Two new compounds from the fruits of Arctium lappa

Article abstract of DOI:10.1080/10286020.2016.1145671

Abstract: Phytochemical investigation of the extract of Arctii Fructus led to the isolation and characterization of two new compounds, named arctiisesquineolignan B (1) and arctiiphenolglycoside A (2). Their structures were elucidated by means of spectroscopic methods (UV, IR, HR-ESI-MS, 1D and 2D NMR) and chemical evidence, as well as by comparison with known analogs in the literature. Compound 2 exhibited stronger antioxidant activity than the positive control ascorbic acid at a concentration of 10?μM.

Full text of DOI:10.1080/10286020.2016.1145671

Journal of Asian Natural Products Research
ISSN: 1028-6020 (Print) 1477-2213 (Online) Journal homepage: http://www.tandfonline.com/loi/ganp20
Two new compounds from the fruits of Arctium
lappa
Jun He, Xiao-Ying Huang, Ya-Nan Yang, Zi-Ming Feng, Jian-Shuang Jiang & Pei-
Cheng Zhang
To cite this article: Jun He, Xiao-Ying Huang, Ya-Nan Yang, Zi-Ming Feng, Jian-Shuang Jiang
&
Pei-Cheng Zhang (2016): Two new compounds from the fruits of Arctium lappa, Journal of
Asian Natural Products Research, DOI: 10.1080/10286020.2016.1145671
To link to this article: http://dx.doi.org/10.1080/10286020.2016.1145671
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Date: 22 March 2016, At: 05:54

Journal of asian natural Products research, 2016
ꢁꢁp://ꢂx.ꢂꢃꢄ.ꢃꢅg/10.1080/10286020.2016.1145671
ꢀ
Two new compounds from the fruits of Arctium lappa
a
b
b
b
b
Jun He , Xiao-Ying Huang , Ya-Nan Yang , Zi-Ming Feng , Jian-Shuang Jiang and
Pei-Cheng Zhangb
ꢆ
b
dꢋpꢆꢅꢁmꢋꢈꢁ ꢃꢌ Pꢀꢆꢅmꢆꢉy, cꢀꢄꢈꢆ-Jꢆpꢆꢈ fꢅꢄꢋꢈꢂꢊꢀꢄp hꢃꢊpꢄꢁꢆꢇ, Bꢋꢄjꢄꢈg 100029, cꢀꢄꢈꢆ; sꢁꢆꢁꢋ Kꢋy lꢆbꢃꢅꢆꢁꢃꢅy ꢃꢌ
Bꢄꢃꢆꢉꢁꢄvꢋ sꢍbꢊꢁꢆꢈꢉꢋꢊ ꢆꢈꢂ fꢍꢈꢉꢁꢄꢃꢈꢊ ꢃꢌ nꢆꢁꢍꢅꢆꢇ Mꢋꢂꢄꢉꢄꢈꢋꢊ, iꢈꢊꢁꢄꢁꢍꢁꢋ ꢃꢌ Mꢆꢁꢋꢅꢄꢆ Mꢋꢂꢄꢉꢆ, cꢀꢄꢈꢋꢊꢋ aꢉꢆꢂꢋmy ꢃꢌ
Mꢋꢂꢄꢉꢆꢇ sꢉꢄꢋꢈꢉꢋꢊ ꢆꢈꢂ Pꢋkꢄꢈg uꢈꢄꢃꢈ Mꢋꢂꢄꢉꢆꢇ cꢃꢇꢇꢋgꢋ, Bꢋꢄjꢄꢈg 100050, cꢀꢄꢈꢆ
ABSTRACT
ARTICLE HISTORY
Phytochemical investigation of the extract of Arctii Fructus led to
the isolation and characterization of two new compounds, named
arctiisesquineolignan B (1) and arctiiphenolglycoside A (2). Their
structures were elucidated by means of spectroscopic methods (UV,
IR, HR-ESI-MS, 1D and 2D NMR) and chemical evidence, as well as
by comparison with known analogs in the literature. Compound
rꢋꢉꢋꢄvꢋꢂ 23 nꢃvꢋmbꢋꢅ 2015
aꢉꢉꢋpꢁꢋꢂ 20 Jꢆꢈꢍꢆꢅy 2016
KEYWORDS
aꢅꢉꢁꢄꢄ fꢅꢍꢉꢁꢍꢊ; Arctium lappa;
ꢊꢋꢊqꢍꢄꢈꢋꢃꢇꢄgꢈꢆꢈ; pꢀꢋꢈꢃꢇꢄꢉ
ꢂꢄgꢇyꢉꢃꢊꢄꢂꢋ; ꢆꢈꢁꢄꢃxꢄꢂꢆꢈꢁ
ꢆꢉꢁꢄvꢄꢁy
2
exhibited stronger antioxidant activity than the positive control
ascorbic acid at a concentration of 10 μM.
1
. Introduction
Arctii Fructus, the dried mature fruit of Arctium lappa L., is an important medicinal plant in
China and Japan which has been used for thousands of years. In our previous studies, more
than 30 new bioactive lignans have been discovered from Arctii Fructus [1–4]. Continued
phytochemical research on this important medicinal plant revealed two new compounds,
arctiisesquineolignan B (1) and arctiiphenolglycoside A (2) (Figure 1). In this study, we
reported the isolation, structure elucidation, and biological evaluation of these two new
compounds.
2
. Results and discussion
Compound 1 was isolated as white amorphous powder. e molecular formula of 1 was
+
determined as C H O from the HR-ESI-MS at m/z 757.2677 [M+Na] . e IR spec-
3
6
46 16
−1
trum showed the presence of hydroxy groups (3407 cm ) and aromatic rings (1602 and
513 cm ). In the H NMR spectrum of 1, nine aromatic proton signals at δ 7.02 (1H, d,
−1
1
1
H
J = 8.5 Hz), 6.98 (1H, brs), 6.96 (1H, d, J = 8.5 Hz), 6.95 (1H, brs), 6.91 (1H, brs), 6.83 (1H,
d, J = 8.5 Hz), 6.80 (1H, d, J = 8.5 Hz), 6.77 (1H, d, J = 8.5 Hz), and 6.68 (1H, d, J = 8.5 Hz)
were observed (Table 1), which revealed the presence of three sets of aromatic rings with
ABX system. ree methoxyl groups at δ 3.75 (6H, s), 3.72 (3H, s), and an anomeric proton
H
CONTACT Pꢋꢄ-cꢀꢋꢈg Zꢀꢆꢈg
pꢉzꢀꢆꢈg@ꢄmm.ꢆꢉ.ꢉꢈ
©
2016 tꢆyꢇꢃꢅ & fꢅꢆꢈꢉꢄꢊ

2
J. HE ET Aꢀ.
Figure 1. sꢁꢅꢍꢉꢁꢍꢅꢋꢊ ꢃꢌ ꢉꢃmpꢃꢍꢈꢂꢊ 1–2.
1
13
Table 1. h nMr (500 Mhz) ꢆꢈꢂ c nMr (125 Mhz) ꢊpꢋꢉꢁꢅꢆꢇ ꢂꢆꢁꢆ ꢃꢌ ꢉꢃmpꢃꢍꢈꢂ 1 ꢄꢈ dMso-d (δ ꢄꢈ ppm,
6
J ꢄꢈ hz).
Position
δH
δC
Position
δH
δC
1
2
3
4
5
6
7
8
9
138.8
111.1
149.1
146.2
115.8
119.5
75.1
1″
2″
3″
4″
5″
6″
7″
8″
9″
133.4
111.5
147.5
145.9
115.3
118.9
71.5
6.95 (bꢅꢊ)
6.98 (bꢅꢊ)
7.02 (ꢂ, 8.5)
6.83 (ꢂ, 8.5)
4.38 (ꢂ, 6.5)
2.42–2.44 (m)
3.59–3.61 (m)
6.68 (ꢂ, 8.5)
6.77 (ꢂ, 8.5)
4.70 (ꢂ, 4.0)
4.21–4.23 (m)
3.56–3.58 (m)
3.23–3.25 (m)
4.85 (ꢂ, 7.5)
3.23–3.25 (m)
3.25–3.27 (m)
3.14–3.16 (m)
3.25–3.27 (m)
3.66 (ꢂ, 9.5)
.45–3.47 (ꢃvꢋꢅꢇꢆp)
3.75 (ꢊ)
51.0
70.1
85.1
60.6
3
.48–3.50 (m)
1
2
3
4
5
6
′
′
′
′
′
′
136.0
111.5
149.9
148.0
115.2
119.2
1‴
2‴
3‴
4‴
5‴
6‴
100.6
73.7
77.5
70.1
77.3
61.2
6.91 (bꢅꢊ)
6.96 (ꢂ, 8.5)
6.80 (ꢂ, 8.5)
3
7′
8′
9′
4.50 (ꢂ, 8.0)
2.14–2.16 (m)
3.45–3.47 (m)
83.7
54.3
62.1
3-och3
3′-och3
3″och3
56.1
56.1
55.9
3.75 (ꢊ)
3.72 (ꢊ)
Figure 2. Kꢋy hMBc ꢉꢃꢅꢅꢋꢇꢆꢁꢄꢃꢈꢊ ꢃꢌ ꢉꢃmpꢃꢍꢈꢂꢊ 1 ꢆꢈꢂ 2.
1
1
at δ 4.85 (1H, d, J = 7.5 Hz) were detected by the H NMR spectrum. In addition, the H
H
NMR spectrum also revealed three oxymethylene protons [δ 3.59–3.61 (1H, m), 3.56–3.58
H
(
1H, m), 3.48–3.50 (1H, m), 3.45–3.47 (2H, m), and 3.23–3.25 (1H, m)], four oxymethine
protons [δ 4.70 (1H, d, J = 4.0 Hz), 4.50 (1H, d, J = 8.0 Hz), 4.38 (1H, d, J = 6.5 Hz), and
H
4
.21–4.23 (1H, m)], and two methine protons [δ 2.42–2.44 (1H, m), and 2.14–2.16 (1H,
H

JꢁURNAꢀ ꢁF ASIAN NATURAꢀ PRꢁDUCTS RESEARCH
3
1
13
Table 2. h nMr (500 Mhz) ꢆꢈꢂ c nMr (125 Mhz) ꢊpꢋꢉꢁꢅꢆꢇ ꢂꢆꢁꢆ ꢃꢌ ꢉꢃmpꢃꢍꢈꢂ 2 ꢄꢈ dMso-d (δ ꢄꢈ ppm,
6
J ꢄꢈ hz).
Position
δH
δC
Position
δH
δC
1
2
3
4
5
150.7
95.3
148.6
130.8
148.6
1″
2″
3″
4″
5″
4.13 (ꢂ, 7.5)
3.16–3.18 (m)
3.04–3.06 (m)
3.08–3.10 (m)
3.66 (ꢂꢂ, 11.5, 5.5)
104.9
73.9
77.2
70.4
66.2
6.33 (ꢊ)
3.00 (ꢁ, 11.5)
6
6.33 (ꢊ)
4.70 (ꢂ, 7.5)
95.3
101.9
73.7
77.0
70.4
76.0
69.6
3-och3
5-och3
3.71 (ꢊ)
3.71 (ꢊ)
56.4
56.4
1
2
3
4
5
6
′
′
′
′
′
′
2.90–2.92 (m)
3.22–3.24 (m)
3.22–3.24 (m)
3.49 (ꢁ, 9.0)
3.94 (ꢂ, 11.5)
.58 (ꢂꢂ, 11.5, 7.0)
3
1
3
m)]. e C NMR spectrum of 1 (Table 1) showed 36 carbon signals, consisting three
methoxy carbon signals (δ 56.1, 56.1, and 55.9), six carbon signals of a glucose unit (δ
C
C
1
00.6, 77.5, 77.3, 73.7, 70.1, and 61.2), and 27 skeleton carbon signals of three C6-C3 units.
In the HMBC spectrum (Figure 2), the correlation peaks of H-7 at δ 4.38 with C-1, C-2,
H
C-6, C-8, C-9, and C-8′, and of H-7′ at δ 4.50 with C-1′, C-2′, C-6′, C-8′, C-9′, C-8, and
H
C-9, confirmed the presence of a tetrahydrofuranoidlignan unit. Moreover, the correlation
of H-7″ resonated at δ 4.70 with C-1″, C-2″, C-6″, C-8″, and C-9″, and of H-8″ resonated
H
at δ 4.21–4.23 with C-4′ verified that 1 was a 4′,8″-O-8,8′-system sesquineolignan [5].
H

e positions of three methoxyl groups were determined by the HMBC correlation peaks
of the methoxy protons at δ 3.75, 3.75, and 3.72 with C-3, 3′, and 3″, respectively. Acid
H
hydrolysis of 1 yielded the sugar part, which was identified as ꢀ-glucose by the positive
optical rotation. e evidence for the β configuration of the glucose unit was determined
by its anomeric proton at δ 4.85 (J = 7.5 Hz). e HMBC correlation of the anomeric
H
proton at δ 4.85 with C-4 indicated that the glucose unit was at C-4. A smaller coupling
H
constant (J7″,8″ = 4.0 Hz) confirmed the erythro configuration of the glycerol part of 1 [2].
Furthermore, the ROESY correlation peaks of H-7/H-8′, H-8′/H-2′, and H-8/H-9′ helped
confirming the trans configurations of H-7′/H-8′ and H-8/H-8′ in 1. Unfortunately, there
was no evidence to determine the relative configuration of H-7/H-8. Consequently, com-
pound 1 was established to be 4,4″,7,7″,9′,9″-hexahydroxy-3,3′,3″-trimethoxy-4′,8″:9,7′-
bis-epoxy-8,8′-sesquineolignan-4-O-β-ꢀ-glucopyranoside, named arctiisesquineolignan B.
Compound 2 was obtained as a white amorphous powder, and its positive HR-ESI-MS
+
data ([M+Na] , m/z 487.1430) indicated the molecular formula to be C H O . e IR
1
9
28 13
1
spectrum similarly revealed the existence of hydroxyl and benzene ring. In the H NMR
spectrum of 2, two aromatic proton signals at δ 6.33 (2H, s) revealed the presence of an
H
1
3
,3,4,5-tetrasubstituted symmetrical aromatic ring. Moreover, two methoxyl protons at δH
.71 (6H, s), a glucopyranosyl anomeric proton at δ 4.70 (1H, d, J = 7.5 Hz) and a xylopyra-
H
1
3
nosyl anomeric proton at δ 4.13 (1H, d, J = 7.5 Hz) were also observed. e C NMR
H
spectrum showed 19 carbon signals, including 11 carbon signals from an O-glucose and an
O-xylose unit, two methoxyl groups, and six carbon signals from an 1,3,4,5-tetrasubstituted
symmetrical aromatic ring. ese NMR data (Table 2) were partially similar to those of
2,6-dimethoxy-p-hydroquinone 1-O-β-ꢀ-xylopyranosyl-(1→6)-O-β-ꢀ-glucopyranosyl [6],

4
J. HE ET Aꢀ.
except that the position of the diglycoside moiety. Furthermore, acid hydrolysis of 2 yielded
ꢀ
-xylose and ꢀ-glucose, which were identified by TLC analysis and optical rotation. e β
configuration of these two sugars were concluded from the signals at δ 4.70 (J = 7.5 Hz)
H
1
and 4.13 (J = 7.5 Hz) in the H NMR spectrum. In the HMBC spectrum of 2, the char-
acteristic correlation between H-1′ and C-1 confirmed that the diglycoside moiety was at
C-1 (Figure 2). On the basis of the above evidence, the structure of 2 was determined as
1
-O-β-ꢀ-xylopyranosyl-(1→6)-O-β-ꢀ-glucopyranosyl-4-hydroxy-3,5-dimethoxyphenol,
named arctiiphenolglycoside A.
Given our previous bioactivity screening results for the lignan glucosides, the hepato-
protective activities and anti-inflammatory activities of these two compounds were tested
through in vitro assays. Unfortunately, all of them exhibited weak hepatoprotective and
anti-inflammatory activities at a concentration of 10 μM. e “1,1-diphenyl-2-picrylhydra-
zyl” (DPPH) radical scavenging activity assay was performed to evaluate the antioxidant
property of the above two compounds with positive reference (ascorbic acid). Compound
2
showed higher antioxidant property (44.39% inhibition) than ascorbic acid (44.00% inhi-
bition) at a concentration of 10 μM.
3
. Experimental
.1. General experimental procedures
Optical rotations were recorded on a Jasco P-2000 polarimeter (Jasco Corp., Tokyo, Japan).
e UV spectra were measured on a Jasco V650 spectrophotometer (Jasco Corp.). e
3

IR spectra were recorded on a Nicolet 5700 spectrometer (ermo Scientific, MA, USA).
HR-ESI-MS was recorded on an Agilent 1100 series LC/MSD ion trap mass spectrometer
1
13
(
Agilent Technologies, Waldbronn, Germany). H NMR (500 MHz), C NMR (125 MHz),
and 2D NMR spectra were obtained using an INOVA 500 spectrometer (Varian Corp.,
CA, USA) with tetramethylsilane as internal standard, and values were given in ppm
(
δ). Column chromatography was carried out with macroporous resin (Diaion HP-20,
Mitsubishi Chemical Corp., Tokyo, Japan) and Sephadex LH-20 (Pharmacia Fine Chemicals,
Uppsala, Sweden). Flash chromatography was conducted using Combiflash RF200 (Teledyne
Isco Corp., NE, USA). Preparative HPLC was carried out on a Shimadzu LC-10A instru-
ment with a SPD-20A detector (Shimadzu Corp., Tokyo, Japan), using YMC-Pack ODS-A
column (250 mm × 20 mm, 5 μm; YMC Corp., Kyoto, Japan). HPLC-DAD analysis was
set up on Agilent 1200 series system (Agilent Technologies) with an Apollo C18 column
(250 mm × 4.6 mm, 5 μm; Alltech Corp., KY, USA).
3
.2. Plant material
Arctii Fructus were collected in October 2011 in Wuchang Town, Heilongjiang Province,
China. e plant material was identified as the fruits of A. lappa by Professor Lin Ma. A
voucher specimen (IDS-2434) is placed in the herbarium of the Department of Chemistry
of Natural Products, Institute of Materia Media, Chinese Academy of Medical Sciences and
Peking Union Medical College, Beijing, China.

JꢁURNAꢀ ꢁF ASIAN NATURAꢀ PRꢁDUCTS RESEARCH
5
3
.3. Extraction and isolation
Arctii Fructus (100 kg) were extracted with 80% EtOH under reflux for three times and
filtered, and the solvent was evaporated in vacuo. e residue obtained (4.0 kg) was sus-
pended in water (10 L) and extracted with EtOAc (3 × 10 L). e aqueous layer (400 g) was
subjected to HP-20 macroporous adsorbent resin (4000 g) column chromatography eluted
with H O, 15% EtOH, 30% EtOH, 50% EtOH, and 95% EtOH (15 L each), to produce five
2
corresponding fractions (Fraction A–E). Fr.B (40 g) was subjected to a flash chromatography
eluting with a gradient MeOH–H O (from 0:100 to 100:0) to give 17 fractions (Fr.B-1–Fr.B-
2
1
7). Fr.B-5 (650 mg) was submitted to Sephadex LH-20 column eluting with H O to yield
2
1
0 fractions (Fr.B-5-1–B-5-10). Fr.B-5-3 (68 mg) was further separated via reversed-phase
preparative HPLC, with the detection wavelength of 280 nm, and a flow rate of 5 ml/min,
and eluted with MeOH/H O (25:75) to provide compound 2 (32 mg, Rt 39 min). Fr.C
2
(
45 g) was subjected to a flash chromatography eluting with a gradient MeOH–H O (from
2
0
:100 to 100:0) to give 20 fractions (Fr.C-1–Fr.C-20). Fr.C-18 (920 mg) was submitted to
Sephadex LH-20 column eluting with H O to yield 12 fractions (Fr.C-18-1–C-18-12). Fr.C-
2
1
8-10 (120 mg) was further separated via reversed-phase preparative HPLC (the detection
wavelength: 280 nm, flow rate: 5 ml/min), eluting with MeOH/H O (35:65) to provide
2
compound 1 (19 mg, Rt 46 min).
3
.3.1. Arctiisesquineolignan B (1)
25
White amorphous powder, [ꢀ]D −10.9 (c 0.16, MeOH); UV (MeOH) λmax(log ε): 230
(
3.12), 278 (2.69) nm; IR (KBr) νmax: 3407, 2936, 1602, 1513, 1464, 1424, 1267, 1227, 1074,
−1
1
13
1
034 cm ; for H and C NMR spectroscopic data, see Table 1. HR-ESI-MS: m/z 757.2677
+
[
M+Na] (calcd for C H O Na,757.2684).
3
6
46 16
3
.3.2. Arctiiphenolglycoside A (2)
White amorphous powder, UV (MeOH) λ (log ε): 235 (3.78) nm; IR (KBr) νmax: 3399,
max
−
1
1
13
1
622, 1517, 1466, 1237, 1118, 1049, 1010 cm ; for H and C NMR spectroscopic data, see
+
Table 2. HR-ESI-MS: m/z 487.1430 [M+Na] (calcd for C H O Na, 487.1428).
1
9
28 13
3
.4. Acid hydrolysis of compounds 1 and 2
Compound 1 (6.0 mg) was dissolved in 1 M HCl (5.0 ml) and refluxed for 2 h. e reaction
mixture was then transferred to a liquid–liquid extractor and extracted with EtOAc (5.0 ml)
three times. e aqueous layer was evaporated and dried under reduced pressure to furnish
a monosaccharide residue. e residue was purified on preparative silica gel thin layer chro-
matography (PTLC) [CHCl –MeOH–H O (7:3:1)] to afford ꢀ-glucose (R = 0.20), which
3
2
f
2
D
5
was confirmed by TLC analysis and positive optical rotation [ꢀ] + 28.1) in comparison
with standard samples. Hydrolysis of 2 and sugar identification were performed accord-
2
D
5
ing to the procedure described for 1. e ꢀ-xylose (R = 0.43, [ꢀ] + 25.6) and ꢀ-glucose
f
2
D
5
(
R = 0.20, [ꢀ] + 19.2) were confirmed by TLC analysis [CHCl –MeOH–H O (7:3:1)] in
f
3
2
comparison with standard samples.

6
J. HE ET Aꢀ.
3
.5. Bioactivity assays
Compounds 1 and 2 were tested in vitro for anti-inflammatory activity by suppressing
the production of NO in lipopolysaccharide-induced BV2 cells [1], and hepatoprotective
activity against ꢀ-galactosamine-induced toxicity in HL-7702 cell [3] according to the
procedure described in the literature. DPPH radical scavenging activity was determined
according to the methods described by Zhou [7] with some modifications. Here, 100 μl of
samples with different concentrations were added to 150 μl of 61 μM DPPH in methanol.



e mixture was mixed vigorously and kept in the dark at room temperature for 60 min.
e absorbance of the resulting solution was measured at 520 nm using microplate reader.
e DPPH radical scavenging rate was calculated according to the following formula:
ꢀ
ꢁ
ꢂ
ꢃ
Inhibition (%) = OD(control) − OD(sample) ∕OD(control) × 100, where OD(control) is the
absorbance of the control and OD(sample) is the absorbance of the tested compounds or
positive drug. In this assay, ascorbic acid was used as a positive drug.
Disclosure statement
No potential conflict of interest was reported by the authors.
Funding

is research was financially supported by the Nation Science and Technology Project of China
[
[
grant number 2012ZX09301002-002]; Fundamental Research Funds for the Central Institutes
grant number 2015CX02]; Youth Funds Project of China-Japan Friendship hospital [grant number
2014-1-QN-2].
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