A new hexenol glycoside from leaves of Smallanthus sonchifolius

Article abstract of DOI:10.1080/14786411003752060

A new hexenol glycoside with two known compounds was isolated from the leaves of Smallanthus sonchifolius. The structure of the new compound was elucidated as Z-hex-3-en-1-ol O-alpha-L-arabinopyransyl (1″-2′)- beta-D-glucopyranoside (1) on the basis of spectroscopic analysis and chemical evidence. The two known compounds were identified as ent-15β-hydroxy-kaur- 16-en-19-oic acid (2) and ent-18-hydroxy-kaur-16-en-19-oic acid (3) by comparison of their spectral data with the reported data. Compounds 2 and 3 were isolated for the first time from the title plant.

Full text of DOI:10.1080/14786411003752060

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A new hexenol glycoside from leaves of
Smallanthus sonchifolius
Xiang Zheng a , Gai Kuo a , Dou De-Qiang a , Chen Gui-Rong a
Kang Ting-Guo a , Shi Yu-Yuan a , Li Xing-Tai b & Dong Feng c
,
a College of Pharmacy, Liaoning University of Traditional Chinese
Medicine , 77 Life One Road, Dalian 116600, China
b College of Life Science, Dalian Nationalities University , 18
Liaohe West Road, Dalian Economic and Technical Development
Zone, Dalian 116600, China
c Zhen-Ao Group Co. Ltd , DD Port, Dalian, China
Published online: 15 Oct 2010.
To cite this article: Xiang Zheng , Gai Kuo , Dou De-Qiang , Chen Gui-Rong , Kang Ting-Guo , Shi
Yu-Yuan , Li Xing-Tai & Dong Feng (2010) A new hexenol glycoside from leaves of Smallanthus
sonchifolius , Natural Product Research: Formerly Natural Product Letters, 24:17, 1592-1597, DOI:
10.1080/14786411003752060
To link to this article: http://dx.doi.org/10.1080/14786411003752060
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Natural Product Research
Vol. 24, No. 17, 20 October 2010, 1592–1597
A new hexenol glycoside from leaves of Smallanthus sonchifolius
a
a
a
a
a
*
Xiang Zheng , Gai Kuo , Dou De-Qiang , Chen Gui-Rong , Kang Ting-Guo ,
Shi Yu-Yuana, Li Xing-Taib and Dong Fengc
aCollege of Pharmacy, Liaoning University of Traditional Chinese Medicine, 77 Life
One Road, Dalian 116600, China; College of Life Science, Dalian Nationalities University,
b
18 Liaohe West Road, Dalian Economic and Technical Development Zone,
Dalian 116600, China; Zhen-Ao Group Co. Ltd, DD Port, Dalian, China
c
(Received 21 October 2009; final version received 2 February 2010)
A new hexenol glycoside with two known compounds was isolated from the
leaves of Smallanthus sonchifolius. The structure of the new compound was
elucidated as Z-hex-3-en-1-ol O-alpha-L-arabinopyransyl (100-20)-beta-D-
glucopyranoside (1) on the basis of spectroscopic analysis and chemical
evidence. The two known compounds were identified as ent-15ꢀ-hydroxy-
kaur-16-en-19-oic acid (2) and ent-18-hydroxy-kaur-16-en-19-oic acid (3)
by comparison of their spectral data with the reported data. Compounds 2
and 3 were isolated for the first time from the title plant.
Keywords: Smallanthus sonchifolius; hexenol glycoside; kaurenoic acid
1. Introduction
Yacon, Smallanthus sonchifolius (Poepp. & Endl.) H. Robinson, an indigenous plant
of the Andes belonging to the family Asteraceae, was introduced into China via
Japan in the early 1990s. Usually, yacon is cultivated as a root vegetable, and recent
research has revealed that its leaf extract has potential antidiabetic effects (Aybar,
Sanchez, Grau, & Sanchez, 2001). Chemical investigations of yacon have revealed
that yacon leaves contain various compounds. Phenolics were found in both tubers
and leaves of yacon, in which chlorogenic acid and caffeic acid displayed antioxidant
activity (Sumio, Kikuo, & Akira, 2006). Diterpenoids and melampolides derivates
were isolated from yacon (Consolacion, Ragasa, Alimboyoguen, & Dennis, 2008;
Karin, Irmgard, & Fernando, 2007; Katerina & Jitka, 2003; Qiu, Kang, & Dou,
2008), which has a physiological role in the pest-resistant and antimicrobial activity
of this plant (Kakuta, Seki, Hashidoko, & Mizutani, 1992; Lin, Hasegawa, &
Kodama, 2003). Polyunsaturated fatty acids (PUFAs), smallanthaditerpenic acids
and octadecatrienoic acids were isolated from the leaves of yacon cultivated in China
(Dou, Tian, & Qiu, 2008; Xiang, Gai, Dou, & Kang, 2009), which possesses a
potential ability of antidiabetes. Other components, such as saccharides and essential
oils were also confirmed in yacon (Katerina & Jitka, 2003).
*Corresponding author. Email: doudeqiang2003@yahoo.com.cn
ISSN 1478–6419 print/ISSN 1029–2349 online
ß 2010 Taylor & Francis
DOI: 10.1080/14786411003752060
http://www.informaworld.com

Natural Product Research
1593
OH
1
4
6
3
O
HO
HO
O
2'
OH
5"
O
O
Compound 1
HO
OH
OH
H
COOH
Compound 2
HO
COOH
Compound 3
Figure 1. Structures of the components isolated from the leaves of S. sonchifolius.
This article deals with the isolation and structure elucidation of the new
compound, named Z-hex-3-en-1-ol O-alpha-L-arabinopyransyl (100-20)-beta-D-gluco-
pyranoside (1), together with two known compounds isolated for the first time from
the leaves of S. sonchifolius (Figure 1).
2. Results and discussion
Compound 1 was isolated as an white amorphous powder. ESI–MS gave its quasi-
molecular ion peak at m/z 417 [M þ Na]þ, and the molecular formula of 1 was
determined as C17H30O10 by the HR-ESI–MS at m/z 417.4027 [M þ Na]þ, (calcd
417.4039), as well as from its NMR spectroscopic data, which were assigned using
1-D and 2-D techniques: heteronuclear single quantum coherence (HSQC);
heteronuclear multiple-bond correlation (HMBC); and correlation spectroscopy
(COSY). Two olefinic protons emerged in the high frequency of the 1H-NMR
spectrum at ꢁ 5.43 (1H, dt, J ¼ 6.6 Hz, 11.4 Hz), 5.39 (1H, dd, J ¼ 6.6 Hz, 11.4 Hz).
Taking into consideration the two tertiary-carbon signals found in the high
frequency of 13C-NMR and DEPT spectra, the molecule was believed to contain one
–CH¼CH– fragment with (Z)-configuration, as indicated by the coupling constant
(JH3–H4 ¼ 11.4 Hz). The proton signals at ꢁ 3.88 (1H, overlapped) and 3.55 (1H,
1
overlapped) in the H-NMR spectrum, in addition to the carbon signal at ꢁ 70.5,
revealed the presence of one –CH2–O–fragment. A methyl signal was found at ꢁ 0.96
1
(3H, t J ¼ 7.8 Hz) in H-NMR spectrum and ꢁ 14.7 in the 13C-NMR spectrum. The
carbon signals at ꢁ 21.5, 28.8 in the 13C-NMR and DEPT spectra belonged to two
methylene groups. On acid hydrolysis, it yielded a glucose and an arabinose, which
were identified by TLC comparison with standard samples of glucose and arabinose,
and the absolute configuration of sugar was also determined. Full details are
presented in Section 3. From the 1H-, 13C-NMR and DEPT spectra, 1 was proposed

1594
X. Zheng et al.
OH
H
C
2
H
H
O
C
C
CH
3
HO
HO
C
C
O
2
'
H
2
OH
H
2
5"
O
O
HMBC
1H–1H COSY
HO
OH
1
Figure 2. Structure and key H–1H COSY and HMBC correlations of compound 1.
to be a ꢂ-L-arabinopyranosyl, ꢀ-D-glucopyranoside and an aglycone with cis-3-
hexenol. The configuration of the two anomeric protons at ꢁ 4.40 (1H, d, J ¼ 7.8 Hz),
4.53 (1H, d, J ¼ 6.6 Hz) in the 1H-NMR spectrum were determined to be ꢀ and ꢂ on
the basis of the coupling constant. Signals of ꢀ-D-glucopyranoside (ꢁ 103.1, 83.2,
77.7, 71.4, 77.9 and 62.6), and ꢂ-L-arabinopyranosyl (ꢁ 105.6, 73.1, 74.0, 69.2 and
66.8) were observed in the 13C-NMR spectrum. The HMBC correlations between H-
10 (ꢁ 4.40) of glucose and C-1 (ꢁ 70.5), and between H-1 (ꢁ 3.88; 3.55) and C-10
(ꢁ 103.1) of glucose showed that the glucose unit was linked at C-1. HMBC
correlations between H-100 (ꢁ 4.53) of arabinose and C-20 (ꢁ 83.2) of glucose, and
between H-20 (ꢁ 3.36) of glucose and C-100 (ꢁ 105.6) of arabinose showed that the
arabinose unit was linked at C-20 of glucose (Figure 2). Following the above
evidence, the structure of 1 was determined to be Z-hex-3-en-1-ol O-alpha-L-
arabinopyransyl (100–20)-beta-D-glucopyranoside, and the NMR spectra data are
shown in Table 1.
Compounds 2 and 3 were identified as ent-15ꢀ-hydroxy-kaur-16-en-19-oic
acid (2) and ent-18-hydroxy-kaur-16-en-19-oic acid (3) on the basis of their
spectroscopic data (Ferinand, Knoll, & Harold, 1980; Lobitz, Tamayo-Castillo,
Poveda, & Merfort, 1998).
3. Experimental
3.1. General experimental procedures
Optical rotations were measured on a Perkin Elmer digital polarimeter, USA.
Nuclear magnetic resonance (NMR) spectra were recorded with transcranial
magnetic stimulation (TMS) as an internal standard on a Brucker AVANCE 500
FT-NMR spectrometer. Electrospray ionisation–mass spectrometry (ESI–MS) was
measured on an Agilent 1100 LC/MSD Trap-SL spectrometer, USA. Column
chromatography was performed on silica gel (200–300 mesh) (Marine Chemical
Factory, Qingdao, China) and high performance liquid chromatography (HPLC)
was performed with a Hitachi LC-7100 chromatograph apparatus using an
octadecylsilyl (ODS) column (YMC-Pack ODS-A) and detected with a UV detector.
3.2. Materials
The S. sonchifolius leaves were collected in Liaoning Province, P.R. China, and were
identified by Prof. Kang Tingguo, College of Pharmacy, Liaoning University of

Natural Product Research
1595
Table 1. NMR data of compound 1 (in CD3OD).
Position
DC
ꢁH
1
2
3
4
5
70.5
28.8
125.9
134.4
21.5
14.7
103.1
83.2
77.7
71.4
77.9
62.6
105.6
73.1
74.0
69.2
66.8
3.88 (1H, overlapped); 3.55 (1H, overlapped)
2.36 (2H, m)
5.39 (1H, dt, J ¼ 6.6, 11.4 Hz)
5.43 (1H, dt, J ¼ 6.6, 11.4 Hz)
2.07 (2H, m)
6
0.96 (3H, t, J ¼ 7.8 Hz)
10
20
30
40
50
60
100
200
300
400
500
4.40 (1H, d, J ¼ 7.8 Hz)
3.36 (1H, overlapped)
3.54 (1H, overlapped)
3.31 (1H, overlapped)
3.25 (1H, m)
3.66 (1H, overlapped); 3.86 (1H, overlapped)
4.53 (1H, d, J ¼ 6.6 Hz)
3.64 (1H, overlapped)
3.57 (1H, overlapped)
3.81 (1H, overlapped)
3.54 (1H, overlapped); 3.91 (1H, overlapped)
Traditional Chinese Medicine (TCM). A voucher specimen (no. yacon20050927) has
been deposited at the Pharmacognosy Laboratory, College of Pharmacy, Liaoning
University of TCM.
3.3. Extraction and isolation
The leaves of S. sonchifolius (6.0 kg) were extracted with water under reflux.
Evaporation of the solvent under reduced pressure gave a condensed aqueous
extract, which was then subjected to HPD-100 macroporous resin and eluted with
water and 95% EtOH. The 95% EtOH elution was collected and the solvent was
removed under reduced pressure to yield 150 g of residues. The extract was then
subjected to normal-phase silica gel column and eluted with a gradient of CHCl3–
MeOH (100 : 0 ! 0 : 100, v/v) to give eight fractions. Fraction 4 (CHCl3–MeOH,
70 : 30, v/v) was subjected to further separation using repeated ODS silica gel,
Sephadex LH-20 column chromatography and HPLC to give compounds 1 (40 mg),
2 (80 mg) and 3 (100 mg).
3.3.1. Z-hex-3-en-1-ol O-alpha-l-arabinopyransyl (100-20)-beta-d-
glucopyranoside (1)
24
White amorphous powder; ½ꢂꢀD ꢁ58.1ꢂ (c 1.00, MeOH); positive ion ESI–MS: m/z 417
[M þ Na]þ; high resolution (HR)-ESI–MS: Calcd for C17H30O10 [M þ Na]þ:
417.4039, Found: 417.4027; 1H- and 13C-NMR data in CD3OD are shown in Table 1.
3.4. Acid hydrolysis
Solution of compound 1 in MeOH–HCl (1 : 1) was placed into a sealed capillary.
After heating at 80ꢂC for 4 h, the solution was subjected to silica gel thin layer

1596
X. Zheng et al.
chromatography (TLC), together with the standard samples. n-BuOH–AcOH–H2O
and CHCl3–MeOH–H2O were used as the developing solvents and O-phthalic acid-
aniline was used as the detection reagent. Glucose and arabinose were detected.
3.5. Determination of sugar components
Compound 1 (3 mg) in 10% HCl–dioxane (1 : 1, 1 mL) was heated at 80ꢂC for 4 h.
The reaction mixture was neutralised with Ag2CO3, filtered and then extracted with
CHCl3 (1 mL ꢃ 3). After concentration, monosaccharide subunits (H2O layer) were
obtained. The sugar residue was then dissolved in 2 mL of H2O and analysed by
HPLC under the following conditions described in the literature (Jiang, Qiu, Cheng,
Kang, & Dou, 2008): column, Kaseisorb LC NH2-60-5, 250 mm ꢃ 4.6 mm i.d.
(Tokyo Kasei Kogyo Co. Ltd); solvent, MeCN–H2O (3 : 1); flow rate, 0.8 mL minꢁ1
;
detection, optical rotation. Determination of D-glucose, L-arabinose present in the
sugar fraction was carried out by comparison of its retention times and optical
rotation with those of the standard sample.
Acknowledgement
The authors are thankful for the Elitist Funding of Innovation in Science and Technology of
the Liaoning Provincial Department of Education.
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