Pheonolic compounds from the fruits of Viburnum sargentii Koehne

Article abstract of DOI:10.3390/molecules200814377

Seven phenolic compounds were isolated from the fruits of Viburnum sargentii Koehne by silica gel column chromatography and preparative HPLC. On the grounds of chemical and spectroscopic methods, their structures were identified as (-)-Epicatechin (1), 5,7,4′-trihydroxy-flavonoid-8-C-β-D-glucopyranoside (2), 1-(4-hydroxy-3-methoxyphenyl)- 2-[4-(3-α-L-rhamnopyranoxypropyl)-2-methoxyphenoxy]-1,3-propane-diol (erythro) (3), 1-(4-hydroxy-3-methoxyphenyl)-2-[4-(3-α-L-rhamnopyranoxypropyl)-2-methoxyphenoxy]- 1,3-propanediol (threo) (4), (R)-4-hydroxylphenol O-(6-O-oleuropeoyl)-β-D-glucopyranoside (5), (R)-3-methoxy-4-hydroxylphenol O-(6-O-oleuropeoyl)-β-D-glucopyranoside (6), quercetin-3-O-rutinoside (7). Compounds 5 and 6 are new monoterpene phenolic glycosides, compounds 1, 3 and 4 were isolated from the Viburnum genus for the first time, and compounds 2 and 7 from the Viburnum sargentii Koehne for the first time. Compounds 1-7 were also assayed for their antioxidant activities with DPPH free radicals.

Full text of DOI:10.3390/molecules200814377

Molecules 2015, 20, 14377-14385; doi:10.3390/molecules200814377
OPEN ACCESS
molecules
ISSN 1420-3049
www.mdpi.com/journal/molecules
Article
Pheonolic Compounds from the Fruits of
Viburnum sargentii Koehne
Yang Xie, Jing Wang, Yan-Mei Geng, Zhi Zhang, Yan-Fei Qu and Guang-Shu Wang *
School of Pharmaceutical Sciences, Jilin University, Changchun 130021, China;
E-Mails: 13514486691@163.com (Y.X.); 13578752256@163.com (J.W.);
gengym0102@163.com (Y.-M.G.); zz4548209@163.com (Z.Z.); wdcq2511@163.com (Y.-F.Q.)
* Author to whom correspondence should be addressed; E-Mail: wgs@jlu.edu.cn;
Tel.: +86-431-8561-9706.
Academic Editor: Derek J. McPhee
Received: 10 June 2015 / Accepted: 3 August 2015 / Published: 6 August 2015
Abstract: Seven phenolic compounds were isolated from the fruits of Viburnum sargentii
Koehne by silica gel column chromatography and preparative HPLC. On the grounds of
chemical and spectroscopic methods, their structures were identified as (−)-Epicatechin (1),
5,7,4′-trihydroxy-flavonoid-8-C-β-D-glucopyranoside (2), 1-(4-hydroxy-3-methoxyphenyl)-
2-[4-(3-α-L-rhamnopyranoxypropyl)-2-methoxyphenoxy]-1,3-propane-diol (erythro) (3),
1-(4-hydroxy-3-methoxyphenyl)-2-[4-(3-α-L-rhamnopyranoxypropyl)-2-methoxyphenoxy]-
1,3-propanediol (threo) (4), (R)-4-hydroxylphenol O-(6-O-oleuropeoyl)-β-D-glucopyranoside
(5),
(R)-3-methoxy-4-hydroxylphenol
O-(6-O-oleuropeoyl)-β-D-glucopyranoside
(6),
quercetin-3-O-rutinoside (7). Compounds 5 and 6 are new monoterpene phenolic glycosides,
compounds 1, 3 and 4 were isolated from the Viburnum genus for the first time, and
compounds 2 and 7 from the Viburnum sargentii Koehne for the first time. Compounds 1–7
were also assayed for their antioxidant activities with DPPH free radicals.
Keywords: Viburnum sargentii; phenolic glycoside; monoterpene; epicatechin; quercetin
1. Introduction
Viburnum sargentii koehne, a deciduous shrub of Caprifoliaceae, is widely distributed in the
northeast and northwest regions of China. As traditional Chinese medicines, the branches are used for

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rheumatoid arthritis and traumatic injuries, the leaves for boils, ringworm and skin itching, and the
fruits for cough [1]. Although there are a number of the pharmacological studies of the fruits of
Viburnum sargentii [2,3], the isolation and structure identification have not been investigated in detail.
As one part of our Caprifoliaceae studies, the isolation and structure identification of chemical
constituents from the fruits of Viburnum sargentii Koehne have been carried out, and we report the
isolation and identification of two new monoterpene phenolic glycosides (5 and 6), together with five
phenolic compounds 1, 2, 3, 4 and 7 in the present study (Figure 1).
OH
O
OH
HO
OH
HO
O
O
OH
O
OH
HO
HO
OH
OH
OH
1
2
OCH3
CH2OH
CH
O
R
O
O
OH
CHOH
O
O
HO
HO
O
OH
O
H3C
HO
OCH3
5 R = H
6 R = OCH3
OH
OH
OH
OH
(erythro)
(threo)
3
4
OCH3
O
OH
OH
CH3
O
OH
O
OH
OH
HO
O
O
O
HO
OH
OH
OH
OH
O
5a
7
Figure 1. Chemical structures of compounds 1–7.
2. Results and Discussion
Compound 5 was obtained as colorless needles. Its HRESIMS displayed a [M + H]+ ion peak at m/z
439.1957 (calcd for C22H31O9, 439.1968), indicating the molecular formula C22H30O9. Acidic
1
13
hydrolysis of 5 yielded D-glucose as a sugar residue. The H- and C-NMR spectra showed two 2H
doublets (δH 6.83 (2H, d, J = 8.7 Hz), 7.03 (2H, d, J = 8.7 Hz)) and signals of six symmetric aromatic
C-atoms at δC 154.3 (C), 152.1(C), 119.5 (2 CH), and 117.4 (2 CH), arising from a symmetrically
1,4-O-disubstituted benzene ring moiety, a set of signals characteristic of β-D-glucopyranosyl moiety
13
(anomeric H-atom signal at δH 4.88 (d, J = 7.5 Hz)). The C-NMR and DEPT spectra showed ten
carbon signals comprising one carboxylic (δC 168.2), one trisubstituted double bond (δC 142.2, 131.5),
two methyl (δC 27.1, 26.6), three methylene (δC 29.1, 26.9, 24.9), one methine (δC 45.7), and one
oxygen-bearing quaternary carbon (δC 72.2). These observations suggested the presence of an
oleuropeic acid unit [4,5]. The positions of the oleuropeoyl ester and glycosidic linkages in 5 were

Molecules 2015, 20
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established by 2D-NMR experiments. In the HMBC spectrum of 5, the glucosyl CH2 (6′) (δH 4.60,
4.22) correlated with the oleuropeoyl carboxylic C-atom C (7″) (δC 168.2), and the glucosyl H-C (1′)
(δH 4.88) with and C (1) (δC 152.1) of 1,4-O-disubstituted benzene ring moiety. The full assignments
of all protons and carbons were preformed through the correlations in 2D-NMR spectra (1H-1H COSY,
HMQC and HMBC) of 5. All the data of 1H-, 13C-, and HMBC-NMR of compound 5 see Table 1, and
key correlations and the structure of compound 5 see Figure 2. Methanolysis of 5 with MeONa in
MeOH afforded 5a which was identified as (R)-oleuropeic acid methyl ester by comparing [α]2D5 and
1H- and 13C-NMR spectra data with the reported [4,5]. Based on the above evidence, the structure of 5
was determined to be (R)-4-hydroxylphenol O-(6-O-oleuropeoyl)-β-D-glucopyranoside.
1
Table 1. H-NMR (methanol-d4, 400 MHz), 13C-NMR (methanol-d4, 100 MHz) and
HMBC data of compound 5 and 6 (TMS as the internal standard, δ in ppm J in Hz).
5
6
No.
δC
δH J (Hz)
HMBC (H→C)
δC
δH J (Hz)
HMBC (H→C)
143.4, 110.4
149.2
1
2
152.1
119.5
117.4
153.0
104.5
149.2
56.8
7.03 d (8.7)
6.83 d (8.7)
154.3, 119.5
152.1, 117.4
6.80 br. s
3.90 s
3
3-OCH3
4
154.3
117.4
119.5
103.3
75.2
143.4
116.2
110.4
103.6
75.2
5
6.83 d (8.7)
7.03 d (8.7)
4.88 d (7.5)
3.29 m
152.1, 117.4
119.5, 154.3
168.2
6.75 d (8.2)
6.65 d (8.2)
4.83 d (7.8)
3.51 m
153.0, 149.2
104.5, 143.4
153.0
6
1′
2′
3′
78.4
3.46 m
78.2
3.53 m
4′
72.2
3.36 m
72.3
3.43 m
5′
75.6
3.75 m
75.8
3.71 m
6′α
6′β
1″
65.6
4.60 d (11.5)
4.22 dd (11.5, 7.7)
168.2
168.2
65.2
4.59 d (11.5)
4.32 dd (11.5, 7.3)
168.2
168.2
131.5
142.2
29.1
131.5
2″
7.04 br. s
2.48 d (16.5)
2.20 m
168.2, 29.1, 45.7 141.8
28.9
7.09 br. s
2.42 d (17.5)
2.12 m
168.2, 45.4
3″α
3″β
4″
45.7
24.9
1.63 m
45.4
24.8
1.65 m
5″α
5″β
6″α
6″β
7″
2.16 m
2.12 m
1.32 m
1.32 m
26.9
2.59 d (16.0)
2.26 m
26.7
2.51 d (16.4)
2.21 m
168.2
72.2
27.1
26.6
169.0
73.2
8″
9″
1.28 s
1.28 s
45.7, 72.2, 26.6 27.3
1.38 s
1.28 s
45.4, 73.2, 26.8
45.4, 73.2, 27.3
10″
45.7, 72.2, 27.1 26.8
Note: The assignments were based on DEPT, HMQC, 1H-1H COSY, and HMBC experiments.

Molecules 2015, 20
14380
O
8''
4''
OH
HO
4
7''
2''
O
1''
6'
O
5'
HO
O
1
O
HO
1'
OH
OCH3
5
8''
4''
OH
3
HO
4
7''
2''
O
1''
6'
O
5'
HO
1
O
HO
1'
OH
6
Figure 2. The Key HMBC Correlation of compound 5 and 6 (arrows point from proton to carbon).
Compound 6 was obtained as colorless needles. Its molecular formula C23H32O10 was elucidated from
the HRESIMS m/z 469.2086 [M + H]+ (calcd for C23H33O10, 469.2074). Acidic hydrolysis of 6 also
1
13
yielded D-glucose as a sugar residue. The H- and C-NMR spectra of 6 were similar to those of 5,
1
13
except for the signals of benzene ring moiety. The H- and C-NMR spectra showed a typical three
proton ABX aromatic spin system at δH 6.75 (1H, d, J = 8.2 Hz), 6.65 (1H, d, J = 8.2 Hz), 6.80 (1H, br. s)
and six aromatic C-atom signals at δC 153.0 (C), 149.2 (C), 143.4 (C), 116.2 (CH), 110.4 (CH) and
104.5 (CH), as well as one signal from a MeO group [δH 3.90 (s, 3H), δC 56.8) ], suggesting that there is a
1,3,4-O-trisubstituted benzene ring moiety in compound 6 in stead of a 1,4-O-disubstituted benzene ring
moiety, and one additional methoxy group. The positions of the oleuropeoyl ester, glycosidic linkages
and MeO group in 6 were also established by 2D-NMR experiments. In the HMBC spectrum of 6, the
glucosyl CH2 (6′) (δH 4.59, 4.32) correlated with the oleuropeoyl carboxylic C-atom C (7″) (δC 169.0),
the glucosyl H-C (1′) (δH 4.83) with C (1) (δC 153.0) of the 1,3,4-O-trisubstituted benzene ring moiety,
and the MeO group δH 3.90 correlated with C (3) (δC 149.2) of 1,3,4-O-trisubstituted benzene ring
moiety. The full assignments of all protons and carbons were preformed through the correlations in
2D-NMR spectra (1H-1H COSY, HMQC and HMBC) of 6. All the data of 1H-, 13C-, and HMBC-NMR
of compound 6 see Table 1, and key correlations and the structure of compound 6 see Figure 2.
Methanolysis of 6 also afforded 5a. Thus, the structure of 6 was determined to be (R)-3-methoxy-4-
hydroxylphenol O-(6-O-oleuropeoyl)-β-D-glucopyranoside.
Using similar methods as described above, compounds 1–4 and 7 were identified as (−)-Epicatechin
(1) [6], 5,7,4′-trihydroxy-flavonoid-8-C-β-D-glucopyranoside (2) [7], 1-(4-hydroxy-3-methoxy-phenyl)-
2-[4-(3-α-L-rhamnopyranoxypropyl)-2-methoxyphenoxy]-1,3-propane-diol (erythro) (3) [8], 1-(4-hydroxy-
3-methoxyphenyl)-2-[4-(3-α-L-rhamnopyranoxypropyl)-2-methoxyphenoxy]-1,3-propanediol (threo)
(4) [8], quercetin-3-O-rutinoside (7) [9].
Compounds 1–7 were next assayed for their antioxidant activity with DPPH free radicals, and the results
are shown in Table 2. The data proved that (−)-Epicatechin showed strongest antioxidant activity.

Molecules 2015, 20
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Table 2. IC50 values of compounds 1–7.
Compound IC50 (µg·mL−1)
1
2
3
4
5
6
7
9.85 ± 0.5
357.1 ± 6.2
520.9 ± 7.6
522.3 ± 8.1
610.8 ± 6.1
620.1 ± 7.3
37.5 ± 0.3
Note: All values are averages of at least three runs in Table 2.
3. Experimental Section
3.1. General Information
NMR spectra were recorded on a Bruker AV-400 spectrometer (Bruke Corporation, Faellanden,
Switzerland). UV Spectra were recorded on a Shimadzu UV-2401A spectrometer (Shimadzu Corporation,
Kyoto, Japan). HR-ESI-MS were recorded on a Bruker microOTOF-Q II mass spectrometer (Bruke
Corporation, Bremen, Germany). Optical rotations were measured with a HORIBA SEPA-300
high-sensitive polarimeter (Horiba Ltd, Kyoto, Japan). Melting points (m.p.) were measured with a
X-4 Microscopic melting point apparatus (Shanghai Hui Tong Optical Instrument Co., Ltd, Shanghai,
China). HPLC was performed Shimadzu LC-10A with a SPD-10A detector (Shimadzu Corporation,
Kyoto, Japan) and Gemini 5μ C18 110A column (250 mm × 10.00 mm, 5 μm, flow rate: 3.0 mL/min,
Phenomenex, Torrance, CA, USA). GC was performed an Agilent 7820A gas chromatograph with a
quartz capillary column (30 mm × 0.32 mm × 0.25 μm, Agilent Technolgies Inc., Santa Clara, CA,
USA); detection, FID. Column chromatography was performed on silica gel (200–300 mesh, Qingdao
Marine Chemical Inc., Qingdao, China), D101 polyporous resin (Tianjin Pesticide Co., LTD., Resin
Branch, Tianjin, China), polyamide (80–120 mesh, Taizhou Luqiao Sijia Biochemical Plastic Factory,
Taizhou, China) and MCI-gel CHP-20P (75–150 μm; Mitsubishi Chemical Co., Tokyo, Japan). TLC
was performed on glass precoated silica gel GF254 plates (Qingdao Haiyang Chemical Co., Ltd,
Qingdao, China), detection under UV light or by spraying with 10% H2SO4 in 95% EtOH followed by
heating. The bioactivities were measured on a DNM-9602 Enzyme immunoassay spectrophotometer
(Beijing, China), using 1,1-diphenyl-2-picrylhydrazyl free radical (DPPH) (Sigma-Aldrich, Shanghai,
China). The fruits of Viburnum sargentii Koehne were collected in Changchun District of Jilin
Province, China. They were identified by Jing-min Zhang of the School of Pharmaceutical Sciences,
Jilin University.
3.2. Extraction and Isolation
The fresh fruits of V. sargentii (8 kg) were extracted with 70% aqueous ethanol at room temperature
(3 L × 10 L, weekly). The extracts were concentrated under reduced pressure and then subjected to
D101 polyporous resin column chromatography eluated with H2O, 10% aqueous ethanol, 30% aqueous
ethanol, 60% aqueous ethanol and 95% aqueous ethanol. The eluate of 30% ethanol was
chromatographed over silica gel, eluting with CHCl3–EtOAc–MeOH–H2O (3.5:1.2:4:1.2, v/v, lower

Molecules 2015, 20
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layer), to afford four fractions, Frs. 1–4. Compound 1 (521 mg) was recrystallized from Fr. 1, Fr. 2 and
4 were further chromatographicly separated by gradient elution with MeOH–H2O (from 0% to 65%,
5% a time, v/v), and recrystallization of compound 2 (45 mg) were obtained from Fr. 2 and compound
7 (100 mg) from Fr. 4. Fr. 3 was further subjected to silica gel column chromatography eluting with
CHCl3–EtOAc–MeOH–H2O (3.0:1.2:4:1.2, v/v, lower layer) to afford three subfractions, Frs. 3a–c.
They were further isolated by semi-preparative RP-HPLC using acetonitrile–H2O as the mobile phase.
Compound 3 (47 mg) and 4 (101 mg) were obtained from Fr. 3a with gradient elution (10%–15%
acetonitrile from 0.00–10.00 min, 15%–18% acetonitrile from 10.00–20.0 0 min, 18% acetonitrile
from 20.00–50.00 min), and by using 18% acetonitrile as the mobile phase compound 5 (62 mg) from
Fr. 3b and compound 6 (57 mg) from Fr. 3c.
Compound 1: Pale amorphous powder, yielded a positive reaction to FeCl3 reagent. mp 234–236 °C.
[α]2D5 −56.8 (c 1.0, MeOH). UV (MeOH), λmax 217, 280 nm. HRESIMS m/z 291.0877 [M + H]+ (calcd
1
for C15H15O6, 291.0869). H-NMR (DMSO-d6, 400 MHz) δ: 2.48 (1H, dd, J = 16.0, 3.6 Hz, H-4a),
2.68 (1H, dd, J = 16.0, 4.8 Hz, H-4b), 4.01(1H, m, H-3), 4.65 (1H, d, J = 4.8 Hz, H-2), 5.89 (1H, d,
J = 2.0 Hz, H-8), 5.72 (1H, d, J = 2.0 Hz, H-6), 6.64 (1H, dd, J = 8.0, 1.6 Hz, H-6′), 6.67 (1H, d,
13
J = 8.0 Hz, H-5′), 6.89 (1H, d, J = 1.6 Hz, H-2′). C-NMR (DMSO-d6,100 MHz) δ: 78.0 (C-2), 64.9
(C-3), 28.2 (C-4), 156.5 (C-5), 94.1 (C-6), 156.2 (C-7), 95.1 (C-8), 155.8 (C-9), 98.5 (C-10), 130.6
(C-1′), 114.9 (C-2′), 144.5 (C-3′), 144.4 (C-4′), 114.7 (C-5′), 117.9 (C-6′).
Compound 2: Yellow amorphous powder, yielded a positive reaction to FeCl3 reagent. mp 238–240 °C.
UV (MeOH), λmax 268, 339. HRESIMS m/z 433.1126 [M + H]+ (calcd for C21H21O10, 433.1135). 1H-NMR
(DMSO-d6, 400 MHz) δ: 8.02 (2H, d, J = 8.0 Hz, H-2′,6′), 6.89 (2H, d, J = 8.0 Hz, H-3′,5′), 6.77 (1H,
s, H-3), 6.28 (1H, s, H-6), 4.69 (1H, d, J = 8.0Hz, Glu-H-1). 13C-NMR (DMSO-d6, 100 MHz) δ: (C-7),
104.6 (C-8), 156.0 (C-9), 104.0 (C-10), 121.6 (C-1′), 128.9 (C-2′), 115.8 (C-3′), 160.3 (C-4′), 115.8 (C-5′),
128.9 (C-6′), 73.3 (Glu-1), 70.8 (Glu-2), 78.6 (Glu-3), 70.5 (Glu-4), 81.8 (Glu-5), 61.3 (Glu-6).
Compound 3: Pale amorphous powder, yielded a positive reaction to FeCl3 reagent. mp 190–192 °C.
[α]2D5 −26.9 (c 0.30, MeOH). UV (MeOH), λmax 228, 280. HRESIMS m/z 525.2328 [M + H]+ (calcd for
C26H37O11, 525.2336). 1H-NMR (methanol-d4, 400 MHz) δ: 7.10 (1H, s, H-2′), 6.92 (2H, d, J = 8.0 Hz,
H-6′,5), 6.88 (1H, s, H-2), 6.83 (1H, d, J = 8.0 Hz, H-5′), 6.75 (1H, d, J = 8.0 Hz, H-6), 4.92 (1H, d,
J = 7.6 Hz, H-7′), 4.73 (1H, s, Rha-H-1), 4.38 (1H, m, H-8′), 3.94 (1H, m, H-9′a), 3.83 (1H, m, H-9′b),
3.74 (1H, m, H-9a), 3.46 (1H, m, H-9b), 2.72 (2H, m, H-7), 1.96 (2H, m, H-8), 3.90 (3H, s, 3′-OCH3),
3.88 (3H, s, 3-OCH3), 1.32 (3H, d, J = 6.4 Hz, Rha-H-6). 13C-NMR (methanol-d4, 100 MHz) δ: 138.1
(C-1), 114.3 (C-2), 152.2 (C-3), 147.5 (C-4), 119.9 (C-5), 122.2 (C-6), 33.3 (C-7), 32.7 (C-8), 68.0 (C-9),
134.4 (C-1′), 112.1 (C-2′), 149.0 (C-3′), 147.3 (C-4′), 116.0 (C-5′), 121.2 (C-6′), 74.4 (C-7′), 86.9 (C-8′),
62.4 (C-9′), 56.8 (3′-OCH3), 56.7 (3′-OCH3), 102.0 (Rha-1), 72.8 (Rha-2), 72.6 (Rha-3), 74.3 (Rha-4),
70.1 (Rha-5), 18.3 (Rha-6).
Compound 4: Pale amorphous powder, yielded a positive reaction to FeCl3 reagent. mp 186–188 °C.
[α]2D5 −29.5 (c 0.30, MeOH). UV (MeOH), λmax 230, 280. HRESIMS m/z 525.2325 [M + H]+ (calcd for
C26H37O11, 525.2336). 1H-NMR (methanol-d4, 400 MHz) δ: 7.11 (1H, s, H-2′), 7.07 (H, d, J = 8.0 Hz,
H-5), 6.95 (1H, d, J = 8.0Hz, H-6′), 6.94 (1H, s, H-2), 6.85 (1H, d, J = 8.0 Hz, H-5′), 6.80 (1H, d,

Molecules 2015, 20
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J = 8.0 Hz, H-6), 4.96 (1H, d, J = 6.8 Hz, H-7′), 4.73(1H, s, Rha-H-1), 4.30 (1H, m, H-8′), 3.80 (1H,
m, H-9′a), 3.74 (1H, m, H-9′b), 3.54 (1H, m, H-9a), 3.45 (1H, m, H-9b), 2.74 (2H, m, H-7), 1.97 (2H,
13
m, H-8), 3.95 (3H, s, 3′-OCH3), 3.91 (3H, s, 3-OCH3), 1.32 (3H, d, J = 6.0 Hz, Rha-H-6). C-NMR
(methanol-d4, 100 MHz) δ: 138.2 (C-1), 114.2 (C-2), 152.0 (C-3), 148.0 (C-4), 119.9 (C-5), 122.4
(C-6), 33.3 (C-7), 32.7 (C-8), 68.0 (C-9), 134.1 (C-1′), 112.0 (C-2′), 149.1 (C-3′), 147.5 (C-4′), 116.2
(C-5′), 121.1 (C-6′), 74.5 (C-7′), 88.0 (C-8′), 62.2 (C-9′), 56.9 (3′-OCH3), 56.7 (3′-OCH3), 102.0 (Rha-1),
72.8 (Rha-2), 72.7 (Rha-3), 74.3 (Rha-4), 70.1 (Rha-5), 18.3 (Rha-6).
Compound 5: colorless needles (MeOH), yielded a positive reaction to FeCl3 reagent. mp 198–200 °C,
[α]2D5 −17.5 (c 1.0, MeOH). UV (MeOH), λmax 210, 261nm. HRESIMS m/z 439.1957 [M + H]+ (calcd
1
13
for C22H31O9, 439.1968). H-NMR (methanol-d4, 400 MHz), see Table 1; C-NMR (methanol-d4,
100 MHz), see Table 1.
Compound 6: colorless needles (MeOH), yielded a positive reaction to FeCl3 reagent. mp 190–192 °C,
[α]2D5 −24.5 (c 0.8, MeOH). UV (MeOH), λmax 215, 269 nm. HRESIMS m/z 469.2086 [M + H]+ (calcd
1
13
for C23H33O10, 469.2074). H-NMR (methanol-d4, 400 MHz), see Table 1; C-NMR (methanol-d4,
100 MHz), see Table 1.
Compound 7: Yellow amorphous powder, yielded a positive reaction to FeCl3 reagent. mp 185–187 °C.
UV (MeOH), λmax 259, 359. HRESIMS m/z 611.1620 [M + H]+ (calcd for C27H31O16, 611.1612).
1H-NMR (DMSO-d6, 400MHz) δ: 6.19 (1H, s, H-6), 6.38 (1H, s, H-8), 7.53 (1H, d, J = 1.6 Hz, H-2′),
6.84 (1H, d, J = 8.0 Hz, H-5′), 7.54 (1H, dd, J = 8.0, 1.6 Hz, H-6′), 5.34 (1H, d, J = 6.8 Hz, Glc-H-1),
4.39 (1H, s, Rha-H-1), 1.00 (3H, d, J = 6.0 Hz, Rha-H-6). 13C-NMR (DMSO-d6, 100 MHz) δ: 156.4 (C-2),
133.3 (C-3), 177.3 (C-4), 161.2 (C-5), 98.6 (C-6), 164.1 (C-7), 93.5 (C-8), 156.5 (C-9), 103.9 (C-10),
121.1 (C-1′), 115.2 (C-2′), 144.7 (C-3′), 148.4 (C-4′), 116.2 (C-5′), 121.5 (C-6′), 101.2 (Glc-1), 74.0
(Glc-2), 76.4 (Glc-3), 70.0 (Glc-4), 75.9 (Glc-5), 66.9 (Glc-6), 100.7 (Rha-1), 70.5 (Rha-2), 70.3 (Rha-3),
71.8 (Rha-4), 68.2 (Rha-5), 17.7 (Rha-6).
3.3. Acid Hydrolysis of 5 and 6
Compounds 5 and 6 (each 6 mg) were hydrolyzed with 1.5 N HCl (2 mL) at 80 °C for 5 h. The
mixture was then neutralized with NaOH (1 N). The mixture was passed through MCI-gel CHP-20P,
developing with H2O. The H2O eluate was evaporated to dryness. The dry powders were dissolved in
pyridine (2 mL), L-cysteine methyl ester hydrochloride (1.5 mg) was added, and the mixture was heated
at 60 °C for 1 h. Trimethylsilylimidazole (1.5 mL) was added, and the mixture was heated at 60 °C for
another 0.5 h. An aliquot (4 μL) of the supernatant was subjected to GC analysis under the following
conditions: column temp 180–280 °C at 3 deg/min, carrier gas N2 (1 mL/min), injector and detector
temp 250 °C, split ratio 1:50. The configurations of D-gluose for compounds 5 and 6 were determined
by comparison of the retentions times of the corresponding derivatives with standard D-glucose
(retention time: 19.208 min), respectively.

Molecules 2015, 20
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3.4. Methanolysis of 5 and 6
A solution of 5 (12 mg) in 0.02 M NaOMe–MeOH (2 mL) was kept standing at room temperature
for 12 h. The solution was then subjected to MCI-gel CHP-20P column chromatography, eluting with
H2O, 60% and 100% MeOH to give (R)-methyl oleuropeic acid methyl ester (5a) (3.0 mg): colorless
25
1
oil; [α]D +65.5 (c 0.2, CHCl3); H-NMR (CDCl3, 400MHz) δ 7.06 (1H, m, H-2), 2.30, 2.00 (m, H-3),
1.53 (m, H-4), 2.01, 1.22 (m, H-5), 2.51, 2.12 (m, H-6), 1.20 (3H, s, H-9), 1.21 (3H, s, H-10), 3.72
13
(3H, s, OCH3); C-NMR (CDCl3, 100MHz) δ 130.2 (C-1), 139.9 (C-2), 27.4 (C-3), 44.5 (C-4), 23.4
(C-5), 25.1 (C-6), 167.8 (C-7), 72.2 (C-8), 27.4 (C-9), 26.6 (C-10), 51.6 (OCH3). Similar methanolysis
of 6 also gave 5a ([α]2D5 +62.7 (c 0.18, CHCl3)).
3.5. Bioactivity Assay
The antioxidant activities of compounds 1–7 were assessed according to their DPPH (1,1-diphenyl-
2-picrylhydrazyl free radical, Sigma-Aldrich, Shanghai, China) scavenging ability. Reaction mixtures,
containing 0.5 mL of the relevant compound (dissolved in EtOH) and 2.5 mL of a 100 μM DPPH
ethanolic solution, were added to 96-well microtiter plates and incubated at 37 °C for 30 min.
Absorbances were measured at 515 nm. Percent inhibition was determined by comparison with an
EtOH-treated control group. IC50 values denote the concentration of samples required to scavenge 50%
of the DPPH free radicals.
4. Conclusions
Compounds 5 and 6 are new monoterpene phenolic glycosides. Compounds 1, 3 and 4 were isolated
from the Viburnum genus for the first time, and compounds 2 and 7 from the Viburnum sargentii
Koehne for the first time. Compounds 1–7 were also assayed for their antioxidant activities with DPPH
free radicals, and the data proved that (−)-Epicatechin showed the strongest antioxidant activity.
Acknowledgments
The authors gratefully thank Jing-Min Zhang (School of Pharmaceutical Sciences, Jilin University)
for the identification of plants.
Author Contributions
Guang-Shu Wang designed research, analyzed the data and wrote the paper; Yang Xie, Jing Wang,
Yan-Mei Geng, Zhi Zhang and Yan-Fei Qu performed research. All authors read and approved the
final manuscript.
Conflicts of Interest
The authors declare no conflict of interest.

Molecules 2015, 20
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Sample Availability: Samples of the compounds 1, 2, 5 and 7 are available from the authors.
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