A simple and efficient one-step, regioselective, enzymatic glucosylation of arbutin by α-glucosidase

Article abstract of DOI:10.1016/j.tetlet.2007.07.152

4-Hydroxyphenyl-β-isomaltoside has been synthesized by α-glucosidase assisted transglycosylation between arbutin as acceptor and sucrose as donor molecules, respectively. Optimum conditions for the transglucosylation reaction were 40 °C for 20 h with 10 m

Full text of DOI:10.1016/j.tetlet.2007.07.152

Tetrahedron Letters 48 (2007) 7222–7224
A simple and efficient one-step, regioselective, enzymatic
glucosylation of arbutin by a-glucosidase
a,
b
b
*
Nenad B. Milosavi c´ , Radivoje M. Prodanovi c´ and Ratko M. Jankov
a
Department of Chemistry, IHTM, University of Belgrade Studentski trg 12, 11000 Belgrade, Serbia
b
Faculty of Chemistry, University of Belgrade, Studentski trg 12, 11000 Belgrade, Serbia
Received 4 June 2007; revised 17 July 2007; accepted 25 July 2007
Available online 28 July 2007
Abstract—4-Hydroxyphenyl-b-isomaltoside has been synthesized by a-glucosidase assisted transglycosylation between arbutin as
acceptor and sucrose as donor molecules, respectively. Optimum conditions for the transglucosylation reaction were 40 ꢀC for
2
0 h with 10 mM arbutin and 1.5 M sucrose in a 100 mM sodium citrate/phosphate buffer at pH 5.0. The new glucoside was
obtained in a 50% molar yield with respect to arbutin.
2007 Elsevier Ltd. All rights reserved.
ꢁ
In some cases enzymatic synthesis is superior to chemi-
cal synthesis, as the enzymatic reactions occur regio-
selectively and stereoselectively without the need to
have been synthesized by cyclomaltodextrin glucano-
transferase (CGTase)-assisted glucanotransferase trans-
glycosylation between arbutin and starch as acceptor
1
11
employ protection and deprotection sequences. In addi-
and donor molecules, respectively.
In addition,
tion, enzymatic reactions proceed under mild conditions
at low temperature and neutral pH. Various com-
pounds, such as drugs, vitamins, and phenolic com-
pounds have been glucosylated anomer-selectively with
4-hydroxyphenyl a-D-maltoside and 4-hydroxyphenyl
a-D-maltotrioside were synthesized using transglycosyla-
1
2
tion of CGTase. In our previous studies we examined
1
3
the stability of maltase and synthesized 4-hydroxyphen-
2
glycosidases from microorganisms.
yl a-D-isomaltotrioside from hydroquinone and maltose
1
0
using maltase from baker’s yeast.
Although a large number of glycosyl hydrolases are
known to perform transglycosylation, the majority of
reports have described the use of almond b-glucosi-
In this Letter, we report that an a-glucosidase from
Saccharomyces cerevisiae catalyzes the glucosidation of
b-arbutin to produce compound 1. The reaction
between sucrose and arbutin is illustrated in Scheme 1.
3
–5
dase. However, a-glucosidase (maltase) is one of the
most abundant glycosyl hydrolases present in Baker’s
6
yeast and has been used for the synthesis of menthyl-
7
and n-alkyl-glucosides. Various natural glycosides of
The enzymatic reaction was stopped by adding 0.1 M
HCl to give pH 3.0 and acetonitrile to give 10% (v/v).
The reaction mixture was then centrifuged, and
analyzed using an Akta Purifier HPLC (column: Waters
Spherisorb 5 lm ODS2 4.6 · 250 mm; mobile phase 10%
(v/v) in 1 mM HCl at 1.0 ml/min at 280 nm).
aromatic compounds have also been prepared using glu-
cosidase. One of them was 4-hydroxyphenyl b-D-gluco-
pyranoside (arbutin), which accumulates in the leaves
8
of plants and is used as a cosmetic ingredient. On the
other hand, 4-hydroxyphenyl a-D-glucopyranoside
(
a-arbutin) has been synthesized enzymatically from
9
–11
hydroquinone and saccharides.
4-Hydroxyphenyl
The reaction mixture containing 10 mM arbutin, 1.5 M
sucrose and 10U a-glucosidase/ml in 100 ml of 0.1 M
sodium citrate/phosphate buffer pH 5.0 was incubated
for 20 h at 30 ꢀC. The reaction was stopped and then
applied to a column packed with Purolite MN102, a
synthetic macroporous polystyrene resin, commercial-
ized by Purolite, Wales, UK. The column was first
washed with water and HCl. Retained compounds were
b-D-maltoside and 4-hydroxyphenyl b-D-maltotrioside
Keywords: a-Anomer-selective glucosylation; Transglucosylation;
4
*
-Hydroxyphenyl-b-isomaltoside; Maltase; Enzyme reactions.
Corresponding author. Tel.: +381 11 333 6656; fax: +381 11
638785; e-mail: nenadmil@chem.bg.ac.yu
0040-4039/$ - see front matter ꢁ 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2007.07.152

N. B. Milosavi c´ et al. / Tetrahedron Letters 48 (2007) 7222–7224
7223
OH
H
H
OH
H
H
O
H
O
OH
HO
H
HOH2C
H
CH2OH
OH
HO
H
O
H
HO
α-glucosidase
HO
H
OH
H
O
H
OH
H
HO
H
S.cerevisiae
H
O
H
O
HO
HO
O
OH
H
O
+
+
H
HO
OH
CH2OH
H
H
OH
H
H
0.1 M citrate/phosphate buffer
H
O
HO
HOH2C
HO
o
pH 5.0; 40 C
HO
O
OH
H
OH
H
H
Arbutin
Sucrose
Fructose
1
Scheme 1. The transglucosylation reaction catalyzed by a-glucosidase from baker’s yeast was optimized with respect to pH, temperature, time and
sucrose concentration (Table 1).
eluted with 96% (v/v) ethanol. The eluent was dried by
evaporation, then dissolved in distilled water and the
residue applied to a Sephadex G-10 column. The frac-
tions were monitored using TLC in ethyl acetate/meth-
anol/water (10:1.7:1.4 by vol) as the solvent. After
purification, 400 mg of compound 1 was obtained.
used for this type of reaction with other physiologically
active phenolic compounds containing a hydroquinone
moiety. Further studies on glucoside 1 with respect to
its inhibitory effect on tyrosinase are in progress in our
laboratory.
Structural analyses: The product was hydrolyzed to glu-
cose and arbutin with a final molar ratio of 1:1 by a-glu-
cosidase. The TOF LC/MS analysis of the product
Acknowledgment
The authors are grateful for the financial support of the
Ministry of Science and Environmental Protection of
Serbia Project No. 142020.
showed a molecular ion peak in positive mode
+
[
M+Na] at 457.13250 (C H O ). The specific optical
1
8
26 12
20
rotation was ½aꢀ +0.669. Sixteen signals were observed
D
1
3
by C NMR analysis. The glycosidic linkages were
determined to be of b-configuration and one of a-config-
References and notes
uration, based on the values of the coupling constants
1
(
J = 6.6, J = 3.6) of the anomeric protons from the H
1
2
. Yasukochi, T.; Inaba, C.; Fukase, K.; Kusumoto, S.
Tetrahedron Lett. 1999, 40, 6585–6589.
. Wong, C. H.; Whitesides, G. M. Enzymes in Synthetic
Organic Chemistry; Pergamon Press: Oxford, 1994; pp
1
4
NMR chemical shift values. From these results, we
concluded that the compound was 4-hydroxyphenyl-b-
isomaltoside 1.
2
52–311.
Under the conditions described in Table 1, 4-hydroxy-
phenyl-b-isomaltoside was obtained in a molar yield of
3. Bassao, A.; Ducret, A.; Gardossi, L.; Lortie, R. Tetrahe-
dron Lett. 2002, 43, 2005–2008.
4
5
6
. Akita, H.; Kurashima, K.; Nakamura, T.; Kato, K.
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. Akita, H.; Kawahara, E.; Kishida, M.; Kato, K. J. Mol.
Catal. B: Enzym. 2006, 40, 8–15.
. Nakagawa, H.; Yoshiyama, M.; Shimura, S.; Usami, K.;
Kirimura, S. Biosci. Biotechnol. Biochem. 1998, 62, 1332–
5
0% with respect to arbutin. This is about twice the yield
of the previously reported transglucosylation of o-, m-,
and p-hydroxybenzyl alcohols catalyzed by amyloglu-
1
5
cosidase. The yield of hydroquinone glucoside ob-
tained was more, 10 times higher, than the previously
published results.9
1
339.
7
. Kosary, J.; Stefanovits-Banyai, E.; Boross, L. J. Biotech-
nol. 1998, 66, 83–90.
By HPLC, only one product was detected in the reaction
mixture, and it was estimated that 50% of the arbutin
had been glycosylated. We previously reported the syn-
thesis of 4-hydroxyphenyl-a-isomaltoside from hydro-
8. Maeda, K.; Fukuda, M. J. Pharmacol. Exp. Ther. 1996,
76, 756–769.
2
9
. Prodanovic, R. M.; Milosavic, N. B.; Sladic, D.; Cirkovic
1
0
Velickovic, T.; Vujcic, Z. Biotechnol. Lett. 2005, 27, 551–
quinone and maltose. We purified glycoside 1, and
5
54.
confirmed its identity as 4-hydroxyphenyl-b-isomalto-
1
3
1
10. Prodanovic, R.; Milosavic, N.; Sladic, D.; Zlatovic, M.;
Bozic, B.; Velickovic Cirkovic, T.; Vujcic, Z. J. Mol.
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side by C NMR and H NMR analyses and TOF
LC/MS.
1
6
1
1. Kurosum, J.; Sato, T.; Yoshida, K.; Tsugane, T.; Shimura,
S.; Kirimura, K.; Kino, K.; Usami, J. J. Biosci. Bioeng.
2002, 93, 328–330.
In conclusion, a stereospecific synthesis of a new arbutin
derivate 4-hydroxyphenyl-b-isomaltoside has been
achieved from sucrose and arbutin with yeast a-glucosi-
dase in a one-step reaction. This biocatalyst could be
12. Sugimoto, K.; Nishimura, T.; Nomura, K.; Sugimoto, K.;
Kuriki, T. Chem. Pharm. Bull. 2003, 51, 798–801.
1
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Table 1. Optimal conditions for the transglucosylation reaction of
arbutin
1
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Lett. 2000, 22, 321–325.
Time (h)
pH
5.0
t (ꢀC)
Sucrose (M)
1.5
Arbutin (mM)
10
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O.; Cirkovic-Velickovic, T.; Vujcic, Z.; Jankov, R. M.
Biocat. Biotrans. 2006, 24, 195–200.
20
40

7224
N. B. Milosavi c´ et al. / Tetrahedron Letters 48 (2007) 7222–7224
00 0 0 0 00
(C-1 ), 98.6 (C-1 ), 78.5 (C-4 ), 77.1 (C-3 ), 76.5 (C-3 ),
1
6. Analytical data for 4-hydroxyphenyl-b-isomaltoside: TOF
LC/MS: C18 12, the concentration of compound
c = 0.1 mg/mL), ion mass (M+Na) 457.13165, measured
00 00 0 0
75.8 (C-5 ), 75.7 (C-2 ), 74.5 (C-2 ), 74.2 (C-5 ), 72.1 (C-
1
H
26
O
+
00
0
00
(
4 ), 68.3 (C-6 ), 63.1 (C-6 ), H NMR (200 MHz, DMSO)
+
mass (M+Na) 457.13250 error (mDa) 0.84965: R
f
= 0.15
6.92 (d, 2H, J = 9.0 Hz, H-2, H-6), 6.68 (d, 2H, J = 9.0 Hz,
20
0
(ethyl acetate/methanol/water 10:1.7:1.4 v/v), ½aꢀ +0.669
(
(
H-3, H-5), 4.68 (d, 1H, J = 3.6 Hz, H-1 ), 4.57 (d, 1H,
D
1
3
00
0
00
0
c = 1.5 mg/mL, H
2
O), C NMR (50 MHz, DMSO) 152.6
J = 6.6 Hz, H-1 ), 3.10–3.70 (m, 12 H, H-2 , H-2 H-3 , H-
00 0 00 0 00 0 0 00 00
C-1), 150.7 (C-4), 118.4 (C-3, C-5), 115.9 (C2, C6), 102.5
3 , H-4 , H-4 , H-5 , H-5 , H-6 A, H-6 B, H-6 , H-6 B).