New monoterpene glucoside from the aerial parts of thyme (Thymus vulgaris L.)

Article abstract of DOI:10.1271/bbb.68.1131

A new monoterpene glucoside (1) was isolated from a methanol extract of the dried aerial parts of thyme (Thymus vulgaris L.), together with known 2- and 5-β-D-glucopyranosylthymoquinols (2 and 3, respectively), and (-)-angelicoidenol-β-D-glucopyranoside (

Full text of DOI:10.1271/bbb.68.1131

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New Monoterpene Glucoside from the Aerial Parts of
Thyme (Thymus vulgaris L.)
Hiroyuki TAKEUCHIa, Zhan-Guo LUa & Tomoyuki FUJITAb
a Research and Development Laboratories, Nippon Terpene Chemicals, Inc.
b Division of Applied Biological Chemistry, Graduate School of Agriculture and Biological
Sciences, Osaka Prefecture University
Published online: 22 May 2014.
To cite this article: Hiroyuki TAKEUCHI, Zhan-Guo LU & Tomoyuki FUJITA (2004) New Monoterpene Glucoside from the
Aerial Parts of Thyme (Thymus vulgaris L.), Bioscience, Biotechnology, and Biochemistry, 68:5, 1131-1134, DOI: 10.1271/
bbb.68.1131
To link to this article: http://dx.doi.org/10.1271/bbb.68.1131
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Biosci. Biotechnol. Biochem., 68 (5), 1131–1134, 2004
Note
New Monoterpene Glucoside from the Aerial Parts of Thyme
(Thymus vulgaris L.)
y
2
Hiroyuki TAKEUCHI,1; Zhan-Guo LU,1 and Tomoyuki FUJITA
1Research and Development Laboratories, Nippon Terpene Chemicals, Inc.,
4-10 Wakinohama-cho 1-chome, Chuo-ku, Kobe 651-0072, Japan
2Division of Applied Biological Chemistry, Graduate School of Agriculture and Biological Sciences,
Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka 599-8531, Japan
Received October 6, 2003; Accepted January 17, 2004
A new monoterpene glucoside (1) was isolated from a
methanol extract of the dried aerial parts of thyme
(Thymus vulgaris L.), together with known 2- and 5-ꢀ-D-
glucopyranosylthymoquinols (2 and 3, respectively), and
(À)-angelicoidenol-ꢀ-D-glucopyranoside (4). The struc-
ture of 1 was elucidated to be (R)-p-cymen-9-yl ꢀ-D-
glucopyranoside by spectral evidence and enantioselec-
tive synthesis from (R)- and (S)-p-cymen-9-ol derived
from p-cymen-8-ol.
pounds and new constituents in the plant, we have
previously isolated three known flavonoid glycosides,
hesperidin, eriocitrin (= eriodictyol-7-rutinoside) and
narirutin, and two phenolic compounds, rosmarinic acid
and arbutin, from the n-BuOH soluble-fraction of a
methanolic extract of the dried aerial parts of thyme.6,7)
In addition to these five compounds, a new monoterpene
glucoside (1), together with three known monoterpene
glucosides (2, 3 and 4) were obtained in the present
study from the same extract. We report here the isolation
of these four monoterpene glucosides from the methanol
extract of thyme, and the structural elucidation of 1
which was based spectral evidence and enantioselective
synthesis.
Key words: Thymus vulgaris L.; thyme; monoterpene
glucoside; (R)-p-cymen-9-yl ꢀ-D-glucopy-
ranoside; enantioselective synthesis
Thyme (Thymus vulgaris L.) is a perennial herbaceous
plant native to Southern Europe. It is one of the spices
widely used as both a food additive and a folk medicine
to treat various illnesses in Europe.1) Five new biphenyl
compounds have previously been isolated from an
acetone extract of the leaves of thyme by Nakatani
and our colleague.2,3) These biphenyls showed more
effective deodorizing activity against methyl mercaptan
than sodium copper chlorophylline, which is commonly
used as an oral deodorizer.2–4) The antioxidative activity
of flavonoids isolated from the acetone extract of the
plant has also been reported by Miura and Nakatani.5) In
the course of our studies on polar deodorizing com-
The dried aerial parts of thyme (5 kg) cultivated in
Spain were soaked in MeOH for one week at room
temperature. The resulting methanol extract was con-
centrated, and the residue was sequentially extracted
with n-hexane, CHCl3, and n-BuOH. According to the
guidance of coloration on TLC with coloring reagents
such as sulfuric acid, thymol-sulfuric acid and ferric
chloride, the n-BuOH extract (50.8 g) was fractionated
by silica gel column chromatography [BW-820H
(Fujisilisia Chemical)] eluting with CHCl3 and an
increasing ratio of MeOH. The eluates were combined
into fifteen fractions on the basis of the TLC pattern.
Four known compounds, hesperidin, eriocitrin, narirutin
Fig. 1. Structures of the Monoterpene Glucosides from Thyme.
y
To whom correspondence should be addressed. Tel: +81-78-231-1331; Fax: +81-78-231-1336; E-mail: takeuchi@nipponterpene.co.jp

1132
H. TAKEUCHI et al.
and arbutin, were isolated from fractions 10–12 as
reported previously.6) After combining fractions 6–9
(10.7 g), rosmarinic acid was removed from the com-
bined fraction by silica gel column chromatography
(Kieselgel 60) eluting with EtOAc. The remaining
components in the column were then chromatographed
by eluting with a mixed solvent of EtOAc–MeOH–H2O
(20:1:0.1, v/v/v). Some of the fractions, including the
positive spots by TLC with thymol-sulfuric acid, were
subjected to preparative HPLC in a Chemcosorb 5-ODS-
H (4:6ꢁ ꢀ 150 mm) column to afford four monoterpene
glucosides, 1 (5.1 mg), 2 [47.5 mg, amorphous powder;
1H-NMR ꢂH (CD3OD, 500 MHz): 1.17, 1.18 (each 3H,
d, J ¼ 7:0 Hz), 2.18 (3H, s), 3.20 (1H, m), 3.70 (1H, dd,
J ¼ 5:2, 11.9 Hz), 3.87 (1H, dd, J ¼ 1:8, 11.9 Hz), 4.66
(1H, d, J ¼ 7:6 Hz), 6.52 (1H, s), 6.98 (1H, s); 13C-
NMR ꢂC (CD3OD): 127.0, 150.3, 116.0, 134.0, 150.4,
117.7, 16.2, 28.0, 23.2, 23.2, 104.3, 75.1, 78.2, 71.5,
78.0, 62.6], 3 [23.1 mg, amorphous powder; 1H-NMR ꢂH
(CD3OD, 500 MHz): 1.14, 1.15 (each 3H, d, J ¼
7:0 Hz), 2.12 (3H, s), 3.47 (1H, m), 3.70 (1H, dd,
J ¼ 5:2, 11.9 Hz), 3.88 (1H, dd, J ¼ 2:1, 11.9 Hz), 4.69
(1H, d, J ¼ 7:9 Hz), 6.61 (1H, s), 6.91 (1H, s); 13C-
NMR ꢂC (CD3OD): 123.2, 151.8, 113.0, 138.2, 149.2,
120.3, 16.1, 27.0, 23.6, 23.7, 104.4, 75.2, 78.3, 71.6,
J ¼ 8:2 Hz), 7.13 (2H, d, J ¼ 8:2 Hz)], one methine
group [ꢂC 40.6 (d); ꢂH 3.02 (1H, m)], one oxygenated
methylene group [ꢂC 76.2 (t); ꢂH 3.64 (1H, dd, J ¼ 6:0,
9.8 Hz), 3.90 (1H, dd, J ¼ 8:2, 9.8 Hz)] and two methyls
[ꢂC 21.1 (q), 19.0 (q); ꢂH 2.28 (3H, s), 1.27 (3H, d,
J ¼ 6:7 Hz)]. The 13C-NMR spectrum also showed the
presence of a ꢀ-glucopyranosyl moiety (ꢂC 104.2, 77.9,
77.8, 74.9, 71.5, and 62.7) by a comparison of the
chemical shifts with those of known monoterpene
glucosides.10) The coupling constant (J ¼ 7:9 Hz) be-
tween the anomeric proton and H0-2 supported the
compound to be a ꢀ-glucopyranoside. In the 1H–1H
COSY spectrum, correlations among the protons of a
methine (ꢂH 3.02), oxygenated methylene (ꢂH 3.64 and
3.90) and methyl (ꢂH 1.27) showed the presence of a
–CH(CH3)CH2O– moiety. The deshielded methyl group
(ꢂH 2.28) would have been directly attached to the 1,4-
di-substituted benzene ring. These spectral data were
used to infer that the aglycone moiety of 1 was p-cymen-
9-ol. The connectivity of these partial structures was
confirmed by HMBC data (H-2/C-7, H-3/C-1 and C-8,
H-7/C-2, H-9/C-4, C-10, and C-10, H-10/C-9). Com-
pound 1 was hydrolyzable by ꢀ-glucosidase (emulsin) to
give p-cymen-9-ol as an aglycone. Consequently, the
structure of 1 was elucidated to be p-cymen-9-yl ꢀ-D-
glucopyranoside.
20
78.0, 62.9] and 4 [2.1 mg, amorphous powder; ½ꢃꢁD
ꢂ30ꢃ (c 0.02, MeOH); 1H-NMR ꢂH (CD3OD,
500 MHz): 0.85, 0.92, 1.08 (each 3H, s), 1.01 (1H, dd,
J ¼ 3:1, 13.4 Hz), 1.31 (1H, br d, J ¼ 13:4 Hz), 1.70
(1H, d, J ¼ 5:2 Hz), 2.18 (1H, ddd, J ¼ 5:2, 9.2,
13.4 Hz), 2.49 (1H, dd, J ¼ 7:9, 13.4 Hz), 3.15–3.33
(4H, m), 3.66 (1H, dd, J ¼ 5:5, 11.6 Hz), 3.85 (1H, dd,
J ¼ 2:4, 11.6 Hz), 3.85 (1H, dd, J ¼ 2:7, 7.6 Hz), 4.05
(1H, ddd, J ¼ 1:8, 2.8, 9.2 Hz), 4.22 (1H, d, J ¼ 7:9
Hz); 13C-NMR ꢂC (CD3OD): 51.0, 82.9, 34.3, 53.6,
75.9, 39.7, 48.7, 21.3, 20.4, 13.4, 102.9, 75.1, 78.2, 71.7,
77.9, 62.8]. Their retention times by HPLC were 5.2, 6.8
and 8.4 min for 1–3 [eluent: H2O:MeOH = 70:30 (v/v),
flow rate: 1.0 ml/min, UV 280 nm], and 6.8 min for 4
[eluent: H2O:MeOH = 65:35 (v/v), flow rate: 1.0 ml/
min, RI detector], respectively. Compounds 2, 3 and 4
were respectively identified as 2- and 5-ꢀ-D-glucopyr-
anosylthymoquinol, and (ꢂ)-angelicoidenol-ꢀ-D-gluco-
pyranoside on the basis of a comparison of their spectral
data with those shown in the literature.8,9)
In order to determine the stereochemistry at C-8 of 1,
both (R)-p-cymen-9-ol [(R)-5] and (S)-p-cymen-9-ol
[(S)-5] were synthesized from p-cymen-8-ol according
to the method of Matsumoto et al.11,12) p-Cymen-8-ol
was dehydrated with aqueous H2SO4 and then hydrated
with BH3–THF and H2O2–NaOH to afford racemic 5.
After acetylating racemic 5 with Ac2O–pyridine, the
racemic p-cymen-9-yl acetate obtained (5.0 g) was
dissolved in methanol (140 ml) and hydrolyzed with
lipase (5.0 g, Type-II, Sigma) in 0.1 M phosphate buffer
(pH 6.86, 460 ml) at 35 ꢃC for 2.5 h. The reaction
mixture was extracted with Et2O, and the resulting
organic layer was evaporated under reduced pressure.
The Et2O extract was subjected to silica gel column
chromatography (BW-820H), successively eluting with
n-hexane-EtOAc (90:10 and then 70:30, v/v). The 30%
EtOAc eluate was further purified by silica gel column
chromatography (BW-820H), eluting with n-hexane–
EtOAc (75:25, v/v), to afford (S)-5 (1.80 g, 73% yield),
½ꢃꢁD ꢂ14:8ꢃ (c 9.01, CHCl3), R=S = 5:95. The 10%
20
Compound 1 was obtained as an amorphous powder,
20
½ꢃꢁD ꢂ30ꢃ (c 0.05, CHCl3). The molecular formula of
EtOAc eluate was recrystallized from MeOH to afford
20
1 was established to be C16H24O6 from HR-CIMS
(reaction gas: isobutane); m=z 313 [M + H]þ: Calcd. for
C16H25O6: 313.1651, Found: 313.1645 (see also the
NMR data in Table 1). The UV and IR spectra of 1
revealed the presence of an aromatic ring and hydroxyl
groups [UV ꢄmax (MeOH) nm ("): 258 (270), 264 (350),
and 272 (320); IR ꢅmax (KBr) cmꢂ1: 3400, 2920, 1520,
(R)-p-cymen-9-yl acetate (2.14 g, 68% yield), ½ꢃꢁD
þ8:0ꢃ (c 10.4, CHCl3). (R)-p-cymen-9-yl acetate
(2.08 g) was hydrolyzed with 5% aqueous sodium
hydroxide (12 ml). The reaction mixture was extracted
with CHCl3 and then worked up in the usual manner.
The CHCl3 extract was applied to silica gel column
chromatography (BW-820H), eluting with n-hexane–
EtOAc (70:30, v/v) to give (R)-5 (1.47 g, 91% yield),
1
1160, 1080, and 1040]. The H-NMR, 13C-NMR and
½ꢃꢁD þ15:7ꢃ (c 9.00, CHCl3), R=S = 98:2.
20
DEPT spectra revealed the presence of one 1,4-di-
substituted benzene ring [ꢂC 128.2 (d, 2 ꢀ C), 129.9 (d,
2 ꢀ C), 136.7 (s), and 142.4 (s); ꢂH 7.08 (2H, d,
Next, alcohols (R)-5 and (S)-5 were separately
glucosidized with Ag2CO3 as a catalyst by the modified

Table 1. 1H- and 13C-NMR Spectral Data for 1, (S)-1, (R)-5, (R)-6, and (S)-6
1 [= (R)-1]ꢄ
13C-NMR
(S)-1ꢄ
(R)-5ꢄꢄ
(R)-6ꢄꢄ
1H-NMR
ꢂH (integral, mult., J Hz)
(S)-6ꢄꢄ
1H-NMR
ꢂH (integral, mult., J Hz)
1H-NMR
ꢂH (integral, mult., J Hz)
13C-NMR
1H-NMR
ꢂH (integral, mult., J Hz)
13C-NMR
13C-NMR
13C-NMR
Position
ꢂC
ꢂC
ꢂC
ꢂC
ꢂC
1
2,6
3,5
4
136.7
128.2
129.9
142.4
21.1
—
136.8
128.3
129.9
142.5
21.0
—
136.0
127.2
129.2
140.4
21.1
135.7
127.1
128.9
140.7
21.0
—
7.08 (2H, s)
136.0
127.2
129.1
140.3
21.0
—
7.10 (2H, s)
7.08 (2H, d, 8.2)
7.13 (2H, d, 8.2)
—
7.07 (2H, d, 8.2)
7.13 (2H, d, 8.2)
—
7.08 (2H, s)
—
7.10 (2H, s)
—
7
2.28 (3H, s)
3.02 (1H, m)
2.28 (3H, s)
3.02 (1H, m)
2.31 (3H, s)
2.96 (1H, m)
2.31 (3H, s)
3.01 (1H, m)
8
40.6
76.2
41.0
76.7
42.0
68.7
39.3
75.5
39.1
75.7
9
3.64 (1H, dd, 6.0, 9.8)
3.90 (1H, dd, 8.2, 9.8)
1.27 (3H, d, 6.7)
4.24 (1H, d, 7.9)
3.15 (1H, dd, 7.6, 9.2)
3.3 (1H, m)
3.52 (1H, dd, 8.6, 9.8)
4.02 (1H, dd, 6.0, 9.8)
1.28 (3H, d, 7.0)
4.27 (1H, d, 7.9)
3.17 (1H, dd, 7.6, 9.2)
3.3 (1H, m)
3.51 (1H, dd, 7.7, 9.5)
3.94 (1H, dd, 6.6, 9.5)
1.22 (3H, d, 7.0)
4.41 (1H, d, 7.9)
4.95 (1H, dd, 7.9, 9.5)
5.14 (1H, t, 9.5)
5.06 (1H, t, 9.5)
3.64 (1H, ddd, 2.4, 4.6, 9.5)
4.12 (1H, dd, 2.4, 12.3)
4.25 (1H, dd, 4.6, 12.3)
3.42 (1H, t, 8.9)
4.02 (1H, dd, 5.2, 9.2)
1.26 (3H, d, 7.0)
4.49 (1H, d, 7.9)
5.03 (1H, dd, 7.9, 9.5)
5.15 (1H, dd, 9.5, 9.5)
5.06 (1H, dd, 9.5, 9.8)
3.66 (1H, ddd, 2.4, 4.6, 9.8)
4.11 (1H, dd, 2.4, 12.5)
4.25 (1H, dd, 4.6, 12.5)
10
Glc-1
19.0
104.2
74.9
77.9
71.5
77.8
62.7
19.0
104.8
75.1
78.1
71.6
77.9
62.7
17.7
18.2
100.8
71.0
72.7
68.4
71.7
61.9
17.9
101.0
71.2
72.8
68.4
71.8
61.9
2
3
4
5
6
3.3 (1H, m)
3.26 (1H, m)
3.3 (1H, m)
3.25 (1H, m)
3.66 (1H, dd, 5.2, 11.9)
3.86 (1H, dd, 1.8, 11.9)
3.65 (1H, dd, 5.2, 11.9)
3.85 (1H, dd, 1.5, 11.9)
CO
170.5
170.1
169.2
169.0
20.77
20.63
20.62
20.40
170.7
170.3
169.4
169.3
20.74
20.61
20.58
20.55
CH3
2.08 (3H, s)
2.01 (3H, s)
1.98 (3H, s)
1.81 (3H, s)
2.08 (3H, s)
2.02 (3H, s)
2.01 (3H, s)
1.98 (3H, s)
The spectra were measured at 270 MHz for 1H and at 67.5 MHz for 13C, with tetramethylsilane used as an internal standard. Coupling constants in Hz are in parentheses.
ꢄTaken in CD3OD. ꢄꢄTaken in CDCl3.

1134
H. TAKEUCHI et al.
Konigs–Knorr method.10,13) An Ag2CO3/Celite (4.68 g,
¨
against methyl mercaptan among the compounds already
isolated from the methanol extract,6,7) although the
monoterpene glucosides (1–4) found here did not show
any deodorizing activity.
43% Ag2CO3) catalyst was added to a solution of (R)-5
(1.42 g) and acetobromo-ꢃ-D-glucose (4.64 g) in Et2O
(30 ml). The solution was refluxed for 6 h in the dark,
before the reaction mixture was cooled to room temper-
ature. After removing the catalyst by filtration, the
filtrate was evaporated under reduced pressure. The
residue was subjected to silica gel column chromatog-
raphy (BW-820H) with n-hexane–EtOAc (70:30, v/v)
and then crystallized from n-hexane–EtOAc to give (R)-
p-cymen-9-yl 2,3,4,6-tetra-O-acetyl-ꢀ-D-glucopyrano-
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cals’’, CRC Press, Boca Raton, pp. 493–495 (1994).
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new deodorant biphenyl compounds from thyme (Thy-
mus vulgaris L.) and their activity against methyl
mercaptan. Agric. Biol. Chem., 53, 1375–1381 (1989).
3) Miura, K., Inagaki, T., and Nakatani, N., Structure and
activity of new deodorant biphenyl compounds from
thyme (Thymus vulgaris L.). Chem. Pharm. Bull., 37,
1816–1819 (1989).
4) Nakatani, N., Hashimoto, J., and Tsuda, H., Deodorant
activity of thyme extract and application to chewing
gum. Shokuhin to Kaihatsu (in Japanese), 28, 42–45
(1993).
5) Miura, K., and Nakatani, N., Antioxidative activily of
flavonoids from thyme (Thymus vulgaris L.). Agric. Biol.
Chem., 53, 3043–3045 (1989).
6) Takeuchi, H., Tsuda, H., Lu, Z.-G., Fujii, T., and Fujita,
T., Studies on the constituents from Thymus vulgaris L.
(1). 43rd Symposium on the Chemistry of Terpenes,
Essential Oils, and Aromatics (in Japanese), pp. 354–356
(1999).
7) Takeuchi, H., Tsuda, H., Lu, Z.-G., Fujii, T., and Fujita,
T., Deodorant compositions containing Thymus vulgaris
extract. Japan Kokai Tokkyo Koho, 2001-89340 (Apr. 3,
2001).
8) Yahara, S., Sakamoto, C., Nohara, T., Niiho, Y.,
Nakajima, Y., and Ito, H., Thymoquinol glucosides from
Schisandrae fructus. Shoyakugaku Zasshi, 47, 420–422
(1993).
9) Inoshiri, S., Saiki, M., Kohda, H., Otsuka, H., and
Yamasaki, K., Monoterpene glucosides from Berchemia
racemosa. Phytochemistry, 27, 2869–2871 (1988).
10) Fujita, T., and Nakayama, M., Monoterpene glucosides
and other constituents from Perilla frutescens. Phyto-
chemistry, 34, 1545–1548 (1993).
side (R)-6 (1.54 g, 34% yield), mp 103–104 ꢃC, ½ꢃꢁD
20
ꢂ21:6ꢃ (c 5.51, CHCl3); IR ꢅmax (KBr) cmꢂ1: 2970,
1
1750, 1520, 1370, 1260 and 1220. H- and 13C-NMR
data: see Table 1. In the same manner, (S)-5 (1.57 g) was
converted to (S)-6 (2.51 g, 50% yield), mp 104–105 ꢃC,
20
½ꢃꢁD ꢂ13:3ꢃ (c 2.12, CHCl3); IR ꢅmax (KBr) cmꢂ1
:
2960, 1740, 1520, 1370, and 1220. The HPLC retention
times of (R)-6 and (S)-6 were 10.3 and 11.0 min,
respectively [Chemcosorb 5-ODS-H (4:6ꢁ ꢀ 150 mm);
eluent, H2O–MeOH (30:70, v/v); flow rate, 1.0 ml/min].
After recrystallization, both (R)-6 and (S)-6 were
confirmed to be optically pure by the HPLC analysis.
To a solution of (R)-6 (1.24 g) in MeOH (90 ml), 10%
KOH (0.3 ml) was added dropwise, and the mixture
stirred for 1 h at room temperature. The reaction mixture
was concentrated in vacuo, and the resulting residue was
subjected to silica gel column chromatography (BW-
820H) with a mixture of CHCl3–MeOH (70:30, v/v) to
give (R)-1 (0.80 g) as colorless needles, mp 85–87 ꢃC,
20
1
½ꢃꢁD ꢂ33:8ꢃ (c 4.10, CHCl3). The IR, H- and 13C-
NMR spectral data of (R)-1 were identical with those of
1. (S)-1 was obtained from (S)-6 in a similar way in a
quantitative yield [(S)-1, mp 119–120 ꢃC, ½ꢃꢁD ꢂ36:4ꢃ
20
(c 1.86, CHCl3); H- and 13C-NMR data: see Table 1].
1
The notable difference between (R)-1 and (S)-1 was the
chemical shift of the methylene protons at C-9 in their
1H-NMR spectra, although the values for their specific
rotation were quite close. The chemical shift of H2-9 in
(R)-1 was ꢂH 3.64 and 3.90, while that in (S)-1 was ꢂH
3.52 and 4.02. Consequently, the stereochemistry of C-8
in 1 was determined to be (R)-configuration.
This study isolated a new compound, (R)-p-cymen-9-
yl ꢀ-D-glucopyranoside (1), and three known mono-
terpene glucosides (2–4) from a methanolic extract of
the dried aerial parts of thyme. This is the first report on
the isolation of these monoterpene glucosides from
thyme. These glucosides seemed to be present as aroma
precursors or as protected forms of their aglycones in the
plant, although their aglycones have not been detected as
volatiles in thyme oil. Eriocitrin and rosmarinic acid
have previously shown highly deodorizing activity
11) Matsumoto, T., Ishida, T., Yoshida, T., Terao, H.,
Takeda, Y., and Asakawa, Y., The enantioselective
metabolism of p-cymene in rabbits. Chem. Pharm. Bull.,
40, 1721–1726 (1992).
12) Matsumoto, T., Takeda, Y., Terao, H., Takahashi, T.,
and Wada, M., Lipase-catalyzed resolution of racemic 1-
acyloxy-2-(p-tolyl)propanes. Chem. Pharm. Bull., 41,
1459–1461 (1993).
13) Miyakoshi, T., and Numata, A., Synthesis of terpenyl ꢀ-
D-glucopyranosides from terpene alcohols and tetra-O-
acetyl-ꢃ-D-glucopyranosyl bromide with silver carbonate
supported on silicagel. Yukagaku (in Japanese), 43, 31–
38 (1994).