Systematic synthesis of four epicatechin series procyanidin trimers and their inhibitory activity on the Maillard reaction and antioxidant activity

Article abstract of DOI:10.1016/j.bmc.2004.07.024

A systematic synthesis of four natural epicatechin series procyanidin trimers {[4,8:4″,8″]-2,3-cis-3,4-trans: 2″,3″-cis- 3″,4″-trans: 2′?,3′?-trans-(-)-epi- catechin-(-)-epicatechin-(+)-catechin, [4,8:4″,8″]-2,3-cis-3,4- trans: 2″,3″-cis-3″,4″-trans: 2′?, 3′?-cis-tri-(-)-epicatechin: procyanidin C1, [4,8:4″, 8″]-2,3-cis-3,4-trans: 2″,3″-trans-3″,4″-trans: 2′?,3′?-trans-(-)-epicatechin-(+)-catechin-(+) -catechin: procyanidin C4, and [4,8:4″,8″]-2,3-cis-3,4-trans: 2″,3″-trans-3″,4″-trans: 2′?, 3′?-cis-(-)-epicatechin-(+)-catechin-(-)-epicatechin} is described. Condensation of (2R,3R,4S)-5,7,3′4′-tetra-O-benzyl-4-(2″- ethoxyethyloxy)flavan derived from (-)-epicatechin as an electrophile with the dimeric nucleophiles in the presence of TMSOTf followed by deprotection yielded trimers. Inhibitory activities on the Maillard reaction and antioxidant activity on lipid peroxide of the synthesized oligomers were also investigated.

Full text of DOI:10.1016/j.bmc.2004.07.024

Bioorganic & Medicinal Chemistry 12(2004) 4783–4790
Systematic synthesis of four epicatechin series procyanidin
trimers and their inhibitory activity on the Maillard reaction
and antioxidant activity
Akiko Saito,a,* Yuki Doi,b Akira Tanaka,c Nobuyasu Matsuura,d Makoto Ubukatae
and Noriyuki Nakajimab,*
aBiotechnology Center, Toyama Prefecture, Kosugi, Toyama 939-0398, Japan
bBiotechnology Research Center, Toyama Prefectural University, Kosugi, Toyama 939-0398, Japan
cDepartment of Biosources Science, College of Technology, Toyama Prefectural University, Kosugi, Toyama 939-0398, Japan
dDepartment of Life Science, Faculty of Science, Okayama University of Science, Ridai-cho, Okayama 700-0005, Japan
eGraduate School of Agriculture, Hokkaido University, Kita-ku, Sapporo 060-8589, Japan
Received 16 June 2004; revised 10 July 2004; accepted 10 July 2004
Available online 6 August 2004
Abstract—A systematic synthesis of four natural epicatechin series procyanidin trimers {[4,8:400,800]-2,3-cis-3,4-trans: 200,300-cis-300,400-
trans: 20000,30000-trans-(À)-epi-catechin-(À)-epicatechin-(+)-catechin, [4,8:400,800]-2,3-cis-3,4-trans: 200,300-cis-300,400-trans: 20000,30000-cis-tri-
(À)-epicatechin: procyanidin C1, [4,8:400,800]-2,3-cis-3,4-trans: 200,300-trans-300,400-trans: 20000,30000-trans-(À)-epicatechin-(+)-catechin-(+)-
catechin: procyanidin C4, and [4,8:400,800]-2,3-cis-3,4-trans: 200,300-trans-300,400-trans: 20000,30000-cis-(À)-epicatechin-(+)-catechin-(À)-
epicatechin} is described. Condensation of (2R,3R,4S)-5,7,3040-tetra-O-benzyl-4-(200-ethoxyethyloxy)flavan derived from (À)-epicate-
chin as an electrophile with the dimeric nucleophiles in the presence of TMSOTf followed by deprotection yielded trimers.
Inhibitory activities on the Maillard reaction and antioxidant activity on lipid peroxide of the synthesized oligomers were also
investigated.
ꢀ 2004 Elsevier Ltd. All rights reserved.
1. Introduction
synthesis of procyanidin oligomers, and further investi-
gated their bioactivities. We previously reported a stere-
oselective synthesis of procyanidin dimers9–12 and
trimers1a consisting of (+)-catechin 1 and (À)-epicate-
chin 2 and the Maillard reaction inhibitory activities
of the synthesized procyanidin dimers,10 procyanidin
B1 5, B2 7, B3 9, and B4 11. The Maillard reaction is
known as a nonenzymatic browning reaction caused
by heating a mixture solution of sugar with protein or
amino acid. This reaction occurs extensively in food sys-
tems and in vivo. The relationship of the Maillard reac-
tion to diabetic complication has been noted in the field
of sitology. There have been many studies of the Mail-
lard reaction inhibitors, and aminoguanidine (AG),13
aspirin,14 vitamin B6,15 taurine,16 quercetin,17 and com-
ponents of tea extracts (catechin derivatives)18 have been
reported as important inhibitors. The strong antioxidant
activity of proanthocyanidins is noteworthy because the
inhibitory activity on the Maillard reaction is considered
to be closely related to antioxidant activity.19 Here we
describe the details of stereoselective synthesis of four
Proanthocyanidins are known as condensed tannins
and/or oligomeric flavonoids.2,3 The investigation of
proanthocyanidins is now increasingly important be-
cause of their various strong bioactivities such as anti-
oxidant activity,4 cardioprotection activity,5 antiviral
activity,6 and antimicrobial activity.7 However, the
structure–activity relationship of proanthocyanidin oligo-
mers has not been proved yet, because a large number
of isomers in the plants makes it very difficult to purify
and supply each pure compound for assay. There are
many reports8 about the isolation and semi-synthesis
of procyanidin dimers and trimers, but no efficient method
for the stereoselective synthesis of each oligomer has yet
been reported. So we have undertook a stereoselective
Keywords: Procyanidin trimers; Maillard reaction; Antioxidant activ-
ity; Stereoselective synthesis.
*
Corresponding authors. Tel.: +81-766567500x568; fax: +81-
766562498; e-mail: nori@pu-toyama.ac.jp
0968-0896/$ - see front matter ꢀ 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2004.07.024

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A. Saito et al. / Bioorg. Med. Chem. 12 (2004) 4783–4790
OBn
OBn
OR1
OR1
OH
OH
BnO
O
R1O
O
HO
O
3
OH
R2
O
OR1
OR1
OH
OBn R
OR1
R1O
TMSOTf
OH
+
2: R = H,(–)-epicatechin
-40°C,CH2Cl2
1: (+)-catechin
R2
OR1
OR1
3: R = OEE, (–)-epicatechin electrophile
OR1
R1O
4 or 6
O
Figure 1. Structure of (+)-catechin, (À)-epicatechin, and its
R4
R3
electrophile.
OR1
12: R1 = Bn, R2 = R3 = OH, R4 = H (100%)
13: R1 = Bn, R2 = R4 = OH, R3 = H (91%)
14: R1 = R4 = H, R2 = R3 = OH (90%)
15: R1 = R3 = H, R2 = R4 = OH (95%)
16: R1 = Ac, R2 = R3 = OAc, R4 = H (73%)
17: R1 = Ac, R2 = R4 = OAc, R3 = H (47%)
a
b
a
b
OR
OR
OR
OR
RO
O
RO
O
OH
O
OH
O
OR
OR
OR
OR
OR
RO
OR
RO
Scheme 1. Synthesis of epicatechin trimers. Reagents: (a) Pd(OH)2/C,
H2; (b) Ac2O, DMAP, py.
OH
OH
OR
OR
respectively. The high condensation yields were only at-
tained at À40ꢁC, whereas either lowering or raising of
the reaction temperature resulted in decreasing the prod-
uct yields. Both protected trimers, 12 and 13, were
hydrogenated in the presence of cat. Pd(OH)2/C and
purified with LH-20 short column and HPLC to give
natural procyanidin trimers 1421 and 1520a,21c,d in 90%
and 95% yields, respectively. And acetylation of these
trimers under the usual conditions afforded peracetate
1621c and 1720a in 73% and 47% yields, respectively.
4: R = Bn
6: R = Bn
5: R = H, procyanidin B1
7: R = H, procyanidin B2
OR
OR
RO
O
RO
O
OR
OR
OH
OH
OR
OR
OR
OR
OR
RO
OR
RO
O
O
OH
OH
OR
OR
8: R = Bn
9: R = H, procyanidin B3
10: R = Bn
11: R = H, procyanidin B4
Two other trimers that have a (+)-catechin unit in the
central part were synthesized as shown in Scheme 2.
The electrophile 3 was condensed with the nucleophile
8 or 10 at À20ꢁC to give trimers 18 and 19 in 70%
and 97% yields, respectively. In a similar manner to that
described above, the best yields were obtained at
À20ꢁC, and lowering or raising the reaction tempera-
ture gave poor results. Natural procyanidin trimers
2022 and 2122 were given by hydrogenation with
Pd(OH)2/C in 100% and 87% yields, and their perace-
tates 22 and 23 were also synthesized in 58% and 81%
yields, respectively.
Figure 2. Structure of the dimeric nucleophiles.
protected procyanidin trimers, containing (À)-epicate-
chin as the upper part, by condensation of (2R,3R,4S)-
5,7,3040-tetra-O-benzyl-4-(200-ethoxyethyloxy)flavan 3 as
an electrophile with four dimeric nucleophiles. And
inhibitory activities on the Maillard reaction of the syn-
thesized trimers and their peracetate and antioxidant
activity of the synthesized dimers and trimers were
investigated (Figs. 1 and 2).
2. Results and discussion
OR1
R1O
O
OR1
2.1. Synthesis of procyanidin trimers
3
+
R2
O
OR1
OR1
OR1
R1O
Decabenzyl protected procyanidin trimers containing
(À)-epicatechin as the upper part were synthesized by
condensation of the upper part of electrophile 3 with
the central and bottom parts of dimeric nucleophiles
(4, 6, 8, and 10) in the presence of TMSOTf as a catalyst.
We report here the synthesis of four trimers (14, 15, 20,
and 21) and their acetates (16, 17, 22, and 23) in a sim-
ilar manner. The procedure is described in Scheme 1;
tandem epicatechin trimers, epicatechin-epicatechin-
catechin 14 and epicatechin-epicatechin-epicatechin 15,
were synthesized by condensation of electrophile 3 with
dimeric nucleophile 4 and 6. These condensation reac-
tions proceeded smoothly at À40ꢁC and afforded deca-
benzyl trimers 12 and 1320 in 100% and 91% yield,
TMSOTf
-20°C, CH2Cl2
R2
OR1
OR1
OR1
R1O
8 or 10
O
R4
R3
OR1
18: R1 = Bn, R2 = R3 = OH, R4 = H (70%)
19: R1 = Bn, R2 = R4 = OH, R3 = H (97%)
20: R1 = R4 = H, R2 = R3 = OH (100%)
21: R1 = R3 = H, R2 = R4 = OH (87%)
22: R1 = Ac, R2 = R3 = OAc, R4 = H (58%)
23: R1 = Ac, R2 = R4 = OAc, R3 = H (81%)
a
b
a
b
Scheme 2. Synthesis of epicatechin trimers. Reagents: (a) Pd(OH)2/C,
H2; (b) Ac2O, DMAP, py.

A. Saito et al. / Bioorg. Med. Chem. 12 (2004) 4783–4790
4785
2.1.1. Inhibitory activity on the Maillard reaction and
antioxidant activity. Inhibitory activity on the Maillard
reaction of natural procyanidin trimers and their perac-
etates was assayed using our reported method.23 The
IC50 values (concentration of 50% inhibitory activity)
are shown in Table 1. The IC50 value of procyanidin
trimers (14, 15, 20, and 21) and their acetyl derivatives
(16, 17, 22, and 23) showed at the range of 0.8–1.9
and 1.0–2.0lM. In comparison with those of (+)-cate-
chin 1 and (À)-epicatechin 2 at 5.0, and 24lM, dimeric
procyanidins at 30–72, and 7–40lM for their peracetate,
procyanidin trimers are effective so as to inhibit the
Maillard reaction. It has also become apparent that
the inhibitory activity on the Maillard reaction of procy-
anidin oligomers rises as the oligomer chain is length-
ened, thus indicating that procyanidin trimers are
powerful inhibitors against the Maillard reaction.
by the length of the oligomer chain, (2) the relationship
between Maillard reaction inhibition and antioxidant
activity was not parallel to each other. Further work
to explain the mechanism of the Maillard reaction inhi-
bition by procyanidins is now under way.
3. Conclusion
We have synthesized four procyanidin trimers contain-
ing (À)-epicatechin as the upper part, and investigated
the Maillard reaction inhibitory activity and antioxidant
activity of the synthesized oligomers.
4. Experimental
4.1. Synthesis
Antioxidant activity on UV-induced lipid peroxide using
the TBA method24 was subsequently investigated (Table
2). The IC50 values of (+)-catechin 1 and (À)-epicatechin
2 were 37 and 40lM, respectively, while those values of
dimeric procyanidins, 5, 7, 9, and 11 were 37, 29, 21, and
39lM, respectively. The IC50 values of trimeric procy-
anidins, 14, 15, 20, and 21, showed at 17, 15, 29, and
28lM, respectively. Interestingly, their peracetates did
not show antioxidant activity at all.
Optical rotation was measured with a Horiba SEPA-300
spectrometer. 1H NMR spectra were measured with
JEOL JNMLA400 spectrometer, and MS spectra were
recorded with a JEOL JMS-AX500 instrument. HPLC
purification was carried out on a Mightysil RP-18 GP
column (Kanto Chemical Co. Inc, Japan; 250 · 20mm,
5lm) using the solvents (A) 0.05% CF3CO2H in CH3CN
and (B) 0.05% CF3CO2H in H2O. Elusion was done
with a linear gradient 5–100% A in 40min (flow rate,
3.0mL/min).
From the results of both inhibitory activity tests, it is
apparent that (1) antioxidant activity was not influenced
4.1.1. [4,8:400,800]-2,3-cis-3,4-trans: 200,300-cis-300,400-trans:
20000,30000-trans-Dodeca-O-benzyl-(À)-epicatechin-(À)-epi-
catechin-(+)-catechin (12). To a solution of 3 (126mg,
0.17mmol) and 4 (886mg, 0.68mmol) in CH2Cl2
(100mL) was added dropwise 0.5M CH2Cl2 solution
of TMSOTf (0.34mL, 0.17mmol) at À40ꢁC. After stir-
ring for 5min, the pale yellow reaction mixture was
quenched with satd sodium hydrogen carbonate. The
aq solution was extracted with CHCl3 and the organic
phase was washed with water and brine, and dried
(Na2SO4). Filtration, concentration, and preparative
Table 1. Inhibitory activity on the Maillard reaction of synthetic
procyanidins and their peracetates
Entry
Compound
IC50 (lM)
1
1
5.0
24
2
2
14
3
1.1
0.8
1.9
1.4
1.5
1.0
1.4
2
4
15
20
5
6
21
silica gel TLC purification (hexane/EtOAc, 2/1) afforded
25
333mg (0.17mmol, 100%) of 12 as a colorless oil: ½aꢀ
7
16 (dodecaAc-14)
17 (dodecaAc-15)
22 (dodecaAc-20)
23 (dodecaAc-21)
Aminoguanidine
8
D
+92.0 (c 1.12, CHCl3); H NMR (400MHz, CDCl3, a
1
9
10
11
.0
0.5:0.5 mixture of rotational isomers) 7.53–6.73 (67H,
300
m), 6.74 (0.5H, d, J = 8.3Hz), 3.45 (0.5H, dd, J = 1.7,
8.3Hz), 6.40 (0.5H, d, J = 8.3Hz), 6.35 (0.5H, s), 6.26
(0.5H, d, J = 2.2Hz), 6.20 (0.5H, s), 6.13 (0.5H, dd,
J = 1.7, 8.3Hz), 6.06 (0.5H, d, J = 2.2Hz), 6.00 (0.5H,
d, J = 2.2Hz), 5.91 (0.5H, s), 5.86 (0.5H, s), 5.72
(0.5H, br s), 5.69 (0.5H, d, J = 2.2Hz), 5.52 (0.5H, br
s), 5.51 (0.5H, br s), 5.17 (0.5H, d, J = 7.5Hz), 5.14–
4.20 (27.0H, m), 4.10–4.06 (0.5H, m), 4.01–3.97 (0.5H,
m), 3.97–3.94 (0.5H, m), 3.58–3.56 (0.5H, m), 3.51–
3.40 (1H, m), 3.05 (0.5H, dd, J = 8.5, 16.4Hz), 3.04
(0.5H, dd, J = 8.8, 16.4Hz), 2.61 (0.5H, dd, J = 9.6,
16.4Hz), 2.52 (0.5H, dd, J = 9.6, 16.4Hz), 1.84 (0.5H,
d, J = 6.1Hz, OH), 1.73 (0.5H, d, J = 6.3Hz, OH),
1.59 (0.5H, d, J = 3.4Hz, OH), 1.52–1.51 (0.5H, m,
OH), 1.43–1.42(0.5H, m, OH), 1.32(0.5H, d,
J = 6.8Hz, OH); 13C NMR (100MHz, CDCl3, a
0.5:0.5 mixture of rotational isomers) 158.3, 158.1,
158.0, 157.4, 156.7, 156.4, 156.0, 155.9, 155.73, 155.67,
Table 2. Inhibitory activity of synthetic procyanidins on lipid perox-
idation by TBA method
Entry
Compound
IC50 (lM)
1
1
37
40
37
29
21
39
17
15
29
28
580
2
2
3
5
4
7
5
9
11
6
7
14
15
8
9
20
21
10
11
DL-l-Tocopherol

4786
A. Saito et al. / Bioorg. Med. Chem. 12 (2004) 4783–4790
155.58, 155.46, 155.36, 155.32, 154.8, 153.2, 152.9,
152.5, 149.2, 149.0 (·4), 148.9, 148.7 (·2), 148.6, 148.3,
148.1, 148.0, 138.2–136.7 (C · 34), 132.9, 132.54,
132.48, 132.3, 131.3, 131.1, 128.5–126.1 (C · 70),
120.21, 120.18, 120.07, 119.9, 119.7, 118.9, 115.1, 115.0
(·2), 114.7, 114.6, 114.1, 113.7 (·3), 113.3, 113.2,
113.1, 111.2, 110.8, 110.7, 110.2, 106.2, 105.6, 104.7,
104.6, 102.3, 101.9, 94.4, 94.3, 94.0, 93.4, 92.4, 92.1,
81.32, 81.25, 76.2, 75.8, 75.6 (·2), 72.6–68.2 (C · 16),
36.5, 36.1, 35.5, 35.3, 27.5, 26.8; IR (neat, cmÀ1) 3550
(m), 3450 (br m), 3088 (m), 3063 (m), 3032 (m), 2920
(m), 2880 (m), 1813 (w), 1736 (w), 1597 (s), 1510 (s),
1454 (s), 1421 (s), 1383 (s), 1325 (m), 1265 (s), 1217
(m), 1121 (s), 1028 (s), 910 (w), 856 (w), 735 (m);
FAB-MS (m/z) 1974 (13.2), 1973 (22.4), 1972 (35.6),
1971 (52.4), 1970 ([M+Na]+, 44), 1952(15.)2, 1951
(30.5), 1950 (53.9), 1948 ([M+H]+, 100), 1511 (19.3),
1510 (46.2), 1509 (65.9), 1508 (68.0), 1506 (19.2); FAB-
HRMS calcd for C129H110O18Na [M+Na]+, 1969.7590;
found: 1969.7609.
1.25 (36H, m): minor isomer was not assigned; 13C
NMR (100MHz, CDCl3) 0.4:0.4:0.2mixture of rota-
tional isomers was observed. However, each rotational
isomer was not assigned; IR (neat, cmÀ1) 3065 (w),
2934 (w), 2855 (w), 2363 (w), 1779 (s), 1599 (m), 1507
(m), 1429 (m), 1371 (s), 1205 (s), 1109 (s), 1042 (s),
943 (w), 903 (m); FAB-MS (m/z) 1523 (42.5), 1522
(63.4), 1521 (98.5), 1520 (99.9), 1519 ([M+Na]+, 100);
FAB-HRMS calcd for C75H68O33Na [M+Na]+,
1519.3541; found: 1519.3588.
4.1.4. [4,8:400,800]-2,3-cis-3,4-trans: 200,300-cis-300,400-trans:
20000,30000-cis-Dodeca-O-benzyl-tri-(À)-epicatechin (13). To
a solution of 3 (20.0mg, 0.027mmol) and 6 (140mg,
0.11mmol) in CH2Cl2 (30mL) was added dropwise
TMSOTf (0.054mL, 0.027mmol, 0.5M solution in
CH2Cl2) at À78ꢁC. After stirring for 5min, the pale yel-
low reaction mixture was quenched with satd sodium
hydrogen carbonate. The aq solution was extracted with
CHCl3 and the organic phase was washed with water
and brine, and dried (Na2SO4). Filtration, concentra-
tion, and preparative silica gel TLC purification (hex-
4.1.2. [4,8:400,800]-2,3-cis-3,4-trans: 200,300-cis-300,400-trans:
20000,30000-trans-(À)-Epi-catechin-(À)-epicatechin-(+)-cate-
chin (14). A solution of 12 (50mg, 0.026mmol) in a mix-
ture of THF/MeOH/H2O (20/1/1) (11mL) was
hydrogenated over 20% Pd(OH)2/C (5mg) for 1h at rt.
Filtration and concentration afforded a pale brown oil,
which was purified by Sephadexꢂ LH-20 short column
chromatography (EtOH–MeOH) and HPLC purifica-
ane/EtOAc, 2/1) afforded 48mg (0.025mmol, 91%) of
25
13 as a colorless oil: ½aꢀ +75.9 (c 0.32, CHCl3) {lit.20a
D
[a]D +72.1 (c 6.9, EtOAc)}; 1H NMR (400MHz, CDCl3,
a 0.5:0.5 mixture of rotational isomers) 7.51–6.74
(66.5H, m), 6.83 (0.5H, dd, J = 1.7, 8.3Hz), 6.75
(0.5H, d, J = 8.3Hz), 6.45 (0.5H, dd, J = 1.7, 8.3Hz),
6.39 (0.5H, d, J = 8.3Hz), 6.35 (0.5H, s), 6.27 (0.5H,
d, J = 2.2Hz), 6.18 (0.5H, s), 6.14 (0.5H, dd, J = 1.7,
8.3Hz), 6.07 (0.5H, d, J = 2.2Hz), 5.95 (0.5H, d,
J = 2.2Hz), 5.90 (0.5H, s), 5.85 (0.5H, s), 5.73 (0.5H,
br s), 5.70 (0.5H, d, J = 2.2Hz), 5.49 (0.5H, br s), 5.22
(0.5H, br s), 5.18–4.16 (28.5H, m), 4.09 (0.5H, br s),
4.07 (0.5H, br s), 3.96 (0.5H, br s), 3.64 (0.5H, br s),
2.95–2.80 (2H, m), 1.85–1.80 (0.5H, br, OH), 1.76–1.69
(0.5H, br, OH), 1.60–1.55 (0.5H, m, OH), 1.50–1.45
(0.5H, br, OH), 1.25–1.17 (1H, br, OH); 13C NMR
(100MHz, CDCl3) 158.3, 158.1, 158.0, 157.4, 156.7,
156.44, 156.36, 156.2, 156.12, 156.08, 156.01, 156.7,
155.5, 155.3, 154.7, 153.1, 152.8, 152.4, 149.2, 149.00,
148.96, 148.93, 148.80, 148.75, 148.69, 148.4 (·2),
148.3, 148.2, 148.1, 138.2, 137.6–136.9 (C · 24), 132.9,
132.5, 132.4, 132.3, 131.3, 131.2, 128.6–126.1 (C · 69),
120.0, 119.9, 119.7, 118.9, 118.84, 118.76, 115.1, 115.0
(·2), 148.8 (·2), 114.2, 113.6 (·2), 113.5, 113.2 (·2),
113.0, 111.2, 111.1, 111.0, 110.1, 106.0, 105.4, 104.7,
104.6, 101.4, 100.8, 94.4 (·2), 94.0, 93.8, 93.4 (·2),
92.6, 92.5, 92.3, 90.3, 78.1, 78.0, 76.3, 75.8, 75.7, 75.6,
72.7, 72.5, 72.2, 71.5–69.6 (C · 24), 69.3, 65.3, 64.9,
tion to give 20mg of pure 12 (90%) as an amorphous
25
solid: ½aꢀ +56.9 (c 0.30, EtOH) (lit.21b,25 [a]D +76.9);
D
1H NMR (400MHz, CD3COCD3/D2O, 15/1) 7.13–6.69
(9H, br), 6.10–5.83 (4H, br), 5.30–5.05 (1H, br), 5.04–
5.03 (1H, br), 4.89–4.54 (3H, br), 4.16–3.95 (3H, br),
2.75–2.60 (1H, br), 2.58–2.51 (1H, br); 13C NMR
(100MHz,
CD3COCD3/D2O,
15/1) 157.4–153.4
(C · 9), 145.4, 145.21, 145.18 (·2), 145.0, 144.8,
132.03, 132.01, 131.97, 119.1–118.6 (·3), 115.7, 115.49,
115.45, 115.43, 114.8, 114.4, 110.9, 107.3, 104.8, 100.7,
96.91, 96.88, 96.5, 95.7 (·2), 81.6, 76.7, 76.6 (·2), 72.8,
71.4, 67.5, 36.8 (·2); FAB-MS (m/z) 890 (5.6), 889
([M+Na]+, 12.8), 888 (7.1), 887 (5.8), 868 (4), 867
([M+H]+, 9.0), 866 (6.7), 329 (100); FAB-HRMS calcd
for C45H38O18Na [M+Na]+, 889.1956; found: 889.1927.
4.1.3. Peracetate of 14 (16). Acetylation of 14 (8mg,
9.2lmol) with the general procedure gave 10mg of per-
acetate 16 (6.7lmol, 73%) as a colorless amorphous
25
solid: ½aꢀ +113.3 (c 0.30, acetone) {lit.8f [a]578 +110
D
(c 0.16, acetone)}; 1H NMR (400MHz, CDCl3,
0.4:0.4:0.2mixture of rotational isomers) major isomers:
7.35–6.59 (6.8H, m), 6.92(0.4H, d, J = 8.3Hz), 6.74
(0.4H, dd, J = 1.7, 8.3Hz), 6.70 (0.4H, d, J = 8.3Hz),
6.64 (0.4H, d, J = 8.3Hz), 6.30 (0.4H, dd, J = 1.7,
8.3Hz), 6.26 (0.4H, d, J = 2.2Hz), 5.96 (0.4H, d,
J = 2.2Hz), 5.91 (0.4H, d, J = 2.2Hz), 5.83 (0.4H, d,
J = 2.2Hz), 5.69 (0.4H, br s), 5.62 (0.4H, br s), 5.41
(0.4H, br s), 5.41–4.59 (1.6H, m), 5.27 (0.4H, br s),
4.93 (0.4H, br s), 4.87 (0.4H, br s), 4.74 (0.4H, br s),
4.62(0.4H, br s), 4.61 (0.4H, br s), 4.47 (0.4H, d,
J = 2.4Hz), 4.44 (0.4H, d, J = 2.0Hz), 4.35 (0.4H, d,
J = 1.9Hz), 3.12(0.4H, dd, J = 5.6, 16.6Hz), 2.74
(0.4H, dd, J = 8.1, 16.6Hz), 3.08–2.45 (0.8H, m), 2.36–
36.5, 36.2, 35.4 (·2), 28.63, 28.57; IR (neat, cmÀ1
)
3570 (m), 3520 (br), 3063 (m), 3032 (m), 2930 (m),
2872 (m), 2361 (w), 1954 (w), 1877 (w), 1813 (w), 1732
(m), 1597 (s), 1514 (s), 1454 (s), 1383 (s), 1265 (s),
1116 (s), 1026 (s), 910 (w), 852 (w), 735 (m); FAB-MS
(m/z) 1974 (12.0), 1973 (25.2), 1970 ([M+Na]+, 63.4),
1950 (26.0), 1949 (56.9), 1948 ([M+H]+, 100), 1510
(43.9), 1509 (44.4), 1508 (74.7); FAB-HRMS calcd for
C129H110O18Na [M+Na]+, 1969.7590; found: 1969.7570.
4.1.5. [4,8:400,800]-2,3-cis-3,4-trans: 200,300-cis-300,400-trans:
20000,30000-cis-Tri-(À)-epicatechin, procyanidin C1 (15). A
solution of 13 (80mg, 0.041mmol) in a mixture of

A. Saito et al. / Bioorg. Med. Chem. 12 (2004) 4783–4790
4787
THF/MeOH/H2O (20/1/1) (22mL) was hydrogenated
over 20% Pd(OH)2/C (5mg) for 1h at rt. Filtration
and concentration afforded a pale brown solid, which
was purified by Sephadexꢂ LH-20 short column chro-
matography (EtOH–MeOH) and HPLC purification to
154.1, 151.7, 149.9, 148.8, 148.1, 148.0, 147.8, 146.9,
142.1, 142.02, 141.95, 141.93, 141.8, 141.5, 136.5,
135.7, 133.2, 125.2, 124.8, 124.2, 123.24, 123.16, 123.0,
122.74 (·2), 122.0, 121.5, 118.8, 117.8, 114.7, 113.3,
112.2, 110.6, 110.5, 107.5, 107.4, 75.1, 73.8, 71.4, 70.9,
66.6, 35.4, 34.3, 26.4, 21.1, 20.9, 20.7–20.6 (C · 7),
give 34mg of pure 15 (0.039mmol, 95%) as a pale brown
27
amorphous solid: ½aꢀ +59.3 (c 0.30, MeOH) {lit.20a [a]D
20.5, 20.2, 20.10 (·2), 20.08, 19.8; IR (neat, cmÀ1
)
D
+70.4 (c 0.22, MeOH), lit.21c [a]578 +92( c 0.19, water)};
1H NMR (400MHz, CD3OD) 7.15–7.09 (1H, br), 7.08–
6.98 (1H, br), 6.98–6.82(2H, m), 6.80–6.63 (5H, m),
6.08–6.02 (1H, br), 6.02–5.98 (1H, br), 5.98–5.83 (2H,
m), 5.26–5.18 (1H, br), 5.10–5.05 (1H, br), 5.02–4.95
(1H, br), 4.74–4.65 (1H, br), 4.61–4.57 (1H, br),
4.35–4.27 (1H, br), 4.05–3.95 (2H, m), 2.98–2.90 (1H,
m), 2.85–2.77 (1H, m); FAB-MS (m/z) 890 (1.9), 889
([M+Na]+, 3.3), 888 (2.2), 887 (1.7), 868 (1.6), 867
([M+H]+, 3.3), 866 (2.5), 613 (8.3), 482 (25.5),
459 (45.8), 328 (100), 306 (100); FAB-HRMS
calcd for C45H38O18Na [M+Na]+, 889.1956; found:
889.2031.
3065 (w), 2973 (w), 2936 (w), 2361 (w), 1779 (s), 1601
(m), 1507 (m), 1429 (m), 1372 (s), 1206 (s), 1111 (s),
1043 (s), 902(m), 735 (m); FAB-MS ( m/z) 1522 (15.7),
1521 (38.5), 1520 (77.2), 1519 ([M+Na]+, 100), 1498
(3.7), 1497 ([M+H]+, 4.6), 1396 (9.1), 1395 (16.7), 1394
(29.9), 1393 (36.2); FAB-HRMS calcd for C75H68O33Na
[M+Na]+, 1519.3541; found: 1519.3574.
4.1.7. [4,8:400,800]-2,3-cis-3,4-trans: 200,300-trans-300,400-trans:
20000,30000-trans-Dodeca-O-benzyl-(À)-epicatechin-(+)-cate-
chin-(+)-catechin (18). To a solution of 3 (132mg,
0.18mmol) and
8 (1.04g, 0.80mmol) in CH2Cl2
(80mL) was added dropwise 0.5M CH2Cl2 solution of
TMSOTf (0.36mL, 0.18mmol) at À20ꢁC. After stirring
for 5min, the pale yellow reaction mixture was quenched
with satd sodium hydrogen carbonate. The aq solution
was extracted with CHCl3 and the organic phase was
washed with water and brine, and dried (Na2SO4). Fil-
tration, concentration, and preparative silica gel TLC
4.1.6. Peracetate of procyanidin C1 (17). Acetylation of
15 (18mg, 0.021mmol) with general procedure gave
15mg of peracetate 17 (0.010mmol, 47%) as a colorless
30
amorphous solid: ½aꢀ +48.6 (c 0.30, acetone) {lit.20a
D
[a]D +55.3 (c 1.04, acetone)}; 1H NMR (400MHz,
CDCl3, 0.67:0.33 mixture of rotational isomers) major
isomer: 7.22–7.00 (6.03H, m), 6.69 (0.67H, d,
J = 2.2Hz), 6.64 (0.67H, s), 6.58 (0.67H, d, J = 2.2Hz),
6.57 (0.67H, s), 5.42–5.38 (0.67H, m), 5.35 (0.67H, br
s), 5.34 (0.67H, br s), 5.32(0.67H, br s), 5.29 (0.67H,
br s), 5.14 (0.67H, br s), 4.71 (0.67H, br s), 4.63
(0.67H, br s), 3.02(0.67H, dd, J = 4.7, 18.3Hz), 2.89
(0.67H, d, J = 18.3Hz), 2.25 (2.01H, s), 2.222 (2.01H,
s), 2.216 (2.01H, s), 2.192 (2.01H, s), 2.188 (2.01H, s),
2.15 (2.01H, s), 2.14 (2.01H, s), 1.95 (2.01H, s), 1.88
(2.01H, s), 1.81 (4.02H, s), 1.75 (2.01H, s), 1.72
(2.01H, s), 1.48 (2.01H, s), 1.31 (2.01H, s); minor isomer:
7.30 (0.33H, d, J = 1.7Hz), 7.22–7.00 (1.65H, m), 6.93
(0.33H, d, J = 1.7Hz), 6.88 (0.33H, d, J = 8.3Hz),
6.81 (0.33H, s), 6.73 (0.33H, dd, J = 1.7, 8.3Hz), 6.53
(0.33H, s), 6.19 (0.33H, d, J = 2.2Hz), 5.87 (0.33H, d,
J = 2.2Hz), 5.64 (0.33H, br s), 5.40–5.29 (0.33H, m),
5.05 (0.33H, br s), 5.04 (0.33H, br s), 4.89–4.87
(0.33H, m), 4.60 (0.33H, br s), 4.58 (0.33H, br s), 4.42
(0.33H, d, J = 2.2Hz), 2.97 (0.33H, dd, J = 4.6,
18.3Hz), 2.84 (0.33H, d, J = 18.3Hz), 2.30 (0.99H, s),
2.23 (0.99H, s), 2.22–2.19 (5.94H, m), 2.16 (0.99H, s),
2.09 (0.99H, s), 2.08 (0.99H, s), 1.88 (0.99H, s), 1.82
(0.99H, s), 1.64 (0.99H, s), 1.43 (0.99H, s); 13C NMR
(100MHz, CDCl3) major isomer: 169.9, 169.1, 169.0,
168.8, 168.42, 168.40, 168.3, 168.1, 168.01, 167.98,
167.93, 167.88, 167.80, 167.7, 167.6, 154.9, 151.9,
151.7, 149.88, 149.87, 148.6, 148.5, 147.6, 147.2, 142.1,
142.02, 141.95, 141.86, 141.81, 141.7, 135.7, 135.4,
135.2, 124.15, 124.08, 123.9, 123.24, 123.16, 123.06,
122.7, 122.0, 121.6, 121.3, 117.7, 117.6, 112.2, 111.6,
111.0, 110.6, 110.0, 109.3, 108.1, 77.2, 74.7, 71.3, 70.5,
66.6, 34.9, 34.3, 26.4, 21.0, 20.73, 20.66–20.5 (C · 7),
20.4 (·2), 20.2, 20.0, 19.7, 19.5; minor isomer: 170.11,
170.06, 169.9, 169.1, 168.7, 168.6, 168.4, 168.1, 168.0,
167.93, 167.86, 167.76, 167.4, 166.2, 166.1, 155.8,
purification (hexane/EtOAc, 2/1) afforded a 244mg
25
(0.13lmol, 70%) of 18 as a colorless oil: ½aꢀ À26.5 (c
D
0.60, CHCl3); 1H NMR (400MHz, CDCl3, 0.82:0.18
mixture of rotational isomers) major isomer: 7.42–6.67
(55.76H, m), 6.54 (0.82H, dd, J = 1.7, 8.3Hz), 6.27
(0.82H, s), 6.02 (0.82H, d, J = 2.2Hz), 5.92 (0.82H, s),
5.52(0.8H2 , d,
J = 2.2Hz), 5.50 (0.82H, br s), 5.14–
4.43 (22.14H, m), 4.04–3.90 (0.82H, m), 3.90–3.94
(0.82H, m), 3.73–3.68 (1.64H, m), 3.54 (0.82H, d,
J = 9.8Hz), 2.98 (0.82H, dd, J = 5.4, 16.6Hz), 2.31
(0.82H, dd, J = 9.1, 16.6Hz), 1.68 (0.82H, d,
J = 5.8Hz, OH), 1.44–1.36 (1.64H, m, OH); minor iso-
mer was not identified. 13C NMR (100MHz, CDCl3)
major isomer: 158.0, 156.8, 156.02, 155.99, 155.5,
155.2, 155.0, 154.6, 153.5, 149.2, 149.1 (·2), 149.0,
148.9, 148.3, 137.9, 137.53, 137.51, 137.46, 137.40,
137.38, 137.31, 137.29, 137.24, 137.17, 137.15, 136.9,
132.8, 131.9, 131.8, 130.9, 128.9–126.0 (C · 32), 120.4,
120.0, 119.1, 115.2, 115.1, 114.8, 114.4, 114.0, 113.4,
112.8, 112.23, 112.15, 112.0, 111.7, 111.2, 104.4, 102.0,
93.4, 93.0, 92.4, 91.4, 82.1, 80.6, 75.0, 74.4, 72.6, 71.5–
69.1 (C · 12), 68.4, 37.4, 35.7, 28.9; IR (neat, cmÀ1
)
3800 (br), 3065 (m), 3032 (m), 2900 (m), 2361 (m),
1508 (s), 1456 (s), 1028 (m), 910 (w), 852 (w), 808 (w),
752(s), 696 (s); FAB-MS ( m/z) 1973 (20.4), 1972 (48),
1971 (50), 1970 ([M+Na]+, 44), 1951 (27.0), 1950
(54.1), 1948 ([M+H]+, 100), 1932 (23.3), 1931 (25.4),
1930 (43.2), 1840 (37.7), 1839 (53.6), 1509 (40.5), 1508
(49.3); FAB-HRMS calcd for C129H110O18Na
[M+Na]+, 1969.7590; found: 1969.7570.
4.1.8. [4,8:400,800]-2,3-cis-3,4-trans: 200,300-trans-300,400-trans:
20000,30000-trans-(À)-Epicatechin-(+)-catechin-(+)-catechin,
procyanidin C4 (20). A solution of 18 (55mg,
0.028mmol) in a mixture of THF/MeOH/H2O (20/1/1)

4788
A. Saito et al. / Bioorg. Med. Chem. 12 (2004) 4783–4790
(22mL) was hydrogenated over 20% Pd(OH)2/C (5mg)
for 2h at rt. Filtration and concentration afforded a pale
brown solid, which was purified by Sephadexꢂ LH-20
short column chromatography (EtOH–MeOH) and
(1H, s), 5.95 (1H, d, J = 2.2Hz), 5.82 (1H, s), 5.45
(1H, d, J = 2.2Hz), 5.45 (1H, br s), 5.12–4.55 (22H,
m), 4.64 (1H, d, J = 8.1Hz), 4.54 (1H, d, J = 11.4Hz),
4.48 (1H, d, J = 11.4Hz), 4.29 (1H, d, J = 11.0Hz),
3.97 (1H, dd, J = 8.1, 9.7Hz), 3.92(1H, br s), 3.78
(1H, br s), 3.75 (1H, br s), 3.52(1H, d, J = 9.7Hz),
2.75 (1H, d, J = 16.8Hz), 2.44 (1H, dd, J = 4.1,
16.8Hz), 1.60 (1H, br, OH), 1.60–1.20 (2H, m, OH);
13C NMR (100MHz, CDCl3) 158.0, 156.7, 156.10,
156.05, 155.8, 155.5, 155.0, 154.5, 153.3, 149.2, 149.0,
148.9, 148.24, 148.21 (·2), 137.9, 137.50, 137.47,
137.41 (·2), 137.37, 137.32 (·2), 137.2, 137.1, 136.8,
132.7, 132.3, 131.8, 128.6–126.0 (C · 37), 120.4, 119.0,
118.7, 115.2( ·2), 114.0, 112.9, 112.7, 112.3, 112.1,
111.7, 111.4, 104.4, 100.2, 93.4, 92.9, 92.4, 91.3, 82.1,
77.2, 75.0, 74.3, 72.5, 71.4 (·2), 71.3, 71.0, 70.8, 70.5,
70.3, 70.2, 69.8, 69.4, 69.1, 69.0, 66.0, 37.1, 35.8, 29.7;
IR (neat, cmÀ1) 3400 (br), 3065 (w), 3032(w), 9236
(m), 2857 (w), 1603 (s), 1512 (s), 1454 (m), 1381 (m),
1267 (m), 1217 (m), 1117 (s), 1078 (m), 1028 (m), 910
HPLC purification to give 24mg of pure 20 (0.028mmol,
23
100%) as an amorphous solid: ½aꢀ À118.8 (c 0.20,
D
EtOH); FAB-MS (m/z) 890 (8.3), 889 ([M+Na]+, 14.0),
888 (9.1), 868 (4.3), 867 ([M+H]+, 7.1), 866 (5.3), 679
(100); FAB-HRMS calcd for C45H38O18Na [M+Na]+,
889.1956; found: 889.1913.
4.1.9. Peracetate of 20 (22). Acetylation of 20 (3.0mg,
l.46lmol) with the general procedure gave 3.0mg of per-
acetate 22 (2.0lmol, 58%) as a colorless amorphous
23
D
solid: ½aꢀ
À106.5 (c 0.20, acetone); 1H NMR
(400MHz, CDCl3) 7.15 (1H, d, J = 2.0Hz), 7.09 (1H,
d, J = 8.5Hz), 6.99 (2H, d, J = 8.5Hz), 6.85 (1H, dd,
J = 2.0, 8.5Hz), 6.78 (1H, d, J = 2.0Hz), 6.64 (1H,
d, J = 2.0Hz), 6.63 (1H, s), 6.59 (1H, s), 6.23 (1H, dd,
J = 2.0, 8.5Hz), 6.21 (1H, d, J = 2.2Hz), 6.18 (1H,
dd, J = 2.0, 8.5Hz), 5.84 (1H, d, J = 2.2Hz), 5.60 (1H,
dd, J = 8.3, 10.2Hz), 5.24 (1H, br s), 5.16 (1H, dd,
J = 2.9, 3.9Hz), 5.12 (1H, br s), 4.84 (1H, br s), 4.35
(1H, d, J = 8.3Hz), 4.34 (1H, br s), 4.26 (1H, d,
J = 10.2Hz), 2.66 (1H, dd, J = 2.9, 17.1Hz), 2.35 (1H,
dd, J = 3.9, 17.1Hz), 2.29 (6H, s), 2.22 (6H, s), 2.20
(3H, s), 2.19 (3H, s), 2.15 (3H, s), 2.13 (3H, s),
2.12 (3H, s), 2.11 (3H, s), 1.98 (3H, s), 1.93 (3H, s),
1.90 (3H, s), 1.73 (3H, s), 1.51 (3H, s); 13C NMR
(100MHz, CDCl3) 171.0, 169.6, 169.3, 169.0, 168.8,
168.7, 168.6, 168.4, 168.1 (·2), 168.0, 167.71, 167.67
(·2), 167.6, 155.4, 155.1, 151.0, 149.2, 148.5, 148.0,
147.8, 147.7, 147.3, 142.2, 142.0, 141.91, 141.90,
141.53, 141.50, 136.0, 135.2, 134.5, 125.1, 124.5, 123.8,
123.2, 122.9, 122.8, 122.4, 122.2, 119.8, 117.9, 117.3,
116.8, 111.6, 111.5, 110.0, 108.9, 108.2, 107.0, 79.3,
77.2, 73.1, 70.7, 70.0, 67.1, 36.6, 33.5, 21.5–20.2
(C · 16); IR (neat, cmÀ1) 3025 (w), 2926 (m), 2855 (w),
2361 (w), 1771 (s), 1669 (m), 1507 (m), 1437 (m), 1372
(s), 1209 (s), 1126 (s), 1068 (s), 945 (m), 758 (m); FAB-
MS (m/z) 1523 (18), 1522 (34), 1521 (55), 1520 (85),
1519 ([M+Na]+, 93), 1498 (10), 1497 ([M+H]+, 7.9),
531 (100); FAB-HRMS calcd for C75H68O33Na
[M+Na]+, 1519.3541; found: 1519.3527.
(w), 851 (w), 756 (s), 696 (s); FAB-MS (m/z)
+
1972(81.8), 1971 (100), 1970 ([M+Na]
, 66.9),
1948 ([M+H]+, 79.6), 1947 (83.6); FAB-HRMS calcd
for C129H110O18Na [M+Na]+, 1969.7590; found:
1969.7563.
4.1.11. [4,8:400,800]-2,3-cis-3,4-trans: 200,300-trans-300,400-
trans: 20000,30000-cis-(À)-Epicatechin-(+)-catechin-(À)-epi-
catechin (21). A solution of 19 (80mg, 0.041mmol) in
a mixture of THF/MeOH/H2O (20/1/1) (22mL) was
hydrogenated over 20% Pd(OH)2/C (5mg) for 1h at rt.
Filtration and concentration afforded a pale brown oil,
which was purified by Sephadexꢂ LH-20 column chro-
matography (EtOH–MeOH) and HPLC purification to
give 31mg of pure 21 (87%) as a colorless amorphous
24
D
27
D
solid: ½aꢀ À112.6 (c 0.40, MeOH) {lit.22 ½aꢀ À97.6 (c
1
1.0, MeOH)}; H NMR (400MHz, CD3OD, 0.89: 0.11
mixture of rotational isomer) major isomer: 7.09–6.58
(8.01H, m), 6.10–5.80 (3.56H, m), 5.28 (0.89H, br),
5.20–4.40 (2.67H, m), 4.50 (0.89H, br), 4.24 (0.89H, br
s), 3.84 (0.89H, br s), 3.21–3.18 (0.89H, m), 2.93
(0.89H, dd, J = 4.1, 16.3Hz), 2.82 (0.89H, d,
J = 16.3Hz); minor isomer was not assigned: 7.09–6.58
(0.99H, m), 6.10–5.80 (0.44H, m), 5.70 (0.11H, br),
5.20–4.40 (0.33H, m), 4.41 (0.11H, br), 4.11
(0.11H, br), 3.72(0.11H, br s), 3.50–3.20 (0.11H, m),
2.94–2.74 (0.22H, m); FAB-MS (m/z) 890 (2.2), 889
([M+Na]+, 4.0), 888 (3.3), 887 (2.1), 868 (2.2), 867
([M+H]+, 3.9), 866 (3.1), 613 (4.2), 483 (11.7), 482
(25.2), 460 (48.2), 328 (100), 306 (100); FAB-HRMS cal-
cd for C45H38O18Na [M+Na]+, 889.1956; found:
889.1882.
4.1.10. [4,8:400,800]-2,3-cis-3,4-trans: 200,300-trans-300,400-
trans: 20000,30000-cis-Dodeca-O-benzyl-(À)-epicatechin-(+)-
catechin-(À)-epicatechin (19). To
a solution of 3
(42mg, 0.057mmol) and 10 (304mg, 0.23mmol) in
CH2Cl2 (30mL) was added dropwise 0.5M CH2Cl2
solution of TMSOTf (0.11mL, 0.057mmol) at À20ꢁC.
After stirring for 5min, the pale yellow reaction mixture
was quenched with satd sodium hydrogen carbonate.
The aq solution was extracted with CHCl3 and the or-
ganic phase was washed with water and brine, and dried
(Na2SO4). Filtration, concentration, and preparative sil-
4.1.12. Peracetate of 21 (23). Acetylation of 21 (5mg,
5.8lmol) with the general procedure gave 7mg of perac-
etate 23 (4.7lmol, 81%) as a colorless amorphous solid:
23
D
ica gel TLC purification (hexane/EtOAc, 2/1) afforded
½aꢀ À4.4 (c 0.25, acetone); 1H NMR (400MHz, CDCl3,
25
D
108mg (0.055mmol, 97%) of 19 as a colorless oil: ½aꢀ
a 0.46:0.46:0.08 mixture of rotational isomers) major
isomers: 7.41 (0.46H, d, J = 2.2Hz), 7.35 (0.46H, dd,
J = 2.2, 8.6Hz), 7.27 (0.46H, d, J = 8.6Hz), 7.20
(0.46H, d, J = 8.6Hz), 7.19 (0.46H, d, J = 2.2Hz),
7.22–7.16 (1.38H, m), 7.10 (0.46H, d, J = 8.6Hz), 7.09
(0.46H, d, J = 8.6Hz), 7.04 (0.46H, dd, J = 2.2,
À46.8 (c 0.4, CHCl3); 1H NMR (400MHz, CDCl3)
7.35–6.88 (62H, m), 6.84 (1H, d, J = 8.3Hz), 6.71 (1H,
dd, J = 1.7, 8.3Hz), 6.66 (1H, d, J = 1.7Hz), 6.59 (1H,
d, J = 8.3Hz), 6.46 (1H, d, J = 8.3Hz), 6.29 (1H, dd,
J = 1.7, 8.3Hz), 6.23 (1H, dd, J = 1.7, 8.3Hz), 6.23

A. Saito et al. / Bioorg. Med. Chem. 12 (2004) 4783–4790
4789
8.6Hz), 6.97 (0.46H, d, J = 8.6Hz), 6.93 (0.46H, d,
Acknowledgements
J = 2.2Hz), 6.89 (0.46H, d, J = 2.2Hz), 6.85 (0.46H,
dd, J = 2.2, 8.6Hz), 6.78 (0.46H, d, J = 2.2Hz), 6.74
(0.46H, s), 6.72(0.46H, s), 6.71 (0.46H, s), 6.62
We thank the Japan Society for the Promotion of Sci-
ence (JSPS) for the Young Science Research Fellowship
(to A.S.).
(0.46H, s), 6.52(0.46H, dd,
J = 2.2, 8.6Hz), 6.32
(0.46H, d, J = 1.7Hz), 6.29 (0.46H, d, J = 1.7Hz),
6.26 (0.46H, dd, J = 2.2, 8.6Hz), 5.92 (0.46H, d,
J = 1.7Hz), 5.86 (0.46H, d, J = 1.7Hz), 5.64 (0.46H, br
s), 5.54 (0.46H, dd, J = 10.0, 10.3Hz), 5.51 (0.46H, dd,
J = 9.5, 10.0Hz), 5.49–5.48 (0.46H, m), 5.22 (0.46H, d,
J = 2.0Hz), 5.20 (0.46H, br s), 5.23–5.20 (0.46H, m),
5.16–5.13 (0.92H, m), 5.12 (0.46H, br s), 4.91 (0.46H,
d, J = 9.5Hz), 4.57 (0.46H, d, J = 10.3Hz), 4.47
(0.46H, d, J = 10.0Hz), 4.46 (0.46H, d, J = 10.0Hz),
4.43 (0.46H, d, J = 2.0Hz), 4.38 (0.46H, br s), 2.99–
2.94 (0.92H, m), 2.88 (0.46H, d, J = 16.6Hz), 2.77
(0.46H, dd, J = 3.1, 17.5Hz), 2.354 (1.38H, s), 2.347
(1.38H, s), 2.32 (1.38H, s), 2.31 (1.38H, s), 2.30
(4.14H, s), 2.29 (1.38H, s), 2.285 (1.38H, s), 2.283
(1.38H, s), 2.263 (1.38H, s), 2.259 (1.38H, s), 2.23
(1.38H, s), 2.213 (1.38H, s), 2.211 (1.38H, s),
2.17 (1.38H, s), 2.10 (1.38H, s), 2.06 (1.38H, s), 1.97
(1.38H, s), 1.91 (1.38H, s), 1.902(1.38H, s), 1.897
(1.38H, s), 1.88 (1.38H, s), 1.85 (1.38H, s),
1.79 (1.38H, s), 1.77 (1.38H, s), 1.76 (1.38H, s), 1.65
(1.38H, s), 1.58 (1.38H, s), 1.55 (1.38H, s); 13C NMR
(100MHz, CDCl3) 170.4, 170.2, 170.1, 169.8, 169.6,
169.4, 169.3, 168.91, 168.86, 168.80, 168.74, 168.72,
168.6 (·2), 168.23, 168.17, 168.13, 168.09, 168.05,
168.03, 167.99, 167.92, 167.90, 167.8, 167.7, 167.6 (·2),
167.5, 167.1, 167.0, 155.7, 155.4, 154.3, 153.8, 153.1,
152.0, 149.4, 149.1, 148.6, 148.5, 148.4, 148.3, 148.2,
147.9, 147.83, 147.78, 142.5, 142.4, 142.2, 142.1, 142.0,
141.9, 141.73, 141.69 (·2), 141.62, 141.59, 141.46,
136.1, 135.6, 135.3, 133.9, 133.8, 128.4, 125.2, 124.8,
124.2, 123.9, 123.8, 127.7, 123.6, 123.2, 123.1, 123.0,
122.9, 122.77, 122.75, 121.9, 121.7, 121.1, 117.6, 117.4,
117.1, 117.0, 116.5, 115.8, 111.7, 111.5, 111.4, 111.3,
110.5, 109.6, 109.5, 108.9, 108.7, 108.6, 107.20, 107.17,
79.6, 79.4, 77.6, 74.0, 73.4, 70.6, 70.5, 66.9, 66.4, 60.4,
37.4, 36.1, 34.6, 31.9, 29.71, 29.67, 29.4, 26.1, 25.6,
22.7, 21.2, 21.14, 21.13, 21.06, 21.04, 21.8, 20.8, 20.72
(·5), 20.68 (·3), 20.65 (·3), 20.55, 20.54, 20.51, 20.41
(·2), 20.37, 20.34, 20.26, 20.21, 20.17, 20.06, 20.03,
14.2, 14.1; IR (neat, cmÀ1) 3027 (m), 2926 (m), 2855
(m), 2361 (w), 2089 (w), 1779 (s), 1747 (s), 1601 (m),
1506 (m), 1427 (m), 1422 (s), 1261 (s), 1261 (s), 1215
(s), 1109 (s), 1049 (s), 954 (w), 903 (m), 758 (s); FAB-
MS (m/z) 1522 (15.2), 1521 (41.3), 1520 (78.0), 1519
([M+Na]+, 100), 1498 (1.7), 1497 ([M+H]+, 2.4),
1396 (12.7), 1395 (21.7), 1394 (29.9); FAB-HRMS
calcd for C75H68O33Na [M+Na]+, 1519.3541; found:
1519.3574.
References and notes
1. This report is Part 8 in the series ÔSynthetic studies of
proanthocyanidinsÕ. See also part 6 and part 7. (a) Part 6:
Saito, A.; Tanaka, A.; Ubukata, M.; Nakajima, N. Synlett
2004, 1069; (b) Part 7: Saito, A.; Tanaka, A.; Ubukata,
M.; Nakajima, N. Synlett, in press.
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4.3. The measurement of antioxidant activity
Inhibitory activity of antioxidant activity was measured
with the general procedure of the TBA method.24

4790
A. Saito et al. / Bioorg. Med. Chem. 12 (2004) 4783–4790
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25. There is no [a]D data of neither concentration nor solvent.