Triterpenoid saponins from Schefflera arboricola

Article abstract of DOI:10.1016/S0031-9422(03)00117-1

Nine triterpenoid saponins were isolated from the leaves and stems of Schefflera arboricola. The saponins were characterised, on the basis of chemical and spectral evidence, as 3-O-[α-L-rhamnopyranosyl-(1→4)-β-D-glucuronopyranosyl] oleanolic acid, 3-O-[α-

Full text of DOI:10.1016/S0031-9422(03)00117-1

Phytochemistry 63 (2003) 401–407
www.elsevier.com/locate/phytochem
Triterpenoid saponins from Schefflera arboricola
a,
b
c
c
F.R. Melek *, Toshio Miyase , S.M. Abdel Khalik , M.R. El-Gindi
aChemistry of Natural Products Department, National Research Centre, Dokki, Cairo, Egypt
bSchool of Pharmaceutical Sciences, University of Shizuoka, Shizuoka 422-8526, Japan
cPharmacognosy Department, Faculty of Pharmacy, Helwan University, Cairo, Egypt
Received in revised form 10 October 2002
Abstract
Nine triterpenoid saponins were isolated from the leaves and stems of Schefflera arboricola. The saponins were characterised, on
the basis of chemical and spectral evidence, as 3-O-[a-l-rhamnopyranosyl-(1!4)-b-d-glucuronopyranosyl] oleanolic acid, 3-O-[a-l-
rhamnopyranosyl-(1!4)-b-d-glucuronopyranosyl] echinocystic acid, 3-O-[b-d-apiofuranosyl-(1!4)-b-d-glucuronopyranosyl]
oleanolic acid 28-O-b-d-glucopyranosyl ester, 3-O-a-l-ramnopyranosyl-(1!4)-[a-l-arabinopyranosyl-(1!2)-] b-d-glucuronopyr-
anosyl oleanolic acid, 3-O-a-l-rhamnopyranosyl-(1!4)-[a-l-arabinopyranosyl-(1!2)-] b-d-glucuronopyranosyl oleanolic acid 28-
O-b-d-glucopyranosyl ester, 3-O-a-l-rhamnopyranosyl-(1!4)-[b-d-galactopyranosyl-(1!2)-] b-d-glucuronopyranosyl oleanolic
acid, 3-O-a-l-rhamnopyranosyl-(1!4)-[b-d-galactopyranosyl-(1!2)-] b-d-glucuronopyranosyl oleanolic acid 28-O-b-d-glucopyr-
anosyl ester, 3-O-b-d-apiofuranosyl-(1!4)-[a-l-arabinopyranosyl-(1!2)-] b-d-glucuronopyranosyl oleanolic acid and 3-O-b-d-
apiofuranosyl-(1!4)-[a-l-arabinopyranosyl-(1!2)-] b-d-glucuronopyranosyl oleanolic acid 28-O-b-d-glucopyranosyl ester.
#
2003 Elsevier Science Ltd. All rights reserved.
Keywords: Schefflera arboricola; Araliaceae; Triterpenoid saponin
1
. Introduction
Schefflera arboricola (Hayata) Merr. is an ornamental
plant which usually grows up to 2–3 m in height. Pre-
vious pharmacological studies (Liao, 1986) showed that
the ethanolic leaf extract of S. arboricola exhibited
sedative, hypnotic, analgesic, anticonvulsant and
smooth muscle relaxant effects. Previous phytochemical
investigation on a mixture of leaves and stems of
S. arboricola has led to the isolation of the two oleanolic
acid glucuronoides cynarasaponin H and olaxoside
(Abdel Khalik, 2001).
As a part of our continuing studies on saponins
from plant species grown in Egypt (Miyase et al.,
1
2
996a; Abdel Khalik et al., 2000, 2001; Melek et al.,
000) we report here the isolation and structure
determination of nine new triterpenoidal saponins
(1–9) from S. arboricola.
*
Corresponding author. Fax: +20-2-519-1271.
E-mail address: asecengf@infinity.com.eg (F.R. Melek).
0031-9422/03/$ - see front matter # 2003 Elsevier Science Ltd. All rights reserved.
doi:10.1016/S0031-9422(03)00117-1

402
F.R. Melek et al. / Phytochemistry 63 (2003) 401–407
2
. Results and discussion
two anomeric proton signals at ꢀ 4.97 (d, J=7.6 Hz) and
1
ꢀ
5.86 (brs) in the H NMR spectrum and assigned to
The concentrated methanolic extract of a mixture of
b-glucuronic acid and a-rhamnose units, respectively. A
H– H COSY experiment allowed analysis of their spin
1
1
leaves and stems of S. arboricola was diluted with ace-
tone to precipitate the crude saponins mixture. Chro-
matography of the mixture using silica gel, Sephadex
LH-20 and the polymer gel Mitsubishi Diaion HP-20
followed by HPLC, afforded nine new saponins. Their
structures were established on the basis of chemical
hydrolysis and NMR data (Tables 1–3).
systems and assignments of their proton resonances.
The assignment of their corresponding carbons, made
by a HMQC spectrum, indicated that rhamnose was a
terminal unit. The Rha-(1!4)-GlcA structure of the
disaccharide moiety at C-3 of the oleanolic acid residue
was deduced from the HMBC correlations between C-3
(ꢀ 89.3) and H-1 (ꢀ 4.97) of GlcA unit and between C-4
(ꢀ 80.4) of the GlcA unit and H-1 (ꢀ 5.86) of the Rha
unit. The relative stereochemistry of each mono-
saccharide was determined as b-d-glucuronopyranose
and a-l-rhamnopyranose based on the characteristic
Saponin 1 had a molecular formula C H O as
4
2
66 13
determined from 13C NMR data and a quasi-molecular
ion peak [M+Na]+ at m/z 801 in the positive-ion FAB-
mass spectrum. The 13C NMR spectrum of 1 exhibited
signals, due to a triterpene moiety, at ꢀ-values similar to
those of oleanolic acid 3-O-glycosides. Acid hydrolysis
of 1 yielded oleanolic acid and the released mono-
saccharide units were identified as d-glucuronic acid
1
3
JH-1,H-2 coupling constants and C NMR data. There-
fore, 1 was assigned the structure of 3-O-[a-l-rhamno-
pyranosyl-(1!4)-b-d-glucuronopyranosyl] oleanolic acid.
Compound 1 was previously obtained after partial
hydrolysis of the saponins olaxoside, previously repor-
ted from a number of Olax species (Forgacs and Pro-
vost, 1981) and narcissiflorinine, isolated from Anemone
(
GlcA) detected by paper chromatography and l-rham-
nose (Rha) identified by GC after being converted to its
thiazolidine derivative (Hara et al., 1986). The dis-
accharide nature of 1 was deduced from the presence of
Table 1
1H NMR spectral data of saponins 1–9 in C
5 5
D N
1
2
3
4
5
Triterpene moiety
3
1
1
1
3.36 (dd, 11.4, 4.5)
5.45 (t, 3.0)
3.39 (dd, 11.4, 4.5)
5.62 (t, 3.5)
5.24 (brs)
3.35 (dd, 11.4, 4.5)
5.42 (t, 3.5)
3.30 (dd, 11.4, 4.4)
5.45 (t, 3.0)
3.29 (dd, 11.4, 4.5)
5.41 (t, 3.5)
2
6(eq)
8
3.28 (dd, 13.9, 3.3)
3.61 (dd, 14.4, 3.4)
3.19 (dd, 14.0, 3.3)
3.27 (dd, 14.0, 3.4)
3.18 (dd, 14.0, 3.5)
3
1
2
3
4
5
-0-Sugar GlcA
4.97 (d, 7.6)
4.06 (t, 8.2)
4.25 (t, 8.2)
4.59
4.99 (d, 7.8)
4.08 (t, 8.5)
4.26 (t, 8.5)
4.61
4.98 (d, 7.6)
4.08 (t, 8.0)
4.98 (d, 7.8)
4.18
4.31
4.98 (d, 7.4)
4.19 (t, 8.6)
4.32
4.58 (t, 8.7)
4.66 (d, 9.0)
4.63 (t, 9.1)
4.54
4.63 (t, 9.2)
4.54
4.60
4.62
At GlcA C-4 Rha
1
2
3
4
5
6
5.86 (brs)
4.75 (brs)
5.88 (brs)
5.85 (brs)
4.73 (brs)
4.52
5.86 (brs)
4.73 (dd, 3.1, 1.5)
4.54
4.77 (dd,2.5,1.5)
4.57 (dd, 9.5, 3.3)
4.29 (t, 9.5)
4.98
4.56 (dd, 9.0, 3.2)
4.27 (t, 9.0)
4.97
4.26 (t, 9.1)
4.94 (dq, 9.1, 6.5)
1.65 (d, 6.5)
4.27
4.95
1.67 (d, 6.3)
1.69 (d, 6.5)
1.65 (d, 6.1)
Api
1
6.09 (d, 2.5)
4.77 (d, 2.5)
2
3
4
4.81 (d, 10.0)
4.16 (brs)
5
At GlcA C-2 Ara
1
2
3
4
5
5.22 (d, 6.5)
4.55
4.19
5.23 (d, 6.2)
4.54 (t, 6.8)
4.22
4.31
3.78 (d, 11.7)
4.38 (dd, 11.7, 3.3)
4.32
3.78 (dd, 12.3, 1.8)
4.38
0
5
(
continued on next page)

F.R. Melek et al. / Phytochemistry 63 (2003) 401–407
403
Table 1 (continued)
1
2
3
4
5
2
1
2
3
4
5
6
6
8-0-Glc
6.30 (d, 7.8)
4.18 (t, 8.0)
6.30 (d, 8.0)
4.19 (t, 8.6)
4.26
4.26 (t, 8.0)
4.33 (t, 8.0)
4.34
4.01 (m)
4.38 (dd, 12.4, 3.0)
4.45 (dd, 12.4, 4.3)
4.01 (m)
4.38
4.45 (dd, 12.0, 2.7)
0
6
7
8
9
Triterpene moiety
3
3.28
5.44 (t, 3.0)
3.28
3.26 (dd, 11.5, 4.5)
5.40 (t, 3.0)
3.18 (dd, 14.0, 3.4)
3.28
5.4 5 (t, 3.0)
3.29
3.28 (dd, 11.5, 4.4)
5.41 (t, 3.5)
3.18 (dd, 14.0, 3.4)
12
8
1
3
1
2
3
4
5
-O-Sugar GlcA
4.96 (d, 7.4)
4.29
4.96 (d, 6.8)
4.28
4.97 (d, 7.6)
4.18
4.32
4.97 (d, 7.4)
4.18
4.31
4.32 (t, 8.0)
4.61 (t, 8.6)
4.53
4.32 (t, 8.0)
4.62 (t, 9.1)
4.52
4.58
4.58
4.58
4.58
At GlcA-C-4
Rha
1
5.85 (brs)
5.85 (brs)
4.72 (d, 2.4)
4.51
2
4.74 (dd, 2.5, 1.8)
4.52 (dd, 8.0, 3.5)
4.27 (t, 9.2)
4.95
3
4
4.26 (t, 9.0)
4.95
1.65 (d, 6.0)
5
6
1.64 (d, 6.2)
Api
1
6.05 (d, 1.2)
4.75 (brs)
6.05 (d, 2.2)
4.74 (d, 2.2)
2
3
4
4.76 (d, 10.0)
4.14 (brs)
4.76 (d, 10.0)
4.14 (brs)
5
At GlcA-C-2 Ara
1
2
3
4
5
5.19
5.19 (d, 6.2)
4.53 (dd, 8.0, 6.2)
4.21
4.55 (t, 7.0)
4.19
4.31
4.31
3.78 (dd, 12.3, 1.2)
4.38
3.78 (d, 12.3)
4.38 (dd, 12.3, 2.4)
0
5
Gal
1
5.24 (d, 7.6)
4.54
5.24 (d, 7.8)
4.54
4.15
2
3
4.14 (dd, 9.2, 3.1)
4.66 (d, 3.1)
4.03 (dd, 6.2, 5.5)
4.38 (dd, 11.1, 6.2)
4.56
4
4.66 (d, 3.1)
4.03
4.38
5
6
0
6
4.57
2
1
2
3
4
5
6
6
8-0-Glc
6.30 (d, 7.8)
4.18
6.30 (d, 8.0)
4.18
4.26 (t, 9.0)
4.32 (t, 8.0)
4.02
4.26 (t, 8.0)
4.34 (t,8.6)
4.01 (m)
4.37
4.44 (dd, 12.4, 2.6)
4.38
4.45 (dd, 12.3, 2.5)
0
Values in parentheses are 1H– H splittings in cases where these are clearly resolved. GlcA=b-d-glucuronopyranose Gal=b-d-galactopyranose;
1
Ara=a-larabinopyranose; Api=b-d-apiofuranose; Rha=a-d-rhamnopyranose Glc=b-d-glucopyranose.

404
F.R. Melek et al. / Phytochemistry 63 (2003) 401–407
Table 2
13C NMR data of the triterpene moieties of saponins 1–3 in C
Table 3
13C NMR data of the sugar moities of saponins 1–9 in C
5
D
5
N
5 5
D N
C
1
2
3
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
38.7
26.6
89.3
39.6
55.9
18.6
33.4
39.8
48.1
37.1
23.8
38.8
26.7
89.2
39.6
55.9
18.6
33.6
40.0
47.2
37.1
23.9
38.7
26.6
89.2
39.5
55.8
18.5
33.2
40.0
48.1
37.0
23.8
Triterpene moiety
3
28
89.3 89.2 89.2 89.3 89.3 89.4 89.4 89.3 89.3
180.2 180.0 176.4 180.2 176.4 180.2 176.5 180.1 176.4
3
1
2
3
4
5
6
-O-Sugar GlcA
107.0 107.0 107.0 105.2 105.1 105.1 105.1 105.2 105.2
75.8 75.8 75.4 83.4 83.4 83.8 83.8 82.8 82.9
76.4 76.4 76.2 76.0 76.0 76.1 76.1 75.5 75.5
80.4 80.4 80.0 79.3 79.3 79.2 79.2 79.2 79.1
76.4 76.4 76.2 76.1 76.1 76.1 76.1 75.7 75.9
172.6 172.6 172.1 172.4 172.3 172.4 172.4 n.d. 171.9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
122.6
144.9
42.3
28.4
23.9
46.8
42.1
46.6
31.0
34.4
33.3
28.3
17.0
15.5
17.5
26.3
180.2
33.3
23.9
122.5
145.2
42.2
36.3
74.8
49.0
41.6
47.4
31.1
36.2
32.9
28.3
17.0
15.6
17.5
27.3
180.0
33.4
24.8
122.9
144.2
42.2
28.3
23.5
47.1
41.8
46.3
30.8
34.1
32.6
28.2
17.0
15.5
17.5
26.2
176.4
33.2
23.7
At GlcA C-4 Rha
1
2
3
4
5
6
102.8 102.8
102.4 102.4 102.4 102.4
72.5 72.5 72.5 72.5
72.8 72.7 72.7 72.7
74.0 74.0 74.0 74.0
70.3 70.3 70.3 70.3
18.5 18.5 18.5 18.5
72.6 72.6
72.8 72.8
74.0 74.0
70.4 70.4
18.6 18.6
Api
1
10.8
110.6 110.6
77.8 77.8
80.4 80.4
75.7 75.7
65.6 65.6
7
8
7
6
7.8
0.4
5.4
5.5
At GlcA C-2 Ara
1
2
3
4
5
106.4 106.4
73.7 73.6
74.3 74.2
69.1 69.1
67.0 66.9
106.4 106.4
73.7 73.7
74.2 74.2
69.1 69.1
66.9 66.9
Gal
1
106.9 106.9
74.6 74.6
75.0 75.0
69.7 69.7
77.0 77.0
61.5 61.5
narcissiflora (Masood et al., 1981). This is the first
reported occurrence of 1 as a natural product.
The molecular formula of saponin 2, C42 H66 O , was
2
3
14
4
assigned by the presence of a quasi-molecular ion peak
at m/z 817 [M+Na]+ in the positive-ion FAB-mass
5
6
spectrum and 13C NMR data. Comparison of the 13
C
2
1
2
3
4
5
6
8-0-Glc
NMR spectral data of 2 with those reported for various
echinocystic acid glycosides (Nagao et al., 1993), sug-
gested 2 to be an echinocystic acid 3-Oglycoside. Acid
hydrolysis of 2 afforded in addition to echinocystic acid,
the sugar components d-glucuronic acid and l-rham-
95.8
74.2
78.9
71.3
79.3
62.3
95.8
74.2
79.0
71.3
79.3
62.4
95.8
74.2
79.0
71.3
79.3
62.4
95.8
74.2
79.0
71.3
79.3
62.4
1
13
nose. The H and C NMR signals due to the sugar
units of 2 were almost identical to those of 1. Therefore,
n.d.=not detected. GlcA=b-d-glucuronopyranose; Rha=a-l-rhamno-
pyranose; Api=b d-apiofuranose; Gal=b-d-galactopyranose;
Ara=a-l-arabinopyranose; Glc=b-d-glucopyranose.
2
(
was concluded to be 3-O-[a-l-rhamnopyranosyl-
1!4)-b-d-glucuronopyranosyl] echinocystic acid.
The molecular formula of 3, C
H
O
was
18,
4
7
74
assigned based on the presence of a quasi-molecular ion
peak at m/z 949 [M+Na]+ in the FAB-mass spectrum.
Acid hydrolysis of 3 yielded oleanolic acid and the sugar
components d-glucuronic acid, d-glucose (Glc) and
deduced from the ꢀ-values of signals due to C-3 (89.2
ppm) and C-28 (176.4 ppm) of the oleanolic acid moi-
ety. The signals at ꢀ 95.8, 74.2, 78.9, 71.3, 79.3 and 62.3
in the C NMR spectrum were typical for a b-d-gluco-
pyranose unit esterifying the oleanolic acid COOH
group. The structure of the disaccharide moiety at C-3
position, was established as Api(1!4)-GlcA from the
HMBC correlations between apiose H-1 (ꢀ 6.09) and
GlcA C-4 (ꢀ 80.0). The anomeric configuration of
1
3
1
d-apiose (Api). The H NMR spectrum of 3 showed the
presence of three anomeric proton signals at ꢀ 4.98 (d,
J=7.4 Hz), 6.09 (d, J=2.5 Hz) and 6.30 (d, J=7.8 Hz)
assignable to d-glucuronic acid, d-apiose and d-glucose
units respectively. The bidesmosidic nature of 3 was

F.R. Melek et al. / Phytochemistry 63 (2003) 401–407
405
glucose was determined to be b from the J value of the
anomeric proton signal of glucose. The anomeric con-
figuration of apiose was determined to be b by the
comparison of the 1 C NMR data for 2 with those for
methyl a- and b-d-apiofuranosides [ C NMR data for
methyl b-d-apiofuranoside: 111.5 (C-1), 77.7 (C-2), 80.3
HMBC). The data allowed identification of a b-d-glu-
curonopyranose unit with anomeric proton at ꢀ 4.96 as
well as b-d-galactopyranose unit with anomeric proton
at ꢀ 5.24 and the H-4 signal was a doublet (J=3.1 Hz),
which is characteristic for galactose. The remaining unit
with the anomeric proton at ꢀ 5.85 was characterised as
a-l-rhamnopyranose unit. A b-configuration of the
anomeric centre of the galactose moiety was deduced
from the JH-1,H-2 coupling constant. The anomeric con-
figurations of the other sugar units were similar to the
corresponding ones in saponin 1. The branched nature of
the trisaccharide moiety at the C-3 position of the olea-
nolic acid moiety was established from the HMBC
correlations between C-3 (ꢀ 89.4) and H-1 (ꢀ 4.96) of
GlcA, between C-2 (ꢀ 83.8) of GlcA and H-1 (ꢀ 5.24) of
Gal between C-4 (ꢀ 79.2) of GLcA and H-1 (ꢀ 5.85) of
Rha. These linkages were also concluded from the
observed inter-residue NOEs. Therefore, the structure of
6 was established as 3-O-a-l-rhamnopyranosyl-(1!4)-
[b-d-galactopyranosyl-(1!2)-] b-d-glucuronopyranosyl
oleanolic acid.
3
1
3
(
C-3), 74.9 (C-4), 65.5 (C-5), 55.5 (1-OCH ); Kitagawa
3
et al., 1989]. Therefore, 3 was assigned the structure of 3
O-[b-d-apiofuranosyl-(1!4)-b-d-glucuronopyranosyl]
oleanolic acid 28-O-b-d-glucopyranosyl ester.
-
+
Saponin 4, C47 H74 O , exhibited [M+Na] at m/z
33. It afforded oleanolic acid, d-glucuronic acid,
17
9
l-arabinose (Ara) and l-rhamnose upon acid hydro-
lysis. The sugar moieties of 4 were characterised by
analysis of the NMR data obtained from the combined
1
1
use of 2D NMR experiments ( H– H COSY, HMQC
and HMBC), as b-d-glucuronopyranose (H-1; ꢀ 4.98),
a-l-arabinopyranose (H-1; ꢀ 5.22) and a-l-rhamnopyr-
anose (H-1; ꢀ 5.85). The ꢀ-values of signals due to C-28
(
180.2 ppm) and C-3 (89.3 ppm) of the triterpene moiety,
indicated that 4 was an oleanolic acid 3-O-glycoside. The
branched nature of the trisaccharide moiety at the C-3
position of the oleanolic acid moiety was revealed from
the inter-residue NOEs, in a NOE difference spectrum
between H-3 of the oleanolic acid residue and GlcA H-1,
between GlcA H-2 and Ara H-1 and between GlcA H-4
and Rha H-1. The HMBC correlations verified the sugar
linkages. Therefore the structure of 4 was elucidated as 3-
O-a-l-rhamnopyranosyl-(1!4)-[a-l-arabinopyranosyl-
Saponin 7 (C54 H86 O ), on acid hydrolysis yielded
23
oleanolic acid, d-glucuronic acid, d-galactose, d-glucose
and l-rhamnose. The 1D and 2D NMR studies of 7 (as
described for the previous saponins) indicated that 7
was the 28-glucosyl derivative of 6 and thus, assigned
the structure of 3-O-a-l-rhamnopyranosyl-(1!4)-[b-d-
galactopyranosyl-(1!2)-] b-d-glucuronopyranosyl olea-
nolic acid 28-O-b-d-glucopyranosyl ester.
(
1!2)-] b-d-glucuronopyranosyl oleanolic acid.
Saponin 8 (C46 H72 O ), yielded oleanolic acid and
17
+
Saponin 5, C
H
095 in its FAB-mass spectrum, 162 mass units more
O , exhibited [M+Na] at m/z
the sugar components d-glucuronic acid, l-arabinose
and d-apiose upon acid hydrolysis. The trisaccharide
nature of 8 was deduced from the presence of three
sugar units characterised as b-d-glucuronopyranose
(H-1; ꢀ 4.97), a-l-arabinopyranose (H-1; ꢀ 5.19) and
b-d-apiofuranose units (H-1; ꢀ 6.05) by NMR studies as
described above. The 28-COOH function of oleanolic
acid was not esterified as shown from the ꢀ value of
C-28 resonance at 180.1 ppm. The attachment of the
terminal units a-l-arabinopyranose and b-d-apiofur-
anose at C-2 and C-4 positions of the inner b-d-glucur-
onopyranose unit respectively, was established from the
inter-residue NOEs and HMBC cross-peaks arising
from the anomeric protons to the signals involved in the
glycosidic linkage. Thus, the structure of 8 was deduced
to be 3-O-b-d-apiofuranosyl-(1!4)-[a-l-arabinopyr-
anosyl-(1!2)-] b-d-glucuronopyranosyl oleanolic acid.
5
3
84
22
1
than that of 4, suggesting the presence of one more
hexose unit. This unit was identified as d-glucose, after
being detected by GC analysis of the acid hydrolysate of
5
, together with d-glucuronic acid, l-arabinose and
l-rhamnose. The triterpene moiety of 5 was identified as
, 28-di-O-substituted oleanolic acid from NMR data.
The assigned NMR signals due to the sugar units of 5
3
1
1
(
HOHAHA, H– H COSY, HMQC, HMBC spectra)
were almost identical to those of 4 except a set of addi-
tional signals in 5 due to 28-O-b-d-glucopyranose unit
as described for saponin 3. This observation suggested
an identical trisaccharide chain at the C-3 position of
the oleanolic acid moiety for 4 and 5. The observed
NOEs interaction and the HMBC correlations verified
the linkages. Thus the structure of 5 was established as 3-
O-a-l-rhamnopyranosyl-(1!4)-[a-l-arabinopyranosyl-
Saponin 9, (C
H
O ), on acid hydrolysis afforded
82 22
5
2
(
1!2)-] b-d-glucuronopyranosyl oleanolic acid 28-O-b-
oleanolic acid, d-glucuronic acid, d-apiose, l-arabinose
and d-glucose. The tetraglycosidic nature of 9 was
d-glucopyranosyl ester.
Saponin 6 (C48 H76 O ), on acid hydrolysis, afforded
1
established from its NMR data. The comparison of H
18
in addition to oleanolic acid, the sugar components
d-glucuronic acid, d-galactose (Gal) and l-rhamnose.
The sugar moieties of 6 were characterised by analysis
of NMR data obtained from the combined use of 2D
and 13C NMR data of 9 (1D and 2D spectra) with those
of 8 suggested that 9 possessed the same trisaccharide
chain at C-3 position of the oleanolic acid moiety, in
addition to a b-d-glucopyranose unit esterifying the
oleanolic acid COOH group. Sequencing of sugar units
1
1
NMR spectra (HOHAHA, H– H COSY, HMQC and

406
F.R. Melek et al. / Phytochemistry 63 (2003) 401–407
was verified from the observed HMBC correlations and
NOEs interactions. Therefore 9 was the 28-glucosyl
derivative of 8 and assigned the structure of 3-O-b-d-
apiofuranosyl-(1!4)-[a-l-arabinopyranosyl-(1!2)-]
b-d-glucuronopyranosyl oleanolic acid 28-O-b-d-gluco-
pyranosyl ester.
with CHCl –MeOH–H O–EtOAc (28:35:5:32). The
3 2
sugars and the rest of phenolic constituents from fr. 3
(CHCl –MeOH; 80:20; 0.9 g) and fr. 4 (CHCl –MeOH;
3
3
70:30; 0.3 g) were removed by passing through a polymer
gel Diaion HP-20 column. Elution was carried out using
H O then MeOH–H O (1:1) and finally MeOH to
2
2
Phytochemical studies, carried out by other workers,
on several species of Schefflera, have resulted in the
identification of triterpene saponins of various aglycone
types (Sung et al., 1991; Maeda et al., 1994; Zhu et al.,
obtain only saponins. The saponin mixtures obtained
from the above processing were repeatedly subjected to
HPLC {ODS column 20 mmꢀ25 cm, [CH CN–H O
3
2
(30:70) for fr 4; (35:65) for fr 3; (40:60) for fr 2; (45:55)
for fr 1]+0.05% TFA, flow rate; 6.5 ml/min, UV; 205
nm} to give in addition to olaxoside and cynarasaponin
H, 1 (40 mg), 2 (22mg), 3 (10 mg), 4 (20 mg), 5 (30 mg),
6 (56 mg), 7 (30 mg), 8 (22 mg) and 9 (25 mg).
1
996). Glucuronides of oleanane-type, bearing a linear
sugar sequence, occur frequently in Schefflera plants.
The newly isolated 2,4 disubstituted glucuronides repre-
sent their first occurrence in the genus Schefflera. Other
glucuronides bearing branched structure with variable
linkage sites have been reported from Aralia members
3.4. Saponin (1)
(
Satoh et al., 1994; Hu et al., 1995; Miyase et al., 1996b).
2
3
ꢂ
Amorphous powder [a]D ꢁ8.4 (c=2.34, MeOH)
FABMS (m/z): 801 [C H O +Na] , 1H and 13
NMR: Tables 1–3.
+
C
4
2
66 13
3
. Experimental
3
.1. General
3.5. Saponin (2)
2
3
ꢂ
Optical rotations were measured with Jasco DIP 1000
digital polarimeter. MS were measured on Jeol-JMX-SX
02 mass spectrometer. NMR spectra were obtained with
Amorphous powder [a]D ꢁ27.8 (c=1.10, MeOH)
+
42 66 14
FABMS (m/z): 817 [C H O +Na] , 1H and 13
C
1
NMR: Tables 1–3.
a Jeol GSX-500 FT NMR spectrometer and chemical
shifts were given in ppm with TMS as internal standard.
GC was performed on a Hitachi G-3000 gas chromato-
graphy. Preparative and analytical HPLC were performed
on a Jasco model 800 instrument.
3.6. Saponin (3)
2
3
ꢂ
Amorphous powder [a]D ꢁ13.1 (c=1.38, MeOH)
FABMS (m/z): 949 [C H O +Na] , 1H and 13
+
C
4
7
74 18
NMR: Tables 1–3.
.7. Saponin (4)
Amorphous powder [a]D ꢁ4.2 (c=0.91, MeOH)
3
.2. Plant material
3
Leaves and stems of S. arboricola (Hayata) Merr.
2
3
ꢂ
were collected from El-Orman Public Garden in Giza in
June 2001 and identified by Mrs. T. Labib, the senior
specialist for plant identification at El-Orman Public
Garden. A voucher specimen was deposited at Chem-
istry of Natural Products Department, NRC.
FABMS (m/z): 933 [C H O +Na] , 1H and 13
+
C
4
7
74 17
NMR: Tables 1 and 3.
3.8. Saponin (5)
2
3
ꢂ
3
.3. Extraction and isolation
Amorphous powder [a]D ꢁ10.2 (c=2.06, MeOH)
+ 1
53 84 22
FABMS (m/z): 1095 [C H O +Na] , H and 13C
Dried powdered mixture of leaves and stems of
S. arboricola (500 g) was extracted with methanol (2ꢀ2
NMR: Tables 1 and 3.
l) at room temperature. The concentrated combined
extract was diluted by adding of large excess Me CO to
3.9. Saponin (6)
2
2
3
ꢂ
precipitate the crude saponins. The crude saponin mix-
ture (4.5 g) was first chromatographed on a silica gel
column eluting with CHCl containing increasing pro-
Amorphous powder [a]D ꢁ10.4 (c=1.95, MeOH)
+
48 76 18
FABMS (m/z) 963 [C H O +Na] , 1H and 13
C
NMR: Tables 1 and 3.
3
portions of MeOH. Four fractions (1–4) were obtained.
In order to remove the non-terpenoidal constituents, fr. 1
3.10. Saponin (7)
(
CHCl –MeOH; 85:15; 2.1 g) and fr. 2 (CHCl –MeOH;
3 3
2
3
ꢂ
83:17; 1.1 g) were chromatographed separately on
Sephadex LH-20 column eluted with a gradient H O–
MeOH followed by prep. TLC on silica gel developed
Amorphous powder [a]D ꢁ12.1 (c=1.28, MeOH)
FABMS (m/z) 1125 [C H O +Na] , 1H and 13
+
C
2
54 86 23
NMR: Tables 1 and 3.

F.R. Melek et al. / Phytochemistry 63 (2003) 401–407
407
3
.11. Saponin (8)
Amorphous powder [a]D ꢁ3.7 (c=1.06, MeOH)
Abdel-Khalik, S.M., Miyase, T., Melek, F.R., El-Ashaal, H.A.,
001. Further saponins from Fagonia cretica. Pharmazie 65, 247–
250.
2
2
3
ꢂ
Abdel Khalik, S.M., 2001. Two triterpenoid saponins from Schefflera
arboricola family Araliaceae. Al-Azhar Journal of Pharmaceutical
Sciences 28, 39–47.
FABMS (m/z) 919 [C H O +Na] , 1H and 13
+
C
4
6
72 17
NMR: Tables 1 and 3.
.12. Saponin (9)
Amorphous powder [a]D ꢁ13.1 (c=1.38, MeOH)
Forgacs, P., Provost, J., 1981. Olaxoside, a saponin from Olax andro-
nensis, O. glabriflora and O. psittacorum. Phytochemistry 20, 1689–
3
1
691.
Hara, S., Okabe, H., Mihashi, K., 1986. Separation of aldose enan-
tiomers by gas–liquid chromatography. Chemical and Pharmaceu-
tical Bulletin 34, 1843–1845.
2
3
ꢂ
FABMS (m/z) 1081 [C H O +Na] , 1H and 13
+
C
5
2
82 22
NMR: Tables 1 and 3.
Hu, M., Ogawa, K., Sashida, Y., Xiao, P.G., 1995. Triterpenoid glu-
curonide saponins from root bark of Aralia armata. Phytochemistry
3
9, 179–184.
3
1
.13. General method for acid hydrolysis (Hara et al.,
986)
Kitagawa, I., Sakagami, M., Hashiuchi, F., Zhou, J.L., Yoshikawa,
M., Ren, J., 1989. Apioglycyrrhizin and araboglycyrrhizin, two new
sweet oleanene—type triterpene oligosaccharides from the root of
Glycyrrhiza inflata. Chemical and Pharmaceutical Bulletin 37, 551–
Each saponin (3 mg) dissolved in dioxane (150 ml) and
ꢂ
5
53.
2
reaction mixture was diluted with H O and extracted
twice with EtOAc. From the EtOAc layer, the aglycone
was detected by HPLC [column YMC R & D ODS; 4.6
N HCl (150 ml) was heated at 100 C for 1 h. The
Liao, N.. In: Chang, H.M., But, P.P.H. (Eds.), Pharmacology and
Applications of Chinese Materia Medica, Vol. I. World Scientific
Press, Singapore, p. 6.
2
Maeda, C., Ohtani, K., Kasai, R., Yamaski, K., Duc, N.M., Nham,
N.T., Quynth Cu, N.K., 1994. Oleanane and ursane glycosides from
Schefflera octophylla. Phytochemistry 37, 1131–1137.
mmꢀ25 cm, solvent MeOH–H O (9:1)+0.05% TFA;
2
flow rate; 1 ml/min; detection; UV 205 nm; oleanolic
acid (tR 11.0 min), echinocystic acid (t , 7.1 min]. The
Masood, M., Minocha, P.K., Tiwari, K.P., Srivastava, K.C., 1981.
Narcissiflorine, narcissiflorinine and narcissifloridine, three tri-
terpene saponins from Anemone narcissiflora. Phytochemistry 20,
R
water layer was passed through an Amberlite IRA-60E
column (6ꢀ60 mm) and the eluate was concentrated. The
residue was examined for sugars by paper chromato-
graphy [n-BuOH–HOAc–H O (4:1:5)] against standard
2
samples as well as by GC after being converted to their
thiazolidine derivatives as described by Hara et al., 1986;
1
675–1679.
Melek, F.R., Miyase, T., El-Gindi, M.R., Abdel-Khalik, S.M., Ghaly,
N.S., El-Kady, M., 2000. Saponins from Fagonia glutinosa. Phar-
mazie 55, 772–776.
Miyase, T., Melek, F.R., El-Gindi, O.M., Abdel-Khalik, S.M., El-
Gindi, M.R., Haggag, M.Y., Hilal, S.H., 1996a. Saponins from
Fagonia arabica. Phytochemistry 41, 1175–1179.
conditions: [column Supelco SPB-TM1 (0.25 mmꢀ27 m,
ꢂ
column temperature; 215 C., carrier gas; N , retention
2
Miyase, T., Sutoh, N., Zhang, D.M., Ueno, A., 1996b. Araliasaponins
XII–XVIII. Triterpene saponins from the roots of Aralia chinensis.
Phytochemistry 42, 1123–1130.
time d-Glc (22.5 min), l-Glc (21.5 min), d-Api (11.9
min) l-Api (10.9 min), d-Gal(24.7 min), l-Gal (23.1
min), d-Ara (11.0 min), l-Ara (11.9 min), d-Rha (12.7
min), l-Rha (12.9 min). From the new saponins, rham-
nose and arabinose were in the l-form, while glucuronic
acid, glucose, galactose and apiose were in the d-form.
Nagao, T., Tanaka, R., Iwase, Y., Okabe, H., 1993. Studies on con-
stituents of Aster scaber thumb. IV. Structures of four new echino-
cystic acid glycosides isolated from the herb. Chemical and
Pharmaceutical Bulletin 41, 659–665.
Satoh, Y., Sakai, S., Katsumata, M., Nagasao, M., Miyakoshi, M.,
Ida, Y., Shoji, J., 1994. Oleanolic acid saponins from root-bark of
Aralia elata. Phytochemistry 36, 147–152.
Sung, T.V., Steglich, W., Adam, G., 1991. Triterpene glycosides from
Schefflera octophylla. Phytochemistry 30, 2349–2356.
References
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Triterpenoid saponins from Fagonia cretica. Phytochemistry 54,
Zhu, M., Yang, S., Philipson, J.D., Greengrass, P.M., Bowery, N.G.,
1996. Triterpene glycosides from Schefflera bodinieri roots. Phyto-
chemistry 43, 1313–1318.
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