Phenolic compounds from the leaves of Cornus controversa

Article abstract of DOI:10.1016/S0031-9422(99)00502-6

Two novel phenolic compounds from the leaves of Cornus controversa (Cornaceae) were characterized as (-)-2,3-digalloyl-4(E)-caffeoyl-L-threonic acid and (-)-2-galloyl-4-(E)-caffeoyl-L-threonic acid, using spectroscopic methods. (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0031-9422(99)00502-6

Phytochemistry 53 (2000) 405±407
www.elsevier.com/locate/phytochem
Phenolic compounds from the leaves of Cornus controversa
Dongho Leea, Shin-Jung Kangb, Seung-Ho Leec, Jaiseup Rob, Kyongsoon Leeb,
A. Douglas Kinghorna,*
aProgram for Collaborative Research in the Pharmaceutical Sciences and Department of Medicinal Chemistry and Pharmacognosy, College of
Pharmacy, University of Illinois at Chicago, Chicago, IL 60612, USA
bCollege of Pharmacy, Chungbuk National University, Cheongju 360-763, South Korea
cCollege of Pharmacy, Yeungnam University, Kyongsan 712-749, South Korea
Received 11 May 1999; accepted 16 September 1999
Abstract
Two novel phenolic compounds from the leaves of Cornus controversa (Cornaceae) were characterized as ( )-2,3-digalloyl-4-
(E)-ca€eoyl-L-threonic acid and ( )-2-galloyl-4-(E)-ca€eoyl-L-threonic acid, using spectroscopic methods. # 2000 Elsevier
Science Ltd. All rights reserved.
Keywords: Cornus controversa; Cornaceae; Leaves; Phenolic compounds; Galloylca€eoylthreonic acids; Kaempferol 3-O-a-L-rhamnoside
1. Introduction
2. Results and discussion
Cornus controversa Hemsl. (Cornaceae) is a tree
found in Korea and the People's Republic of China
which has been used as an astringent and a tonic (Lee,
1993). Various ¯avonoids, phenolic compounds and
terpenoids have been reported from this plant (Jang et
al., 1998; Kurihara & Kikuchi, 1972; Lee, Lee, Chung,
Ro, & Lee, 1995; Nakaoki & Morita, 1958; Nishino,
Kobayashi, & Fukushima, 1988; Tanaka, 1971). In
this investigation, four additional phenolic compounds,
( )-2,3-digalloyl-4-(E)-ca€eoyl-L-threonic acid (1),
( )-2-galloyl-4-(E )-ca€eoyl-L-threonic acid (2), ( )-4-
(E)-ca€eoyl-L-threonic acid (3) and kaempferol 3-O-a-
L-rhamnoside (Matthes, Luu, & Ourisson, 1980), have
been obtained from the leaves of C. controversa. The
structure elucidation of the novel compounds 1 and 2
was performed by spectral data interpretation. The un-
Compound 1, [a]2D0 388, was obtained as an amor-
phous dark brown powder and gave a dark blue color
in the FeCl3 test. The negative-ion ESMS showed a
1
quasimolecular ion at m/z 601. In the H NMR spec-
trum of 1, two proton singlets (dH 6.96 and 7.03) cor-
responded to two galloyl groups (Lee et al., 1995).
Also, a broad singlet at dH 7.17, a doublet of doublets
ꢀJ ˆ 8:5 and 1.5 Hz) at dH 7.07, and a doublet ꢀJ ˆ
8 Hz† at dH 6.85, which were observed as an AMX sys-
tem, and two ole®nic doublets ꢀJ ˆ 15:9 Hz, trans ),
which were observed at dH 7.60 and 6.43, indicated the
presence of a ca€eoyl group (Han & Nahrstedt, 1993).
The signals coupled to each other at dH 5.46
ꢀJ ˆ 3:2 Hz), dH 5.86 (multiplet), dH 4.50 ꢀJ ˆ
5:1 and 11:6 Hz† and dH 4.56 ꢀJ ˆ 7:3 and 11:6 Hz† and
the carbonyl carbon signal at dC 168.3, suggested the
presence of threonic acid (Han & Nahrstedt, 1993).
The positions of substitution of threonic acid were
assigned using the HMBC technique as C-2 and C-3
(two galloyls) and C-4 (ca€eoyl). Alkaline hydrolysis
of 1 yielded gallic acid, ca€eic acid, and L-threonic
acid. The 1H NMR spectral data of gallic acid and
ca€eic acid and the optical rotation of L-threonic acid
1
ambiguous assignments of the H NMR signals of the
known compound 3 (Han & Nahrstedt, 1993) are also
presented.
* Corresponding author.
0031-9422/00/$ - see front matter # 2000 Elsevier Science Ltd. All rights reserved.
PII: S0031-9422(99)00502-6

406
D. Lee et al. / Phytochemistry 53 (2000) 405±407
Table 1
were consistent with literature values (Han & Nahr-
stedt, 1993; Lee et al., 1995). Therefore, the structure
of 1 was assigned as ( )-2,3-digalloyl-4-(E)-ca€eoyl-L-
threonic acid.
a
1H and 13C NMR data for compounds 1 and 2 in DMSO-d6
1
2
Compound 2, [a ]2D0 278, was obtained as an amor-
phous dark brown powder and gave a dark blue color
in the FeCl3 test. The negative-ion ESMS showed a
Carbon
dH
dC
dH
dC
1
2
3
168.3
71.0 5.33, brs
172.7
73.0
70.0
65.3
5.46, d (3.2)
5.86, m
1
quasimolecular ion at m/z 449. The H NMR spectrum
69.5 4.53, m
62.0 4.31, dd (6.6, 11.0)
4.41, dd (6.3, 11.0)
of 2 was similar to that of 1 except for the absence of
one galloyl signal and an observed up®eld shift of the
H-3 signal at dH 4.53 of the threonic acid moiety.
Analysis of the ESMS, 1H, and 13C NMR data
suggested that compound 2 is a derivative of 1 missing
one galloyl group at the C-3 position of threonic acid.
The positions of the galloyl and ca€eoyl substituents
were con®rmed to be at C-2 and C-4 on threonic acid,
respectively, using the HMBC technique. The products
of alkaline hydrolysis of 2 were also the same as those
of 1. The structure of 2 was therefore identi®ed as ( )-
2-galloyl-4-(E )-ca€eoyl-L-threonic acid (2).
4.50, dd (5.1, 11.6)
4.56, dd (7.3, 11.6)
Ca€eoyl
1'
2'
3'
4'
5'
6'
7'
8'
125.4
127.6
115.3
146.8
149.7
116.5
123.3
148.2
114.2
165.9
7.17, brs
114.6 7.07, brs
145.4
148.5
6.85, d (8)
115.8 6.80, d (8.5)
122.0 6.98, dd (1.6, 8.3)
146.5 7.71, d (15.9)
112.9 6.38, d (16)
165.9
7.07, dd (1.5, 8.5)
7.60, d (15.9)
6.43, d (15.9)
9'
2-Galloyl
10
118.8
121.1
110.2
146.5
140.0
165.5
1
20, 60
30, 50
40
6.96, s
7.03, s
108.7 7.10, s
145.3
138.7
The H NMR spectrum of 3 was also similar to that
of 1 except for the absence of two galloyl groups and
the consequent up®eld shift of two proton signals of
the threonic acid moiety. The signals at dH 4.09
ꢀJ ˆ 2:4 Hz), dH 4.05 ꢀJ ˆ 2:5 and 6.3 Hz), and dH
4.12 ꢀJ ˆ 6:4 Hz† were assigned unambiguously to the
C-2, C-3, and C-4 positions of threonic acid, respect-
ively, by 2D NMR techniques.
70
165.5
3-Galloyl
11
118.6
108.9
145.3
138.5
164.9
21, 61
31, 51
41
71
a TMS was used as the internal standard; chemical shifts are
shown in the d scale with J values (Hz) in parentheses.
spectrometer and a GE Omega 500 MHz spectrometer.
Mass spectra were obtained on a HPLC-ESMS system
(Hewlett-Packard 5989B mass spectrometer, 59987A
electrospray interface) and a Finnigan MAT 90 instru-
ment (70 eV).
3.1. Plant material
Fresh leaves of Cornus controversa were collected in
Cheongju, Korea, in May 1992. A voucher specimen
has been deposited in the College of Pharmacy,
Chungbuk National University, Cheongju, Korea.
3.2. Extraction and isolation
The fresh plant material (8 kg) was cut and
extracted with 80% aqueous acetone (3 Â 10 L). The
extracts were combined and concentrated in vacuo at
408C. The resultant precipitation was removed by ®l-
tration and the ®ltrate was concentrated again. Frac-
tionation was initiated by column chromatography
over Sephadex LH-20 as stationary phase using a
H2O±MeOH gradient as mobile phase to a€ord three
fractions. Again using a H2O±MeOH gradient as
3. Experimental
MPs uncorr.; optical rotations: Perkin-Elmer model
241 polarimeter; UV: Beckman DU-7 spectrometer;
IR: ATI Mattson Genesis series FT-IR spectropho-
1
tometer. H, 13C, COSY, HMQC and HMBC NMR
experiments were conducted on a Bruker DPX-300

D. Lee et al. / Phytochemistry 53 (2000) 405±407
407
mobile phase, fraction 2 was passed sequentially over
MCI-gel CHP 20P and Sephadex LH-20, to a€ord
compounds 1 (20 mg) and 2 (15 mg). Fraction 3 from
the initial column was puri®ed further using MCI-gel
CHP 20P as stationary phase with a H2O±MeOH gra-
dient as mobile phase to a€ord compound 3 (450 mg)
and ®ve subfractions. Of these, subfraction 3 was chro-
matographed on TSK-gel Toyopearl HW 40F and
Cosmosil 75 C18-OPN with a H2O±MeOH gradient
and EtOH, respectively, to a€ord kaempferol 3-O-a-L-
rhamnoside (30 mg). This compound was identi®ed by
comparison of its physical and spectroscopic data to
published values (Matthes et al., 1980).
(1H, d, J ˆ 15:9, H-7'); HMBC correlations: H-2/C-1;
H-3/C-4; H-4/C-3, C-9'; H-7'/C-1', C-2', C-6', C-9';
H-8'/C-1', C-9', 13C NMR and MS, consistent with lit-
erature values (Han & Nahrstedt, 1993).
3.6. Hydrolysis of 1±3
Samples of 1±3 (10 mg) were dissolved in MeOH,
with 1% NaOH added, and then each mixture was
stirred for 4 h at 208C. The reactants were acidi®ed
with 1 N HCl and separated into organic-soluble and
water-soluble fractions by partitioning with EtOAc.
The EtOAc-soluble fraction was puri®ed by passage
over Sephadex LH-20 and then the resultant gallic
acid and ca€eic acid were subjected to spectroscopic
evaluation (Han & Nahrstedt, 1993; Lee et al., 1995).
The water-soluble fraction was dried, and the resultant
L-threonic acid was subjected to an optical rotation
measurement (Han & Nahrstedt, 1993).
3.3. ( )-2,3-Digalloyl-4-(E )-ca€eoyl-L-threonic acid
(1)
Amorphous dark brown powder; mp 215±2178; [a ]D20
MeOH
max
388 (c 0.05, MeOH); UV l
nm (log E): 220
1
(2.79), 282 (2.45), 331 (2.22); IR nmax (KBr) cm
:
3420, 1700, 1624; 1H and 13C NMR data of 1, see
Table 1; HMBC correlations: H-2/C-1, C-70; H-3/C-
71; H-4/C-9; H-7'/C-1', C-6'; H-8'/C-1', C-9'; H-20,
60/C-70; H-21, 61/C-71; ESMS m/z: [M±H] 601;
EIMS (70 eV) m/z (rel. int.): 170 (100), 163 (10), 153
(78), 136 (10), 126 (26).
Acknowledgements
The authors thank Dr. Darrick S.H.L. Kim, Dr.
Dong Seon Kim, Mr. Soobong Park and Mr. Nam-
Cheol Kim, Department of Medicinal Chemistry and
Pharmacognosy, University of Illinois at Chicago
(UIC), for helpful discussions. Also, we are grateful to
Dr. Young Geun Shin and Mr. R. Dvorak, Depart-
ment of Medicinal Chemistry and Pharmacognosy,
UIC, for the mass spectral data and the Research
Resources Center, UIC, for providing assistance and
spectroscopic equipment.
3.4. ( )-2-Galloyl-4-(E)-ca€eoyl-L-threonic acid (2)
Amorphous dark brown powder; mp 128±1308, [a ]D20
MeOH
max
278 (c 0.09, MeOH); UV l
nm (log E): 255
1
(4.98), 294 (5.28), 330 (5.27); IR nmax (KBr) cm
:
3367, 1697, 1609; 1H and 13C NMR data of 1, see
Table 1; HMBC correlations: H-2/C-1, C-70; H-4/C-9';
H-7'/C-1, C-9'; H-8'/C-2', C-6', C-9'; H-20, 60/C-70;
ESMS m/z: [M±H] 449; EIMS (70 eV) m/z (rel. int.):
170 (87), 163 (100), 153 (79), 136 (12), 135 (40), 125
(27).
References
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