A C-glucoside benzoic acid derivative from the leaves of Peltophorum dubium

Article abstract of DOI:10.1016/j.phytol.2010.07.002

From the methanolic extract of the leaves of Peltophorum dubium Taub (Leguminosae) was isolated after successive chromatographic procedures a new C-glucoside benzoic acid derivative, 3αC-glucopyranosil-4,5-dihydroxy-2- methoxy-benzoic acid. The structure

Full text of DOI:10.1016/j.phytol.2010.07.002

Phytochemistry Letters 3 (2010) 168–170
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Phytochemistry Letters
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A C-glucoside benzoic acid derivative from the leaves of Peltophorum dubium
a
c
d
Marcus V. Bahia a,b, Jorge M. David a, , Larissa C. Rezende , Maria L.S. Guedes , Juceni P. David
*
a Instituto de Quı´mica, Universidade Federal da Bahia, 40170290 Salvador, BA, Brazil
b Centro de Formac¸a˜o de Professores, Universidade Federal do Recoˆncavo da Bahia, 45300000 Amargosa, BA, Brazil
c Instituto de Biologia, Universidade Federal da Bahia, 40170290 Salvador, BA, Brazil
d
´
Faculdade de Farmacia, Universidade Federal da Bahia, 40170290 Salvador, BA, Brazil
A R T I C L E I N F O
A B S T R A C T
Article history:
From the methanolic extract of the leaves of Peltophorum dubium Taub (Leguminosae) was isolated after
successive chromatographic procedures a new C-glucoside benzoic acid derivative, 3 C-glucopyranosil-
Received 22 March 2010
Received in revised form 4 July 2010
Accepted 9 July 2010
a
4,5-dihydroxy-2-methoxy-benzoic acid. The structure of this compound was determined by 1D and 2D
NMR and MS data analysis. The new compound showed moderate antioxidant activity in the assay and
Available online 23 July 2010
the auto-oxidation of
b-carotene in a linolenic acid suspension method.
ß 2010 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.
Keywords:
Peltophorum dubium
Leguminosae
Benzoic acid C-glucoside
1. Introduction
2. Results and discussion
The species Peltophorum dubium Taub is a tree belonging to the
Leguminosae family (Caesalpinoideae). It occurs in Brazil from
Bahia to Rio de Janeiro states, especially in the Atlantic forest
Compound 1a was obtained as an amorphous white powder
[m.p 198 8C (dec.)] and its structure was elucidated by spectro-
metric data analysis of the pure compound and the peracetylated
derivative (1b). The ESIMS of 1a showed a negative pseudo-
molecular ion at m/z 345.0834 and, the combination with
hydrogen and carbon counts obtained by 1H, 13C and DEPT NMR
spectra permitted to propose the molecular formulae as C14H18O10
to this compound (requires 345.0822). The IR spectra permitted to
identify presence of hydroxyl groups and conjugate carboxyl group
´
complex, and also in other Brazilian regions as Minas Gerais, Goias,
´
ˆ
Mato Grosso do Sul, Parana and Sao Paulo in deciduous forests,
usually found in clay soils, deep and well common in riparian
habitats (Lorenzi, 2000). In Brazil it is popularly known as
‘‘amendoim bravo’’, ‘‘faveiro’’, ‘‘pau vermelho’’, ‘‘angico’’ and
‘‘canela de veado’’. Its wood is employing in constructions, roof
and the wood power is used for extraction of a red dye (da Silva,
2004). To date there is no records in literature regarding its
chemical composition. Previously it was reported the antimicro-
bial activity (Salvat et al., 2004) and trypsin inhibition (Trancoso
et al., 2003) of extracts of P. dubium.
(
n
1702 cmꢀ1). The analysis of 1HNMR spectrum permitted to
observe a singlet at 7.75 of a pentasubstituted aromatic ring
d
besides the presence of methoxyl group and hydrogens of sugar
moiety (Table 1). The 13CNMR spectra, including DEPT experiments
(1358 and 908) permitted to corroborate with the previous
statements and, moreover pointed the observed peak for the
methoxyl group (d 60.4) was indicative it was ortho-disubstituted.
The comparison of oxymethine and oxymethylene carbons with
the NMR data of sugars (Agrawal et al., 1989) permitted to identify
However from P. africanum was previously isolated catechins
and derivatives of gallic acid (Bam et al., 1988; Ferreira et al., 2005).
The MeOH extract of this species showed inhibition of HIV-1
(Bessong et al., 2005), bactericidal (Samie et al., 2005) and
antioxidant activities (Bizimenyera et al., 2007). Beside these, the
ethanol extract of P. pterocarpum showed antimicrobial activity
(Voravuthikunchai and Limsuwan, 2006).
This work describes the isolation of a new unusual C-glucoside
benzoic acid derivative (Fig. 1) besides known triterpenes from the
AcOEt extract of leaves of P. dubium.
the presence of glucose and, the anomeric carbon at
indicative of that 1 was a C-glucoside derivative of benzoic acid.
The correlations of H-6 ( 7.75) and carboxyl carbon ( 164.6), C-2
142.0) and C-4 ( 152.7) observed in the HMBC spectra as well as
the correlation of the peaks at 4.5 (anomeric H), methoxyl
hydrogens and C-2 ( 142.0) permitted to locate the glucose at C-5.
d 75.6 was
d
d
(
d
d
d
d
The Dd of 13CNMR signals of 1 and the acetylated derivative 1a
corroborated with the presence of two vicinal hydroxyl groups
at C-3 and C-4. Thus the new compound 1 could be identified as
* Corresponding author. Tel.: +55 7132836864; fax: +55 7132355166.
E-mail address: jmdavid@ufba.br (J.M. David).
3aC-glucopyranosil-4,5-dihydroxy-2-methoxy-benzoic acid.
1874-3900/$ – see front matter ß 2010 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.
doi:10.1016/j.phytol.2010.07.002

[
M.V. Bahia et al. / Phytochemistry Letters 3 (2010) 168–170
169
3.2. Extraction and isolation
The dried leaves (1000 g) of P. dubium were powdered and
submitted to extraction with MeOH at room temperature. The
solution obtained was partitioned between hexane furnished the
hexanic extract (2.0 g). Sequentially, the MeOH phase was
diluted with H2O and then submitted to liquid extraction with
CHCl3 and EtOAc. The EtOAc extract (1.2 g) was chromato-
graphed in a polyamide 6 CC eluted with mixtures of MeOH:H2O.
The fraction (300 mg) obtained after elution with MeOH:H2O
(1:4) was submitted to CC on Sephadex LH-20 employing
CHCl3:MeOH (1:4) mixtures. This procedure permitted to isolate
1 (62 mg). The Si gel CC of the hexane extract eluted with
Fig. 1. New glucoside and derivative from Peltophorum dubium.
mixtures of hexane:ETOAc permitted to obtain
a mixture
This work is the first report of 1, however, compounds with
(43.4 mg) of lupeol and larreagenin-A. These compounds were
identified by direct comparison of MS and NMR spectral data (1H,
13C and DEPT) with the literature (Mahato and Kundu, 1994;
Ahmad et al., 1984).
close structures, like norbergenin and bergenin were isolated from
P. africanum (Mebe and Makuhunga, 1992) besides catechins
esterified with gallic acid (Bam et al., 1988; Ferreira et al., 2005).
Larreagenin-A was previously isolated from Larrea divaricata
(Habermeeh and Christ, 1974) and Guaiacum officinale (Ahmad
et al., 1984), two species of Zygophyllaceae family but this is the
first occurrence in Leguminosae.
The extracts and the isolates were submitted to brine shrimp
test employing Artemia salina nauplii and compound 1 was
submitted to antioxidant tests (quenching of DPPH and inhibition
3a
C-Glucopyranosil-4,5-dihydroxy-2-methoxy-benzoic acid (1):
max (cmꢀ1): 3408, 3090, 1702, 1613, 1528, 1071, 1044; 1H NMR
(C5D5N, 300 MHz): 7.75 (s, 1H, H-2),
4.50 (d, J = 4.5 Hz, H-100),
4.41–4.18 (m, 7H, H-10-H60, glucose moiety),
3.98 (s, 3H, OMe);
IV
n
d
d
13C NMR (C5D5N, 75 MHz): Table 1. HRESIMS m/z: 345.0834
[MꢀH]+
Preparation of derivative: Compound 1 (20.0 mg) was added to a
solution of pyridine (0.5 ml), acetic anhydride (0.5 ml) and
dimethylaminepyridine (DMAP) for 24 h at room temperature
and the peracetyl derivative (1a, 23 mg) was extracted with CHCl3.
of co-oxidation of
AcOEt extract showed IC50 320
moderate activity. However, the hexane extract as well as the
isolates were inactive (IC50 > 500 g/ml). The IC50 values ( g/ml)
b
-carotene in a suspension of linolenic acid). The
m
g/ml in the BST indicating
m
m
1H NMR (C5D5N, 300 MHz):
d 7.76 (s, 1H, H-2), 3.91 (s, 3H, OMe);
for 50% of DPPH scavenging radicals were calculated by linear
extrapolation of values obtained from curve of antioxidant activity
13C NMR (C5D5N, 75 MHz): Table 1.
versus concentration. The results show that compound
1
3.3. Brine shrimp and antioxidant tests
(IC50 > 120) did not present antioxidant activity when compared
with gallic acid (IC50 32.2) and quercetin (IC50 11.2). However, in
The hexane and AcOEt extracts and isolated compounds were
submitted to a Artemia salina lethality test (David et al., 2001). The
antioxidant activities were evaluated by the ability of the new
compound (1) and the gallic acid (Sigma) and quercetin (Sigma)
scavenging the 1,2-diphenyl-2-picryl-hydrazyl (DPPH, Sigma) free
radical and was carried out according to established protocol
(Barreiros et al., 2004). The inhibition of the AA of the isolates was
relation to inhibition of auto-oxidation of
b-carotene method the
data with 95% of confidence indicated that compound
1
(AA = 10.52; 11.16%) presented the highest antioxidant activity
than gallic acid (AA = 8.75; 9.2%) but lower than quercetin
(AA = 95.09; 100%).
3. Experimental
measured using the method of auto-oxidation of b-carotene
(Merck) in a suspension of linolenic acid (Aldrich) (Barreiros et al.,
2000). The results were compared to those from the commercial
antioxidant gallic acid and BHT (Merck).
3.1. Plant material
The leaves of P. dubium Taub were collected at Ondina Campus,
Universidade Federal da Bahia, Salvador, BA, Brazil. A voucher of A
voucher is deposited at Herbarium Alexandre Leal da Costa of
Instituto de Biologia da UFBA under number 69237.
Acknowledgments
The authors are grateful to CNPq, CAPES, FAPESB and Instituto
´
ˆ
do Milenio do Semi-Arido (IMSEAR) for fellowship support and
grants.
Table 1
13C NMR chemical shifts (75 MHz) of compound 1 [C5D5N,
d
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