Triterpene glycosides from Kalopanax septemlobum. II. Glycosides E, K, and L from leaves of Kalopanax septemlobum var. maximowiczii introduced to Crimea

Article abstract of DOI:10.1007/s10600-005-0140-9

The known hederagenin 3-O-β-D-glucopyranosyl-(1→4)-O-β-D- xylopyranosyl-(1→3)-O-α-L-rhamnopyranosyl-(1→2) -O-α-L-arabinopyranoside (sapindoside C) and its 28-O-α-L- rhamnopyranosyl-(1→4)-β-D-glucopyranosyl-(1→6) -O-β-D-glucopyranosyl and 28-O-α-L-rhamnopyranosyl-(1→4)-O-6-O- acetyl-β-D-glucopyranosyl-(1→6)-O-β-D-glucopyranosyl esters, new triterpene glycosides, were isolated from leaves of Kalopanax septemlobum var. maximowiczii introduced to Crimea. The structures of these compounds were established using chemical methods and two-dimensional NMR spectroscopy. 2005 Springer Science+Business Media, Inc.

Full text of DOI:10.1007/s10600-005-0140-9

Chemistry of Natural Compounds, Vol. 41, No. 3, 2005
TRITERPENE GLYCOSIDES FROM
.
Kalopanax septemlobum
II. GLYCOSIDES E, K, AND L FROM LEAVES OF
Kalopanax
VAR.
INTRODUCED TO CRIMEA
maximowiczii
septemlobum
D. A. Panov,1 V. I. Grishkovets,1
V. V. Kachala,2 and A. S. Shashkov2
UDC 547.918:543.422
β
→
β
→
α
The known hederagenin 3-O- -D-glucopyranosyl-(1 4)-O- -D-xylopyranosyl-(1 3)-O- -L-
→
α
α
rhamnopyranosyl-(1 2)-O- -L-arabinopyranoside (sapindoside C) and its 28-O- -L-rhamnopyranosyl-
→
β
→
β
α
→
(1 4)- -D-glucopyranosyl-(1 6)-O- -D-glucopyranosyl and 28-O- -L-rhamnopyranosyl-(1 4)-O-6-O-
β
→
β
acetyl- -D-glucopyranosyl-(1 6)-O- -D-glucopyranosyl esters, new triterpene glycosides, were isolated
Kalopanax septemlobum maximowiczii
from leaves of
var.
introduced to Crimea. The structures of these
compounds were established using chemical methods and two-dimensional NMR spectroscopy.
Key words:
var.
, Araliaceae, triterpene glycosides, hederagenin glycosides.
maximowiczii
Kalopanax septemlobum
We have previously reported the method for isolating glycosides E (1), K (2), and L (3) from leaves of
Kalopanax
[1]. These glycosides were additionally purified of phenolic impurities by rechromatography
maximowiczii
var.
septemlobum
over silica gel. Total acid hydrolysis of 1-3 showed that the carbohydrate fragments in all glycosides were glucose, xylose,
rhamnose, and arabinose whereas the aglycon was hederagenin.
Glycoside 1 was insensitive toalkaline hydrolysis. However, it was methylated bydiazomethane in ether. This defines
it as a monodesmoside that lacks a carbohydrate chain on the hederagenin carboxyl. On the other hand, compounds 2 and 3
were bisdesmosides and underwent alkaline hydrolysis, as a result of which both 2 and 3 afforded 1. Furthermore, 2 converted
under mild alkaline hydrolysis into 3, which indicates that it contains an additional acyl fragment. Treatment of 3 with
an enzyme prepared from hepatopancreatic fluid of the grape snail (
Helix pomatia
), which cleaves terminal glucose
units, produced from it the previouslydescribed glycoside 3-O-β-D-xylopyranosyl-(1→3)-O-α-L-rhamnopyranosyl-(1→2)-O-
α-L-arabinopyranosyl-28-O-α-L-rhamnopyranosyl-(1→4)-β-D-glucopyranosyl-(1→6)-O-β-D-glucopyranosyl ester of
hederagenin [1].
12
COOR
2
28
3
R O
1
CH OH
2
23
1 - 3
R1
R2
H
1: β-D-Clcp→4β-D-Xylp→3α-L-Rhap→2α-L-Arap
2: β-D-Clcp→4β-D-Xylp→3α-L-Rhap→2α-L-Arap
3: β-D-Clcp→4β-D-Xylp→3α-L-Rhap→2α-L-Arap
←β-D-Clcp6←(β-D-Clcp6 ←OAc)4←α-L-Rhap
←β-D-Clcp6←β-D-Clcp4 ←α-L-Rhap
1) V. I. Vernadskii Tauris National University, 95007, Ukraine, Simferopol′, prospekt Vernadskogo, 4, e-mail:
vladgri@ukr.net; 2) N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, B-334, Leninskii
prospekt, 47. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 260-262, May-June, 2005. Original article submitted
February 3, 2005.
0009-3130/05/4103-0322 ©2005 Springer Science+Business Media, Inc.
322

TABLE 1. Chemical Shifts of 13C Atoms of Aglycons of Glycosides 1-3
C atom
1
2, 3*
C atom
1
2, 3*
1
2
39.0
26.2
81.1
43.6
47.7
18.2
32.8
39.8
48.2
36.9
23.8
122.6
144.8
42.2
28.3
39.1
26.4
81.2
43.6
47.7
18.3
32.8
40.0
48.3
37.0
23.9
123.0
144.2
42.2
28.4
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
23.7
46.6
42.0
46.4
30.9
34.2
33.2
64.0
14.2
16.1
17.4
26.3
180.2
33.2
23.8
23.4
47.1
41.7
46.3
30.8
34.1
32.7
64.0
14.2
16.3
17.6
26.2
176.7
33.2
23.8
3
4
5
6
7
8
9
10
11
12
13
14
15
______
*Here and in Table 2, average chemical shifts are given for these compounds. Deviations for individual compounds are less
than ±0.1 ppm.
It is interesting tonote that this same product was obtained byenzymatic degradation of2 since the enzyme preparation
contains glucosidase and esterase enzymes that cleave sterically unsubstituted acyl groups. Furthermore, it can be concluded
that the additional terminal glucose unit is located in the carbohydrate chain on C-3 of hederagenin because enzymatic
hydrolysis of 1 (and progenins of glycosides 2 and 3) produced hederagenin 3-O-β-D-xylopyranosyl-(1→3)-O-α-L-
rhamnopyranosyl-(1→2)-O-α-L-arabinopyranoside. NMRspectroscopywasusedtodeterminethebondingsiteoftheadditional
terminal glucose and to confirm conclusively the structures of 1-3.
The nature of the aglycon in 1-3 was confirmed by analyzing the chemical shifts of C atoms in the one-dimensional
13
C NMR spectrum. The shifts are completely identical to those of 3-O-glycosylated hederagenin in 1 [2] and 3,2-di-O-
13
glucosylated hederagenin in 2 and 3 [2]. Table 1 lists the chemical shifts of the C atoms in NMR subspectra of the aglycons
of 1-3.
For 1 (and progenins of glycosides 2 and 3), a combination of two-dimensional COSY, HSQC, and ROESY methods
13
was used to assign completely and unambiguously the signals in the PMR and C NMR spectra. Signals of skeletal protons
of monosaccharides in the PMR spectrum (Table 2) were assigned based on the COSY and TOCSY spectra, starting with
nonoverlapping signals in the low-field protion of the spectrum for anomeric H atoms and the methyl signals for rhamnose in
the high-field portion. The multiplicity and magnitude of the spin—spin coupling constants for the skeletal protons of
monosaccharides confirmed that they belonged to α-arabino-, α-rhamno-, β-xylo-, and β-glucopyranoses.
13
Signals for C atoms of monosaccharide units were completely assigned using the two-dimensional HSQC method
based on the magnitudes of the chemical shifts for skeletal protons. The magnitudes of the chemical shifts for C atoms
compared with those reported for unsubstituted monosaccharide units [3] revealed significant positive α-effects from
glycosylation for C-2 of arabinose, C-3 of rhamnose, and C-4 of xylose. Small negative β-effects on the corresponding
neighboring C atoms were observed. Glycosylation did not affect the terminal glycopyranose unit. The bonding sequence of
themonosaccharideswasdeterminedbyenzymatichydrolysisandROESYspectra, in which structurallyinformativecrosspeaks
were identified between rhamnose H-1 and arabinose H-2, xylose H-1 and rhamnose H-3, terminal glucose H-1 and xylose H-4,
and arabinose H-1 and aglycon H-3.
The above data define unambiguously the structure of 1 (and progenins of 2 and 3) as hederagenin 3-O-β-D-
glucopyranosyl-(1→4)-O-β-D-xylopyranosyl-(1→3)-O-α-L-rhamnopyranosyl-(1→2)-O-α-L-arabinopryanoside.
323

TABLE 2. Chemical Shifts of 1H and 13C Atoms of Carbohydrates of Glycosides 1-3
13C atom
1-3*
1H atom
1-3*
13C atom
2
1H atom
2
13C atom
3
1H atom
3
Ara-1
104.6
75.4
74.9
69.6
66.0
Ara-1
5.06
4.53
4.05
4.15
3.69
4.27
Glc-1
90.7
73.9
78.6
70.8
78.1
69.4
Glc-1
2
6.19
4.09
4.18
4.21
4.10
4.64
4.32
Glc-1
95.7
73.9
78.6
70.8
78.1
69.3
Glc-1
2
6.18
4.10
4.20
4.28
4.07
4.63
4.30
2
3
4
5
2
2
3
4
5
6
2
3
4
5
6
3
3
3
4
4
4
5a
5e
5
5
6A
6B
6A
6B
Rha-1
101.4
71.9
82.9
72.9
69.7
18.6
Rha-1
6.22
4.83
4.65
4.42
4.66
1.56
Glc-1
104.7
75.1
76.4
79.4
73.8
63.8
20.9
171.0
Glc-1
2
4.98
3.92
4.10
4.07
3.82
4.62
4.52
1.93
Glc-1
104.8
75.3
76.5
78.5
77.2
61.3
Glc-1
2
4.97
3.90
4.10
4.32
3.63
4.18
4.05
2
3
4
5
6
2
3
4
5
6
2
2
3
4
5
6
3
4
3
3
4
4
5
5
5
6
6A
6B
-OAc
6A
6B
-OAc
-OAc
Xyl-1
107.0
75.3
76.2
78.0
64.9
Xyl-1
5.22
4.02
4.12
4.25
4.30
3.57
Rha-1
103.0
72.4
72.6
73.9
70.8
18.6
Rha-1
5.50
4.55
4.47
4.28
4.79
1.68
Rha-1
102.8
72.5
72.7
73.9
70.5
18.6
Rha-1
5.76
4.64
4.50
4.28
4.87
1.65
2
3
4
5
2
2
3
4
5
6
2
3
4
5
6
2
3
4
5
6
2
3
4
5
6
3
4
5e
5a
Glc-1
103.6
74.4
78.1
71.7
78.8
62.7
Glc-1
2
4.93
3.96
4.17
4.10
3.94
4.52
4.24
2
3
4
5
6
3
4
5
6A
6B
13
The C NMR spectra of 2 and 3, when compared with that of 1, contained additional signals for C atoms of
trisaccharide units bonded to the aglycon by an acylglycoside bond at C-28. Comparison of the chemical shifts, for example,
with those previously reported [1], identified them unambiguously as 28-O-α-L-rhamnopyranosyl-(1→4)-O-6-O-acetyl-β-D-
glucopyranosyl-(1→6)-O-β-D-glucopyranosyl and 28-O-α-L-rhamnopyranosyl-(1→4)-β-D-glucopyranosyl-(1→6)-O-β-D-
glucopyranosyl fragments, which are verycharacteristic ofglycosides ofAraliaceae plants [4]. The structuresofthesefragments
were additionally confirmed using two-dimensional NMR methods, as described above for 1. Table 2 gives the chemical shifts
1
13
of H and C atoms of these fragments.
Thus,2and3are3-O- -D-glucopyranosyl-(1→4)-O-β-D-xylopyranosyl-(1→3)-O-α-L-rhamnopyranosyl-(1→2)-O-α-
L-arabinopyranosyl-28-O-α-L-rhamnopyranosyl-(1→4)-O-6-O-acetyl-β-D-glucopyranosyl-(1→6)-O-β-D-glucopryanosyland
3-O-β-D-glucopyranosyl-(1→4)-O-β-D-xylopyranosyl-(1→3)-O-α-L-rhamnopyranosyl-(1→2)-O-α-L-arabinopyranosyl-28-O-α-
L-rhamnopyranosyl-(1→4)-β-D-glucopyranosyl-(1→6)-O-β-D-glucopyranosyl esters of hederagenin and are new triterpene
glycosides. The structure of 1 is identical to that of sapindoside C, which was isolated previously from Sapindus mukorossi [5].
The structure of this glycoside was established using only chemical methods and was not confirmed by NMR spectroscopy.
324

EXPERIMENTAL
General comments have been published [1]. Enzymatic hydrolysis was carried out by dissolving glycoside in a 100-
fold excess of water, adding a 5-10-fold weight excess of the appropriate enzyme, and thoroughly stirring the mixture and
holding it at 40-50°C from several hours to one day with TLC monitoring. After the process was complete, a 3-5-fold excess
of CH OH was added. The mixture was heated to boiling. The denatured enzyme was separated by centrifugation. The
3
supernatant was evaporated to dryness. The enzymolysis products were analyzed by TLC.
The method for isolating 1 (300 mg), 2 (860 mg), and 3 (350 mg) from leaves of K. septemlobum var. maximowiczii
has been reported [1]. The crude glycosides were additionally purified by rechromatography over silica gel with elution by
water-saturated CHCl :isopropanol (4:1) for glycoside E and water-saturated CHCl :isopropanol (1:1) for glycosides K and L.
3
3
This produced pure 1 (150 mg), 2 (550 mg), and 3 (210 mg).
The total acid hydrolysates of 1-3 contained hederagenin and the sugars glucose, xylose, rhamnose, and arabinose.
Alkaline hydrolysis of 2 and 3 afforded 1. Mild alkaline hydrolysis of 2 afforded 3. Enzymatic hydrolysis of 1 afforded
hederagenin 3-O-β-D-glycopyranosyl-(1→4)-O-β-D-xylopyranosyl-(1→3)-O-α -L-rhamnopyranosyl-(1→2)-O-α-L-
arabinopyranoside; of 2 and 3, hederagenin 3-O-β-D-xylopyranosyl-(1→3)-O-α-L-rhamnopyranosyl-(1→2)-O-α-L-
arabinopyranosyl-28-O-α-L-rhamnopyranosyl-(1→4)-β-D-glucopyranosyl-(1→6)-O-β-D-glucopyranosyl ester.
13
1
13
Table 1 gives chemical shifts of C atoms in the NMR of the aglycons of 1-3; Table 2, of H and C in the
carbohydrate parts of 1-3.
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1.
2.
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(1996).
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4.
5.
P. A. J. Gorin and M. Mazurek, Can. J. Chem., 53, 1212 (1975).
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