Chemical constituents from root barks of erythrina mildbraedii and stem barks of erythrina addisoniae

Article abstract of DOI:10.4314/bcse.v28i1.19

The β-D-galactopyranoside of the tetracosanoic acid (1) was isolated from the stem barks of Erythrina addisoniae along with known tetracosanoic acid (2), α-sophoradiol (3), stigmasterol (4), warangalone (5), 3-Oβ-D-glucopyranoside of β-sitosterol (6) and

Full text of DOI:10.4314/bcse.v28i1.19

Bull. Chem. Soc. Ethiop. 2014, 28(1), 155-159.
Printed in Ethiopia
DOI: http://dx.doi.org/10.4314/bcse.v28i1.19
ISSN 1011-3924
 2014 Chemical Society of Ethiopia
SHORT COMMUNICATION
CHEMICAL CONSTITUENTS FROM ROOT BARKS OF ERYTHRINA MILDBRAEDII
AND STEM BARKS OF ERYTHRINA ADDISONIAE
Emmanuel Talla1*, Emmanuel Yankep2 and Joseph Tanyi Mbafor2
1Department of Chemistry, Faculty of Science, University of Ngaoundere, P.O. Box 454
Ngaoundere, Cameroon
2Department of Organic Chemistry, Faculty of Science, University of Yaounde, P.O. Box 812,
University of Yaounde I, Yaounde, Cameroon
(Received June 7, 2013; revised November 1, 2013)
ABSTRACT. The β-D-galactopyranoside of the tetracosanoic acid (1) was isolated from the stem barks of
Erythrina addisoniae along with known tetracosanoic acid (2), α-sophoradiol (3), stigmasterol (4), warangalone
(5), 3-Oβ-D-glucopyranoside of β-sitosterol (6) and 7-O-β-D-glucopyranoside of daidzein (7). Two known
compounds (erythrinasinate (8) and erycristagallin (9)) were also isolated from the root barks of Erythrina
mildbraedii. Their structures were assigned on the basis of spectroscopic data and chemical transformation.
KEY WORDS: Erythrina addisoniae, Erythrina mildbraedii, Root barks, Stem barks, Leguminosae, Glucoside
acid
INTRODUCTION
The genus Erythrina (Leguminosae) has a significant history of folkloric use for treatment of
various diseases [1, 2]. Previous chemical studies of Cameroonian Erythrina species has
resulted in the isolation of flavonoids, alkaloids, cinnamate esters and neutral compounds [3-8].
We here report the isolation and structural elucidation of the new β-D-galactopyranosyl ester of
tetracosanoic acid (1) from the EtOAc extract of the stem barks of Erythrina addisoniae along
with six known compounds, namely tetracosanoic acid (2) [9], α-sophoradiol (3) [10],
stigmasterol (4) [11], warangalone (5) [12], β-sitosterol 3-O-β-D-glucopyranoside (6) [13] and
daidzein7-O-β-D-glucopyranoside (7) [14]. Two known compounds namely erythrinasinate (8)
[15] and erycristagallin (9) [16] were also isolated from the root barks of Erythrina mildbraedii.
EXPERIMENTAL
General procedures. Melting points were determined on a micro-melting point apparatus and
are not corrected. IR spectra were run from KBr pallet on a Perkin-Elmer 577 spectrometer. The
NMR and two dimensional experiments spectra were recorded with a Bruker AMX 500 (500
1
MHz for H and 125 MHz for 13C). Chemical shifts are given in ppm with tetramethylsilane as
internal standard. The HREIMS and EIMS at 70 eV were recorded on a JEOL JMSD-300 mass
spectrometer. HPLC was performed by using a system comprised of a CCPM pump, a CCPX-
8010 controller, and RI – 8010 detector and a Shodex OR-2 and a Rheodyne injection port with
a 20 µL sample loop. Column chromatography was performed using Sephadex LH-20, silica gel
Merck 70-230 or 240-400 mesh ASTM. Analytical TLC was carried out on pre-coated silica gel
60 F254 plates (Merck 0.25 mm thickness). The plates were checked under UV light (254 nm)
and developed with H2SO4 in EtOH.
__________
*Corresponding author. E-mail: tallae2000@yahoo.fr

156
Emmanuel Talla et al.
Plant material. The stem barks of Erythrina addisoniae and root barks of Erythrina mildbraedii
were collected respectively in April 1996 at Yaounde (Centre region of Cameroon Republic)
and in July 1998 in Buea (South-West region of Cameroon Republic). They were identified at
the National Herbarium; Yaounde, Cameroon where voucher specimens have been deposited
under the references 41617/HNC and 50452/HNC, respectively.
Extraction and isolation. The air-dried root barks of Erythrina mildbraedii (5 kg) was
exhaustively extracted at room temperature with ethyl acetate to yield 250 g of residue. Part of
this residue (150 g) was subjected to column chromatography over silica gel (400 g) using
hexane-ethyl acetate of increasing polarity as solvent. A total of 210 fractions of 250 mL each
were collected and combined on the basis of their TLC analysis leading to four major series A
(5 g, hexane-EtOAc 9:1), B (3 g, hexane-EtOAc, 8:2), C (17 g, hexane-EtOAc, 2:8) and D (2 g,
EtOAc). Further purification of series A, B, C and D were achieved by column chromatography
followed by PTLC (MeOH-CHCl3-toluene: 1:4:5) and/or by permeation through Sephadex LH-
20 with MeOH as solvent. Series A afforded α-sophoradiol (3) (17 mg) and stigmasterol (4) (13
mg). Series B afforded warangalone (5) (15 mg). Series C afforded of tetracosanoic acid β-D-
galactopyranoside (1) (25 mg), β-sitosterol 3-O-β-D-glucopyranoside (6) (19 mg) and
daidzein7-O-β-D-glucopyranoside (7) (8 mg). Series D afforded tetracosanoic acid (2) (20 mg).
The air-dried stem barks of Erythrina addisoniae (7 kg) was exhaustively extracted with
EtOAc at room temperature yielding (200 g) of residue. Part of this residue (100 g) was
subjected to column chromatography over silica gel eluted with hexane-EtOAc gradient system.
Elution with hexane-EtOAc (6:4) gave erythrinasinate (8) (21 mg). Erycristagallin (9) (15 mg)
was obtained with hexane-EtOAc (6:4).
Physical and spectral data of the compound (1). Amorphous solid. Rf 0.6 (MeOH-CH2Cl2-
cyclohexane 1:4:5). HREIMS M+/z = 530.5308 (calcd. for C30H58O7, 530.7880); EIMS: m/z (%)
= 530 [M+], 367 (69.2), 163 (30.7), 145 (27.3), 127 (23.9), 109 (20.5), 91 (17.1). IR: νmax 1730
and 3450 cm-1. 1H and 13C-NMR (see Table 1).
Acid hydrolysis of (1). Compound (1) (10.5 mg) was refluxed with 12 mL of 15% HCl/MeOH at
80 °C for 4 h. After cooling, the reaction mixture was concentrated and the residue partitioned
with CHCl3/H2O. The organic layer was concentrated to dryness to yield 8 mg of a white
material. Purification of this material by PTLC using silica gel and MeOH-CH2Cl2 (0.25:9.75)
as eluent yielded 3 mg of aglicone (2) identified as tetracosanoic acid by comparison of its
physical and spectral data with the previously isolated compound (2). The aqueous layer was
evaporated and the residue analyzed by HPLC under the following conditions: column HPX –
87 H (7.8 mm i.d. x 300 mm); solvent 5 µm H2SO4; flow rate 0.6 mL/min; detection, refractive,
index and optical rotation. The sugar was confirmed as D–galactose by comparison of its
retention time and optical rotation with those of an authentic sample retention time (min) of D–
galactose 9.62 (positive optical rotation).
OH
OH
H
O
H
O
(CH2)22
HO
CH3
H
OH
C
O
OH
CH3 (CH2)22
(2)
H
H
O
(1)
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Short Communication
157
29
30
19
20
21
H
H
12
26
22
13
18
15
OH
11
17
25
28
1
14
16
9
6
2
8
10
3
27
5
7
4
H
HO
H
(3)
24
23
29
21
28
22
19
20
17
12
24
27
23
11
25
26
13
14
18
16
1
2
9
15
10
8
7
3
5
HO
6
4
(4)
O
O
O
OH
OH
H
O
H
O
HO
H
OH
OH
OH
H
H
(5)
(6)
OH
H
H
O
HO
HO
1
8
5
O
O
7
2
H
OH
2'
H
H
3
1'
6
3'
4'
4
O
6'
OH
5'
(7)
Bull. Chem. Soc. Ethiop. 2014, 28(1)

158
Emmanuel Talla et al.
O
O
CH3
(CH2)27
MeO
OH
(8)
H
Hax
4
HO
O
6
4a
Heq
H
3
7
6a
H
H
8
9
2
6b
11b
1'
2'
1
11a
4'
H3C
H
3'
O
10a
OH
H
10
1"
CH3
5'
H
2"
3"
H3C
4"
CH3
5"
(9)
RESULTS AND DISCUSSION
Compound (1) was obtained as a white amorphous solid. Its molecular formula C30H58O7 was
deduced from HRMS. The IR spectrum disclosed absorption bands at 3430 cm-1 due to hydroxyl
1
group and at 1735 cm-1 due to an ester carbonyl. The H and 13C spectroscopic spectral data
(Table 1) revealed the presence of a sugar residue and chemical shifts sequence of
tetracosanoyloxy moiety. The presence of an anomeric carbon signal at
(1) to be a tetracosanoic acid glycoside [17]. Upon acid hydrolysis (1) afforded the aglycone (2)
and D-galactose. The -configuration of D-galactopyranosyl moiety was deduced from the
coupling constant J = 7.8 Hz of anomeric proton signal 4.81 ppm in the 1H-NMR spectrum [18].
δ = 100.5 ppm indicated
β
On the basis of the above evidence, the structure of (1) was determinate as
galactopyranoside of tetracosanoic acid.
β-D-
Table 1. 1H-NMR (500 MHz, DMSO-d6) and 13C-NMR (125 MHz, DMSO-d6) data of compound (1).
N°
1
δH (mult, J)
δC (DEPT)
175.3 (C)
2
2.48 (2H, t, 6.9)
34.7 (CH2)
3
1.65 (2H; m)
22.68-31.90 (CH2)
22.68-31.90 (CH2)
14.10 (CH3)
100.10 (CH)
73.60 (CH)
4-23
24
1’
2’
3’
4’
5’
6’
1.26 (40H, m)
0.91 (3H, t, 7.0)
4.81 (1H, d, 7.0)
3.22 (1H, dd, 8.6, 7.9)
3.40 (1H, m)
76.90 (CH)
3.40 (1H, dd, 3.6, 3.5)
3.32 (1H, 1H, m)
3.75 (1H, dd, 11.4, 5.6)
3.51 (1H, dd, 11.4, 2.4)
70.20 (CH)
76.70 (CH)
61.30 (CH2)
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159
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