Biomimic transformation of resveratrol

Article abstract of DOI:10.1016/j.tet.2005.08.023

Resveratrol was treated with several kinds of peroxidases and inorganic reagents so as to prepare ε-viniferin. Among several inorganic reagents, which were investigated in this study, thallium(III) nitrate in methanol gave (±)-ε-viniferin in the yield of 68%. On the other hand, peroxidases did not lead to ε-viniferin, but some stilbenedimers such as pallidol, resveratrol trans-dehydrodimer, and leachianol F were obtained.

Full text of DOI:10.1016/j.tet.2005.08.023

Tetrahedron 61 (2005) 10285–10290
Biomimic transformation of resveratrol
Yoshiaki Takaya, Kenji Terashima, Junko Ito, Yue-Hua He, Maki Tateoka, Naho Yamaguchi
*
and Masatake Niwa
Faculty of Pharmacy, Meijo University, Tempaku, Nagoya, 468-8503, Japan
Received 20 July 2005; revised 4 August 2005; accepted 5 August 2005
Available online 24 August 2005
Abstract—Resveratrol was treated with several kinds of peroxidases and inorganic reagents so as to prepare 3-viniferin. Among several
inorganic reagents, which were investigated in this study, thallium(III) nitrate in methanol gave (G)-3-viniferin in the yield of 68%. On the
other hand, peroxidases did not lead to 3-viniferin, but some stilbenedimers such as pallidol, resveratrol trans-dehydrodimer, and leachianol
F were obtained.
q 2005 Elsevier Ltd. All rights reserved.
1
. Introduction
In our previous papers, we reported the transformation from
C)-3-viniferin (2a) to (K)-vitisin B (4), (C)-vitisin C (5),
(C)-hopeaphenol (3a), and (K)-isohopeaphenol (6) by
(
There are many oligostilbenes isolated from Vitaceaeous
plants, and they are generated from a stilbene, resveratrol
2
,3
using horseradish peroxidase, and from (C)-3-viniferin
(2a) to (C)-ampelopsin A (7), (C)-ampelopsin B (8), (K)-
ampelopsin D (9), and (C)-ampelopsin F (10) under acidic
(
from plants of other families, such as Dipterocarpaceae,
1). Some of them are the enantiomers of oligostilbenes
1
Leguminosae, Cyperaceae, and Gnetaceae. For instance,
3,4
conditions. But we have never obtained 3-viniferin (2) by
(
C)-3-viniferin (2a), a resveratrol dimer, and (C)-hope-
the transformation of resveratrol (1). Resveratrol (1) is
supposed to dimerize oxidatively by peroxidase or
phenoloxidase in plant cells to afford 3-viniferin (2).
Langcake and Pryce reported the treatment of resveratrol
aphenol (3a), a resveratrol tetramer, are obtained from
Vitaceaeous plants, but their enantiomers (2b and 3b,
respectively), are from plants of other families. It is
estimated that the stereochemistry of the oligostilbenes
from Vitaceaeous plants are initially regulated when two
molecules of resveratrol (1) oxidatively couple to form (C)-
5
(1) with horseradish peroxidase. According to their result,
3-viniferin (2) was not obtained by the reaction but
resveratrol-trans-dehydrodimer (11) was. Sako et al. also
investigated the nonenzymatical oxidative coupling of
resveratrol with several inorganic oxidative reagents, but
3-viniferin (2a), and based on the stereochemistry of 2a,
further biotransformations are estimated to occur (Fig. 1).
Figure 1. Plausible biogenesis of oligostilbenes.
Keywords: Resveratrol; Peroxidase; 3-Viniferin; Thallium(III) nitrate.
*
Corresponding author. Tel.: C81 52 832 1781; fax: C81 52 834 8090; e-mail: masa@ccmfs.meijo-u.ac.jp
0040–4020/$ - see front matter q 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2005.08.023

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Y. Takaya et al. / Tetrahedron 61 (2005) 10285–10290
they reported that the formation of 3-viniferin (2) was not
observed.
2.2. Treatment of resveratrol (1) with oxidizing reagents
6
Resveratrol (1) was treated with several inorganic oxidizing
reagents in certain solvents as shown in Table 1. These
In this study, to substantiate the hypothesis to form (C)-3-
viniferin from resveratrol (1) in Vitaceaeous plants, we
investigated the participation of peroxidase and inorganic
oxidizing reagents in oligomerization of resveratrol (1). As
the result, the treatment of thallium(III) nitrate led to
8
reagents are usually used for phenol oxidation. Among
them, thallium(III) nitrate (TTN) in methanol at K50 8C
transformed resveratrol (1) to (G)-3-viniferin (2), consum-
ing 30% of the starting material, within 5 min along with
56% of recovered resveratrol (1). But when this reaction
was carried out at over 0 8C, the reaction gave just a
complex mixture. The product obtained by the reaction at
K50 8C was analyzed by HPLC equipped with CD detector
using a chiral column. As the result, the product was
revealed to be a mixture of (C)- and (K)-3-viniferins (2a
and 2b) as shown in Figure 2. Potassium hexacyanofer-
rate(III) is also a good reagent to form 3-viniferin (2), and
3
-viniferin (2) in good yield, and potassium hexacyano-
ferrate, and iron(III) chloride also gave 2, whereas no
commercially available peroxidases, which were tested in
this study, provided 3-viniferin (2).
2
. Results and discussion
2
.1. Synthesis of resveratrol (1)
In this study, synthetic resveratrol (1) under the procedure
shown in Scheme 1 was used for the transformation with
oxidizing reagents. The starting material, methyl 3,5-
dihydroxybenzoate (13), was tert-butyldimethylsilylated
followed by reduction of the methoxy carbonyl group with
lithium aluminum hydride to afford 3,5-bis(tert-butyldi-
methylsilyloxy)benzyl alcohol (14). Compound 14 was
converted to the benzyl chloride (15), and 15 was
transformed into phosphonate (16). Resveratrol (1) was
obtained by the reaction of 16 and 4-tert-butyldimetylsilyl-
7
oxybenzaldehyde (18), which was prepared from
4-hydroxybenzaldehyde (17), followed by deprotection.
No cis-isomer of 1 was found in this preparation.
Figure 2. Analysis of the reaction mixture of TTN treatment.
Scheme 1. Synthesis of resveratrol (1). Reaction conditions: (a) TBSCl, imidazole, DMF, rt; (b) LiAlH
P(OEt) , NaI; (e) TBSCl, imidazole, DMF, rt; (f) 16 NaH, THF, K55 8C; (g) concd HCl, EtOH, rt.
4
, THF, 0 8C; (c) p-TsCl, Et
3 2 2
N, DMAP, CH Cl , rt; (d)
3
Table 1. Treatment of resveratrol (1) with oxidizing reagents
Reagents
Solvent
Temperature (8C)
Time
2 (%)
11 (%)
12 (%)
Tl(NO
Tl(NO
3
)
)
3
MeOH
MeOH
MeOH
MeOH
Acetone
K50
K30
25
K50
25
25
5 min
5 min
10 min
26 h
20 h
24 h
30.1
3.9
21.9
3.7
0.9
—
—
—
22.5
8.4
97.0
91.0
—
—
15.7
—
1.5
9.0
3
3
K
3
[Fe(CN)
Ce(SO
FeCl
MnO
6
]
4
)
2
3
2
CH
2
Cl
2
The percentage in this table means the ‘degree of transformation (%DT)’. See Section 3.

Y. Takaya et al. / Tetrahedron 61 (2005) 10285–10290
10287
Scheme 2. Hypothesis for the dimerization of resveratrol (1).
cerium(IV) sulfate, and iron(III) chloride afforded 3-vini-
ferin (2), though the yields were low. On the other hand,
iron(III) chloride, and manganese(IV) oxide mainly gave
2.3. Treatment of resveratrol (1) with peroxidases
3-Viniferin (2) is supposed to generate from resveratrol (1)
via oxidative coupling with peroxidase or phenoloxidase via
the proposed intermediates shown in Scheme 2. In order to
investigate the participation of peroxidase in the formation
of 3-viniferin (2), resveratrol (1) was treated with several
commercially available peroxidases in two kinds of
solvents. In this study, we used peroxidases from soybean,
fungus (Arthromyces ramosus), and horseradish. The
reactions were carried out at 27 8C, because when we tried
it at 37 8C, the reaction gave only a complex mixture. As the
result, 3-viniferin (2) was not obtained by using any of the
peroxidases tested, though several resveratrol dimers were
obtained (Table 2). In all cases, (G)-resveratrol-trans-
(
G)-resveratrol-trans-dehydrodimer (11). The mechanism
for the dimerization of resveratrol (1) is suggested as shown
in Scheme 2. When the reaction occurs in a short period, as
in the case using TTN, the intermediate [A] would generate
predominantly and then it reacts with intermediate [B] to
afford 3-viniferin (2). Resveratrol-trans-dehydrodimer (11)
is supposed to form by the reaction of intermediate [B] and
[
C]. On the basis of our result obtained when we used
iron(III) chloride, and mangan(IV) oxide, and the result
6
reported, during the long reaction time and at compara-
tively higher temperature when 11 was mainly provided,
sterically less hindered intermediate [C] would be easily
involved in the reaction. But an appropriate account for the
distinction of the reactivity cannot be made only with this
evidence (Table 1).
5
9,10
dehydrodimer (11) and (G)-pallidol (12) were major
products and compounds 20 and 21 (Fig. 3), all of which
were estimated to form via two molecules of intermediate
Figure 3. Products obtained by the treatment of resveratrol (1) with oxidizing reagents and peroxidases.
Table 2. Diversity of the products obtained by the treatment of resveratrol (1) with peroxidases
Origins of peroxidases
Solvent
11 (%)
12 (%)
20 (%)
21 (%)
Glycine max
aq Acetone
aq Acetone
aq Acetone
aq EtOH
21.4
18.4
12.6
12.1
13.1
7.2
7.4
10.2
9.5
1.8
4.6
—
5.2
4.6
—
—
—
8.6
8.2
Arthromyces ramosus
Horseradish
Glycine max
Arthromyces ramosus
aq EtOH
5.0
The percentage in this table means the ‘degree of transformation (%DT)’. See Section 3.

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Y. Takaya et al. / Tetrahedron 61 (2005) 10285–10290
[
B] in Scheme 2, were obtained as minor products.
97.5%). Compound 23 (109 g) was dissolved to THF
(350 mL), and lithium aluminum hydride (5.6 g) was added
at 0 8C. After 20 h, the reaction mixture was extracted with
ethyl acetate, and the ethyl acetate layer was washed with
water and brine, dried over anhydrous magnesium sulfate,
and evaporated. The residue was purified by silica-gel
column chromatography using hexane/ethyl acetate 95:5 as
an eluent to give alcohol 14 (89.9 g, 88.7%).
Accordingly, some specific oxidizing enzymes would be
involved to form 3-viniferin (2) in the plants. The reaction
time in each case was short enough (0.5–1.5 h) to form
3
-viniferin (2), if the reaction proceeded like that with
inorganic oxidizing reagents. Furthermore, the pattern of the
reaction was the same as those, which were observed when
(
form (K)-vitisin B, (C)-vitisin C, (C)-hopeaphenol, and
C)-3-viniferin (2a) was treated horseradish peroxidase to
2
K)-isohopeaphenol. So, judging from the evidence, no
,3
1
3,5-Bis(tert-butyldimetylsilyloxy)benzoate (23). H NMR
(
intermediate [A] seemed to be generated in those enzymatic
reactions, and the reaction proceeded via the less hindered
intermediates [B] and [C]. Because resveratrol-trans-
dehydrodimer (11) was resulted from intermediate [B] and
(600 MHz, CDCl ) d 7.10 (2H, d, JZ2.2 Hz), 6.50 (1H, t,
3
JZ2.2 Hz), 3.86 (3H, s), 0.96 (18H, s), 0.18 (12H, s); EI-
MS m/z 396 (M ).
C
1
[
G (20), and a mixture of (G)-quadrangularin B and C
C], and other products, a mixture of (G)-leachianols F and
3,5-Bis(tert-butyldimetylsilyloxy)benzyl alcohol (14).
H
1
1
NMR (400 MHz, CDCl ) d 6.44 (2H, d, JZ2.2 Hz), 6.23
3
9
21), were formed via two molecules of intermediate [B].
(
(1H, t, JZ2.2 Hz), 4.54 (2H, s), 0.95 (18H, s), 0.17 (12H, s);
EI-MS m/z 368 (M ).
C
3. Experimental
3.2.2. 3,5-Bis(tert-butyldimetylsilyloxy)benzyl chloride
(15). p-Toluenesulfonyl chloride (44.4 g) was added to the
CH Cl solution (400 mL) of alcohol (14, 71.4 g), triethyl-
3
.1. General
2
2
amine (32.5 mL), and 4-dimethylaminopyridine (DMAP)
(11.9 g) at 0 8C. The reaction solution was stirred at rt for
12 h, and extracted with chloroform. The organic layer was
washed with water and brine, dried over anhydrous
magnesium sulfate and evaporated. The crude product was
purified by silica-gel chromatography using hexane/ethyl
acetate 95:5 as an eluent to give chloride 15 (45.7 g, 61.0%).
UV and IR spectra were recorded on JASCO Ubest V-560
cell length 10 mm) and FT-IR-410 spectrophotometers,
respectively. Optical rotations were measured with a
(
1
JASCO P-1020 polarimeter (cell length 100 mm). H and
C NMR spectra were recorded on JEOL ALPHA-600 ( H:
1
3
1
1
00 MHz and C: 150 MHz), JEOL ECP-500 ( H:
3
1
6
5
(
1
00 MHz and C: 125 MHz), and JEOL ALPHA-400
3
1
13
H: 400 MHz and C: 100 MHz) spectrometers. Chemical
1
3,5-Bis(tert-butyldimetylsilyloxy)benzyl chloride (15).
H
1
13
shifts for H and C NMR are given in parts per million (d)
relative to solvent signal (chloroform-d: dH 7.26 and dC
NMR (600 MHz, CDCl ) d 6.45 (2H, d, JZ1.8 Hz), 6.26
3
(1H, t, JZ1.8 Hz), 4.43 (2H, s), 0.96 (18H, s), 0.18 (12H, s);
EI-MS m/z 386, 388 (M ).
C
7
and d 24.9) as internal standards, respectively. LR and HR
7.0, methanol-d : d 3.30 and d 49.0, acetone-d : d 2.04
4
H
C
6
H
C
FAB-MS were obtained with JEOL JMS HX-110 using m-
nitrobenzyl alcohol as matrix. Analytical TLC was
performed on silica gel 60 F254 (Merck). Column
chromatography was carried out on silica gel BW-820MH
3.2.3. Diethyl [3,5-bis(tert-butyldimetylsilyloxy)phenyl]
methylphosphonate (16). To a mixture of chloride (15,
31.5 g) and triethyl phosphite (23.7 mL), NaI (1.3 g) was
added, and stirred at 135 8C for 3 h. Triethyl phosphite
(23.7 mL) and NaI (1.3 g) was added again and stirred
another 3 h. The reaction solution was extracted with ethyl
acetate. The organic layer was washed with water and brine,
dried over anhydrous magnesium sulfate, and evaporated.
The crude product was purified by silica-gel chromato-
graphy using hexane/ethyl acetate 7:3 as an eluent to afford
phosphonate (16) (34.2 g, 86.1%).
(
Fuji Silysia Chemicals, Co. Ltd). ODS (Develosil ODS
UG-5, f20!250 mm, Nomura Chemical, Seto, Japan), C-8
Develosil C8-5, f20!250 mm, Nomura Chemical, Seto,
(
Japan), and C-8 (YMC-Pack C8, f20!250 mm, YMC,
Kyoto, Japan) columns were used for preparative HPLC,
and C-8 (Develosil C8-5, f4.6!250 mm, Nomura Chemi-
cal, Seto, Japan) column were used for analytical HPLC.
Peroxidases from soybean (Glycine max), A. ramosus were
purchased from Sigma and peroxidase from horseradish
were from Wako Pure Chemicals, Osaka, Japan.
Diethyl [3,5-bis(tert-butyldimetylsilyloxy)phenyl]methyl-
phosphonate (16). H NMR (600 MHz, CDCl ) d 6.43
1
3
(2H, d, JZ2.2 Hz), 6.26 (1H, t, JZ2.2 Hz), 4.00 (4H, m),
3
3
.2. Synthesis of resveratrol (1)
3.03 (2H, d, JZ21.6 Hz), 1.25 (6H, t, JZ7.0 Hz), 0.94
(
C
18H, s), 0.19 (12H, s); EI-MS m/z 488 (M ).
.2.1. 3,5-Bis(tert-butyldimetylsilyloxy)benzyl alcohol
(
5
14). To a solution of methyl 3,5-dihydroxybenzoate (13,
0.0 g) in DMF (300 mL), imidazole (21.6 g) and tert-
3.2.4. 4-(tert-Butyldimetylsilyloxy)benzaldehyde (18). To
a solution of methyl 3,5-dihydroxybenzoate (17, 16.8 g) in
DMF (100 mL), imidazole (11.3 g) and TBSCl (25.0 g) was
added and stirred at rt for 21 h. The reaction solution was
extracted with ethyl acetate, and the ethyl acetate layer
was washed with water and brine, dried over anhydrous
magnesium sulfate. The solvent was removed in vacuo, and
the crude product was purified by silica-gel column
chromatography using hexane/ethyl acetate 95:5 as an
eluent to afford compound 18 (18.9 g, 58.1%).
butyldimethylsilyl chloride (TBSCl) (48.8 g) was added and
stirred at rt for 21 h. The reaction solution was extracted
with ethyl acetate, and the ethyl acetate layer was washed
with water and brine, dried over anhydrous magnesium
sulfate. The solvent was removed in vacuo, and the crude
product was purified by silica-gel column chromatography
using hexane/ethyl acetate 97:3 as an eluent to afford methyl
3
,5-bis(tert-butyldimetylsilyloxy)benzoate (23) (115 g,

Y. Takaya et al. / Tetrahedron 61 (2005) 10285–10290
10289
1
-(tert-Butyldimetylsilyloxy)benzaldehyde (18). H NMR
4
(
by using a chiral column (Chiralpak AD, f4.6!150 mm,
Daicel Chemical Industries, Osaka) by using hexane/
isopropyl alcohol/trifluoroacetic acid 80:20:0.5 as a mobile
phase at flow rate of 1 mL/min.
600 MHz, CDCl ) d 9.89 (1H, s), 7.79 (2H, d, JZ8.8 Hz),
3
6.95 (2H, d, JZ8.8 Hz), 0.99 (9H, s), 0.25 (6H, s); EI-MS
C
m/z 236 (M ).
0
A solution of phosphonate (16, 23.4 g) in THF (40 mL) was
3
.2.5. 3,5,4 -Tris(tert-butyldimetylsilyloxy)stilbene (19).
3.4.2. Treatment with potassium hexacyanoferrate(III).
To a solution of resveratrol (1, 7.7 mg) in methanol (1 mL),
a mixed solution of K CO (4.1 mg) and K [Fe(CN) ]
added dropwise to a suspension of NaH (2.45 g) in THF
(
2
3
3
6
20 mL) at K55 8C for 1 h, and the reaction mixture was
stirred at 0 8C for 1 h. The mixture was cooled to K55 8C
again, and a solution of compound 18 (12.5 g) in THF
(9.8 mg) in 0.5 mL of water was added at rt. After 10 min,
the reaction mixture was analyzed by HPLC with C-8
column using a mixed solvent of methanol/water 6:4 as an
eluent at 0.5 mL/min, and the amount of a product was
quantified on the basis of the area of the peak. 3-Viniferin (2,
RtZ10.0 min, 21.9%DT), resveratrol-trans-dehydrodimer
(11, RtZ14.9 min, 22.5%DT), and pallidol (12, RtZ
6.7 min, 15.7%DT) was detected along with recovered
resveratrol (1, RtZ9.1 min, 39.9%).
(
20 mL) was added dropwise for 1 h. The reaction
temperature was raised to 0 8C for 3 h, and was kept at
8C for 20 h. The solution was stirred at rt for 6 h,
0
neutralized with 2 M HCl, and extracted with ethyl acetate.
The ethyl acetate layer was washed with water and brine,
dried over anhydrous magnesium sulfate, and evaporated.
The crude product was purified by silica-gel column
chromatography using chloroform/methanol 97:3 as an
eluent to give compound 19 (13.9 g, 50.8%).
3.4.3. Treatment with cerium(IV) sulfate. To a solution of
resveratrol (1, 1.0 mg) in methanol (1 mL), CeSO (1.4 mg)
4
was added at K50 8. After 26 h, the reaction mixture
extracted with ethyl acetate and water. The organic layer
was washed with water, brine, and dried over anhydrous
magnesium sulfate, and evaporated. The residue was
analyzed by HPLC with C-8 column using a mixed solvent
of methanol/water 6:4 as an eluent at 0.5 mL/min, and the
amount of a product was quantified on the basis of the area
of the peak. 3-Viniferin (2, 3.7%DT), and resveratrol-trans-
dehydrodimer (11, 8.4%DT) was detected along with
recovered resveratrol (1, 53%).
0
1
,5,4 -Tris(tert-butyldimetylsilyloxy)stilbene (19). H NMR
3
(
600 MHz, CDCl ) d 7.37 (2H, d, JZ8.7 Hz), 6.95 (1H, d,
3
JZ16.5 Hz), 6.84 (1H, d, JZ16.5 Hz), 6.82 (2H, d, JZ
8
0
.7 Hz), 6.59 (2H, d, JZ2.2 Hz), 6.24 (2H, d, JZ2.2 Hz),
.96 (27H, s), 0.19 (18H, s); EI-MS m/z 570 (M ).
C
3.2.6. Resveratrol (1). To a solution of compound 19
5.7 g) in ethanol (12 mL), a mixture of concd HCl (20 mL)
(
and ethanol (100 mL) was added, and stirred at rt for 26 h.
The reaction solution was evaporated and extracted with
ethyl acetate. The ethyl acetate layer was washed with water
and brine, dried over anhydrous magnesium sulfate, and
evaporated. The crude product was purified by silica-gel
chromatography using chloroform/methanol 95:5 as an
eluent to give resveratrol (1) (1.8 g, 79.0%).
3.4.4. Treatment with iron(III) chloride. To a solution of
resveratrol (1, 6.1 mg) in acetone (1 mL), FeCl (4.4 mg)
3
was added at rt. After 20 h, the reaction mixture was
analyzed by HPLC with C-8 column using a mixed solvent
of methanol/water 6:4 as an eluent at 0.5 mL/min, and the
amount of a product was quantified on the basis of the area
of the peak. 3-Viniferin (2, 0.9%DT), resveratrol-trans-
dehydrodimer (11, 97%DT), and pallidol (12, 1.5%DT) was
detected.
3
.3. Evaluation of the reactivity
In this study, ‘Degree of transformation’ was defined as
follows. This term means the amount of resveratrol (1),
which was consumed to form stilbenedimers, and the values
3.5. Treatment of resveratrol (1) with peroxidases
(
%DT) are used throughout the following investigations.
3.5.1. General procedure of treatment with peroxidases
in aqueous acetone. A mixture of resveratrol (ca. 10 mg),
Degree of transformation (%DT)Z(mole of product!2)/
mole of resveratrol (1))!100.
(
acetone (1 mL), water (1 mL), 0.5 M phosphate buffer (pH
6
.0) (0.4 mL) and enzyme solution (0.1 mL in 0.5 M
phosphate buffer (pH 6.0)) was stirred at 27 8C for 5 min.
Then 30% H O (3 mL) was added to this reaction solution.
3
3
.4. Treatment of resveratrol (1) with oxidizing reagents
2
2
.4.1. Treatment with thallium(III) nitrate. To a solution
After 30 min, the reaction solution was extracted with ethyl
acetate. The organic layer was washed with water, and
brine, dried over anhydrous magnesium sulfate, and
evaporated. The residue was fractionated by preparative
HPLC with C-8 column (YMC) using a mixed solvent of
methanol/water 1:1.
of resveratrol (5 mg) in methanol (1.5 mL), Tl(NO3)3
10.7 mg) was added at K50 8C. The solution was stirred
at K50 8C for 30 min under N atmosphere. Water (1 mL)
(
2
was added to the solution and the reaction mixture was
extracted with ethyl acetate. The organic layer was washed
with water and brine, died over anhydrous magnesium
sulfate, evaporated. The crude product was purified by
preparative HPLC equipped with ODS column using a
mixed solvent of methanol/water 6:4 as an eluent to give
3.5.1.1. Peroxidase from soybean (Glycine max). For
this reaction, resveratrol (10.8 mg) and peroxidase from
soybean (G. max) as a solution (4 mg/mL) were used. Crude
product of 6.3 mg was obtained, and by the preparative
HPLC of the product, resveratrol-trans-dehydrodimer (11,
3-viniferin (2, 1.5 mg, 30.1%DT), along with the recovered
resveratrol (1, 2.8 mg, 56%).
2.3 mg, 21.4%), pallidol (12, 0.8 mg, 7.2%), and a mixture
of leachianol F and G (20, 0.2 mg, 1.8%) were obtained.
The resulted 3-viniferin (2) was submitted to HPLC analysis

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Y. Takaya et al. / Tetrahedron 61 (2005) 10285–10290
3
.5.1.2. Peroxidase from Arthromyces ramosus. For
of leachianol F and G (20, 2.4 mg, 4.6%), and a mixture of
quadrangularin B and C (21, 4.5 mg, 8.2%) were obtained.
this reaction, resveratrol (10.4 mg) and peroxidase from
A. ramosus as a solution (4 mg/mL) were used. Crude
product of 8.5 mg was obtained, and by the preparative
HPLC of the product, resveratrol-trans-dehydrodimer (11,
1.9 mg, 18.4%), pallidol (12, 0.8 mg, 7.4%), and a mixture
of leachianol F and G (20, 0.5 mg, 4.6%) were obtained.
Acknowledgements
This research was financially supported by a Grant-in-Aid
for High-Tech Research Center Project and for The
Advancement of Graduate School from the Ministry of
Education, Culture, Sports, Science and Technology of
Japan, which are gratefully acknowledged.
3
.5.1.3. Peroxidase from horseradish. For this reaction,
resveratrol (10.4 mg) and peroxidase from horseradish as a
solution (10 mg/mL) were used. Crude product of 7.9 mg
was obtained, and by the preparative HPLC of the product,
resveratrol-trans-dehydrodimer (11, 1.3 mg, 12.6%), and
pallidol (12, 1.1 mg, 10.2%) were obtained.
3.5.2. General procedure of treatment with peroxidases
in aqueous ethanol. A mixture of resveratrol (50 mg),
References and notes
ethanol (5 mL), water (5 mL), 0.5 M phosphate buffer (pH
6
.0) (2 mL) and enzyme solution (0.5 mL in 0.5 M
phosphate buffer (pH 6.0)) was stirred at 27 8C for 5 min.
Then 30% H O (15 mL) was added to this reaction solution.
1. Takaya, Y.; Niwa, M. Trends Heterocycl. Chem. 2001, 7,
41–54.
2. Ito, J.; Niwa, M. Tetrahedron 1996, 52, 9991–9998.
3. Takaya, Y.; Yan, K.-X.; Terashima, K.; He, Y.-H.; Niwa, M.
Tetrahedron 2002, 58, 9265–9271.
2
2
After 30 min, wet 1 g of Amberlite XAD-2 (Organo, Tokyo)
was added to the solution and eluted with water, 50%
aqueous methanol, methanol, and acetone. The acetone
elute was evaporated and fractionated by preparative HPLC
with C-8 column (Develosil) using a mixed solvent of
methanol/water 1:1.
4. Takaya, Y.; Yan, K.-X.; Terashima, K.; Ito, J.; Niwa, M.
Tetrahedron 2002, 58, 7259–7265.
5. Langcake, P.; Pryce, R. J. J. Chem. Soc., Chem. Commun.
1977, 208–210.
6
. Sako, M.; Hosokawa, H.; Ito, T.; Iinuma, M. J. Org. Chem.
2004, 69, 2598–2600.
3
.5.2.1. Peroxidase from soybean (Glycine max).
Peroxidase from soybean (G. max) was used as a solution
40 mg/mL). By the preparative HPLC, resveratrol-trans-
dehydrodimer (11, 6.0 mg, 12.1%), pallidol (12, 4.9 mg,
.5%), a mixture of leachianol F and G (20, 2.7 mg, 5.2%),
7. Nikaido, M.; Aslanian, R.; Scavo, F.; Helquist, P.; Aakermark,
B.; Baeckvall, J. E. J. Org. Chem. 1984, 49, 4738–4740.
8. Yamamura, S. The Chemistry of Phenol; Wiley: West Sussex,
England, 2003; pp 1153–1346.
(
9
and a mixture of quadrangularin B and C (21, 4.7 mg, 8.6%)
were obtained.
9. Waffo-Teguo, P.; Lee, D.; Cuendet, M.; M e´ rillon, J.-M.;
Pezzuto, J. M.; Kinghorn, A. D. J. Nat. Prod. 2001, 64,
1
36–138.
3
.5.2.2. Peroxidase from Arthromyces ramosus. Per-
10. Adesanya, S. A.; Nia, R.; Martin, M.-T.; Boukamcha, N.;
Montagnac, A.; Pa ¨ı s, M. J. Nat. Prod. 1999, 62, 1694–1695.
11. Ohyama, M.; Tanaka, T.; Iinuma, M. Phytochemistry 1995,
38, 733–740.
oxidase from A. ramosus was used as a solution (4 mg/mL).
By the preparative HPLC, resveratrol-trans-dehydrodimer
11, 6.5 mg, 13.1%), pallidol (12, 2.6 mg, 5.0%), a mixture
(