A new 2-(2-phenylethyl)chromone glycoside in Chinese agarwood “Qi-Nan” from Aquilaria sinensis

Article abstract of DOI:10.1080/10286020.2016.1187602

A new 2-(2-phenylethyl)chromone glycoside, 2-[2-(4-glucosyloxy-3-methoxyphenyl)ethyl]chromone (1), was isolated from the high-quality Chinese agarwood “Qi-Nan” originating from Aquilaria sinensis (Lour.) Glig. The structure including the absolute configuration of the sugar moiety was elucidated by spectroscopic techniques (UV, IR, 1D and 2D NMR), MS analysis, PMP-labeling HPLC analysis methods, as well as comparison with literature data. To the best of our knowledge, it is the first time that chromone glycoside was discovered in agarwood, or even in the whole Aquilaria plants.

Full text of DOI:10.1080/10286020.2016.1187602

Journal of Asian Natural Products Research
ISSN: 1028-6020 (Print) 1477-2213 (Online) Journal homepage: http://www.tandfonline.com/loi/ganp20
A new 2-(2-phenylethyl)chromone glycoside
in Chinese agarwood “Qi-Nan” from Aquilaria
sinensis
Hang Shao, Wen-Li Mei, Fan-Dong Kong, Wen-Hua Dong, Wei Li, Guo-Peng
Zhu & Hao-Fu Dai
To cite this article: Hang Shao, Wen-Li Mei, Fan-Dong Kong, Wen-Hua Dong, Wei Li, Guo-
Peng Zhu & Hao-Fu Dai (2016): A new 2-(2-phenylethyl)chromone glycoside in Chinese
agarwood “Qi-Nan” from Aquilaria sinensis, Journal of Asian Natural Products Research, DOI:
10.1080/10286020.2016.1187602
To link to this article: http://dx.doi.org/10.1080/10286020.2016.1187602
Published online: 29 Jun 2016.
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Date: 03 July 2016, At: 08:37

Journal of asian natural Products research, 2016
ꢁꢁp://ꢂx.ꢂꢃꢄ.ꢃꢅg/10.1080/10286020.2016.1187602
ꢀ
A new 2-(2-phenylethyl)chromone glycoside in Chinese
agarwood “Qi-Nan” from Aquilaria sinensis
a,b
a
a
a
a
b
Hang Shao , Wen-Li Mei , Fan-Dong Kong , Wen-Hua Dong , Wei Li , Guo-Peng Zhu
and Hao-Fu Daia
ꢈKꢉy lꢈbꢃꢅꢈꢁꢃꢅy ꢃꢇ Bꢄꢃꢋꢃgy ꢈꢆꢂ Gꢉꢆꢉꢁꢄꢌ rꢉꢊꢃꢍꢅꢌꢉꢊ ꢃꢇ tꢅꢃpꢄꢌꢈꢋ cꢅꢃpꢊ, Mꢄꢆꢄꢊꢁꢅy ꢃꢇ agꢅꢄꢌꢍꢋꢁꢍꢅꢉ, iꢆꢊꢁꢄꢁꢍꢁꢉ ꢃꢇ
tꢅꢃpꢄꢌꢈꢋ Bꢄꢃꢊꢌꢄꢉꢆꢌꢉ ꢈꢆꢂ Bꢄꢃꢁꢉꢌꢀꢆꢃꢋꢃgy, cꢀꢄꢆꢉꢊꢉ aꢌꢈꢂꢉmy ꢃꢇ tꢅꢃpꢄꢌꢈꢋ agꢅꢄꢌꢍꢋꢁꢍꢅꢈꢋ sꢌꢄꢉꢆꢌꢉꢊ, hꢈꢄkꢃꢍ 571101,
b
cꢀꢄꢆꢈ; hꢃꢅꢁꢄꢌꢍꢋꢁꢍꢅꢈꢋ ꢈꢆꢂ Gꢈꢅꢂꢉꢆ cꢃꢋꢋꢉgꢉ, hꢈꢄꢆꢈꢆ uꢆꢄvꢉꢅꢊꢄꢁy, hꢈꢄkꢃꢍ 570228, cꢀꢄꢆꢈ
ABSTRACT
ARTICLE HISTORY
rꢉꢌꢉꢄvꢉꢂ 3 Jꢈꢆꢍꢈꢅy 2016
aꢌꢌꢉpꢁꢉꢂ 4 Mꢈy 2016
A new 2-(2-phenylethyl)chromone glycoside, 2-[2-(4-glucosyloxy-
3
-methoxyphenyl)ethyl]chromone (1), was isolated from the high-
quality Chinese agarwood“Qi-Nan”originating from Aquilaria sinensis
Lour.) Glig. The structure including the absolute configuration of the
KEYWORDS
(
Qꢄ-nꢈꢆ; ꢈgꢈꢅwꢃꢃꢂ; Aquilaria
sinensis; 2-(2-pꢀꢉꢆyꢋꢉꢁꢀyꢋ)
ꢌꢀꢅꢃmꢃꢆꢉ ꢂꢉꢅꢄvꢈꢁꢄvꢉ;
gꢋyꢌꢃꢊꢄꢂꢉ
sugar moiety was elucidated by spectroscopic techniques (UV, IR, 1D
and 2D NMR), MS analysis, PMP-labeling HPLC analysis methods, as
well as comparison with literature data.To the best of our knowledge, it
is the first time that chromone glycoside was discovered in agarwood,
or even in the whole Aquilaria plants.
1
. Introduction
Agarwood is the resinous heartwood from Aquilaria or Gyrinops species of ymelaeaceae
1]. It is well known as precious traditional Chinese medicine for its therapeutic effect in
[
stomachache, fever, cough, rheumatism and other illness [2]. Agarwood was also very
famous as natural flavor, and was widely used in aromatherapy and religious ceremony.
“
Qi-Nan” as the most precious kind of agarwood can be smelt without burning for its
mysterious and elegant fragrance. Owing to the scarcity and high commercial value, study
on its chemical composition has aroused worldwide interest. Japanese researchers have iso-
lated many sesquiterpenes and 2-(2-phenylethyl)chromone derivatives from the “Qi-Nan”
of Vietnam originating from Aquilaria agallocha Roxb [3,4]. De-lan Yang has isolated a
series of 2-(2-phenylethyl)chromone derivatives and sesquiterpenes from Chinese agarwood
“
Lv Qi-Nan” originating from Aquilaria sinensis (Lour.) Glig [5,6]. Our further chemical
study on the ethanol extract of this “Lv Qi-Nan” led to the isolation and identification of
a new 2-(2-phenylethyl)chromone glycoside (1) (Figure 1). Although, the aglycone of 1,
2
-[2-(3-methoxy-4-hydroxyphenyl)ethyl]chromone, has been isolated from the same sam-
ple before [5], and 2-(2-phenylethyl)chromone glycoside has ever been found from Imperata
cylindrica [7], Ononis vaginalis [8], Cucumis melo L var. reticulatus [9], compounds of this
CONTACT hꢈꢃ-fꢍ dꢈꢄ
ꢂꢈꢄꢀꢈꢃꢇꢍ@ꢄꢁbb.ꢃꢅg.ꢌꢆ; Gꢍꢃ-Pꢉꢆg Zꢀꢍ
gꢍꢃpꢉꢆgzꢀꢍ@163.ꢌꢃm
©
2016 iꢆꢇꢃꢅmꢈ uK lꢄmꢄꢁꢉꢂ, ꢁꢅꢈꢂꢄꢆg ꢈꢊ tꢈyꢋꢃꢅ & fꢅꢈꢆꢌꢄꢊ Gꢅꢃꢍp

2
H. SHAꢀ ꢁT AL.
Figure 1. cꢀꢉmꢄꢌꢈꢋ ꢊꢁꢅꢍꢌꢁꢍꢅꢉ ꢃꢇ ꢌꢃmpꢃꢍꢆꢂ 1.
1
1
Figure 2. Kꢉy hMBc, roesY, ꢈꢆꢂ h- h cosY ꢌꢃꢅꢅꢉꢋꢈꢁꢄꢃꢆꢊ ꢃꢇ ꢌꢃmpꢃꢍꢆꢂ 1.
type were discovered in agarwood for the first time in this study. Herein, the isolation and
structure elucidation of the new chromone glycoside (1) were described.
2
. Results and discussion
Compound 1 was obtained as colorless solid. Its molecular formula was deduced to be
+
C H O on the basis of HR-ESI-MS (m/z 481.1466 [M+Na] ). e IR spectrum revealed
2
4
26
9
−1
−1
the presence of hydroxyls (3437 cm ) and α, β-unsaturated carbonyl group (1641 cm )
1
moieties. e H NMR spectrum showed the presence of a methoxy group at δ 3.71, one
H
olefinic proton at δ 6.14 (1H, s, H-3), one set of ABX coupling system at δ 6.72 (1H, dd,
H
H
J = 8.2, 1.8 Hz, H-6′), δ 6.83 (1H, d, J = 1.8 Hz, H-2′), and δ 7.02 (1H, d, J = 8.2 Hz, H-5′),
H
H
ascribable to 1,3,4-trisubstituted phenyl moiety. e other set of signals at δ 8.05 (1H, dd,
H
J = 7.6, 1.4 Hz, H-5), δ 7.43 (1H, dd, J = 7.6, 7.6 Hz, H-6), δ 7.75 (1H, ddd, J = 8.4, 7.6,
H
H
1
.4 Hz, H-7), and δ 7.55 (1H, d, J = 8.4 Hz, H-8) revealed the presence of an ortho-disub-
H
stituted aromatic ring. e presence of two methylene groups and a trisubstituted double
1
3
bond were evidenced by the C and DEPT NMR resonances at δ 33.6, 37.1, and δ 110.7
C
C
(
CH), 171.8 (qC), respectively. e signals at δ 180.6 and 56.6 confirmed the existence
C
of a conjugated ketone and a methoxy group. In addition, six characteristic oxygenated
1
3
1
carbon signals at δ 74.9~102.9 in the C NMR spectrum, as well as the corresponding H
C
NMR signals between 3.31 and 4.79 ppm, were evident for a glucose moiety, indicating the
glycosylation of 1. Except for the additional glucose unit, the remaining NMR resonances
of 1 were nearly identical with those of the known compound 2-[2-(3-methoxy-4-hydroxy-
1
1
phenyl)ethyl]chromone [5]. H- H COSY and HMBC data depicted in Figure 2 confirmed

JꢀURNAL ꢀF ASIAN NATURAL PRꢀDUCTS RꢁSꢁARCH
3
this deduction. e methoxy group was located at C-3′ (δ 150.7) by the HMBC correlations
C
from 3′-OCH (δ 3.71), H-2′ (δ 6.83) and H-5′ (δ 7.02) to C-3′ (δ 150.7), as well as the
3
H
H
H
C
ROESY correlation from 3′-OCH (δ 3.71) to H-2′ (δ 6.83). Furthermore, the coupling
3
H
H
constants of H-1″ with H-2″ (J = 7.3 Hz), H-2″ with H-3″ (J = 8.9 Hz), H-3″ with H-4″
1
(
J = 6.8 Hz), and H-4″ with H-5″ (J = 6.8 Hz) in the H NMR spectrum were consistent
with a β-glucopyranosyl unit [7], which was located at C-4′ based on HMBC correlations
from H-1″ (δ 4.79) to C-4′ (δ 146.6). Acidic hydrolysis of 1 liberated D-glucose, which
H
C
was determined by PMP-labeling HPLC analysis and by comparison of the optical rotation
25
25
value ([ꢀ] + 54; H O) with the standard glucose ([ꢀ] + 49; H O) and that reported in
D
2
D
2
25
literature ([ꢀ] + 52; H O) [10]. Based on these findings, the structure of 1 was determined
D
2
to be 2-[2-(4-glucosyloxy-3-methoxyphenyl)ethyl]chromone.
Compound 1 was evaluated for the inhibitory activity against AChE by Ellman Method
[

11] and cytotoxicity against K562, BEL-7402, SGC-7901 cell lines by MTT method [12].
e results showed that compound 1 was inactive against AChE and all the cell lines.
3
. Experimental
3
.1. General experimental procedures
Optical rotations were recorded on a Rudolph Autopol III polarimeter (Rudolph Research
Analytical, Hackettstown, NJ, USA). UV spectra were recorded on a Shimadzu UV-2550
spectrometer (Beckman, Brea, CA, USA). IR absorptions were obtained on a Nicolet 380
FT-IR instrument (ermo, Pittsburgh, PA, USA) using KBr pellets. e NMR spectra were
recorded on Bruker Avance 500 NMR spectrometers (Bruker, Bremen, Germany), using
TMS as an internal standard. HR-ESI-MS were measured with an API QSTAR Pulsar mass
spectrometer (Bruker, Bremen, Germany) or Waters Autospec Premier (Waters, Atlanta,
GA, USA). Column chromatography was performed with silica gel (60–80, 200–300
mesh, Qingdao Haiyang Chemical Co., Ltd, Qingdao, China), ODS gel (20–45 μm, Fuji
Silysia Chemical Co., Ltd, Durham, NC, USA), and Sephadex LH-20 (Merck, Darmstadt,
Germany). TLC was carried out on silica gel GF254 (Qingdao Haiyang Chemical Co., Ltd),
and spots were detected by spraying with 5% H SO in EtOH followed by heating. HPLC
2
4
purifications were performed on an analytical reversed-phase column (YMC-packed C ,
1
8
2
50 mm × 10 mm, 5 μm) (YMC, Kyoto, Japan) using a G1311C 1260 Quat Pump VL and
detected with a G1315D 1260 DAD VL detector (254 nm) (Agilent Technologies 1260
infinity, PaloAlto, California, USA).
3
.2. Plant material
Chinese agarwood “Lv Qi-Nan” was donated by Mr. Xiao-Wu Zhang and Mr. Mao-You Guan
in July 2011. e specimen was identified as “Lv Qi-Nan” originating from A. sinensis by
Prof. Hao-Fu Dai and Dr. Xi-Long Zheng. A voucher specimen (QN 20110830) has been
deposited at the Institute of Tropical Bioscience and Biotechnology, Chinese Academy of
Tropical Agricultural Sciences.

4
H. SHAꢀ ꢁT AL.
1
13
Table 1. h (500 Mhz) ꢈꢆꢂ c (125 Mhz) nMr ꢊpꢉꢌꢁꢅꢈꢋ ꢂꢈꢁꢈ ꢃꢇ 1 in CD od.
3
Position
δC
δH
Position
δC
δH
2
3
4
5
6
7
8
9
171.8
110.7
180.6
126.2
126.6
135.6
119.3
158.0
124.3
136.2
114.0
150.7
4′
5′
6′
7′
146.6
118.1
122.0
33.6
37.1
102.9
74.9
77.8
71.3
78.1
62.4
56.6
6.14, ꢊ
7.02, ꢂ (8.2)
6.72, ꢂꢂ (8.2, 1.8)
3.00~3.02, m
2.97~3.00, m
4.79, ꢂ (7.3)
3.41, ꢂꢂ (7.3, 8.9)
3.44, ꢂꢂ (8.9, 6.8)
3.34, ꢁ (6.8)
3.31~3.33, m
3.81, bꢅ ꢂ (12.0)3.63, ꢂꢂ (12.0, 5.2)
3.71, ꢊ
8.05, ꢂꢂ (7.6, 1.4)
7.43, ꢂꢂ (7.6, 7.6)
7.75, ꢂꢂꢂ (8.4, 7.6, 1.4)
7.55, ꢂ (8.4)
8′
1′′
2′′
3′′
4′′
5′′
6′′
3′-oMꢉ
1
1
2
3
0
′
′
′
6.83, ꢂ (1.8)
3
.3. Extraction and isolation
“
Lv Qi-Nan” (dry weight 180.2 g) was mixed with 1.5 L of ether by ultrasonic extraction 3
times (30 min/time), and the residue af er filtering liquid was extracted with 95% ethanol
by heating reflux three times, to get the ethanol extract (15.8 g) by vacuum concentration.

e ethanol extract was divided into 11 fractions QE1 ~ QE11 by the reduced pressure
chromatography (CHCl ‒MeOH, v/v = 1:0–0:1, 1 L). Fraction QE8 (2.6 g) using the ODS
3
column chromatography (MeOH‒H O, v/v = 3:7–1:0, 1 L) was divided into QE8–1–QE8–16.
2
QE8–9 (42.4 mg) was applied to Sephadex LH‒20 (pure MeOH) and silica gel column
chromatography (CHCl ‒MeOH = 20:1) to obtain compound 1 (3.0 mg).
3
3
.3.1. 2-[2-(4-Glucosyloxy-3-methoxyphenyl)ethyl]chromone (1)
25
C H O , colorless oil;[ꢀ] + 36 (c 0.05, MeOH); UV (MeOH) λ (logε): 203 (5.34), 224
2
4
26
9
D
max
−1
1
13
(
6.25), 296 (4.65) nm; IR (KBr) vmax 3437, 1641, 1016 cm ; for H and C NMR spectral
data see Table 1; HR-ESI-MS: m/z 481.1466 [M + Na] (calcd for C H O Na, 481.1469).
+
2
4
26
9
3
.4. The configuration determination of glucose
3
.4.1. Acid hydrolysis of compound 1
−1
Compound 1 (2.0 mg) was refluxed with HCl solution (1 molL , 1ml) on a water bath
at 70 °C for 5 h. e reaction mixtures were added to saturated solution of Na CO for
2
3
neutralizing the residual acid. e liquid was extracted with ethyl acetate three times. e
water layer was then evaporated under vacuum to obtain the dry monosaccharide (0.7 mg).
3
.4.2. 1-Phenyl-3-methyl-5-pyrazolone (PMP) derivatization

e authentic D-glucose (2.0 mg) and acid hydrolysis monosaccharides of 1 (0.7 mg) were
directly labeled with PMP respectively by adding 120 μl of PMP solution (0.5 M in methanol)
and 100 μl of sodium hydroxide solution (0.3 M), vortexing, and refluxing at 70 °C for 1 h.
e mixture was then neutralized by adding 100 μl of hydrochloric acid solution (0.3 M).
Chloroform (0.5 ml) was added and mixed thoroughly by vortexing and phase separation
was enhanced by brief centrifugation for 10 min (13,000 r/min). e organic phase was
carefully removed for discarding the remaining PMP. e process of extraction was repeated
at least three times. e resulting aqueous phase was mixed with water for HPLC analysis
[
13]. Chromatographic condition: Mobile phase: acetonitrile-phosphate buffer (KH PO ,
2 4

JꢀURNAL ꢀF ASIAN NATURAL PRꢀDUCTS RꢁSꢁARCH
5
pH 8.3) (17:83, v/v); Chromatographic column: Agilent YMC-packed C chromatographic
18
column (250 mm × 10 mm, 5 μm); Flow rate: 1.0 ml/min; Column temperature: 30 °C;
Sample quantity: 20 μl; Detector: the SPD – 20A UV detector (254 nm) DAD.
Disclosure statement
No potential conflict of interest was reported by the authors.
Funding

is research was financially supported by Special Fund for Agro-scientific Research in the Public
Interest [201303117], National Nonprofit Institute Research Grant of CATAS-ITBB [ITBB2015ZD02],
and Major Technology Project of Hainan Province [ZDZX2013023-1].
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