By various chromatography methods, two flavonolignan silychristin (1) and isosilychristin (2)were isolated from the fruits of Silybum marianum (L.) Gaertn. cultivated in the North of Vietnam. Their structures were elucidated by analyses of the NMR (1D-, 2D-NMR) and ESI spectra. This is the first report of both 1 and 2 from S. marianum cultivated in Vietnam

Bang, Bui Thi

Braca, Alessandra

Diep, Trinh Thi

Dong, Nguyen Thuong

Kiem, Phan Van

Minh, Chau Van

Tung, Nguyen Huu

Vietnam Academy of Science and Technology: Journals Online

106
Journal of Chemistry, Vol. 45 (1), P. 106 - 109, 2007 
SILYCHRISTIN AND ISOSILYCHRISTIN FROM THE FRUITS OF  
SILYBUM MARIANUM (L.) GAERTN. 
Received 31 May 2006 
TRINH THI DIEP1, PHAN VAN KIEM2, NGUYEN THUONG DONG1, NGUYEN HUU TUNG2,
BUI THI BANG1, CHAU VAN MINH2, ALESSANDRA BRACA3
1National Institute of Medicinal Materials, Ministry of Health 
2Institute of Natural Products Chemistry, VAST 
3Department of Bioorganic Chemistry and Biopharmaceutics University of Pisa, Italia 
 
SUMMARY 
By various chromatography methods, two flavonolignan silychristin (1) and isosilychristin (2)
were isolated from the fruits of Silybum marianum (L.) Gaertn. cultivated in the North of 
Vietnam. Their structures were elucidated by analyses of the NMR (1D-, 2D-NMR) and ESI 
spectra. This is the first report of both 1 and 2 from S. marianum cultivated in Vietnam.  
 
I - INTRODUCTION 
In previous papers, we have reported the 
isolation and structural elucidation of 
flavonolignan, flavonoid, and lignan 
compositions of the fruits of Silybum marianum 
(L.) Gaertn. cultivated in the North of Vietnam 
and used in folk medicine [1 - 4]. Here, we 
report the isolation and structural determination 
of two flavonolignan silychristin (1) and 
isosilychristin (2) isolated from the fruits of 
Silybum marianum (L.) Gaertn. cultivated in the 
North of Vietnam. The structures were 
elucidated by analyses of the NMR and ESI 
spectra, and by the reported data. This is the 
first report of both 1 and 2 from S. marianum 
cultivated in Vietnam.  
II - EXPERIMENTAL 
1. General experimental procedures 
The Electronspray Ionization (ESI) mass 
spectrum was obtained using a AGILENT 1100 
LC-MSD Trap spectrometer. The NMR spectra 
were recorded on a Bruker AM500 FT-NMR 
spectrometer using TMS as the internal 
standard. Column chromatography (CC) was 
performed on silica gel (Kieselgel 60, 70 - 230 
mesh and 230 - 400 mesh, Merck) or YMC RP-
18 resins (30 - 50 µm, FuJisilisa Chemical Ltd.). 
Thin layer chromatography (TLC) was 
performed on DC-Alufolien 60 F254 (Merck 
1.05715) or RP18 F254s (Merck) plates. 
2. Plant material  
The fruits of Silybum marianum (L.) Gaertn. 
were collected in Sapa, Lao Cai Province in 
June, 2004 and were identified by Dr Nguyen 
Tap, Department of Botany and Medicinal Plant 
Resources, National Institute of Medicinal 
Materials. 
3. Extraction and isolation  
Air-dried and powdered fruits of Silybum 
marianum (L.) Gaertn (200 g) were defatted with 
petroleum and then extracted with methanol. 
After removal of the solvent under vacuum, the 
residue (5.8 g) was obtained, which was then 
repeated chromatographed on silica gel columns 
to get 1 (30 mg) as colorless amorphous powder 
and 2 (50 mg) as yellow crystals. 
107
III - RESULTS AND DISCUSSION 
Compound 1 was obtained as colourless 
amorphous powder from methanolic extract of 
the fruits of S. marianum (L.), mp. 174 - 176oC. 
The 1H-NMR spectrum of 1 exhibited two 
doublets at H 5.85 and 5.90 ppm (J = 1.5 Hz), 
two doublets at H 6.82 and 6.87 ppm, three 
other aromatic protons at H 6.79 (d, J = 8.0
Hz), 6.81 (dd, J = 8.0, 1.0 Hz) and 6.99 (d, J =
1.0 Hz). Two doublet of doublets of two protons 
at trans configuration were at  5.00 (dd, J =
11.5, 2.5 Hz) and 4.49 (dd, J = 11.5, 5.5 Hz) 
[5], a doublet at  5.46 (J = 7.0 Hz), a multiplet 
at  3.49. The methylene group bearing oxygen 
atom was at  3.64 (dd, J = 10.0, 10.5 Hz) and 
3.71 (dd, J = 10.5, 5.5 Hz), and methoxyl group 
was at 3.75 as a singlet signal. All the 1H-NMR 
data suggested the flavonolignan type of 1,
which was similar to the isolated compounds 
from the same sources [1, 2]. 
 
Table 1: The NMR data of 1
C Ca Cb,d   Hc,d (J in Hz) 
2 85.2 83.20 5.00 (dd, 11.5, 2.5) 
3 73.8 71.66 4.49 (dd, 11.5, 5.5) 
4 198.2 197.53 -
5 165.2 163.25 -
6 97.4 96.01 5.90 (d, 1.5) 
7 168.7 166.97 -
8 96.3 94.96 5.85 (d, 1.5) 
9 164.4 162.49 -
1’ 130.0  128.99  - 
2’ 116.6  115.26  6.87 (d, 1.5) 
3’ 147.5  147.02  - 
4’ 142.1  140.66  - 
5’ 131.5  129.90  - 
6’ 116.9  115.58  6.82 (d, 1.5) 
 89.1  86.96  5.46 (d, 7.0) 
 55.5  53.29  3.49 (m) 
 64.8  62.94  3.64 (dd, 10, 10.5); 3.71 (dd, 5.5, 10.5) 
1” 134.8  132.38  - 
2” 110.6  110.43  6.99 (d, 1.0) 
3” 149.0  147.5  - 
4” 147.5  146.33  - 
5” 116.2  115.26  6.79 (d, 8.0) 
6” 119.7  118.64  6.81 (dd, 1.0, 8.0) 
OCH3 56.4  55.64  3.75 (3H, s) 
5-OH   11.89 (br s) 
a C of silychristin [5], b125 MHz, c500 MHz, dMeasured in DMSO-d6.
108
O
OH
O
O
HO
OH
2
3
45
6
7 8 9
10
1'
2'
3'
4'
5'
6'
OH
CH2OH
OH
OCH3
1"
2"
3"
4"
5"
6"



1
O
OH
O
HO
OH
2
3
45
6
7
8
9
10
1'
2'
3'
4'
5'
6'
1"
2"
3" 4"
5"
6"



O
H3CO OH
HOH2C
OH
2
Fig.1. The structures of 1 & 2
The 13C-NMR spectrum of 1 showed the 
signals of 25 carbons including 12 quaternary, 
11 methine, 1 oximethylene and 1 methoxyl 
carbons, suggesting a flavonolignan compound. 
The carbonyl group was at  197.53, the 
methylene bearing oxygen atom was at  62.94 
and methoxyl group was at  55.64. All NMR 
assignments of 1 were made from analysis of 
HSQC, HMBC spectra and by comparison with 
those of isolated compound (dehydrosily-
christin) [3] as well as with those of silychristin 
reported in the literature [5]. In the HMBC 
spectrum, H-2 ( 5.00) correlated with C-3 (
71.66)/C-4 ( 197.53)/C-1’ (128.99)/C-2’ 
115.26), and H-3 ( 4.49) had only correlations 
with C-2 ( 83.2) and C-1’ (128.99) confirming 
the position of two oximethine carbons at C-2 
and C-3. In addition, the H-C long-range 
correlations were observed between H- (
5.46) and carbons C- ( 53.29)/C-1” (
132.38)/C-6” ( 118.64)/C-2” (110.43)/C-
(62.94), as well as the H-C long-range 
correlations were observed between H- (
3.49) and carbons C1” ( 132.38)/C- (62.94) 
also confirming the positions of C-, C- and 
C- of two oximethine and oximethylene 
groups. The selected H-C correlations in the 
HMBC spectrum of 1 were shown in Fig. 2. 
Furthermore, the negative ESI mass spectrum of 
1 exhibited an ion peak at m/z 481 [M-H]+ with 
strongest intensity, corresponding to the 
molecular formula of C25H22O10. From the above 
data, compound 1 was determined to be 
silychristin, which was first isolated from 
Silybum marianum (L.) Gaertn. cultivated in the 
North of Vietnam. This compound also was 
reported to be inhibitor of horseradish 
peroxidases and lipoxygenase and 
antihepatotoxic agent [5]. 
Compound 2 was obtained as yellow 
crystals from methanolic extract of the fruits of 
S. marianum (L.), mp. 155 - 157oC and had 
similar NMR spectra as compound 1, suggesting 
the same flavonolignan type. 25 carbons 
corresponding to 25 carbon signals were 
observed in the 13C-NMR spectrum of 2
(including 12 quaternary, 11 methine, 1 
oximethylene and 1 methoxy carbons as 1). 
Detailed comparison from NMR spectrum of 2
with those of 1, especially at C-2, C-3, C- and 
C- showed that 2 must be a derivative of 1, as 
isosilychristin, which was also isolated from 
Silybum marianum (L.) Gaertn [6]. The ESI 
mass spectrum of 2 was taken confirming the 
molecular formula of C25H22O10 of 2 from the 
appearance of an ion peak at m/z 483 [M+H]+ in 
the positive and an ion peak at m/z 481 [M-H]+
in the negative spectra. All NMR assignments 
of 2 were made carefully from HSQC and 
HMBC and from the comparison with those of 1
as shown in table 2. The H-C long-range 
correlations in the HMBC were shown in Fig.2 
further confirming the structure of 2 as 
isosilychristin, which also was first isolated 
from Silybum marianum (L.) Gaertn. cultivated 
the North of Vietnam 
 
109
Table 2: The NMR data of 2
C Ca,b   Ha,c (J in Hz) 
2 79.87 5.17 (d, 12.0) 
3 71.48 4.66 (dd, 12.0, 6.0) 
4 197.99 -
5 163.33 -
6 96.10 5.92 (d, 1.5) 
7 166.83 -
8 95.03 5.87 (d, 1.5) 
9 162.55 -
10 100.49  - 
1’ 128.85  - 
2’ 119.42  6.95 (d, 8.0) 
3’ 116.08  6.74 (d, 8.0) 
4’ 145.92  - 
C Ca,b   Ha,c (J in Hz) 
5’ 141.56  - 
6’ 124.44  - 
 86.36  5.57 (d, 2.0) 
 51.97  3.68 (m) 
 63.49  3.46 (dd, 10, 10.5) 
3.72 (dd, 5.5, 10.5) 
1” 132.83  - 
2” 110.28  6.86 (d, 1.5) 
3” 147.44  - 
4” 146.27  - 
5” 115.15  6.71 (d, 8.5) 
6” 118.48  6.76 (dd, 8.5, 1.5) 
OCH3 55.59  3.71 (3H, s) 
5-OH 11.90 (br s) 
aMeasured in DMSO-d6,
b125 MHz, c500 MHz.
O
OH
O
O
HO
OH
2
45
6
7
8
9
10
1'
2'
3'
4'
5'
OH
CH2OH
OH
OCH3
1"
2"
3"
4"
5"
6"



O
OH
O
HO
OH
3
45
6
7
8
9
10
2'
3'
4'
5'
1"
2"
3" 4"
5"
6"


O
H3CO OH
HOH2C
OH
 
Figure 2: H-C long-range correlations in the HMBC of 1 and 2
Acknowledgements: The authors wish to thank  
Mr Dang Vu Luong, the NMR Lab., Institute of 
Chemistry, Vietnamese Academy of Science and 
Technology for recording the NMR spectrum, 
and Dr. Nguyen Tap, Department of Botany and 
Medicinal Plant Resources, National Institute 
of Medicinal Materials for the plant 
identification. This study was supported by a 
grant from the Vietnam- Italia international 
cooperation project. 
REFERENCES 
1. Vo Van Chi. Vietnamese Medical Plant 
Dictionary, Ha Noi Medicine Pub. (1997). 
2. T. T. Diep, N. T. Dong, B. T. Bang, C. V. 
Minh, P. V. Kiem. Journal of Medicinal 
Materials, Vol. 10(6), 175 - 178 (2005). 
3. T. T. Diep, N. T. Dong, B. T. Bang, C. V. 
Minh, P. V. Kiem. Journal of Medicinal 
Materials, Vol. 11(1), 9 - 13 (2006). 
4. T. T. Diep, N. T. Dong, B. T. Bang, C. V. 
Minh, P. V. Kiem. Vietnamese Journal of 
Chemistry, 2006 (accepted). 
5. H. Tanaka, M. Hiroo, K. Ichino, K Ito. 
Chem. Pharm. Bull., Vol. 37(6), pp. 1441 - 
1445 (1989). 
6. M. Kalonga, Z. Naturforsch., B, Vol. 36, 
262 - 266 (1981). 
110
7. 


Silychristin and isosilychristin from the fruits of Silybum marianum (L.) Gaertin

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Silychristin and isosilychristin from the fruits of Silybum marianum (L.) Gaertin

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