Aromatic diglycosides from Cladogynos orientalis

Article abstract of DOI:10.1016/j.phytochem.2006.10.027

Two unusual aromatic diglycosides with galloyl substitution, 4″-O-galloyl-violutoside and 4″-O-galloyl-benzyl-O-α-l-rhamnopyranosyl-(1 → 6)-β-d-glucopyranoside, were isolated from the aerial portion of Cladogynos orientalis along with isovitexin, apigenin 6-C-(2″-O-galloyl)-β-d-glucopyranoside, apigenin 8-C-(2″-O-galloyl)-β-d-glucopyranoside, syringic acid β-d-glucopyranoside, 3,4,5-trimethoxyphenyl β-d-glucopyranoside, (6S,9R)-roseoside, and violutioside. The structural elucidations were based on analyses of chemical and spectroscopic data by including 1D and 2D NMR analyses.

Full text of DOI:10.1016/j.phytochem.2006.10.027

PHYTOCHEMISTRY
Phytochemistry 68 (2007) 692–696
www.elsevier.com/locate/phytochem
Aromatic diglycosides from Cladogynos orientalis
Tripetch Kanchanapoom *
Department of Pharmaceutical Botany and Pharmacognosy, Faculty of Pharmaceutical Sciences, Khon Kaen University, Khon Kaen 40002, Thailand
Received 1 June 2006; received in revised form 13 July 2006
Available online 11 December 2006
Abstract
0
0
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Two unusual aromatic diglycosides with galloyl substitution, 4 -O-galloyl-violutoside and 4 -O-galloyl-benzyl-O-a-L-rhamnopyrano-
syl-(1 ! 6)-b-D-glucopyranoside, were isolated from the aerial portion of Cladogynos orientalis along with isovitexin, apigenin
00
00
6
-C-(2 -O-galloyl)-b-D-glucopyranoside, apigenin 8-C-(2 -O-galloyl)-b-D-glucopyranoside, syringic acid b-D-glucopyranoside, 3,4,5-
trimethoxyphenyl b-D-glucopyranoside, (6S,9R)-roseoside, and violutioside. The structural elucidations were based on analyses of chem-
ical and spectroscopic data by including 1D and 2D NMR analyses.
ꢀ
2006 Elsevier Ltd. All rights reserved.
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0
Keywords: Cladogynos orientalis; Euphorbiaceae; Aromatic diglycoside; Violutoside; 4 -O-galloyl-violutoside; Galloyl substitution
1
. Introduction
2. Results and discussion
Cladogynos orientalis Zipp. Ex Span. (Thai name: Chet-
The methanolic extract of the aerial portion of C. orien-
talis was partitioned with Et O, n-BuOH, and H O. The
ta-phang-khi), a member of the family Euphorbiaceae of
the monotypic genus, is a shrub up to 2 m high native in
tropical regions of Asia. It is used in Thai traditional med-
icine for the relief of stomach-ache and abdominal pain. In
continuing studies on Thai medicinal plants from this fam-
ily (Kanchanapoom et al., 2002, 2003), the constituents of
this plant were investigated, following plant collection from
the Chaiyaphum province, Thailand. Pervious investiga-
tions of this plant resulted in ent-halimane diterpenes and
guainane sesquiterpene being reported (Sato et al., 1970,
2
2
n-BuOH soluble fraction was subjected to using a column
chromatography highly porous copolymer resin of styrene
and divinylbenzene, with H O, MeOH and Me CO as elu-
2
2
ants, successively. The portion eluted with MeOH was
repeatedly subjected to silica gel, RP-18, and preparative
HPLC-ODS chromatography to provide nine compounds.
Compounds 1, 2 and 3 have been assigned as the flavone
00
C-glycosides; isovitexin, apigenin 6-C-(2 -O-galloyl)-b-D-
00
glucopyranoside, apigenin 8-C-(2 -O-galloyl)-b-D-gluco-
1
971; Kanlayavattanakul et al., 2005). The present paper
pyranoside, respectively (Markham and Chari, 1982; Lin
1
13
deals with the isolation and structural determination of
nine polar compounds, including three flavone C-glyco-
sides (1–3), two aromatic glucosides (4, 5), one megastig-
mane glucoside (6), as well as two new unusual aromatic
diglycosides bearing with a galloyl moiety (8, 9) from the
aerial part of this plant.
et al., 2000; Latt e´ et al., 2002). The H and C NMR spec-
troscopic data of compounds 4 and 5 were coincident with
those of syringic acid b-D-glucopyranoside (Inoshiri et al.,
1987), and 3,4,5-trimethoxyphenyl b-D-glucopyranoside
(Shimomura et al., 1988), respectively. Compound 6 was
elucidated as a megastigmane glucoside, (6R,9S)-3-oxo-a-
ionol-b-D-glucopyranoside, by comparison of its physical
and NMR spectroscopic data with reported data (Pabst
et al., 1992).
*
Compound 7 was isolated as an amorphous powder and
determined as C H O by high-resolution (HR)-FAB
Tel.: +66 43 202378; fax: +66 43 202379.
E-mail address: trikan@kku.ac.th.
1
9
26 12
0
031-9422/$ - see front matter ꢀ 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.phytochem.2006.10.027

T. Kanchanapoom / Phytochemistry 68 (2007) 692–696
693
1
mass spectrometric analysis. The H NMR spectroscopic
et al., 1997). From these spectroscopic data, compound 7
could be identified as methyl salicylate a-L-arabinopyrano-
syl-(1 ! 6)-b-D-glucopyranoside. In order to confirm the
absolute configurations of the sugar units, compound 7
was hydrolyzed with sulfuric acid to give the sugar fraction
from an aqueous layer. The absolute configurations of glu-
cose and arabinose were determined to be D- and L-forms,
respectively; by comparison of the optical rotations with
those of authentic samples. The structure of compound 7
was identical to violutoside, isolated compound from Viola
cornuta L. in 1926 (Picard, 1926a,b) and was reported as a
synthetic compound in 1932 (Robertson and Waters,
1932). So far this compound was not been reported since
then; therefore the physical and spectroscopic data were
given as shown in Table 1.
data showed the characteristic of a 1,2-disubstituted aro-
matic ring system from the chemical shifts at dH 7.38 (1H,
br d, J = 8.3 Hz), 7.51 (1H, br dd, J = 8.3, 6.8 Hz), 7.06
1H, br dd, J = 7.8, 6.8 Hz), and 7.69 (1H, br d,
J = 7.8 Hz), together with a singlet methoxyl signal at d
.83 (3H) for an aglycone moiety. The C NMR spectrum
displayed 19 carbon signals, of which eight were assignable
to one oxy-aryl carbon at d 158.2, four aryl-methines at dC
19.2, 123.6, 132.0 and 135.3, one non-protonated carbon
at dC 122.4, and two carbon signals of a carbomethoxyl
group at d 168.5 and 52.8 for an aglycone, indicative of
a methyl salicylate derivative. The remaining carbon signals
belonged to the sugar moiety, and could be identified as a-L-
arabinopyranosyl-(1 ! 6)-b-D-glucopyranosyl unit by
comparing chemical shifts with the reported data (Matsuda
(
1
3
3
C
1
C
Table 1
NMR spectroscopic data of violutoside (7) and compound 8
OH
No.
7
8
HO
O
O
HO
HO
d
C
d
H
d
C
d
H
O
1
2
3
122.4
158.5
122.3
158.6
HO
O
OH
119.2 7.38 (1H, br d,
J = 8.3 Hz)
119.2 7.42 (1H, dd, J = 8.3,
2.2 Hz)
135.4 7.40 (1H, br dd, J = 8.3,
6.6 Hz)
123.7 7.00 (1H, ddd, J = 7.8,
6.6, 2.2 Hz)
132.0 7.68 (1H, br d, J = 7.8 Hz)
HO
HO
O
4
5
6
135.3 7.51 (1H, br dd,
J = 8.3, 6.8 Hz)
123.6 7.06 (1H, br dd,
J = 7.8, 6.8 Hz)
132.0 7.69 (1H, br d,
J = 7.8 Hz)
2
OH
HO
OH
HO
OH
7
8
168.5
52.8 3.83 (3H, s)
168.6
52.8 3.83 (3H, s)
OH
HO
Glc
1
0
O
O
OH
103.8 4.83 (1H,
J = 7.1 Hz)
74.9 3.47 (1H)
103.9 4.83 (1H, d, J = 7.5 Hz)
74.9 3.49 (1H, dd, J = 9.0,
O
HO
a
O
O
0
2
7
.5 Hz)
77.5 3.43 (1H, dd, J = 9.0,
.8 Hz)
0
a
3
77.4 3.45 (1H)
8
OH
O
0
3
4
71.5 3.37 (1H, dd,
J = 9.3, 8.8 Hz)
77.4 3.65 (1H, m)
71.5 3.35 (1H, dd, J = 9.3,
8.8 Hz)
77.5 3.65 (1H, m)
70.4 3.78 (1H, dd, J = 11.7,
6.6 Hz); 4.12 (1H, br d,
J = 11.7 Hz)
0
0
5
6
OR
4
a
69.6 3.78 (1H) ; 4.08
4
"
O
(1H, br d,
HO
2
1"HO
O
J = 11.5 Hz)
OH
O
1
HO
1
'
Ara
OH
COOMe
7
00
1
105.0 4.27 (1H, d,
J = 6.6 Hz)
74.1 3.55 (1H)
72.4 3.55 (1H)
69.4 3.74 (1H)
105.6 4.35 (1H, d, J = 6.6 Hz)
R
a
7:
H
0
0
0
0
0
0
0
0
a
2
3
4
5
73.0 3.69 (1H)
O
a
a
72.7 3.67 (1H)
7
"'
a
HO
72.8 5.12 (1H, br s)
64.9 3.59 (1H, br d, 11.9 Hz);
3.95 (1H, dd, 11.9, 2.2 Hz)
a
1"'
66.6 3.44 (1H) ; 3.80
(1H, dd, J = 11.9,
HO 4"'
8
:
2.0 Hz)
OH
O
Galloyl moiety
0
0
0
0
0
00
00
00
00
00
3
1
2
3
4
7
121.6
O
000
000
4
, 6
, 5
110.4 7.08 (2H, br s)
146.5
1"
HO
HO
1"'
Me
O
O
HO
HO
7"'
O
O
4"
1
139.9
168.0
1'
7
HO
OH
OH
4"'
a
Chemical shifts obtained approximately by HSQC.
OH
9

694
T. Kanchanapoom / Phytochemistry 68 (2007) 692–696
The molecular formula of compound 8 was determined
as C H O by HR-FAB mass spectrometric analysis.
aryl-methines at dC 128.8, 129.2 (2C), and 129.3 (2C),
one non-protonated carbon at d 138.8, and one oxy-meth-
2
1
6
30 16
C
13
The H NMR spectroscopic data also showed the presence
of a set of 1,2-disubstituted aromatic ring systems from the
chemical shifts at 7.42 (1H, dd, J = 8.3, 2.2 Hz), 7.40 (1H,
br dd, J = 8.3, 6.6 Hz), 7.00 (1H, ddd, J = 7.8, 6.6, 2.2 Hz),
and 7.68 (1H, br d, J = 7.8 Hz), as well as two anomeric
protons at dH 4.83 (1H, d, J = 7.5 Hz) and 4.35 (1H, d,
ylene carbon at dC 71.8 in the C NMR spectrum. The
remaining signals could be assigned to a galloyl moiety as
compared to compound 8, and the sugar moiety was iden-
tified as an a-L-rhamnopyranosyl-(1 ! 6)-b-D-glucopyr-
anosyl unit (De Tommasi et al., 1996). The chemical
shifts of compound 9 were closely related to those of ben-
zyl-O-a-L-rhamnopyranosyl-(1 ! 6)-b-D-glucopyranoside
(De Tommasi et al., 1996), except for the occurrence of
additional signals of a galloyl moiety. This functional
J = 6.6 Hz) and a methyl singlet signal at d 3.83 (3H).
H
1
13
The H and C NMR spectroscopic data were very similar
to those of compound 7. In addition, the signals of a gal-
00
loyl moiety were observed from the chemical shifts at dH
group was located at C-4 of the rhamnopyranosyl unit
1
00
7
(
.08 (2H) in the H NMR spectrum, and at d 110.4
due to the downfield shift of C-4 and the upfield shifts
C
1
3
00
00
2C), 121.6, 139.9, 146.5 (2C), and 168.0 in the C NMR
of C-3 and C-5 by +0.8, ꢀ1.7, and ꢀ1.8 ppm, respec-
tively. The HMBC experiments provided further confirma-
tion of the structure by detection of long range correlations
spectrum. Therefore, the structure of compound 8 was
assumed to be a galloyl derivative of violutoside (7). This
00
00
000
00
0
0
functional group was assigned to be linked to C-4 , since
between (i) H-4 and C-7 , (ii) H-1 and C-6 , and (iii) H-1
0
0
the chemical shift of H-4 appeared downfield at d 5.12,
and C-2 as shown in Fig. 2. Therefore, the structure of
H
00
00
00
and the chemical shifts of C-4 and C-5 were significantly
compound 9 was determined to be 4 -O-galloyl-benzyl-O-
changed to d 72.8 and 64.9, respectively, as compared to
a-L-rhamnopyranosyl-(1 ! 6)-b-D-glucopyranoside.
C
violutoside (7). The assignment was supported by the
results from analyses of COSY, HSQC and HMBC exper-
iments. In the HMBC spectrum, three bond correlations
3. Concluding remarks
0
0
000
00
were found between (i) H-4 and C-7 , (ii) H-1 and C-
6
0
0
, and (iii) H-1 and C-2 as illustrated in Fig. 1. Accord-
Cladogynos is a monotypic genus in the tribe Epiprineae,
together with the genera Cleidiocarpon, Epiprinus, and Koi-
lodepas which is found in Thailand. Only the chemical inves-
tigations of C. orientalis have been reported. Among the
compounds isolated from this species, the present study
reported polar compounds bearing galloyl moieties attached
to the sugar part, which were quite rare to find in plants.
ingly the structure of compound 8 was elucidated to be
0
0
-O-galloyl-violutoside.
4
The molecular formula of compound 9 was determined
as C H O by HR-FAB mass spectrometric analysis.
2
6
32 14
The NMR spectroscopic data displayed the presence of
characteristic signals of benzyl alcohol part as an aglycone
from the chemical shifts of five protons in the aromatic
region at dH 7.24 (2H, m), 7.27 (1H, m), 7.38 (2H, br d,
00
Other examples include: apigenin 6-C-(2 -O-galloyl)-b-D-
00
glucopyranoside (2), apigenin 8-C-(2 -O-galloyl)-b-D-gluco-
00
00
J = 7.8 Hz), and two methylene protons at dH 4.65 and
pyranoside (3), 4 -O-galloyl-violutoside (8) and 4 -O-gal-
loyl-benzyl-O-a-L-rhamnopyranosyl-(1 ! 6)-b-D-glucopyr-
anoside (9). Compounds 2 and 3 have previously been
isolated from Terminalia catappa (Combretaceae) (Lin
et al., 2000), and from Pelargonium reniforme (Geraniaceae)
1
4
.88 (each 1H, d, J = 11.8 Hz) in the H NMR spectrum,
together with the results from the chemical shifts of five
(
Latt e´ et al., 2002). Only compound 3 has been identified
H
O
before from the family Euphorbiaceae, Conceveiba guianen-
sis (tribe Acalyphae) (Braca et al., 2004). The occurrence of
the constituents with galloyl substitution might be useful
for further chemotaxonomic studies of tribe Epiprineae.
HO
HO
H
O
H
O
H
H
H
O
H
HO
O
O
H
OH
HO
HO
OH
H
OH
H
O
OMe
4. Experimental
Fig. 1. The significant HMBC correlation of compound 8.
4.1. General procedures
NMR spectra were recorded in CD OD using a JEOL
3
1
H
O
O
JNM a-400 spectrometer (400 MHz for H NMR and
1
3
HO
HO
Me
100 MHz for C NMR). UV spectra were recorded on a
Shimadzu UV-1700 spectrophotometer. MS values were
obtained on a JEOL JMS-SX 102 spectrometer. Optical
rotations were measured with a Jasco P-1020 digital polar-
imeter. For column chromatography, silica gel 60 (70–
230 mesh, GE0049, Scharlau Chemie SA), RP-18 (50 lm,
O
H
O
O
HO
HO
O
HO
OH
H
OH
H
H
H
OH
Fig. 2. The significant HMBC correlation of compound 9.

T. Kanchanapoom / Phytochemistry 68 (2007) 692–696
695
YMC), and Diaion HP-20 (Mitsubishi Chemical Industries
Table 2
NMR spectroscopic data of compound 9
Co. Ltd.) were used. Preparative HPLC (Jasco PU-980
pump) was carried out on an ODS column (250 · 20 mm
i.d., YMC) with a Jasco RI-2031 refractive index detector.
The flow rate was 6 ml/min. The solvent systems were: (I)
No.
d
C
d
H
1
138.8
2, 6
129.3 7.38 (2H, br d, J = 7.8 Hz)
129.2 7.24 (2H, m)
128.8 7.27 (1H, m)
3
4
7
, 5
EtOAc–MeOH (9:1); (II) EtOAc–MeOH–H O (40:10:1);
2
(
III) EtOAc–MeOH–H O (70:30:3); (IV) 10–80% aqueous
2
71.8 4.65 (1H, d, J = 11.8 Hz) 4.88 (1H, d, J = 11.8 Hz)
MeOH; (V) 10% aqueous MeCN; (VI) 15% aqueous
MeCN; (VII) 20% aqueous MeCN; and (VIII) 40% aque-
ous MeOH. The spraying reagent used for TLC was 10%
H SO in 50% EtOH.
Glc
0
1
2
3
4
5
6
103.2 4.35 (1H, d, J = 7.8 Hz)
75.2 3.26 (1H, dd, J = 8.3, 7.8 Hz)
78.1 3.31 (1H, dd, J = 9.3, 8.3 Hz)
71.6 3.33 (1H, dd, J = 9.3, 9.3 Hz)
76.9 3.39 (1H, m)
0
0
0
0
2
4
4
.2. Plant material
0
67.9 3.70 (1H, dd, J = 11.3, 5.6 Hz) 4.02 (1H, br d,
J = 11.3 Hz)
The aerial portion of C. orientalis Zipp. Ex Span. was
Rha
collected in March 2005 from Chaiyaphum Province, Thai-
land. The identification of the plant was confirmed by Dr.
Thaweesak Thitimetharoch, Department of Pharmaceuti-
cal Botany and Pharmacognosy, Faculty of Pharmaceutical
Sciences, Khon Kaen University. A voucher specimen (TK-
PSKKU-0055) was deposited in the Herbarium of the Fac-
ulty of Pharmaceutical Sciences, Khon Kaen University.
0
0
00
0
0
0
0
0
1
2
3
4
5
6
102.3 4.84 (1H, br s)
72.4 3.94 (1H, br d, J = 3.4 Hz)
70.6 3.98 (1H, dd, J = 9.8, 3.4 Hz)
75.7 5.10 (1H, dd, J = 9.8, 9.8 Hz)
68.2 3.96 (1H, m)
0
0
0
18.0 1.15 (3 H, d, J = 6.3 Hz)
Galloyl moiety
0
1
2
3
4
7
121.6
0
0
0
00
00
00
000
000
, 6
, 5
110.3 7.09 (2H, br s)
4
.3. Extraction and isolation
146.5
139.9
168.2
The aerial portion of C. orientalis (3.4 kg) was extracted
000
three times with hot MeOH (8 l for each extraction, under
reflux). The MeOH extract was concentrated in vacuo to
give a powder (381.9 g). This residue was suspended in
H O (1.0 l), and then partitioned with Et O (1.0 l) and n-
six fractions (fr. e-1 to e-6). Fraction e-4 provides the major
2
2
BuOH (1.0 l), successively. The n-BuOH soluble fraction
106.4 g) was subjected to highly porous synthetic resin col-
constituent, compound 7 (1.2 g) by precipitation.
(
umn chromatography (Diaion HP-20), and eluted with
H O, MeOH and (CH ) CO, successively. The fraction
4.4. Violutoside (7)
2
3 2
2
D
9
ꢂ
eluted with MeOH (65.9 g) was subjected to a column of
silica gel using solvent systems I (6.5 l), II (6.0 l) and III
Amorphous powder, ½aꢁ ꢀ 50:4 (MeOH c 0.50); UV
1
13
k
MeOH (nm): 284; for H and C NMR (CD OD)
3
max
(
4.0 l), to provide six fractions (Fr. a–f), monitored by
spectra, see Table 1; negative HR-FAB-MS, m/z:
445.1357 M–H]ꢀ (calcd. for C H O , 445.1346).
TLC. Fraction b (32.1 g) was subjected to a column of
RP-18 using solvent system IV to give nine fractions (fr.
b-1 to b-9). Fraction b-7 was purified by preparative
HPLC-ODS with solvent systems VII and VIII, respec-
tively, to afford compounds 2 (65.9 mg) and 3 (43.1 mg).
Fraction c (4.8 g) was subjected to a column of RP-18 using
solvent system V to provide seven fractions (fr. c-1 to c-7).
Fraction c-3 was purified by preparative HPLC-ODS with
solvent system V to give compounds 4 (9.0 mg) and 5
1
9
25 12
4.5. Acid hydrolysis of violutoside (7)
A solution of compound 7 (20 mg) in 1,4-dioxane (1 ml)
and 5% H SO (1 ml) was heated at 90 ꢁC for 3 h. After
2
4
cooling, H O (2 ml) was added and the whole extracted
2
with EtOAc. The aqueous layer was neutralized with satu-
rated NaHCO and concentrated to dryness. The residue
3
(
20.9 mg). Fraction c-5 was purified by preparative
HPLC-ODS using solvent system VI to provide compound
(123.5 mg). Similarly, fraction c-6 was purified by pre-
was applied to a silica gel column, using CHCl –MeOH–
3
H O (40:10:1) as solvent system to obtain L-arabinose
2
2
d
9
29
d
1
(2 mg;½aꢁ þ 98:8) and D-glucose (3 mg;½aꢁ þ 49:5) in
parative HPLC-ODS using solvent system VII to afford
compounds 6 (35.2 mg) and 9 (5.6 mg). Fraction d (6.5 g)
was subjected to a column of RP-18 using solvent system
IV, giving nine fractions (fr. d-1 to d-9). Fraction d-8 was
semi-purified by preparative HPLC-ODS using solvent sys-
tem VII, and followed by solvent system VIII to provide
compound 8 (9.8 mg). Finally, fraction e was separated
by a column of RP-18 using solvent system IV to provide
comparison with authentic samples.
00
4.6. 4 -O-galloyl-violutoside (8)
2
D
8
ꢂ
Amorphous powder, ½aꢁ þ 19:4 (MeOH c 0.63); UV
1
13
k
MeOH (nm): 279.5; for H and C NMR (CD OD)
3
max
spectra, see Table 1; negative HR-FAB-MS, m/z:
ꢀ
597.1457 [M–H] (calcd. for C H O , 597.1456).
2
6
29 16

696
T. Kanchanapoom / Phytochemistry 68 (2007) 692–696
0
0
4
.7. 4 -O-galloyl-benzyl-O-a-L-rhamnopyranosyl-(1 ! 6)-
roots of Thai medicinal plant, Trigonostemon reidioides. Tetrahedron
Letters 43, 2941–2943.
Kanchanapoom, T., Chumsri, P., Kasai, R., Otsuka, H., Yamasaki, K.,
b-D-glucopyranoside (9)
2
003. Lignan and megastigmane glycosides from Sauropus androgynus.
2
D
8
ꢂ
Amorphous powder, ½aꢁ ꢀ 25:7 (MeOH c 0.37); UV
Phytochemistry 63, 985–988.
1
13
k
MeOH (nm): 277; for H and C NMR (CD OD):
Table 2; negative HR-FAB-MS, m/z: 567.1721 [M–H]
calcd. for C H O , 567.1714).
Kanlayavattanakul, M., Ruangrungsi, N., Watanabe, T., Kawahata, M.,
Therrien, B., Yamaguch, K., Ishikawa, T., 2005. ent-Halimane
diterpenes and a guaiane sesquiterpene from Cladogynos orientalis.
Journal of Natural Products 68, 7–10.
max
3
ꢀ
(
2
6
31 14
Latt e´ , K.P., Ferreira, D., Venkatraman, M.S., Kolodziej, H., 2002. O-
Galloyl-C-glycosylflvones from Pelargonium reniforme. Phytochemis-
try 59, 419–424.
Lin, Y.-L., Kuo, Y.-H., Shiao, M.-S., Chen, C.-C., Ou, J.-C., 2000.
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Acknowledgements
This study was financially supported from The Thailand
Research Fund and Commission of Higher Education,
Thailand. Author also thanks Mr. Bunlert Khamya and
Mr. Bamrung Thavinchiua of the Department of Pharma-
ceutical Botany and Pharmacognosy, Faculty of Pharma-
ceutical Sciences, Khon Kaen University, for obtaining
the plant material.
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