New glycosides from the twigs and leaves of Rhododendron latoucheae

Article abstract of DOI:10.1080/10286020.2019.1585823

Six new glycosides (1?6), together with three known ones, were isolated from the twigs and leaves of Rhododendron latoucheae. Their structures were elucidated based on the spectroscopic data, including infrared spectrometry, mass spectrometry, and nuclear magnetic resonance experiments, along with Mosher's method. In addition, all compounds were tested their antiviral (herpes simplex virus-1 and influenza A/95-359) activities.

Full text of DOI:10.1080/10286020.2019.1585823

Journal of Asian Natural Products Research
ISSN: 1028-6020 (Print) 1477-2213 (Online) Journal homepage: https://www.tandfonline.com/loi/ganp20
New glycosides from the twigs and leaves of
Rhododendron latoucheae
Ya-Nan Wang, Fei Liu, Yong Li, Shuang-Gang Ma, Jing Qu, Yun-Bao Liu,
Chang-Shan Niu, Zhong-Hai Tang, Yu-Huan Li, Ru-Bing Wang & Shi-Shan Yu
To cite this article: Ya-Nan Wang, Fei Liu, Yong Li, Shuang-Gang Ma, Jing Qu, Yun-Bao Liu,
Chang-Shan Niu, Zhong-Hai Tang, Yu-Huan Li, Ru-Bing Wang & Shi-Shan Yu (2019): New
glycosides from the twigs and leaves of Rhododendronꢀlatoucheae, Journal of Asian Natural
Products Research, DOI: 10.1080/10286020.2019.1585823
To link to this article: https://doi.org/10.1080/10286020.2019.1585823
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JOURNAL OF ASIAN NATURAL PRODUCTS RESEARCH
https://doi.org/10.1080/10286020.2019.1585823
New glycosides from the twigs and leaves
of Rhododendron latoucheae
a
a
a
a
a
a
ꢀ
ꢀ
Ya-Nan Wang , Fei Liu , Yong Li , Shuang-Gang Ma , Jing Qu , Yun-Bao Liu ,
Chang-Shan Niua, Zhong-Hai Tanga, Yu-Huan Lib, Ru-Bing Wanga and
Shi-Shan Yua
aState Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia
Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050,
b
China; NHC Key Laboratory of Biotechnology of Antibiotics, Institute of Medicinal Biotechnology,
Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
ABSTRACT
ARTICLE HISTORY
Received 20 December 2018
Accepted 19 February 2019
Six new glycosides (1ꢁ6), together with three known ones, were
isolated from the twigs and leaves of Rhododendron latoucheae.
Their structures were elucidated based on the spectroscopic data,
including infrared spectrometry, mass spectrometry, and nuclear
magnetic resonance experiments, along with Mosher’s method. In
addition, all compounds were tested their antiviral (herpes sim-
plex virus-1 and influenza A/95-359) activities.
KEYWORDS
Ericaceae; Rhododendron
latoucheae; glycosides;
antiviral activities
1. Introduction
Rhododendron latoucheae Franch, a plant of the family Ericaceae, is mainly distrib-
uted in southern and southwestern mainland China. It has been historically used as a
traditional folk medicine for its effects in eliminating phlegm, suppressing cough,
activating blood and dissolving stasis [1]. Previous phytochemical studies of
CONTACT Ru-Bing Wang
Y.-N. Wang and F. Liu contributed equally to this work.
ß 2019 Informa UK Limited, trading as Taylor & Francis Group
wangrubing@imm.ac.cn; Shi-Shan Yu
yushishan@imm.ac.cn
ꢀ

2
Y.-N. WANG ET AL.
Figure 1. Structures of compounds 1ꢁ9.
Rhododendron latoucheae mostly focused on the phenols and iridoids [2,3]. In previ-
ous papers, we reported on some minor triterpenoids from the CH2Cl2-soluble frac-
tion of Rhododendron latoucheae [4–6]. Here we describe the isolation and structural
identification of six new glycosides, together with two known compounds from the
EtOAc-soluble fraction of Rhododendron latoucheae. The structures of new com-
pounds 1–6 were elucidated by nuclear magnetic resonance (NMR), mass spectrom-
etry (MS), and Mosher's method (Figure 1). In addition, all compounds were tested
for their antiviral [herpes simplex virus-1 (HSV-1) and influenza A/
95 ꢁ 359] activities.
2. Results and discussion
Compound 1 was obtained as a colorless oil and its molecular formula was estab-
lished as C23H28O11 by high-resolution electrospray ionization mass spectrometry
(HRESIMS) at m/z 503.1530 [M þ Na]þ, indicating 10 degrees of unsaturation. The
1H NMR spectrum (Table 1) of 1 displayed signals of one methyl group (dH 1.06),
and six aromatic protons. Its 13C NMR data (Table 1) revealed 23 carbon signals,
including 1 methyl, 3 methylenes, 12 methines, and 2 quaternary aromatic carbons, 4
1
oxygenated aromatic carbons, and 1 carbonyl carbon. The H and 13C NMR spectra
of 1 (Table 1) resembled those of the known compound 7 [7], except that an oxygen-
ated methine (dC 65.3), rather than a ketone carbon, was observed at C-2 in 1. This
deduction was further confirmed by the fragment [‒CH3(1)–CH(2)‒CH2(3)–CH2(4)–]
in the 1H-1H COSY spectrum and the heteronuclear multiple bond correlation
(HMBC) correlations of H-2 with C-1, C-3, C-4 (Figure 2). Acid hydrolysis of 1 with
HCl afforded an aglycone (1a) and glucose. The relatively large coupling constant
1
(7.6 Hz) for the anomeric proton in the H NMR spectrum (Table 1) suggested a
b-configuration for the glucopyranosyl moiety, and the absolute configuration of D-
glucose was determined by gas chromatography (GC). The absolute configuration of
1a was determined by modified Mosher's method, which was used to produce (R)-
and (S)-a-methoxy-a-trifluoromethylphenylacetic acid (MTPA) esters of 1a. The

JOURNAL OF ASIAN NATURAL PRODUCTS RESEARCH
3
Table 1. 1H NMR (600 MHz) and 13C NMR (150 MHz) spectral data of 1 and 2 in DMSO-d6.
1
2
no.
dH (J in Hz)
dc, type
dH (J in Hz)
1.96 s
dc, type
1
2
3
1.06 d (6.2)
3.54–3.56 m
1.53–1.55 m
1.53–1.55 m
2.54–2.56 m
2.54–2.56 m
23.6
65.3
41.0
29.6
207.9
44.3
2.52–2.54 m
2.52–2.54 m
2.50–2.52 m
2.50–2.52 m
4
30.8
28.5
1’
2’
3’
4’
5’
6’
1’’
2’’
3’’
4’’
5’’
6’’
135.8
129.1
116.1
155.3
116.1
129.1
100.6
73.3
76.5
70.0
73.8
63.6
132.3
116.4
145.0
144.7
115.7
122.6
102.2
73.3
75.5
69.7
74.0
63.4
7.05 dd (8.7, 2.4)
6.92 dd (8.7, 1.5)
6.81 d (2.0)
6.92 dd (8.7, 1.5)
7.05 dd (8.7, 2.4)
4.84 d (7.6)
3.28–3.30 m
3.32–3.34 m
3.27–3.29 m
3.67–3.69 m
4.45–4.47 m
4.22–4.24 m
6.67 d (8.0)
6.62 dd (8.0, 2.0)
4.70 d (7.6)
3.31–3.33 m
3.31–3.33 m
3.32–3.34 m
3.67–3.69 m
4.47 dd (11.9, 2.0)
4.30 dd (11.9, 5.5)
1’’’
2’’’
3’’’
4’’’
5’’’
6’’’
C ¼ O
119.4
108.8
145.6
138.6
145.6
108.8
165.8
119.5
108.6
145.5
138.3
145.5
108.6
165.8
6.99 d (2.0)
6.97 brs
6.97 brs
6.99 d (2.0)
Figure 2. Selected 2D NMR correlations for 1 and 2.
calculated differences in chemical shifts [d of protons in the (S)-MTPA-ester minus d
of the corresponding protons in the (R)-MTPA-ester] led to the assignment of the S-
absolute configuration for C-2 (Figure 3). On the basis of the above data analyses,
compound 1 was established to be (2S)-4-(40-O-[600-O-galloyl-b-D-glucopyranosyl]-
phenyl)-2-butanol.
Compound 2, a colorless oil, had a molecular formula of C23H26O12 as established
by HRESIMS at m/z 517.1321 [M þ Na]þ, indicating 11 degrees of unsaturation.
1
Analysis of the H and 13C NMR spectra of 2 (Table 1) revealed 23 carbon signals
due to 2 quaternary aromatic carbons, 5 oxygenated aromatic carbons, and 2 carbonyl
1
carbons, 10 tertiary carbons, 3 methylenes, and 1 methyl group. The H- and 13C-

4
Y.-N. WANG ET AL.
1
Figure 3. Selected Dd H NMR values (data obtained in pyridine-d5) in ppm for MTPA esters of 1a.
NMR spectra of 2 were quite similar to those of the known compound 8 [8], and the
only difference was that the glucopyranosyl moiety was connected to C-30 in 2 instead
of C-40 in 8. This deduction was confirmed by the HMBC correlations from H-60 to
C-20, C-40, C-50, C-4, from H-20 to C-30, C-40, C-60, C-4, and from H-100 to C-30
(Figure 2). Acid hydrolysis of 2 with HCl produced the same b-D-glucose as 1.
Therefore, the structure of compound 2 was determined as 4-[30-O-(600-O-galloyl-b-D-
glucopyranosyl)-40-hydroxyphenyl]-butan-2-one.
Compound 3 was obtained as colorless oil. Its molecular formula was established
to be C27H22O16 by HRESIMS at m/z 603.0990 [M þ H]þ. The 1D NMR spectra
(Table 2) of 3 were similar to quercetin 3-O-a-(200-galloylarabinofuranoside) [9], with
the only difference being that 3 included an extra hydroxyl group. The assignment of
the 50-hydroxyl group was determined by the HMBC correlations from H-60 to C-20,
C-40, C-50, C-2 (Figure 4). Acid hydrolysis of 3 with HCl afforded arabinose. The
absolute configuration of L-arabinose was determined by GC analysis. Thus, the
structure of 3 was elucidated as myricetin 3-O-a-L-(200-galloylarabinofuranoside).
Compound 4, a colorless oil, possessed a molecular formula of C27H22O16 estab-
lished on the basis of HRESIMS at m/z 603.0983 [M þ Na]þ, indicating 17 degrees of
1
unsaturation, which was the same as that of compound 3. The H and 13C NMR data
(Table 2) of 4 were very close to 3, except for small differences in chemical shift of
1
the glycosyl. Finally, the assignment of the H NMR data of the arabinose [dH 5.48
brs (H-100), 4.41 d (J ¼ 3.3 Hz, H-200), 3.99-4.01 m (H-300), 4.05–4.07 m (H-400),
4.18–4.20 m (H-500a), 4.18–4.20 m (H-500b)] was determined by the further analysis of
2D NMR and the galloyl moiety connected to C-500 in 4 instead of C-200 in 3 was
confirmed by the HMBC correlations from H-500 to C-1000 (Figure 4). Acid hydrolysis
of 4 with HCl produced the same L-arabinose as 3. Consequently, the structure of 4
was established as myricetin 3-O-a-L-(600-galloylarabinofuranoside).
Compound 5, a colorless oil, possessed a molecular formula of C22H26O9 estab-
lished on the basis of HRESIMS at m/z 457.1478 [M þ H]þ, indicating 10 degrees of
unsaturation. The 1D NMR spectra (Table 2) of 5 were similar to those of the known
compound 9 [10], with the only difference being that there was a methoxyl group at
C-50 in 5 instead of a hydroxyl group at C-50 in 9. This was determined by the
HMBC correlations from H3-70 to C-50 (Figure 4). Acid hydrolysis of 5 with HCl pro-
duced D-glucose. Thus, the structure of 5 was elucidated as E-30-O-b-D-glucopyrano-
syl-stilbene-3, 50-dimethoxy-4-ol.
Compound 6 contained an HRESIMS ion at m/z 601.1927 [M þ H]þ, which corre-
1
sponded to the molecular formula of C30H32O13. The H NMR data (Table 2) (dH

JOURNAL OF ASIAN NATURAL PRODUCTS RESEARCH
5
Table 2. 1H NMR and 13C NMR spectral data of 3–6 in CD3OD.
3a
4a
5b
6b
no.
dH (J in Hz)
dc
dH (J in Hz)
dc
dH (J in Hz)
dc
dH (J in Hz)
dc
1
2
3
4
5
6
7
8
130.9
110.5 6.94 (1.7)
149.2
130.7
110.4
149.0
147.6
116.2
121.2
130.3
126.5
56.3
159.4
134.6
179.7
163.1
99.8 6.21 d (2.2)
166.0
94.7 6.38 d (2.2)
158.5
105.7
121.8
109.5 7.13 brs
146.8
138.0
146.8
159.7 7.14 d (1.9)
134.8
179.8
163.0 6.77 d (8.1)
99.9 6.99 dd (8.1, 1.9)
166.0 7.07 d (16.2)
94.8 6.93 d (16.2)
158.5 3.90 s
105.6
122.0
109.6 6.91 t (2.3)
146.7
137.9 6.58 t (2.3)
146.7
109.6 6.75 t (2.3)
147.8
116.3 6.71 d (8.1)
121.4 6.76 dd (8.1, 1.7)
130.6 6.83 d (16.1)
126.8 6.67 d (16.1)
56.4 3.86 s
6.20 d (2.1)
6.39 d (2.1)
9
10
1’
2’
3’
4’
5’
6’
7’
1’’
2’’
3’’
4’’
5’’
141.4
107.9 6.71 t (1.7)
160.5
102.9 6.42 t (1.7)
162.3
107.2 6.58 t (1.7)
55.8
102.5 4.98 d (7.6)
75.0 3.49–3.51 m
78.0 3.52–3.54 m
71.6 3.43 t (9.1)
78.3 3.80–3.82 m
141.3
106.2
160.2
104.3
159.6
108.7
7.16 brs
7.16 brs
109.5 7.13 brs
5.80 brs
107.0 5.48 brs
85.8 4.41 d (3.3)
77.1 3.99–4.01 m
87.6 4.05–4.07 m
62.1 4.18–4.20 m
4.18–4.20 m
109.4 4.92 d (7.6)
83.5 3.46–3.48 m
79.1 3.47–3.49 m
84.6 3.37–3.39 m
64.5 3.47–3.49 m
101.9
74.8
77.8
72.3
75.6
5.50 d (2.0)
4.16 dd (6.1, 2.0)
3.94-3.96 m
3.54-3.56 m
3.54-3.56 m
6’’
3.93 dd (12.1, 2.2)
62.6 4.90–4.92 m
65.3
3.70 dd (12.1, 6.2)
4.26 dd (11.9, 7.5)
1’’’
2’’’
3’’’
4’’’
5’’’
6’’’
7’’’
8’’’
9’’’
167.3
120.7
110.3 7.00 brs
146.5
140.2
146.5
110.3 7.00 brs
168.1
121.1
110.2
146.3
139.8
146.3
110.2
168.0
121.0
108.0
148.6
141.7
148.6
108.0
56.6
7.07 brs
7.07 brs
7.21 brs
7.21 brs
3.71 s
3.71 s
56.6
a1H NMR data recorded at 400 MHz and 13C NMR data recorded at 100 MHz.
b1H NMR data recorded at 600 MHz and 13C NMR data recorded at 150 MHz.
3.71 s, H-8000, H-9000; dH 7.21 s, H-3000, H-7000) and the 13C NMR data (Table 2) (dC
168.0, C-1000; dC 121.0, C-2000; dC 108.0, C-3000, C-7000; dC 148.6, C-4000, C-6000; dC 141.7,
C-5000; dC 56.6, C-8000, C-9000) showed a 4000, 6000-dimethoxyl-5000-hydroxyl-benzoyl. The
1
rest H NMR and 13C NMR data (Table 2) of 6 resembled those of 9, except for the
additional 4000, 6000-dimethoxyl-5000-hydroxyl-benzoyl group at C-600, which was con-
firmed by the HMBC correlations from H-3000 to C-1000, C-4000, C-5000, C-7000, and from
H-600 to C-1000 (Figure 4). Acid hydrolysis of 6 with HCl produced D-glucose.
Therefore, the structure of 6 was defined as E-30-O-[600-O-E-(4000, 6000-dimethoxy-5000-
hydroxy)-benzoyl]-b-D-glucopyranosyl-stilbene-3-methoxy-4, 50-diol.
The three known compounds, 4-(40-hydroxyphenyl)-2-butanone 40-O-b-D-(600-O-
galloyl)-glucopyranoside [7], 3,4,5-trihydroxybenzoic acid [8], and trans-isorhapontin
[10] were also identified on the basis of their spectroscopic profiles (NMR, UV, and
MS) and comparison to the published data.
These glycosides were assayed for the antiviral (HSV-1) and influenza A/95 ꢁ 359
activities. But none of them showed remarkable antiviral activity.

6
Y.-N. WANG ET AL.
Figure 4. Selected 2D NMR correlations for 3-6.
3. Experimental
3.1. General experimental procedures
Optical rotations were measured with a JASCO P-2000 automatic digital polarimeter
(JASCO, Tokyo, Japan). IR spectra were measured on a Nicolet 5700 Fourier-trans-
form infrared spectroscopy (FT-IR) microscope instrument (FT-IR microscope trans-
mission; Thermo Electron Corporation, Madison, WI, USA). 1D and 2D NMR
spectra were obtained on an Agilent-NMR-vnmrs 600 (Agilent Technologies Ltd.,
Santa Clara, CA, USA) or a Bruker-400 NMR spectrometer (Bruker Biospin
Corporation, Fallanden, Switzerland). Chemical shifts are given in d (ppm) with the
solvent (DMSO or CD3OD) peaks used as references. (þ)-HRESIMS data of com-
pounds 1–6 were recorded using an Agilent 6520 Accurate-Mass Q-TOF LC/MS
spectrometer (Agilent Technologies Ltd., Santa Clara, CA, USA). Polyamide resin
(30 ꢁ 60 mesh, Jiangsu Linjiang Chemical Reagents Factory, Linjiang, China), macro-
porous resin (D101 type, Chemical Plant of Nankai University, Nankai, China), MCI
gel (Mitsubishi Chemical Corporation), Sephadex LH-20 (GE Chemical Corporation),
Silica gel (200–300 mesh, Qingdao Marine Chemical Factory, Qingdao, China), and
ODS (50 lm, Merck, Germany) were used for column chromatography (CC). Thin
layer chromatography was carried out with glass precoated Silica gel GF254 plates
(Qingdao Marine Chemical Factory, China). Spots were visualized by spraying with
10% H2SO4 in EtOH followed by heating.

JOURNAL OF ASIAN NATURAL PRODUCTS RESEARCH
7
3.2. Plant material
Twigs and leaves of Rhododendron latoucheae were collected from Zhangjiajie, Hunan
Province, China, in October 2014 and identified by associate Prof. Lin Ma of the
Chinese Academy of Medical Sciences and Peking Union Medical College. A voucher
specimen (ID-22815) was deposited in the herbarium at the Department of Medicinal
Plants, Institute of Materia Medica, Chinese Academy of Medical Sciences.
3.3. Extraction and isolation
The air-dried twigs and leaves of Rhododendron latoucheae (107 kg) were extracted
with 95% EtOH/H2O (2 h ꢂ 3) under reflux conditions. The crude extract (6000 g)
was suspended in 30 L of H2O and then partitioned with petroleum ether, CH2Cl2,
EtOAc, and n-butanol (3 ꢂ 30 L). The EtOAc-soluble fraction (1300 g) was subjected
to a macroporous resin (D101 type) column eluted with EtOH‒H2O (30:70, 60:40,
95:5 v/v) to afford Fr.A1‒Fr.A3. Fr.A1 (650 g) was then further separated over a poly-
amide resin (30 ꢁ 60 mesh) column and eluted with EtOH–H2O (30:70, 60:40, 95:5 v/
v) to obtain Fr.A1-1 to Fr.A1-3. Fr.A1-1 (287 g) was subjected to Si gel column and
eluted with a gradient of CH2Cl2ꢁCH3OH (100:1!1:1 v/v) to afford Fr.A1-1-1 to Fr.
A1-1-7. Fr. A1-1-4 (2 g) was applied to a Sephadex LH-20 column (MeOH) and fur-
ther purified by preparative high performance liquid chromatography (HPLC) with
MeCN-H2O (20:80 v/v, 6 ml/min) to give compounds 1 (50 mg), 2 (60 mg), 7
(22 mg), 8 (28 mg), and 9 (50 mg). Fr.A1-3 (25 g) was subjected to silica gel column
and eluted with a gradient of CH2Cl2ꢁCH3OH (100:1!1:1 v/v) to afford Fr.A1-3-1
to Fr.A1-3-5. Fr.A1-3-2 (1 g) was applied to a Sephadex LH-20 column (MeOH) and
further purified by preparative HPLC with MeCN-H2O (20:80 v/v, 6 ml/min) to
obtain compounds 3 (19 mg) and 4 (32 mg). Fr.A2 (200 g) was then further separated
over a polyamide resin (30 ꢁ 60 mesh) column and eluted with EtOH–H2O (30:70,
60:40, 95:5 v/v) to obtain Fr.A2-1 to Fr.A2-3. Fr.A2-2 (87 g) was subjected to silica
gel column and eluted in a gradient of CH2Cl2ꢁCH3OH (100:1!1:1 v/v) to afford
Fr.A2-2-1 to Fr.A2-2-7. Fr.A2-2-3 (1.5 g) was applied to a Sephadex LH-20 column
(MeOH) and repeatedly purified by preparative HPLC with MeCN–H2O (25:75 v/v,
6 ml/min) to afford compounds 5 (15 mg) and 6 (20 mg).
3.3.1. (2S)-[40-O-(600-O-galloyl-b-D-glucopyranosyl)-phenyl]-2-butanol (1)
20:2
Colorless oil; ½aꢃD ꢁ20:11 (c 0.1, MeOH); IR (KBr) ꢀmax: 3343, 1686, 1612, 1510,
1
1449, 1371, 1229, 1064, 770 cmꢁ1; H NMR and 13C NMR spectral data, see Table 1;
HRESIMS: m/z 503.1530 [M þ Na]þ (calcd for C23H28O11Na, 503.1524).
3.3.2. 4-(30-O-[600-O-galloyl-b-D-glucopyranosyl]-40-hydroxyphenyl)-butan-2-on (2)
20:2
Colorless oil; ½aꢃD ꢁ26:72 (c 0.25, MeOH); IR (KBr) ꢀmax: 3355, 1701, 1609,
1
1514, 1444, 1349, 1278, 1227, 1072, 1042, 768, 640 cmꢁ1; H NMR and 13C NMR
spectral data, see Table 1; HRESIMS: m/z 517.1321 [M þ Na]þ (calcd for
C23H26O12Na, 517.1316).

8
Y.-N. WANG ET AL.
3.3.3. Myricetin 3-O-a-L-(200-galloylarabinofuranoside) (3)
20:2
Colorless oil; ½aꢃD ꢁ52:87 (c 0.10, MeOH); IR (KBr) ꢀmax: 3321, 1649, 1605, 1451,
1
1348, 1199, 1037, 957, 763 cmꢁ1; H NMR and 13C NMR spectral data, see Table 2;
HRESIMS: m/z 603.0990 [M þ H]þ (calcd for C27H23O16, 603.0981).
3.3.4. Myricetin 3-O-a-L-(600-galloylarabinofuranoside) (4)
20:2
Colorless oil; ½aꢃD ꢁ74:14 (c 0.33, MeOH); IR (KBr) ꢀmax: 3366. 1650, 1606, 1451,
1
1346, 1200, 1039, 951, 765 cmꢁ1; H NMR and 13C NMR spectral data, see Table 2;
HRESIMS: m/z 603.0983 [M þ H]þ (calcd for C27H23O16, 603.0981).
3.3.5. E-30-O-b-D-glucopyranosyl-stilbene-3,50-dimethoxy-4-ol (5)
20:2
Colorless oil; ½aꢃD ꢁ26:48 (c 0.16, MeOH); IR (KBr) ꢀmax: 3367, 2932, 1595, 1515,
1
1273, 1075, 1045 cmꢁ1; H NMR and 13C NMR spectral data, see Table 2; HRESIMS:
m/z 457.1478 [M þ Na]þ (calcd for C22H26O9Na, 457.1469).
3.3.6. E-30-O-[600-O-E-(4000,6000-dimethoxy-5000-hydroxy)-benzoyl]-b-D-glucopyranosyl-
stilbene-3-methoxy-4,50-diol (6)
20:2
Colorless oil; ½aꢃD ꢁ21:14 (c 0.25, MeOH); IR (KBr) ꢀmax: 3391, 2974, 1678, 1602,
1
1515, 1461, 1336, 1117, 1078 cmꢁ1; H NMR and 13C NMR spectral data, see Table 2;
HRESIMS: m/z 601.1927 [M þ H]þ (calcd for C30H33O13, 601.1916).
3.4. Acid hydrolysis and determination of absolute configurations of the sugar
moiety in 1–6
Compound 1 (5 mg) was dissolved in 3 M HCl (3 ml). The solution was heated at
70 ꢄC for 6 h. After the removal of HCl by evaporation, the reaction mixture was
diluted with H2O (10.0 ml) and extracted with EtOAc. The organic phase was concen-
trated to yield aglycone 1a (2 mg). The H2O-soluble phase was again evaporated and
dried in vacuo to furnish the monosaccharide residue. The residue (1 mg) was dis-
solved in pyridine (1 ml), to which 2 mg L-cysteine methyl ester hydrochloride was
added. The mixture was kept at 60 ꢄC for 2.5 h. After the removal of the solvent
under reduced pressure and drying in vacuo, N-trimethylsilylimidazole (0.2 ml) was
added to trimethylsilylate for 2.5 h at 60 ꢄC. The mixture was partitioned between n-
hexane and H2O (1 ml each), and the n-hexane extract obtained was analyzed using
gas chromatography (GC) under the following conditions: Agilent 19091J-216
(60 m ꢂ 0.32 mm ꢂ 1 lm) column; FID detector; injection temperature of 210 ꢄC;
detector temperature of 250 ꢄC; initial column temperature of 200 ꢄC raised to 280 ꢄC
at the rate of 10 ꢄC/min and maintained at 280 ꢄC for 38.5 min under N2 carrier gas.
In the acid hydrolysate of 1, D-glucose was verified by comparison of the retention
times of its derivatives with that of the corresponding control sample of the derivative
prepared in the same way, which exhibited retention times at 29.419 and 29.615 min,
respectively. The constituent sugars of compounds 2ꢁ6 were also identified by the
same method, with the result showing the presence of D-glucose and/or L-arabinose
in compounds 2ꢁ6. The retention times of the derivatives for L-arabinose in 3ꢁ4
and the corresponding control sample were 19.015 and 19.097 min, respectively.

JOURNAL OF ASIAN NATURAL PRODUCTS RESEARCH
9
3.5. Prepmation of (R)- and (S)-MTPA esters of 1a
A solution of 1a (1.0 mg) in deuterated pyridine (150 ll) was reacted with 5 ll of (S)-
(þ)-MTPA-Cl at room temperature. In a similar manner, 1a (1.0 mg) was reacted
with 5 ll of (R)-(þ)-MTPA-Cl at room temperature. After 12 h reaction time, the
1
final H NMR spectrum was recorded. The D(S-R) values between (S)- and (R)-
1
MTPA esters were recorded with the H NMR (see Figure 3).
3.6. Biological assays
All compounds were assayed for their antiviral (HSV-1) and influenza A/95 ꢁ 359
activities as described previously [4].
Acknowledgments
The authors are grateful to the Department of Instrumental Analysis at our institute for the
spectroscopic measurements.
Disclosure statement
No potential conflict of interest was reported by the authors.
Funding
This work was financially supported by grants from the National Natural Science Foundation
of China (No. 21732008) and the CAMS Innovation Fund for Medical Sciences (CIFMS) (No.
2016-I2M-1-010 and No. 2016-I2M-3-010).
References
[1] The China Medicinal Materials Group. Main Record of Resource of Chinese Material
Medicine in China (Science Press, Beijing, 1994), p. 892.
[2] C. Q. Fan, G. J. Yang, W. M. Zhao, B. Y. Ding, and G. W. Qin, Chin. Chem. Lett. 10,
567 (1999).
[3] C. Q. Fan, W. M. Zhao, B. Y. Ding, and G. W. Qin, Fitoterapia 72, 449 (2001).
[4] F. Liu, Y. N. Wang, Y. Li, S. G. Ma, J. Qu, Y. B. Liu, C. S. Niu, Z. H. Tang, T. T.
Zhang, Y. H. Li, L. Li, and S. S. Yu, Sci. Rep. 7, 7944 (2017).
[5] F. Liu, Y. N. Wang, Y. Li, S. G. Ma, J. Qu, Y. B. Liu, C. S. Niu, Z. H. Tang, Y. H. Li, L.
Li, and S. S. Yu, J. Nat. Prod. 81, 1721 (2018).
[6] F. Liu, Y. N. Wang, Y. Li, S. G. Ma, J. Qu, Y. B. Liu, C. S. Niu, Z. H. Tang, Y. H. Li, L.
Li, and S. S. Yu, Tetrahedron 75, 296 (2018).
[7] G. Nonaka, I. Nishioka, T. Nagasawa, and H. Oura, Chem. Pharm. Bull. 29, 2862 (1981).
[8] I. Chevalley, A. Marston, and K. Hostettmann, Pharm. Biol. 38, 222 (2011).
[9] D. H. Fan, H. Wang, D. Zhi, and Y. M. Shen, Chromatographia 72, 1013 (2010).
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[10] D. G. Mulat, H. Latva-Maenpaa, H. Koskela, P. Saranpaa, and K. Wahala, Phytochem.
Anal. 25, 529 (2014).