 104.8 117.8 120.2 124.5 114.9
Compound 6 was obtained as an amorphous powder, and its IR
spectrum showed absorption bands for OH (3379 cm-1), conjugated
CO (1662 cm-1), and aromatic (1595 and 1511 cm-1) groups. The
molecular formula C19H26O10 of 6 was indicated by HRFABMS.
The NMR spectra of 6 in MeOH-d4 displayed resonances due to
glyceryl, 3′,4′-disubstituted trans-phenylpropenal, and ꢀ-glucopy-
ranosyl moieties and to a methoxy signal (Tables 1 and 2).
Enzymatic hydrolysis of 6 yielded D-glucose and 6a. The 1H NMR
and ESIMS spectroscopic data of 6a were consistent with those of
2-{2-methoxy-4-[(E)-formylvinyl]phenoxyl}propan-1,3-diol.20 The
HMBC experiment of 6 revealed that it was 1-O-ꢀ-D-glucopyra-
nosyl-2-{2-methoxy-4-[(E)-formylvinyl]phenoxyl}propan-3-ol. The
negative optical rotation of 6 suggested that it had a 2R configu-
ration.21 Therefore, 6 was determined to be as (-)-(2R)-1-O-ꢀ-D-
glucopyranosyl-2-{2-methoxy-4-[(E)-formylvinyl]phenoxyl}propane-
3-ol.
7′
8′
9′
1′′
2′′
3′′
4′′
5′′
128.2
129.1
61.5
31.1 128.4
34.1 130.3
31.0
31.1
67.8
31.1 155.4
31.2 127.9
67.9 196.1
72.5
55.2
62.6
60.1
61.5
101.8 101.8 101.8 102.9 103.0 104.7 100.1
73.6
76.4
69.8
77.1
60.8
55.7
73.6
76.4
69.7
77.0
60.7
55.7
73.6
76.3
69.9
77.3
60.8
55.6
56.0
14.8
73.4
76.7
70.0
76.8
61.0
55.6
73.5
76.7
70.0
76.8
61.1
55.4
55.6
13.8
75.0
78.0
71.6
78.0
62.8
56.6
73.2
76.8
69.6
77.0
60.6
55.7
55.5
6′′
3-OMe
3′/5′-OMe
∆δC8-C7
a
14.2
14.6
15.2
13C NMR data (δ) were measured in DMSO-d6 for 1-5 and 7 and
MeOH-d4 for 6 at 125 MHz. The assignments were based on DEPT,
1H-1H COSY, HMQC, and HMBC experiments. b Data of the
3′′′-methoxy-4′′′-hydroxyphenyl unit at C-7′ of 7, δ 131.2 (C-1′′′), 113.9
(C-2′′′), 146.5 (C-3′′′), 144.7 (C-4′′′), 114.5 (C-5′′′), 121.8 (C-6′′′), 55.4
(OMe-3′′′).
Compound 7 was obtained as a gum, and its molecular formula
C33H40O14 was indicated by HRESIMS. The IR spectrum of 7
displayed absorption bands for OH (3426 cm-1) and aromatic ring
(1608 and 1514 cm-1) groups. The 1H NMR spectrum of 7 showed
signals due to two 1,3,4-trisubstituted phenyl groups, a 1,3,4,5-
tetrasubstituted phenyl group, and three methoxy groups. In
addition, it showed signals attributed to three oxymethine protons
at δ 5.46 (H-7), 4.83 (H-7′), and 4.87 (H-1′′), partially overlapped
methylene and methine protons between δ 3.14 and 3.70, and broad
signals due to eight OH protons between δ 4.10 and 5.30. In
addition to carbon resonances corresponding to the above units,
the 13C NMR and DEPT spectra of 7 displayed carbon signals
attributed to two oxymethines at δ 86.5 (C-7) and 72.5 (C-7′), two
oxymethylenes at δ 63.4 (C-9) and 62.6 (C-9′), and two aliphatic
methines at δ 53.5 (C-8) and 55.2 (C-8′). These spectroscopic data
suggested that 7 was a dihydro[b]benzofuran neolignan glycoside
with an additional tri- or disubstituted aryl group.22 Enzymatic
hydrolysis of 7 produced D-glucose and 7a, and the 1H NMR data
of 7a were in agreement with those of leptolepisol C isolated from
Larix leptolepis.23 This indicated that 7 was leptolepisol C ꢀ-D-
glucoside, which was confirmed by HMQC and HMBC experiments
of 7. In the HMBC spectrum, a correlation from the anomeric proton
to C-4 indicated unequivocally that the ꢀ-glycopyranosyl moiety
was located at C-4. Consequently, 7 was determined to be
leptolepisol C 4-O-ꢀ-D-glucopyranoside. The CD spectra of 7 and
7a did not give any useful Cotton effect due to interaction among
three aromatic rings, and the absolute configuration of 7 and 7a
remains to be determined.
1H NMR spectra of 2a and its acetonide 2b in CDCl3 showed J7,8
values of 3.6 and 9.0 Hz (Table S1, Supporting Information),
respectively, suggesting that 2 possessed an erythro relative
configuration.11,17 The CD spectra of 2 and 2a displayed positive
Cotton effects at 237 and 238 nm (Figures S2 and S3, Supporting
Information), respectively, indicating that 2 and 2a possessed an
8S configuration.18,19 Therefore, 2 was determined to be (-)-
(7R,8S)-4,7,9,3′,9′-pentahydroxy-3-methoxy-8–4′-oxyneolignan-3′-
O-ꢀ-D-glucopyranoside.
Compound 3 was obtained as an amorphous powder, and its
HRESIMS at m/z 577.1851 [M + Na]+ indicated the molecular
formula C26H34O13. The UV, IR, and NMR spectroscopic features
of 3 were similar to those of 1, except that the NMR signals of the
3′,4′-disubstituted trans-arylpropenoxy unit in 1 were replaced by
those attributed to a 3′,4′,5′-trisubstitued trans-arylpropenoxy unit
and a methoxy in 3 (Tables 1 and 2). These data indicated that 3
was an analogue of 1 with an additional methoxy at C-5′. This
was confirmed by the HMBC spectrum of 3, which showed
correlations of C-3′ with H-2′ and H-1′′, C-4′ with H-2′ and H-6′,
and C-5′ with H-6′ and the additional methoxy protons. An erythro
configuration of 3 was confirmed by the J7,8 (4.2 Hz) of 3a in
CDCl3. In the CD spectra of 3 and 3a, respective negative Cotton
effects at 235 and 236 nm (Figures S2 and S3, Supporting
Information) indicated that they had 8R configuration. Therefore,
3 was determined to be (-)-(7S,8R,7′E)-4,7,9,3′,9′-pentahydroxy-
3,5′-dimethoxy-8–4′-oxyneolign-7′-ene-3′-O-ꢀ-D-glucopyrano-
side.
Compound 8 showed IR absorption bands for OH (3374 cm-1
)
Compound 4 was assigned the molecular formula C25H34O12, as
indicated by HRESIMS. The NMR data suggested that 4 was an
isomer of 2. The anomeric proton of 4 was shielded ∆δ 0.66 ppm
by comparison with that of 2, while two multiplets at δ 3.74 (H-
9′a) and 3.38 (H-9′b) in 4 replaced the triplet of H2-9′ in 2. This
indicated that the glucopyranosyloxy moiety was located at C-9′
in 4, which was confirmed by the HMBC experiment of 4 showing
correlations from both H-9′a and H-9′b to C-1′′ and from H-1′′ to
and aromatic (1612 and 1513 cm-1) functional groups. The ESIMS
of 8 gave [M + Na]+ and [M + K]+ peaks at m/z 429 and 445.
1
The H NMR spectrum of 8 in DMSO-d6 showed a two-proton
aromatic singlet at δ 6.64, a six-proton methoxy singlet at δ 3.75,
two deshielded oxymethine doublets at δ 4.63 (H-7) and 4.25 (H-
1′), and partially overlapped oxymethylene and/or oxymethine
multiplets integrated for nine protons between δ 3.00 and 3.75

650 Journal of Natural Products, 2008, Vol. 71, No. 4
Gan et al.
Table 3. NMR Data for Compounds 8 and 9a
8
9
no.
H
C
H
C
1
2
3
4
5
6
7
131.9
104.6
147.4
134.3
147.4
104.6
72.6
132.7
111.5
147.0
145.4
114.6
119.4
72.5
6.64 s
6.64 s
6.97 d (1.2)
6.67 d (8.0)
6.73 dd (8.0, 1.2)
4.63 d (4.0)
4.63 d (4.4)
8
3.75 m
84.6
3.72 m
84.9
9a
9b
1′
2′
3′
4′
5′
6′a
6′b
OMe
3.42 dd (11.2, 4.4)
3.29 dd (11.2, 4.8)
4.25 d (8.0)
3.00 dd (8.8,8.0)
3.10 dd (8.8, 8.8)
3.02 dd (8.8, 8.8)
3.10 m
3.66 dd (11.6, 1.6)
3.38 dd (11.6, 5.2)
3.73 s
61.1
3.39 dd (11.2, 5.2)
3.25 dd (11.2, 4.8)
4.26 d (7.6)
3.00 dd (8.8, 7.6)
3.13 dd (8.8,8.8)
3.02 dd (8.8, 8.4)
3.10 m
3.64 brd (12.0)
3.39 (12.0, 6.4)
3.74 s
61.1
103.1
73.8
76.4
70.1
76.9
61.0
103.3
73.9
76.4
70.1
76.9
61.0
55.9
55.6
a
1H NMR data (δ) were measured in DMSO-d6 at 400 MHz. Proton coupling constants (J) in Hz are given in parentheses. 13C NMR data (δ) were
measured in DMSO-d6 at 125 MHz.
(Table 3). The 13C NMR and DEPT spectra of 8 displayed
characteristic signals for 1-C-syringylglycerol and ꢀ-glucopyranosyl
moieties (Table 3). Enzymatic hydrolysis of 8 with ꢀ-glucosidase
yielded 8a with [R] -19.6 (c 0.25, MeOH) and D-glucose. The
NMR data of 8a (Tables S11 and S13) were in good agreement
with those of erythro-1-C-syringylglycerol,24,25 indicating that it
was (-)-erythro-1-C-syringylglycerol ꢀ-D-glucopyranoside. Com-
parison of the NMR data of 8 and 8a indicated that C-8 of 8 was
significantly deshielded by ∆δ 9.3 ppm. This suggested that the
ꢀ-D-glucopyranosyl moiety was located at C-8 of (-)-erythro-
syringylglycerol in 8. Since erythro-arylglycerols with 7R,8S
configuration were reported to have negative [R]D values,26,27 the
absolute configuration at C-7 and C-8 of 8a was assigned as 7R,8S.
Thus, the structure of 8 was determined to be (-)-(7R,8S)-
syringylglycerol 8-O-ꢀ-D-glucopyranoside.
spectra and/or optical rotations of their aglycones, and 13 was obtained
as a natural product for the first time.
Coupling constants (J7,8) of the deshielded benzylic proton
1
(H-7) signal in the H NMR spectra of the acetates of erythro
(J7,8 e 5.3 Hz) and threo (J7,8 g 6.3 Hz) 8–4′-oxyneolignan
aglycones and glycosides,12,18 as well as acetonide derivatives
of threo (J7,8 < 2.0 Hz) and erythro (J7,8 > 8.0 Hz) 8–4′-
oxyneolignan aglycones,11,17 unambiguously distinguished eryth-
ro and threo isomers in CDCl3. However, there were several
cases where the values of J7,8 of 8–4′-oxyneolignans were directly
applied for the differentiation of erythro and threo isomers
without derivatization.5,6,14a,15,42 A systematic analysis of H
1
NMR data of 1-5 in DMSO-d6 (Table 1) and 1a-5a, 10a, 11a,
5, 10, and 11 in different solvents (Tables S1-S5, Supporting
Information), in combination with the data of 8–4′-oxyneolignan
derivatives in the literature,11–15,17,44 indicated that the values
of J7,8 were variable in different solvents due to possible dynamic
conformational changes.43 In Me2CO-d6 + D2O or CDCl3, the
J7,8 values of the threo 8–4′-oxyneolignan aglycones 5a and 11a
(6.0 and 6.6 Hz in Me2CO-d6 + D2O and 8.4 and 8.4 Hz in
CDCl3, respectively) were larger than those of the erythro
analogues 1a, 2a (4a), 3a, and 10a (4.8, 4.8, 3.0, and 5.4 Hz in
Me2CO-d6 + D2O and 4.2, 3.6, 4.2, and 4.2 Hz in CDCl3,
respectively). Meanwhile, in C5D5N, the J7,8 values of the
glycosides 5 and 11 (6.0 and 5.4 Hz) were larger than that of
the erythro analogue 10 (4.8 Hz). However, in CD3OD, the J7,8
values of the threo aglycones 5a and 11a (6.0 and 5.4 Hz) were
smaller than or equal to the erythro aglycones 10a (6.0 Hz),
and in DMSO-d6, D2O, and CD3OD, the J7,8 values of threo
glycosides 5 and 11 were smaller than or equal to those of the
erythro glycosides. In addition, it was clear that the differences
of the J7,8 values between threo and erythro aglycones in Me2CO-
d6 + D2O and glycosides in C5D5N are small and close to the
range of NMR instrument errors. Therefore, the direct application
of the J7,8 values was ambiguous to differentiate erythro and
threo 8–4′-oxyneolignans with the exception of aglycone ac-
etonides (J7,8 > 8.0 Hz for erythro, and J7,8 < 2.0 Hz for threo)
and glycoside acetates (J7,8 e 5.3 Hz for erythro, and J7,8 g 6.3
Compound 9 gave [M + Na]+ and [M + K]+ peaks at m/z 399
and 415 in the positive ESIMS. The IR and NMR data were similar
to those of 8 except that the syringyl unit in 8 was replaced by a
guaiacyl unit in 9. This suggested that 9 was a demethoxy derivative
of 8. Hydrolysis of 9 yielded 9a, with [R] –12.4 (c 0.33, MeOH),
and D-glucose. The NMR data of 9a (Tables S12 and S13) were
identical to those of (7S,8R)-guaiacylglycerol except for an opposite
optical rotation ([R] +11).8,27 Therefore, 9 was determined to be
(-)-(7R,8S)-guaiacylglycerol 8-O-ꢀ-D-glucopyranoside.
The known compounds were identified by comparison of spectro-
scopic data with those reported in the literature as (-)-(7R,8S,7′E)-
4,7,9,9′-tetrahydroxy-3,3′-dimethoxy-8–4′-oxyneolign-7′-ene-9′-O-ꢀ-
D-glucopyranoside (hyuganoside IIIa, 10),11 (-)-(7S,8S,7′E)-4,7,9,9′-
tetrahydroxy-3,3′-dimethoxy-8–4′-oxyneolign-7′-ene-9′-O-ꢀ-D-
glucopyranoside (hyuganoside IIIb, 11),11 (+)-(7S,8S)-syringylglycerol
8-O-ꢀ-D-glucopyranoside (12),7 (+)-(7S,8S)-guaiacylglycerol 8-O-ꢀ-
D-glucopyranoside (13),30 (-)-(7S,8R)-guaiacylglycerol 9-O-ꢀ-D-glu-
copyranoside (14),8 (-)-(7R,8R)-guaiacylglycerol 9-O-ꢀ-D-glucopy-
ranoside (15),8 (-)-(7R,8R)-syringylglycerol 9-O-ꢀ-D-glucopyranoside
(16),31 (-)-(7R,8R)-guaiacylglycerol 7-O-ꢀ-D-glucopyranoside,32 (-)-
tachioside,33 (-)-liriodendrin (17),34 (-)-sweroside,35 (-)-11,13-
dihydrodeacylcynaropicrin 3-O-ꢀ-D-glucopyranoside,36 (-)-3,5-di-
methoxy-4-hydroxyphenyl ꢀ-D-glucopyranoside (incorrect nomenclature
was given in the literature37), (-)-(1′R)-1′-(3-hydroxy-4-methoxyphe-
nyl)ethane-1′,2′-diol 3-O-ꢀ-D-glucopyranoside,38 (-)-3-hydroxy-1-(4-
hydroxy-3-methoxyphenyl)-1-propanone 3-O-ꢀ-D-glucopyranoside,39
(-)-2-hydroxy-5-(2-hydroxyethyl)phenyl ꢀ-D-glucopyranoside,32 (-)-
2-methoxy-4-(1-propionyl)phenyl ꢀ-D-glucopyranoside,40 and (-)-4-
propionyl-2,6-dimethoxyphenyl ꢀ-D-glucopyranoside.41 The absolute
configurations of 10, 11, and 12 were determined on the basis of CD
Hz for threo) in CDCl3, as well as aglycones in CDCl3 (J7,8
5.0 Hz for erythro, and J7,8 g 8.0 Hz for threo).
e
In order to evaluate a possible application of the 13C NMR
spectroscopic data for distinguishing erythro and threo 8–4′-
oxyneolignan derivatives, the 13C NMR data of 1-5 in DMSO-d6
(Table 2) and 1a, 2a (4a), 5a, 10a, 11a, 2, 5, 10, and 11 in different
solvents (Tables S6 and S7, Supporting Information), together with

Glycosides from the Root of Iodes cirrhosa
Journal of Natural Products, 2008, Vol. 71, No. 4 651
the data of 8–4′-oxyneolignan derivatives in the literature,11,15,17,44a
were investigated. The chemical shift difference between C-8 and
C-7 (∆δC8-C7) was used in the discussion to eliminate the systematic
errors. The ∆δC8-C7 values of the erythro and threo isomers (10
and 11, and 10a and 11a) were variable in different solvents. In
DMSO-d6, C5D5N, or CD3OD, the ∆δC8-C7 values of the erythro
glycoside 10 (12.1, 12.6, or 12.1 ppm) were smaller than those of
the threo isomer 11 (13.4, 13.9, or 13.1 ppm). Meanwhile, in
Me2CO-d6, CD3OD, or CDCl3, the ∆δC8-C7 values of the erythro
aglycone 10a (12.9, 12.1, or 14.6 ppm) were smaller than those of
the threo isomer 11a (14.7, 13.2, or 15.5 ppm). These were fully
consistent with data reported in the literature.11,15,17,44a However,
in D2O the ∆δC8-C7 value of the erythro glycoside 10 (11.0 ppm)
was larger than that of the threo isomer 11 (10.7 ppm), and in
CD3OD the ∆δC8-C7 value of the erythro glycoside 2 (13.7 ppm)
was larger than that of its threo isomer (12.9 ppm).15 In the same
solvent, the ∆δC8-C7 values of the 8–4′-oxyneolignan analogues
[1-5, 1a, 2a (4a), and 10a] were variable due to substituent
differences at C-3′ and/or C-5′. Therefore, the ∆δC8-C7 values may
be useful to distinguish the erythro and threo 8–4′-oxyneolignan
isomers when the data are obtained in the same solvent.
Table 4. Activities of Selected Compounds to Glutamate-
Induced Neurotoxicity in PC12 Cellsa
compound
relative protection (%)
control
glutamate-treated
100 ( 1.9
0.0 ( 2.8#
NGF
4
9
12
13
17
108.2 ( 2.1**
36.4 ( 3.1*
-46.6 ( 2.2**
-28.4 ( 1.9**
-32.9 ( 1.9**
20.5 ( 1.8**
a The data are expressed as mean ( SD of three independent ex-
periments. (#p < 0.05 vs control; *p < 0.05, **p < 0.01 vs glutamate-
treated group).
induced cytotoxicity, whereas, 11-13 increased the cell damage.
The other compounds were all inactive.
Experimental Section
General Experimental Procedures. Optical rotations were measured
on a Rudolph Research Autopol III automatic polarimeter. UV spectra
were measured on a Cary 300 spectrophotometer. CD spectra were
recorded on a JASCO J-810 spectropolarimeter. IR spectra were
recorded as KBr disks on a Nicolet 5700 FT-IR instrument. NMR
The J7,8 values of arylglycerol acetates were used to distinguish
threo- (J7,8 > 7.0 Hz) and erythro- (J7,8 < 6.5 Hz) arylglycerols,29,30,44b,45
and our previous investigation indicated that the chemical shift
difference of C-7 and C-8 (∆δC8-C7) was also applicable to
differentiate threo- and erythro-arylglycerols without substituent(s)
at C-7 and/or C-8 of the glycerol moiety.25 A systematic analysis
of the NMR data of 8, 9, 12, and 13 in D2O, DMSO-d6, C5D5N, or
CD3OD (Tables S8-S10, Supporting Information) and the data of
erythro- and threo-arylglycerol 8-O-ꢀ-D-glucopyranosides in the
literature7–9,29–31 (the relative configurations at C-7 and C-8 were
wrongly assigned in ref 9) indicated that the values of both J7,8
and ∆δC8-C7 were variable in different solvents. However, in
DMSO-d6, C5D5N, or CD3OD except for D2O, the differences of
J7,8 and ∆δC8-C7 between erythro- and threo-arylglycerol 8-O-ꢀ-
D-glucopyranosides were significant and may be directly applicable
to distinguish erythro- (J7,8 e 4.4 Hz in DMSO-d6, C5D5N, or
CD3OD, ∆δC8-C7 e 12.5 ppm in DMSO-d6 or C5D5N, and ∆δC8-C7
< 11.0 ppm in CD3OD) and threo-arylglycerol 8-O-ꢀ-D-glucopy-
ranosides (J7,8 g 6.0 Hz in DMSO-d6, C5D5N, or CD3OD, ∆δC8-C7
g 14.0 ppm in DMSO-d6 or C5D5N, and ∆δC8-C7 > 12.0 ppm in
CD3OD). The ∆δC8-C7 of the aglycones 8a, 9a, 12a, and 13a in
Me2CO-d6, CD3OD, C5D5N, and DMSO-d6 were consistent with
those of our previously reported data for erythro- (∆δC8-C7 < 1.0
ppm in Me2CO-d6, CD3OD, or C5D5N, and ∆δC8-C7 e 1.4 in
DMSO-d6) and threo- (∆δC8-C7 g 2.0 ppm in all tested solvents)
arylglycerols without substituent(s) at C-7 and/or C-8,25 although
the values of J7,8 were indistinguishable among the aglycones
without substituent(s) at C-7 and/or C-8 (Tables S11-S13). In
addition, an investigation of the NMR data of three known erythro-
and threo-arylglycerol 9-O-ꢀ-D-glucopyranosides (14-16) (Tables
S14 and S15, Supporting Information) in different solvents, together
with the data of erythro- and threo-arylglycerol 9-O-ꢀ-D-gluco-
pyranosides7–9,28,31 (the relative configurations at C-7 and C-8 were
wrongly assigned in refs 7 and 9) indicated that there was no
significant difference among J7,8 values of erythro- and threo-
arylglycerol 9-O-ꢀ-D-glucopyranosides. However, in DMSO-d6 or
C5D5N except for in D2O or CD3OD ∆δC8-C7 values are applicable
to distinguish erythro- (∆δC8-C7 e 0.5 ppm in DMSO-d6 or C5D5N)
and threo- (∆δC8-C7 > 1.0 ppm in DMSO-d6 or C5D5N) arylglycerol
9-O-ꢀ-D-glucopyranosides.
1
spectra were obtained at 400, 500, or 600 MHz for H and 100, 125,
or 150 MHz for 13C, respectively, on Inova 400, 500, and 600 MHz
spectrometers in DMSO-d6, C5D5N, CD3OD, Me2CO-d6, D2O, or CDCl3
with solvent peaks (or TMS, in the case of D2O) used as references.
ESIMS data were measured with a Q-Trap LC/MS/MS (Turbo Ionspray
Source) spectrometer. HRFABMS and HRESIMS data were respec-
tively measured using a Micromass Autospec-Ultima ETOF and an
AccuToFCS JMS-T100CS spectrometer. Column chromatography (CC)
was performed with silica gel (200–300 mesh, Qingdao Marine
Chemical Inc. China) and Sephadex LH-20 (Pharmacia Biotech AB,
Uppsala Sweden). HPLC separation was performed on an instrument
consisting of a Waters 600 controller, a Waters 600 pump, and a Waters
2487 dual λ absorbance detector with an Alltima (250 × 10 mm i.d.)
preparative column packed with C18 (5 µM). TLC was carried out with
glass precoated silica gel GF254 plates. Spots were visualized under
UV light or by spraying with 7% H2SO4 in 95% EtOH followed by
heating.
Plant Material. The root of I. cirrhosa (6.0 kg) was collected at
Dayao Moutain, Guangxi Province, China, in August 2002. The plant
was identified by Mr. Guang-Ri Long (Guangxi Forest Administration,
Guangxi 545005, China). A voucher specimen (no. YG02011) was
deposited at the Herbarium of the Department of Medicinal Plants,
Institute of Materia Medica, Beijing, China.
Extraction and Isolation. The air-dried root of I. cirrhosa (6 kg)
was powdered and extracted with 95% EtOH (3 × 15 L) at room
temperature for 3 × 48 h. The ethanolic extract was evaporated under
reduced pressure to yield a dark brown residue (640 g). The residue
was suspended in H2O (2000 mL) and then partitioned with EtOAc (5
× 2000 mL). The aqueous phase was applied to a HDP100 macroporous
adsorbent resin (1000 g, dried weight) column. A successive elution
of the column with H2O, 30% EtOH, 60% EtOH, and 95% EtOH (5000
mL each) yielded four corresponding portions after removing solvents.
The portion (24.0 g) eluted by 30% EtOH was separated by MPLC
over reversed-phase silica gel eluting with a gradient of increasing
MeOH (0-60%) in H2O to give four fractions (A-D) on the basis of
TLC analysis. Subsequent separation of fraction A (7.5g) over Sephadex
LH-20 eluted with H2O gave four subfractions (A1-A4). Subfraction
A2 (0.98 g) was further fractionated via silica gel CC, eluting with
CHCl3-MeOH (8:1), to yield two fractions (A2–1, A2–2). Fraction A2–1
(0.31 g) was subjected to reversed-phase preparative HPLC, using a
mobile phase of MeOH-H2O-HOAc (6.5:93.5:0.5), to afford 8 (110
mg), 9 (51 mg), 12 (15 mg), and 13 (15 mg). Fraction B (13.0 g) was
separated by normal silica gel CC, eluting with a gradient of increasing
MeOH (10-50%) in CHCl3, to afford five fractions (B1-B5). B1 (4.60
g) was further separated into five subfractions (B1–1-B1–5) by reversed-
phase flash chromatography using step-gradient elution with increasing
MeOH (0-30%) in H2O. Fraction B1–2 (0.68 g) was subjected to CC
over Sephadex LH-20, eluting with H2O, to give four mixtures
(B1–2–1-B1–2–4). B1–2–2 (96 mg) was purified by reversed-phase prepara-
The neuroprotective activity of the purified compounds against
glutamate-induced neurotoxicity in cultures of PC12 cells was
evaluated by the MTT assay. As shown in Table 4, treatment with
glutamate (20 µM) resulted in significant inhibition of MTT
reduction. However, exposure of compounds 4 and 17 at the
concentration of 10-5 M for 24 h remarkably attenuated glutamate-

652 Journal of Natural Products, 2008, Vol. 71, No. 4
Gan et al.
Chart 1
tive HPLC using the mobile phase of MeCN-H2O-HOAc
(10:90:0.5) to afford 6 (16 mg). Fraction B1–2–3 (54 mg) was separated
by reversed-phase preparative HPLC using MeOH-H2O--HOAc (21:
79:0.5) to yield 1 (13 mg) and 2 (15 mg). B1–4 (0.75 g) was subjected
to CC over Sephadex LH-20 with H2O as eluent to give four mixtures
(B1–4–1-B1–4–4). Fraction B1–4–3 (243 mg) was separated by reversed-
phase preparative HPLC with the mobile phase MeOH-H2O (30:70)
to yield 3 (10 mg), 4 (12 mg), 5 (26 mg), 7 (11 mg), 10 (17 mg), and
11 (21 mg).
see Table 2; ESIMS m/z 549 [M + Na]+ and 565 [M + K]+; HRESIMS
m/z 549.1963 [M + Na]+ (calcd for C25H34O12Na 549.1948).
(-)-(7S,8R,7′E)-4,7,9,3′,9′-Pentahydroxy-3,5′-dimethoxy-8–4′-oxy-
neolign-7′-ene-3′-O-ꢀ-D-glucopyranoside (3): amorphous powder;
[R]20 –9.0 (c 0.10, MeOH); UV (MeOH) λmax (log ꢀ) 204 (4.3), 221
D
(4.2), 269 (3.8) nm; CD (MeOH) 226 (∆ꢀ –0.46), 235 (∆ꢀ –2.84), 250
(∆ꢀ +0.72) nm; IR (KBr) νmax 3422, 1590, 1508,1076, 1037 cm-1; 1H
NMR (DMSO-d6, 500 MHz) data, see Table 1; 13C NMR (DMSO-d6,
125 MHz) data, see Table 2; ESIMS m/z 577 [M + Na]+, 593 [M +
K]+, and 553 [M - H]–; HRESIMS m/z 577.1851, [M + Na]+ (cacld
for C26H34O13Na 577.1897).
(-)-(7S,8R,7′E)-4,7,9,3′,9′-Pentahydroxy-3-methoxy-8–4′-oxyneo-
lign-7′-ene-3′-O-ꢀ-D-glucopyranoside (1): amorphous solid; [R]20
D
-6.2 (c 0.08, MeOH); UV (MeOH) λmax (log ꢀ) 205 (4.3), 261 (3.9)
nm; CD (MeOH) 221 (∆ꢀ –0.82), 233 (∆ꢀ –2.08), 250 (∆ꢀ +0.07)
nm; IR (KBr) νmax 3358, 2920, 1602, 1509, 1453, 1267, 1072, 1024
(-)-(7R,8S)-4,7,9,3′,9′-Pentahydroxy-3-methoxy-8–4′-oxyneolig-
nan-9′-O-ꢀ-D-glucopyranoside (4): colorless gum; [R]20 -12.5 (c
D
0.08, MeOH); UV (MeOH) λmax (log ꢀ) 207 (4.4), 280 (3.7) nm; CD
1
cm-1; H NMR (DMSO-d6, 500 MHz) data, see Table 1; 13C NMR
(MeOH) 226 (∆ꢀ –1.52), 238 (∆ꢀ +1.14), 250 (∆ꢀ –0.12) nm; IR (KBr)
(DMSO-d6, 125 MHz) data, see Table 2; ESIMS m/z 547 [M + Na]+
and 563 [M + K]+; HRFABMS m/z 547.1801 [M + Na]+ (calcd for
C25H32O12Na, 547.1791).
1
νmax
3413, 1604, 1512, 1277, 1030 cm-1; H NMR (DMSO-d6, 500
MHz) data, see Table 1; 13C NMR (DMSO-d6, 125 MHz) data, see
Table 2; ESIMS m/z 549 [M + Na]+, 565 [M + K]+, and 525 [M -
H]–; HRESIMS m/z 549.1963 [M + Na]+ (cacld for C25H34O12Na
549.1948).
(-)-(7R,8S)-4,7,9,3′,9′-Pentahydroxy-3-methoxy-8–4′-oxyneolig-
nan-3′-O-ꢀ-D-glucopyranoside (2): amorphous powder; [R]20D -17.6
(c 0.45, MeOH); UV (MeOH) λmax (log ꢀ) 207 (4.4), 278 (3.6) nm;
CD (MeOH) 228 (∆ꢀ –2.34), 237 (∆ꢀ +1.54), 244 (∆ꢀ –0.18) nm; IR
(KBr) νmax 3381, 1604, 1509, 1270, 1026 cm-1; 1H NMR (DMSO-d6,
500 MHz) data, see Table 1; 13C NMR (DMSO-d6, 125 MHz) data,
(+)-(7S,8S)-4,7,9,9′-Tetrahydroxy-3,3′-dimethoxy-8–4′-oxyneolig-
nan-9′-O-D-glucopyranoside (5): amorphous solid; [R]20D +2.0 (c 1.20,
MeOH); UV (MeOH) λmax (log ꢀ) 230 (4.1), 280 (3.4) nm; CD (MeOH)
226 (∆ꢀ +0.48), 236 (∆ꢀ +1.75), 250 (∆ꢀ +0.15); IR (KBr) νmax 3283,

Glycosides from the Root of Iodes cirrhosa
Journal of Natural Products, 2008, Vol. 71, No. 4 653
1
1558, 1513, 1259, 1032 cm-1; H NMR (DMSO-d6, 500 MHz) data,
Cell Culture and MTT Assay. PC12 cells at a density of 5 × 103
cells per well in 96-well plates were suspended in Dulbecco’s modified
Eagle’s medium (DMEM, Gibico) supplemented with 5% fetal bovine
serum (FBS, Hyclone), 5% horse serum, penicillin (100 IU/mL),
streptomycin (100 µg/mL), and L-glutamine (2 µM) and incubated in
a CO2 incubator (5%) at 37 °C for 24 h. Then the cells were pretreated
with test compounds (10-5 M) and NGF (50 ng/mL), respectively, for
another 24 h before exposed to glutamate (20 µM). After incubation
for an additional 24 h, MTT (0.5 mg/mL) was added to the medium
and incubated for 4 h. Absorbance was measured at 570 nm using a
microplate reader, and the cell viability was evaluated by relative
protection, which was calculated as 100 × [optical density (OD) of
test compound + glutamate-treated culture - OD of glutamated-treated
culture]/[OD of control culture - OD of glutamated-treated culture].46
see Table 1; 13C NMR (DMSO-d6, 125 MHz) data, see Table 2; ESIMS
m/z 563 [M + Na]+ and 539 [M - H]–; HRESIMS m/z 563.2097 [M
+ Na]+ (cacld for C26H34O12Na 563.2104).
(-)-(2R)-1-O-ꢀ-D-Glucopyranosyl-2-{2-methoxy-4-[(E)-formyl-
vinyl]phenoxyl}propane-3-ol (6): yellowish, amorphous powder; [R]20
D
-7.5 (c 0.08, MeOH); UV (MeOH) λmax (log ꢀ) 202 (4.4), 224 (4.3),
237 (4.3), 334 (4.5) nm; IR (KBr) νmax 3379, 2921, 1662, 1595, 1511,
1272, 1137, 1078 cm-1; 1H NMR (CD3OD, 500 MHz) data, see Table
1; 13C NMR (CD3OD, 125 MHz) data, see Table 2; ESIMS m/z 437
[M + Na]+ and 453 [M + K]+; HRFABMS m/z 437.1406 [M + Na]+
(calcd for C19H26O10Na, 437.1424).
Leptolepisol C 4-O-ꢀ-D-glucopyranoside (7): colorless gum; [R]20
D
-6.0 (c 0.10, MeOH); UV (MeOH) λmax (log ꢀ) 208 (4.8), 279 (4.0)
nm; IR (KBr) νmax 3426, 1608, 1514, 1268, 1030 cm-1 1H NMR
;
Acknowledgment. The authors are grateful to Mr. W.-Y. He for
his assistance in obtaining NMR spectra. Financial support from the
New Century Excellent Talent (NCET) Program of Chinese Ministry
of Education, the Natural Sciences Foundation of China (NSFC, Grant
No. 20432030), the National “973” Program of China (Grant No.
2004CB13518906), and the Program for Changjiang Scholars and
Innovative Research Team in University (PCSIRT, Grant No. IRT0514)
is gratefully acknowledged.
(DMSO-d6, 500 MHz) data, see Table 1; 13C NMR (DMSO-d6, 125
MHz) data, see Table 2; ESIMS m/z 683 [M + Na]+, 699 [M + K]+,
and 659 [M - H]–; HRESIMS m/z 683.2338 [M + Na]+ (calcd for
C33H40O14Na 683.2316).
(-)-(7R,8S)-Syringylglycerol 8-O-ꢀ-D-glucopyranoside (8): white,
amorphous powder; [R]20 -14.3 (c 0.30, MeOH); UV (MeOH) λmax
D
(log ꢀ) 211 (4.2), 232 (3.7), 271 (3.4) nm; IR (KBr) νmax 3374, 1612,
1
1513, 1228, 1073, 1043 cm-1; H NMR (DMSO-d6, 400 MHz) and
13C NMR (DMSO-d6, 125 MHz) data, see Table 3; ESIMS m/z 429
[M + Na]+ and 445 [M + K]+.
Supporting Information Available: Detailed extraction and isola-
tion procedure including known compounds. Figure S1 for HMBC
correlation scheme of compounds 1 and 7. Figures S2 and S3 of the
CD spectra of compounds 1-5, 10, 11, 1a-5a, 10a, and 11a. 1D NMR
spectra of compounds 1-9. Tables S1-S15 of the NMR data for
1a-5a, 8a-13a, 1b, 2b, 5b, 5, and 8-16 in different solvents. This
material is available free of charge via the Internet at http://pubs.acs.org.
(-)-(7R,8S)-Guaiacylglycerol 8-O-ꢀ-D-glucopyranoside (9): white,
amorphous powder; [R]20 –21.5 (c 0.55, MeOH); UV (MeOH) λmax
D
(log ꢀ) 230 (3.8), 278 (3.2) nm; IR (KBr) νmax 3383, 1605, 1517, 1272,
1073, 1028 cm-1 1H NMR (DMSO-d6, 400 MHz) and 13C NMR
;
(DMSO-d6, 125 MHz) data, see Table 3; ESIMS m/z 399 [M + Na]+
and 415 [M + K]+.
Enzymatic Hydrolysis of 1–13. A solution of each compound in
H2O (3 mL) was individually hydrolyzed with ꢀ-glucosidase (10 mg,
Almonds Lot 1264252, Sigma-Aldrich) at 37 °C for 24 or 36 h. Each
reaction mixture was extracted with EtOAc (3 × 3 mL) to yield the
individual EtOAc extract and H2O phase after removing the solvents.
The EtOAc extracts were separately chromatographed over silica
gel, eluting with CH3Cl-MeOH (12:1) for the hydrolysates from 1-7
(3–12 mg), 10 (6 mg), and 11 (11 mg) to yield aglycones 1a–7a, 10a,
and 11a, respectively, and eluting with CH3Cl-MeOH (10:1) for the
hydrolysates from 8, 9, 12, and 13 (each 10 mg) to yield 8a, 9a, 12a,
and 13a.
References and Notes
(1) (a) Editorial Committee of Chinese Materia Medica, State Administra-
tion Bureau of Traditional Chinese Medicine. Chinese Materia Medica
(Zhonghua Bencao); Shanghai Science & Technology Press: Shanghai,
2000; Vol. 5, pp 227–228. (b) Editorial Committee of Chinese Flora,
Chinese Academy of Sciences. Chinese Flora (Zhongguo Zhiwu Zhi);
Science Press: Beijing, 1981; Vol. 46, pp 54–56..
(2) Wang, Y.; Wang, S. J.; Mo, S. Y.; Li, S.; Yang, Y. C.; Shi, J. G. Org.
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(3) Xue, Z.; Li, S.; Wang, S. J.; Wang, Y. H.; Yang, Y. C.; Shi, J. G.;
He, L. J. Nat. Prod. 2006, 69, 907–913.
(4) Sinkkonen, J.; Karonen, M.; Liimatainen, J.; Pihlaja, K. Magn. Reson.
Chem. 2006, 44, 633–636.
(5) Gao, J. J.; Jia, Z. J. Indian J. Chem. 1995, 34B, 466–468.
(6) Wang, C. Z.; Jia, Z. J. Planta Med. 1997, 63, 241–244.
(7) Kijima, H.; Ide, T.; Otsuka, H.; Ogimi, C.; Hirata, E.; Takushi, A.;
Takeda, Y. Phytochemistry 1997, 44, 1551–1557.
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(9) Mohamed, K. M. Phytochemistry 2001, 58, 615–618.
(10) Hudson, C. S.; Dale, J. K. J. Am. Chem. Soc. 1917, 39, 320–328.
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(12) (a) Gellerstedt, G.; Lundquist, K.; Wallis, A. F. A.; Zhang, L. M.
Phytochemistry 1995, 40, 263–265. (b) Johansson, A.; Lundquist, K.;
Stomberg, R. Acta Chem. Scand. 1992, 46, 901–905.
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Bull. 2002, 50, 73–77. (b) Braga, A. C. H.; Zacchino, S.; Badano, H.;
Sierra, M. G.; Rúveda, E. A. Phytochemistry 1984, 23, 2025–2028.
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Compound 1a (2.0 mg): [R]20D +1.5 (c 0.20, MeOH), CD (MeOH)
236 (∆ꢀ –1.26); 2a (2.1 mg): [R]20 –7.9 (c 0.21, MeOH), CD
D
(MeOH) 238 (∆ꢀ +1.46); 3a (1.4 mg): [R]20 –2.8 (c 0.14, MeOH),
D
CD (MeOH) 236 (∆ꢀ –0.58); 4a (1.8 mg): [R]20D –4.2 (c 0.18, MeOH),
CD (MeOH) 238 (∆ꢀ +0.58); 5a (7.4 mg): [R]20 +16.9 (c 0.67,
D
MeOH), CD (MeOH) 235 (∆ꢀ +2.59); 6a (3.2 mg); 7a (2.2 mg): [R]20
D
+4.0 (c 0.22, MeOH); 8a (4.0 mg): [R]20 –19.6 (c 0.25, MeOH); 9a
D
(4.0 mg): [R]20 –12.4 (c 0.33, MeOH); 10a (2.1 mg): [R]20 –4.0 (c
D
D
0.21, MeOH), CD (MeOH) 236 (∆ꢀ +0.50); 11a (3.8 mg): [R]20D +2.4
(c 0.38, MeOH), CD (MeOH) 236 (∆ꢀ +0.58); 12a (4.5 mg): [R]20
D
+25.1 (c 0.30, MeOH); 13a (4.5 mg): [R]20 +17.0 (c 0.30, MeOH).
D
1H NMR and 13C NMR data of 1a-5a and 8a-13a in different solvents,
see Tables S1-S3, S6, and S11-S13 in the Supporting Information.
1H NMR (Me2CO-d6, 600 MHz) and 13C NMR (Me2CO-d6, 150 MHz)
data of 6a and 7a were identical with that reported in the literature.20,23
The aqueous phases of the hydrolysates of 1-13 were separately
subjected to CC over silica gel eluted with MeCN-H2O (8:1) to yield
glucose with positive optical rotations, and the [R]20 values ranged
D
from +42.5 to +49.7 (c in a range of 0.11 to 0.31, H2O). The solvent
system MeCN-H2O (6:1) was used for TLC identification of glucose
(Rf, 0.33).
Preparation of Acetonide Derivatives (1b, 2b, and 5b). A solution
of 1a (0.8 mg) in dry acetone (1 mL) was treated with 2,2-
dimethoxypropane (0.1 mL) and (1S)-(+)-camphorsulforic acid (CSA)
(1 mg, 0.004 mmol), and the mixture was stirred at ambient temperature
for 4 h. The reaction mixture was quenched by addition of triethylamine
and then evaporated in Vacuo to give a crude product. The residue was
purified by reversed-phase preparative HPLC using MeOH-H2O
(64:36) to afford acetonide 1b (0.6 mg). Similarly, 2a (1.7 mg) and 5a
(2.1 mg) were transformed into acetonide derivatives 2b (1.5 mg) and
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