A new fatty aldol ester from the aerial part of Mimosa invisa (Mimosaceae)

Article abstract of DOI:10.1080/14786419.2011.639073

A new aldol ester named 17-O-triacontanoylheptadecanal (1) was isolated from the aerial part of Mimosa invisa (Mimosaceae) together with eight known compounds identified as β-sitosterol (2), α-amyrine (3), lupeol (4), 4-O-methylepinumisoflavone (5), alpinumisoflavone (6), betulinic acid (7), 3-O β- D-glucopyranoside of sitosterol (8) and epirobinetinidol (9). The structures of compounds were determined on the basis of NMR and mass spectrometry data as well as by comparing the data reported in the literatures. The antimicrobial activities of the crude extract and compounds 1 and 9 were investigated against seven microbial species. The natural products showed moderate activities compared to that of the crude extract.

Full text of DOI:10.1080/14786419.2011.639073

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A new fatty aldol ester from the aerial
part of Mimosa invisa (Mimosaceae)
Frederic Nana a , Louis Pergaud Sandjo a , Felix Keumedjio a
Victor Kuete b & Bonaventure Tchaleu Ngadjui c
,
a Department of Organic Chemistry, University of Yaoundé I, P.O.
Box 812, Yaoundé, Cameroon
b Department of Biochemistry, University of Dschang, P.O. Box 67,
Dschang, Cameroon
c Department of Pharmaceutical Sciences and Traditional
Pharmacopeia, Faculty of Medicine and Biomedical Sciences,
University of Yaoundé I, P.O. Box 8664, Yaoundé, Cameroon
Version of record first published: 25 Nov 2011.
To cite this article: Frederic Nana , Louis Pergaud Sandjo , Felix Keumedjio , Victor Kuete &
Bonaventure Tchaleu Ngadjui (2012): A new fatty aldol ester from the aerial part of Mimosa invisa
(Mimosaceae), Natural Product Research: Formerly Natural Product Letters, 26:19, 1831-1836
To link to this article: http://dx.doi.org/10.1080/14786419.2011.639073
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Natural Product Research
Vol. 26, No. 19, October 2012, 1831–1836
A new fatty aldol ester from the aerial part of Mimosa invisa (Mimosaceae)
a
Frederic Nana , Louis Pergaud Sandjo , Felix Keumedjio , Victor Kuete and
a
a
b
*
c**
Bonaventure Tchaleu Ngadjui
a
´
´
Department of Organic Chemistry, University of Yaounde I, P.O. Box 812, Yaounde, Cameroon;
bDepartment of Biochemistry, University of Dschang, P.O. Box 67, Dschang, Cameroon;
cDepartment of Pharmaceutical Sciences and Traditional Pharmacopeia, Faculty of Medicine and
´ ´
Biomedical Sciences, University of Yaounde I, P.O. Box 8664, Yaounde, Cameroon
(Received 1 July 2011; final version received 5 September 2011)
A new aldol ester named 17-O-triacontanoylheptadecanal (1) was isolated from
the aerial part of Mimosa invisa (Mimosaceae) together with eight known
compounds identified as ꢀ-sitosterol (2), ꢁ-amyrine (3), lupeol (4), 40-O-
methylepinumisoflavone (5), alpinumisoflavone (6), betulinic acid (7), 3-O-ꢀ-D-
glucopyranoside of sitosterol (8) and epirobinetinidol (9). The structures of
compounds were determined on the basis of NMR and mass spectrometry data as
well as by comparing the data reported in the literatures. The antimicrobial
activities of the crude extract and compounds 1 and 9 were investigated against
seven microbial species. The natural products showed moderate activities
compared to that of the crude extract.
Keywords: Mimosaceae; Mimosa invisa; fatty aldol ester; antimicrobial activity
1. Introduction
Mimosa invisa Linn (Mimosaceae) is a creeping leguminous plant widespread in the humid
climate zone and some desert parts of Africa. It grows up in the southern part of
Cameroon (Letouzey, 1970) and is difficult to handle because of prickles on its branches.
This plant is used to restore the soil fertility (Toxopeus, 1952) and in traditional
pharmacopeia, people prepare it as a decoction with some ingredients to treat bronchitis
and asthma (Berhaut, 1975). Its extract obtained by infusion is used as a mouthwash by
some tribes to relieve tooth pain (Bouquet, 1969). With the aim of promoting the
ethnopharmacological uses, these species were biologically and phytochemically studied.
We herein report the structure elucidation of new fatty aldol ester and its antimicrobial
activities as well as that of the crude extract.
2. Results and discussion
The ethnopharmacological use of M. invisa (Mimosaceae) prompted us to investigate the
antimicrobial activities of the crude extract and some isolated compounds. Thus, the crude
extract showed good antimicrobial activities against seven microbial strains with the MIC
values ranging from 128 to 256 mg mLꢀ1 (Table 1). In order to identify the natural products
responsible for these activities, the remaining extract was subjected to repeated column
Corresponding authors. Email: *plsandjo@yahoo.fr; **ngadjuibt@yahoo.fr
ISSN 1478–6419 print/ISSN 1478–6427 online
ß 2012 Taylor & Francis
http://dx.doi.org/10.1080/14786419.2011.639073
http://www.tandfonline.com

1832
Table 1. MIC values of compounds 1 and 9, crude extract and reference molecules.
Microorganismsa and MIC (mg mLꢀ1
F. Nana et al.
)
Samples
EC
EA
SA
PA
KP
ST
CA
512
256
4512
1
Crude extract
Compound 1
Compound 9
RAb
512
256
128
2
258
256
256
16
128
256
512
2
128
256
128
32
128
64
64
4
256
128
128
1
Notes: The final concentration of DMSO was lower than 2.5% and does not affect the microbial
growth.
aMicroorganisms: EC, Escherichia coli; EA, Enterobacter aerogenes; SA, Staphylococcus aureus;
PA, Pseudomonas aeruginosa; KP, Klebsiella pneumoniae; ST, Salmonella typhi; CA, Candida
albicans.
bRA, reference antibiotics (ciprofloxacin for bacteria and nystatin for fungi).
2
O
17
O
O
1´
1
2'
30´
Compound 1
O
O
O
Scheme 1. Some relevant HMBC correlations.
chromatography on silica gel affording nine secondary metabolites. Among them, a new
fatty aldol identified as 17-O-triacontanoylheptadecanal (1) and eight known compounds
as ꢀ-sitosterol (2) (De-Eknamkul & Potduang, 2003), ꢁ-amyrine (3) (Mahato & Kundu,
1994), lupeol (4) (Mahato & Kundu, 1994), 40-O-methylepinumisoflavone (5) (Nkengfack
et al., 2001), alpinumisoflavone (6) (Nkengfack et al., 2001), betulinic acid (7) (Mahato &
Kundu, 1994), 3-O-ꢀ-D-glucopyranoside of sitosterol (8) (Walter, 1963) and epirobineti-
nidol (9) (Cronje, Steynberg, Brandt, Young, & Ferreira, 1993).
Compound 1 was obtained as a white powder from the mixture hexane/ethyl acetate
3-1 (v/v). Its HREIMS displayed the peak at m/z 704.7057 (calcd 704.7046) corresponding
to the molecular formula C47H92O3 accounting for two degrees of unsaturation. The IR
spectrum presented the absorption band of carbonyl at 1733 cmꢀ1. The 1H- and 13C-NMR
spectra (Exp. part) showed the characteristic signals of fatty acid ester (Zu-Jian, Ming-An,
& Qing-Wei, 2009), which were the terminal CH3 group at ꢂH/ꢂC 1.01 (t, 6.7)/14.1, the
sequence of CH2 groups at ꢂH/ꢂC 1.42 (br s)/[23.0–33.9] and the CH2 groups at ꢂH/ꢂC 2.59
(t, 6.5)/34.9 and 2.50 (br t, 6.7)/44.0 in ꢁ of aldehyde and carboxylic functions,
respectively. A methylene oxide at ꢂH/ꢂC 4.36 (t, 6.2)/64.9 and an unresolved resonance of
aldehyde at ꢂH/ꢂC 9.94 (s)/202.6 were further observed. The HMBC spectrum exhibited a
correlation (Scheme 1) between the resonance at ꢂH 4.36 and the carbon signal at ꢂC 173.5,
justifying the esterification of fatty acid moiety. Methanolysis of 1 led to the fatty acid

Natural Product Research
1833
O
O
O
C28H57
m/z 393
(b) – C19
H35O3
C28H53O3
m/z 437
(a) – C19H39
(b) Mc- lafferty rearrangement
–C28H57
O
O
O
O
O
O
f
H
a
b
C19H37O3
m/z 313
–CO
d
e
c
O
O
H
g
C18H37O2
–C2H4
(e) – C6H12
(c) – C2H4
(d) – C4H8
m/z 285
C43H84O3
m/z 648
C41H80O3
m/z 620
C45H88O3
m/z 676
O
O
H
C16H33O2
m/z 257
Scheme 2. Fragmentation pattern of compound 1.
methyl ester identified at m/z 466 corresponding to the molecular formula [C31H62O2]. þ.
These data suggested that 1 contains a fatty acid and fatty aldol both linked by an ester
function with the methylene oxide borne by the aldehyde moiety. Besides, some
fragments collected from the mass spectrometry spectrum supported the proposed
structure. Thus, the fragments at m/z 313 and 393 (Scheme 2) from residual ions of Mc
Lafferty rearrangement confirmed the length of aldol moiety and consequently those
of fatty acid unit. The foregoing data led the identification of 1 as 17-O-
triacontanoylheptadecanal.
The structures of known compounds were determined by the comparison of their
NMR data with those reported in the literatures as well as their physical data.
2.1. Antimicrobial assays
The antimicrobial activities of some obtained compounds were already investigated.
In fact, compound 6 was found to be active on several bacterial species, including
Mycobacterium smegmatis, Candida albicans and some Gram-positive and Gram-negative
bacteria (Kuete, Ngameni, et al., 2008). Compound 4 also exhibited moderate inhibitory
effects against Escherichia coli and M. smegmatis, (Kuete, Wansi, et al., 2008). Meanwhile,
the antimicrobial activities of 7 (Mbaveng et al., 2008), 2 and 8 (Kuete et al., 2007;
˜
Manrıquez-Torres, Zu´ niga-Estrada, Gonzalez-Ledesma, & Torres-Valencia, 2007) were
´ ´
also reported.
Compounds 1 and 9 were subjected to biological assays (Table 1), and 1 displayed
activity against the seven tested microorganisms (MIC values ranged from 64–
256 mg mLꢀ1) with Klebsiella pneumoniae being the most sensitive species (MIC:
64 mg mLꢀ1). Compound 9 was also active on six tested bacterial species but not against
C. albicans. However, the activities of 1 and 9 could be considered as moderate, since the
MIC values obtained were greater than those of ciprofloxacin and nystatin used as
reference drugs. Therefore, both tested compounds significantly contribute to the
antimicrobial activity of M. invisa, together with other isolated metabolites.

1834
F. Nana et al.
3. Experimental
3.1. General
Vacuum column chromatography (VCC), column chromatography (CC) and thin-layer
chromatography (TLC) were performed over silica gel 60 H (particle size 90% 545 mm),
200–300 mesh silica gel silica gel GF254, respectively. The melting point (m.p.) was
measured by an Electro thermal IA 9000 digital m.p. apparatus; uncorrected. IR spectra
were carried out on a JASCO A-302 spectrophotometer in CHCl3. Studies on 1D and 2D
NMR spectra were carried out with Bruker DRX-400 MHz. HR–EI–MS and LR–EI–MS
were recorded with variant JEOL MS mass spectrometer instrument.
3.2. Plant material
Mimosa invisa (Mimosaceae) was collected from Yaounde
October 2007. A voucher specimen has been deposited in the National Herbarium,
Yaounde, Cameroon under the registration number 42881/HNC.
´
central region of Cameroon in
´
3.2.1. Extraction and isolation
The aerial part of Mimosa invisa was cut into small pieces, air-dried and extracted with 5 L
of mixture methylene chloride/methanol (1 : 1, v/v) for 2 days. In this method, 200.0 g of
crude extraction obtained from 1.0 kg of plant material was rotary evaporated and
subjected to VCC. The VCC was carried out on silica gel in the gradient condition using
hexane, hexane/ethyl acetate (3 : 1, 1 : 1 and 1 : 3) and ethyl acetate, yielding five fractions
(A–E). Fraction A was purified by CC with hexane yielding the compounds 3 (7.2 mg) and
5 (9.0 mg). Fraction B was further purified by CC with different mixtures of hexane/ethyl
acetate in the order of increasing polarity, affording 6.0 mg of compound 1, 10.0 mg of 2
and 5.2 mg of 4. Fractions C and D were mixed on the basis of comparative TLC and
purified in the gradient condition with the mixture of hexane/ethyl acetate affording 4.0
and 6.2 mg of compounds 6 and 7, respectively. Also, 11.0 and 5.0 mg of compounds 8 and
9, respectively, were obtained from the fraction E eluted with the mixture of MeOH and
methylene chloride in the gradient condition.
3.2.1.1. 17-O-triacontanoylheptadecanal (1). White powder, m.p 83.7–84.0ꢁC, IR 2918,
2848, 1733 and 1465 cmꢀ1; HR–EI–MS m/z: 704.7057 [calcd for C47H92O3, 704.7046];
1
LR–EI–MS: Scheme 2; NMR data: H-NMR (400 MHz, Pyridin-d5): 9.94 (1H, s, H-1),
2.59 (2H, t, 6.5, H-2), 1.42 [80H, br s, H-(3–16, 40–290)], 1.88 (2H, m, H-17), 4.36 (2H, t,
6.2, H-18), 2.50 (2H, br t, 6.7, H-20), 1.72 (2H, m, H-30) and 1.01 (3H, t, 6.7, H-300);
13C-NMR (100 MHz, Pyridin-d5): 202.6 (C-1), 34.9 (C-2), 23.0–33.9 (C-3), 26.4 (C-17),
64.9 (C-18), 173.5 (C-10), 44.0 (C-20), 29.2 (C-30) and 14.1 (C-300).
3.2.1.1.1. Methanolysis of compound 1
In this method, 1.5 mg of 1 was refluxed (70ꢁC) for 18 h in 2.5 mL of MeOH containing
1.5 mL of 0.9 N HCl under magnetic stirring. The mixture was neutralised with an aqueous
solution of NaHCO3 and extracted with hexane. The fatty acid methyl ester was carefully
characterised by EI–MS at m/z 466 corresponding to [C31H62O2]. þ.
3.2.1.2. Compounds 2–9. The NMR and some physical data are reported as
supplementary data.

Natural Product Research
1835
3.3. Antimicrobial assay
The crude extract, compound 1, compound 9 and the reference antibiotics were analysed
for their antimicrobial activities using the XTT colorimetric assay performed according to
Eloff (1998) as modified by Kuete, Mbaveng, et al. (2008). The antibacterial activities
against Staphylococcus aureus (ATCC 25922), Salmonella typhi (ATCC 6539),
Pseudomonas aeruginosa (PAO1), E. coli (ATCC 10536), K. pneumoniae ATCC 29916,
Enterobacter aerogenes ATCC 13048 and the antifungal activities against C. albicans
(ATCC 9002) were carried out, with ciprofloxacin (Sigma–Aldrich, St. Quentin Fallavier,
France) and nystatin (Sigma), respectively, as positive control.
4. Conclusions
The ethnopharmacological uses of some plant species sometimes bring information about
the expected biological activities. Thus, Mimosa invisa could enter in the list of plants of
which the biological activity corroborates with the traditional use, although the significant
activity of its crude extract is a synergic effect of phytocomponents. Therefore, its
traditional use against lung diseases could be attributed to flavonoids since some species
rich in this class of compounds display antitussive activities (Garcia, Arts, Sterne,
Thompson, & Shaheen, 2005). The expectorant effect of some sterols and triterpenoids
was further reported (Gairola, Gupta, Bansal, Singh, & Maithani, 2010), which matches
with its employment as anti-asthmatic. This plant appears to have a wide spectrum of
biological activities since some known compounds obtained were reported to be endowed
with anticancer (Cichewicz & Kouzi, 2004), hypoglycaemic (Panda, Jafri, Kar, & Meheta,
˜
2009) and analgesic properties (Villasenor, Angelada, Canlas, & Echegoyen, 2002).
Acknowledgement
We thank Mehdi Yemloul (Laboratory of the NMR Methodology, Jean Barriol Institute, Univerity
Henri Poincare of Nancy-France) for the NMR analyses.
´
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