Hindawi
Journal of Chemistry
Volume 2022, Article ID 9003143, 7 pages
https://doi.org/10.1155/2022/9003143
Research Article
Oleanane and Stigmasterol-Type Triterpenoid
Derivatives from the Stem Bark of Albizia gummifera and
Their Antibacterial Activities
Tamrat Tesfaye Ayele,1,2 Getahun Tadesse Gurmessa,1 Zelalam Abdissa,1 Girmaye Kenasa,3
and Negera Abdissa 2
1
Department of Chemistry, College of Natural and Computational Sciences, Nekemte, Wollega University, Ethiopia
Department of Chemistry, College of Natural Sciences, Jimma University, Jimma, Ethiopia
3
Department of Biology, College of Natural and Computational Sciences, Wollega University, Nekemte, Ethiopia
2
Correspondence should be addressed to Negera Abdissa; negeraabdisa@gmail.com
Received 26 October 2021; Revised 13 January 2022; Accepted 29 January 2022; Published 18 February 2022
Academic Editor: Liviu Mitu
Copyright © 2022 Tamrat Tesfaye Ayele et al. This is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is
properly cited.
Chromatographic separation of methanol extract of stem bark of Albizia gummifera led to the isolation of two oleanane-type
triterpenoids (1 and 2), a stigmasterol derivative (3), and stigmasterol (4). The structures of the compounds were elucidated based
on 1D and 2D NMR spectroscopic data and comparing with reported literature values. The crude extract and the isolated
compounds were evaluated for their antibacterial activities against five bacterial strains. Compounds 1, 2, and 4 showed marginal
antibacterial activity with the growth inhibition zone ranging from 6.8 to 13.2 mm against the tested bacterial strains, with
compounds 2 and 4 showing significant inhibition (13.0 and 13.2 mm) against S. flexneri and S. typhimurium, respectively. While,
the standard drug, gentamycin showed inhibition zone 20.0 and 24.0 mm against S. flexneri and S. typhimurium, respectively.
1. Introduction
The genus Albizia (family, Fabaceae) comprising of more
than 160 species is widely distributed in subtropical and
tropical regions with the major diversity in Africa and
South America [1, 2]. Albizia gummifera C.A. Smith is a
species of native to sub-Saharan Africa and Madagascar
[3] and commonly known in the indigenous medical
system to treat various human ailments [1, 4, 5]. The
extracts of different solvents have reported to possess
antimicrobial [6], antigonorrheal [7], antiplasmodial, and
antileishmanial [8] activities. The plant elaborates triterpenoids [5, 9] as a common metabolite with proapoptotic and antiplasmodial activities. The stem bark of
A. gummifera has been commonly visited by traditional
healers for the treatment of bacterial infection in the
eastern part of Ethiopia. However, the phytochemical and
biological profile of this plant is not exhaustively studied.
Thus, hereby, we report the isolation of four compounds
(1–4) (Figure 1) from the stem bark of A. gummifera along
with their antibacterial activities.
2. Materials and Methods
2.1. General Experimental Procedures. Solvents and reagents
used for extraction and purification of the compounds were
of analytical and HPLC grade. Analytical TLC precoated
sheets ALUGRAM Xtra SIL G/UV254 (layer: 0.20 mm
silica gel 60 with the fluorescent indicator UVF254/365) were
used for purity analysis. Silica gel 100–200 mesh was used
for column chromatography. Visualization was made on
TLC by spraying with 10% H2SO4 acid solution and heating
on a hot plate. NMR spectra were recorded on an
Av600 MHz spectrometer (Bruker, Billerica, MA, USA).
Chemical shifts were expressed in parts per million (ppm)
downfield of trimethylsilane (TMS) as an internal
®
2
Journal of Chemistry
O
30
29
20
1
3
HO
23
1'
3'
O
16'
13'
O
5'
1
12
25
26
7'
13
27
OH
14
1
23
1'
3'
5'
12
O
29
O
8
5
24
23
19
2
24
25
22
3
O
O
HO
6
O
22
OH
3
4
1
29
9'
24
25'
8'
H3C (H2C)16
30
17'
O
27
26
O
7'
22
25
18'
8'
O
5'
6
7' O
1'
3'
HO
3
4
Figure 1: Structures of the isolated compounds from stem bark of A. gummifera.
reference. Whatman filter paper No. 3, 1% dimethylsulfoxide (DMSO), Petri dishes, and gentamycin were used for
antibacterial analysis.
2.2. Plant Materials. The stem bark of A. gummifera was
collected from Wollega University, Nekemte campus, in
September 2019. The plant was authenticated by botanist,
Dr. Fikadu Gurmessa, and a voucher specimen (TTA004Ag)
has been deposited in Wollega University Herbarium.
2.3. Extraction and Isolation. The maceration extraction
was employed [10] in this experiment to extract secondary
metabolites from the stem bark of A. gummifera. About
940 g of sample was extracted with methanol (2 L) three
times each. The filtrate was evaporated using a rotary
evaporator to yield 10 g of semisolid extract. The crude
extract (9 g) was suspended in water and extracted with
petroleum ether and chloroform to yield 3 g (yellow
semisolid) and 4 g (brown semisolid), respectively. Then,
2.50 g of crude extract of petroleum ether was adsorbed on
3 g of silica gel and subjected to column chromatography.
The column was eluted with n-hexane (100%) and continued with n-hexane/ethyl acetate (95/5, 90/10, 85/15, 80/
20, . . ., 25/75, v/v) to obtain 77 fractions, each 200 mL. The
fractions were grouped into six subfractions (1–6) based on
their TLC profile. Subfraction 2 showed a precipitate and
washed repeatedly with petroleum ether to obtain a white
powder compound (4) (20 mg). Subfraction 4 was subjected
to small column chromatography over silica gel and eluted
with n-hexane in increasing gradient of ethyl acetate to
afford a light yellow powder compound (1) (20 mg).
The chloroform crude (3.50 g) was also subjected to
column chromatography over silica gel and eluted with
dichloromethane/ethyl acetate (80/20, 70/30, 60/40, and
50/50), each 200 mL. Sixty-four fractions were collected and
combined into five (1–5) subfractions. Subfraction 5 was
again subjected to small column chromatography over silica
gel and eluted with n-hexane/ethyl acetate (80/20, 70/30, and
60/40) to afford a white powder compound (3) (21 mg) and
light yellow compound (2) (13 mg).
2.4. Pathogenic Bacterial Strains. Five pathogenic bacterial
strains, one Gram-positive (Staphylococcus aureus
(ATCC25923)) and four Gram-negative (Escherichia coli
(ATCC25922), Pseudomonas aeruginosa (ATCC27853),
Salmonella typhimurium (ATCC13311), and Shigella flexneri
(ATCC29903)) were obtained from the Department of Biology, Wollega University, and used for evaluation of antibacterial activities.
2.5. Antibacterial Assay of the Isolated Compounds. The
paper disc diffusion method was employed to determine the
antibacterial activities of the isolated compounds as described by Kumara et al. [11] with slight modification. The
pathogens were seeded on Muller–Hinton agar media
(model), and simultaneously, sterile circular discs of 6 mm in
diameter were prepared from Whatman filter paper No. 3.
The solutions of crude extract 20 μg/mL, each and compounds (1, 2 and 4) (10 μg/mL, each), were prepared in 1%
dimethylsulfoxide (DMSO). The discs were impregnated
with these solutions and applied aseptically to the Petri
dishes of microbial culture [12]. The applied substances let to
diffuse to the agar for half an hour and then incubated at
35°C for 24 h. Both DMSO (1%) and gentamycin (impregnated disc, 10 μg/mL) were used as negative and positive
controls, respectively. All tests were performed in triplicate,
and zone of inhibition was measured from the edge of each
disc with a ruler.
Journal of Chemistry
2.6. Statistical Analysis. Data were measured as mean ± SD.
Statistical analysis was performed using SPSS version 20
Software. The global comparison was done using two-way
ANOVA followed by the least significant difference (LSD)
multiple comparison test. Pairwise testing was done with the
help of the unpaired post hoc test. P < 0.05 implies that it is
statistically significant.
3. Results and Discussion
Compound 1 was obtained as a light yellow solid. The 1H
NMR spectrum (Table 1) displayed seven singlets at δH 0.99
(3H, s, H-23), 0.78 (3H, s, H-24), 0.93 (3H, s, H-25), 0.77
(3H, s, H-26), 1.13 (3H, s, H-27), 0.92 (3H, s, H-29), and 1.43
(3H, s, H-30), integrated for three protons each for seven
methyl groups; a triplet olefinic protons resonating at δH
5.27(1H, t, J � 3.7 Hz, H-12), a doublet of doublets methine
proton at δH 3.21 (1H, dd, J � 11.3, 4.3 Hz, H-3), and two
methine protons signals at δH 1.56 (1H, m, H-9) and 2.82
(1H, dd, J � 13.8, 4.7 Hz, H-18), which are the typical
characteristics of an oleanane-type of triterpene [13–15].
Furthermore, di-ortho/meta coupling protons at δH 7.53
(2H, td, J � 5.8, 3.5 Hz, H-4′ and H-5′) and the deshielded
proton signals at δH 7.71(2H, dd, J � 12.5, 5.7, 3.3 H z, H-3′
and H-6′) are a characteristic of ortho-disubstituted benzene
moiety [15]. The oxygenated methylene protons at δH 4.08
(2H, d, J � 6.7 Hz, H-1″), multiple proton signals for methine
protons at δH 2.04 (1H, m, H-2″), 1.32 (1H, m, H-6″), two
doublet for methyl protons at δH 0.99 (3H, d, J � 6.4 Hz,
H-9″), 0.90 (3H, d, J � 6.0 Hz, H-10″), and one triplet for
methyl protons at δH 0.92 (3H, t, J � 3.7 Hz, H-8″) indicate
the presence of geranyl unit (monoterpene) linked through
an ester bond.
The 13C NMR spectrum (Table 1) showed carbon signals
for 48 carbon atoms, of which 30 carbon atoms are for
aglycone core, 8 carbon atoms for phthalate moiety, and 10
carbon atoms for the two isoprene chains. The downfield
shifted carbon signals at δC 167.8 (C-7′), 167.7 (C-8′), 132.5
(C-2′), 132.4 (C-1′), 130.9 (C-4′and C-5′), and 128.9 (C-3′
and C-6′) are carbons for phthalate moiety, while the signals
resonate at δC 71.8 (C-1″) and 27.7 (C-2″ and C-3″), three
methyl carbons resonate at 11.0 (C-8″), 19.2 (C-9″), and 14.1
(C-10″) for the geranyl unit (monoterpene), whereas the
signals of seven methyls of aglycone core (C-23, C-24, C-25,
C-26, C-27, C-29, and C-30) are resonated at δC 28.1, 15.5,
15.3, 17.1, 25.9, 33.1, and 23.7, respectively. The signals
resonating at δC 38.4 (C-1), 79.0 (C-3), 122.6 (C-12), 143.6
(C-13), 40.9 (C-18), and 183.7 (C-28) are in accordance with
the reported literature data for oleanoloate [13–16] except
signal at δC 68.2 (C-22) which could be due to the oxygen
attachment with the phthalate moiety. The gross structure of
the aglycone and position of the substituent was determined
by analysis of 1H-1H COSY and HMBC experiments
(Figure 2). The 1H-1H COSY cross-peaks showed the coupling
of hydroxymethine proton H-3 (δH 3.21) with H-2 (δH 1.64),
H-12 (δH 5.27) with H-11(δH 1.90), H-15 (δH 1.32) with
H-16 (δH 0.94), H-18 (δH 2.82) with H-19 (δH 1.61), and
H-21 (δH1.71) with H-22 (δH 4.22) enabled to construct the
structure of aglycone. The correlation of proton H-3′ (δH
3
7.71) with H-4′ and H-5′ (δH 7.53) through ortho/meta
coupling further confirm the phthalate moiety. Similarly, the
cross-peaks from oxymethylene proton H-1″ (δH 4.08) with
H-2″ (δH 2.04) and H-5″ (δH 1.78) with H-6″ (δH 1.32) also
revealed the geranyl unit (monoterpene).
The long-range HMBC coupling (Figure 2) from oxymethine proton at δH 4.22 (H-22) to carbon signal at δC 23.6
(C-16), δC 38.7 (C-21), δC 30.7 (C-20), and δC 167.8 (C-7′)
enabled to establish the phthalate moiety at C-22 through an
ester bond. The oxymethylene protons peaks at δH 4.08 (H1″ showed an HMBC correlation to carbon signals at δC
167.7 (C-8′) and δC 27.7 (C-2″)) confirmed the attachment
of geranyl unit at C-8′ of phthalate. Thus, based on the above
spectroscopic analysis, the structure of compound 1 was
deduced to be a 3-hydroxy-22-(2-((2, 6-dimethyloctyloxy)
carbonyl) benzoyloxy)olean-12-en-28-oic acid.
Compound 2 was obtained as a yellow powder. The
NMR spectral data showed similar spectral feature with
compound 1 except for some substituted positions. The 1H
NMR spectrum (Table 1) displayed five aromatic protons at
δH7.70 (1H, dd, J � 5.7, 3.3 Hz, H-2′ and H-6′) and δH 7.53
(1H, dd, J � 5.7, 3.3 Hz, H-3′, H-4′, and H-5′), containing
HSQC correlations with carbons at δC 128.8 (C-2′ and C-6′)
and 130.9 (C-3′, C-4′, and C-5′), respectively. However, the
13
C NMR spectrum (Table 1) showed an esteric carbonyl
carbon at δC 167.8 (C-7′) and one quaternary carbon at δC
132.5 (C-1′), indicating the benzoate linked to oleanolic
moiety. The long-range HMBC correlations (Figure 2) between oxymethine protons at δH 4.22 (H-22) and carbon
signals at δC 38.7 (C-21), δC 30.7 (C-20), and δC 23.6 (C-16)
and carbonyl carbon at δC 167.8 (C-7′) established the
linkage of benzoate at C-22. Therefore, based on the above
findings, the structure of compound 2 was defined to be 22(benzoyloxy)-3-hydroxyolean-12-en-28-oic acid.
Compound 3 was obtained as a white solid. The 1H and
13
C NMR spectra data are similar to that of stigmasterol (4)
(coisolated from the same fraction) except for some signals
for C-28, C-29, and C-3 of the stigmasterol (could be due to
the substitution effect). The 1H NMR spectrum displayed
doublet of doublets oxymethylene protons at δH 4.22 (2H,
dd, J � 11.4, 5.9 Hz, H-29). These protons showed a longrange HMBC cross-coupling (Figure 3) with carbonyl easter
of benzoate moiety, whose presence is evidenced from
strongly deshielded doublet of doublets at δH7.70 (2H, dd,
J � 5.7, 3.3 Hz) for H-2″ and H-6″ and multiplet at δH 7.53
(3H, for H-3″, H-4″, and H-5″), indicating that the position
of the benzoate substituent at C-29.
The 1H NMR spectrum also showed signals for aliphatic
carboxylate (Table 1). In this regard, 13C NMR spectrum
showed that a downfield shifted carbon signal at δC 178.5 is
assignable to carbonyl carbon (C-1′) and the signal at δC 33.8
for C-2′. The HSQC spectrum confirmed the connectivity
between protons at δH 2.35 (2H, t, J � 7.5 Hz), 1.65 (2H, dt,
J � 34.2, 7.1 Hz), 1.33 (2H, m), and 0.91(3H, t, J � 6.8 Hz)
with carbon atoms at δC 33.8 (C-2′), 24.7 (C-3′), 23.0 (C17′), and 14.1 (C-18′), respectively.
The triplet methylene protons at δH 2.35 (2H, t,
J � 7.6 Hz) showed strong HMBC correlations with carbon at
δC 178.5 (carbonyl carbon, C-1′) and δC 24.7 (C-3′),
4
Journal of Chemistry
Table 1: 1H NMR and
C/H
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
1′
2′
3′
4′
5′
6′
7′
8′
9′
10′
11′
12′
13′
14′
15′
16′
17′
18′
19′
20′
21′
22′
23′
24′
25′
1
δH (m, J in Hz)
δC (ppm)
1.62 (m)
38.4
1.64 (m)
27.2
3.21 (dd, 11.3, 4.3)
79.0
—
38.8
0.74 (m)
55.2
1.57 (m)
18.3
1.45 (m)
32.6
—
39.3
1.56 (m)
47.6
—
37.1
1.90 (m)
23.4
5.27 (t, 3.7)
122.6
—
143.6
—
41.6
1.32 (m)
28.9
0.94 (m)
23.6
—
46.5
2.82 (dd, 13.8, 4.7)
40.9
1.62 (m)
45.9
—
30.7
1.70 (m)
38.7
4.22 (dd, 11.5, 5.9)
68.2
0.99 (s)
28.1
0.78 (s)
15.5
0.93 (s)
15.3
0.77 (s)
17.1
1.13 (s)
25.9
—
183.7
0.92 (s)
33.1
1.43 (s)
23.7
—
132.4
—
132.5
7.71 (dd, 12.5, 5.7, 3.3)
128.8
7.53 (dt, 5.8, 3.5)
130.9
7.53 (dt, 5.8, 3.5)
130.9
7.71 (dd, 12.5, 5.7, 3.3)
128.9
—
167.8
—
167.7
4.08 (d, 6.7)
71.8
2.04 (m)
27.7
1.01 (m)
27.7
1.62 (m)
22.9
1.78 (m)
32.4
1.32 (m)
33.8
1.50 (m)
30.4
0.94 (t, 3.7)
11.0
0.99 (d, 6.4)
19.2
0.90 (d, 6.0)
14.1
13
C NMR (600 MHz) spectroscopic data for compounds 1–4 in CDCl3.
2
δH (m, J in Hz) δC (ppm)
1.62 (m)
38.4
1.64 (m)
27.2
3.22 (dd,11.3,4.3)
79.0
—
39.3
0.75 (m)
55.2
1.56 (m)
18.3
1.36 (m)
32.6
—
37.1
1.56 (m)
47.6
—
38.8
1.90 (m)
23.4
5.28 (t, 3.7)
122.6
—
143.6
—
41.6
1.08 (m)
27.7
1.42 (m)
23.6
—
46.5
2.82 (dd, 13.8, 4.7)
41.0
1.15; 1.64 (m)
45.9
—
30.7
1.70 (m)
38.7
4.22 (dd, 11.4, 5.9)
68.2
1.00 (s)
28.1
0.76 (s)
15.5
0.93 (s)
15,3
0.75 (s)
17.1
1.16 (s)
25.9
—
183.5
0.94 (s)
33.1
1.43 (s)
23.8
—
132.5
7.70 (dd, 5.7, 3.3)
128.8
7.53 (dd, 5.7, 3.3)
130.9
7.53 (dd, 5.7, 3.3)
130.9
7.53 (dd, 5.7, 3.3)
130.9
7.70 (dd, 5.7, 3.3)
128.8
—
167.8
respectively. Based on the above spectral data, the structure
of compound 3 was defined as 29-benzoyl-3-octadecanoyl
stigmasterol.
3
4
δH (m, J in Hz) δC (ppm) δH (m, J in Hz) δC (ppm)
1.14 (m)
37.3
1.14 (m)
37.3
1.55 (m)
31.6
1.55 (m)
31.7
3.52 (td, 11.2, 5.7)
71.8
3.52 (td, 11.2, 5.7)
71.8
2.30 (d, 5.0)
42.2
2.30 (d, 5.0)
42.2
—
140.7
—
140.8
5.35 (dd, 5.4, 1.9)
121.7
5.35 (dd, 5.4, 1.9)
121.7
1.83 (m)
31.9
1.83 (m)
31.9
1.45 (m)
31.9
1.45 (m)
31.9
0.93 (m)
50.2
0.93 (m)
50.2
—
36.5
—
36.5
1.30 (m)
22.7
1.30 (m)
21.1
1.83 (m)
39.7
1.83 (m)
39.7
—
42.3
—
42.3
1.00 (m)
56.9
1.00 (m)
56.9
1.55 (m)
24.4
1.55 (m)
24.4
1.33 (m)
28.9
1.33 (m)
28.9
1.15 (m)
56.0
1.15 (m)
56.0
0.68 (s)
12.1
0.68 (s)
12.0
1.03 (s)
19.8
1.03 (s)
19.8
2.04 (m)
40.5
2.04 (m)
40.5
1.04 (m)
21.1
1.04 (m)
21.2
5.15 (m)
138.3
5.15 (m)
138.3
5.03 (dd, 15.1, 8.8)
129.3
5.03 (dd, 15.1, 8.8)
129.3
1.55 (m)
51.3
1.55 (m)
51.2
1.45 (m)
31.9
45.8
0.94 (m)
11.0
0.82 (d, 6.6)
21.1
1.42 (m)
23.7
0.80 (d, 6.6)
19.0
1.70 (m)
38.7
0.71 (s)
25.4
4.22 (dd, 11.4, 5.9)
68.2
1.03 (s)
12.3
—
—
132.5
7.70 (dd, 5.7, 3.3)
128.8
7.53 (dd, 5.7, 3.3)
130.9
7.53 (dd, 5.7, 3.3)
130.9
7.53 (dd, 5.7, 3.3)
130.9
7.70 (dd, 5.7, 3.3)
128.8
—
167.8
—
178.5
2.35 (t, 7.5)
33.8
1.65 (dt, 34.2, 7.1)
24.7
1.86 (m)
31.9
1.55 (m)
31.9
1.30–1.45 (m)
29.7
1.30–1.45 (m)
29.5
1.30–1.45 (m)
29.3
1.30–1.45 (m)
29.5
1.30–1.45 (m)
29.6
1.30–1.45 (m)
29.4
1.30–1.45 (m)
29.7
1.30–1.45 (m)
29.7
1.30–1.45 (m)
29.7
1.30–1.45 (m)
29.7
1.27 (m)
30.4
1.33 (m)
23.0
0.91 (t, 7.5)
14.1
Compound 4 was isolated as a white powder. The 1H
NMR spectrum (Table 1) displayed three doublet of doublets
peaks at δH 5.35 (1H, dd, J � 5.2, 2.2 Hz), 5.15(1H, dd, J � 15.1,
Journal of Chemistry
5
O
O
O
O
O
O
O
OH
O
HO
OH
1
HO
2
1
1
Figure 2: Key HMBC (curved arrow) and H- H COSY (bold line) correlations of compounds 1 and 2.
H
H
O
O
O
7''
O
2''
H
Figure 3: Key HMBC (curved arrow) and 1H-1H COSY (bold line) correlations of compound 3.
Table 2: Bacterial growth inhibition zone in diameter (mm) of crude extracts (20 μg/mL each) and isolated compounds (1, 2, and 4) (10 μg/
mL each).
Compounds/extracts
ME
PE
CHE
1
2
4
Gentamycin
S. aureus
9
8
—
7
—
7.4
16
E. coli
8
9
7
7
7.3
7
21
Tested micro-organism
P. aeruginosa
S. typhimurium
7
10
7
11
11
7
7.2
—
10
6.8
7.3
13.2
14
20
S. flexneri
10
7
14∗
—
13
6.9
24
—, not active; ME, methanol extract; PE, petroleum ether extract; CHE, chloroform extract. All values are mean values ± standard deviation of three replicates.
8.7 Hz), and 5.01(1H, dd, J � 15.2, 8.7 Hz), which are typical
signals for olefinic proton (H-6) of the steroidal skeleton and
olefinic protons (H-22 and H-23), respectively. The proton
signal at δH 3.52(1H, dd, J � 11.2, 6.5, 4.7 Hz) integrating for
1H was indicative of hydroxymethine proton of H-3. Two
singlet peaks at δH 0.86 (3H, s) and 1.05(3H, s) were assigned
to two tertiary methyl groups attached to C-13 (H-18) and
C-10 (H-19), respectively. The spectrum further revealed
three doublet peaks at δH 1.01 (3H), 0.86 (3H), and 0.93 (3H)
which are assigned to methyl groups at C-20 (H-21) and
C-25 (H-26 and H-27), respectively.
The 13C NMR spectrum (Table 1) also showed the
presence of 29 carbon atoms, of which the signal at δC 71.8 is
assignable to C-3. The signals at δC 140.8, 121.7, 138.3, and
129.3 are corresponding to olefinic carbons at C-5, C-6,
C-22, and C-23, respectively. Based on these data and
comparison to the reported literature [17–19], compound 4
was found to be stigmasterol. This is the first report of
compound 4 from A. gummifera.
Compounds 1, 2, and 4 were evaluated for their antibacterial activities against five pathogenic bacteria strains:
Staphylococcus aureus (ATCC25923), Escherichia coli
(ATCC25922), Pseudomonas aeruginosa (ATCC27853),
Salmonella typhimurium (ATCC13311), and Shigella flexneri
(ATCC29903) (Table 2) using the disk diffusion method.
The crude extracts showed weak to moderate activity on
both Gram-positive and Gram-negative bacterial strains
with zone of inhibition ranging 7–14 mm with chloroform
extract demonstrating the highest zone of growth inhibition
(14 mm) (P < 0.05) against S. flexneri. This is in agreement
6
Journal of Chemistry
with the report that the hydroalcoholic extract of
A. gummifera exhibited growth inhibition against bacterial
pathogens [6, 20]. The isolated compounds also showed
moderate antibacterial activity against the test strains. These
activities vary from strain to strain. Compound 4 showed
significant inhibition (13.2 mm) against S. typhimurium
(ATCC13311). Gram-negative bacteria showed greater
susceptibility to 2 and 4 than Gram-positive. It might be due
to the thickness of the peptidoglycan layer. It is worth to
highlight that stigmasterol has been reported to inhibit
several proinflammatory and matrix degradation mediators
typically involved in human osteoarthritis- (OA-) induced
cartilage degradation, at least in part through the inhibition
of the NF-κB pathway [21]. It also showed good membrane
stabilizing activity in HRBC with minimum stabilization
62.74% at 10 μg/mL and maximum stabilization 65.19% at
40 μg/mL [22].
The antibacterial activity results confirm the traditional
value of the plant (A. gummifera), provided that these results
further supported with in vivo and cytotoxicity tests.
4. Conclusion
Four triterpenoids 1, 2, 3, and 4 were isolated from stem bark
of A. gummifera. This is the first report of compounds 1, 2,
and 3. The crude extract and isolated compounds showed
moderate antibacterial activity with compound 4 exhibiting
the highest. The observed antibacterial activities of the extracts and pure compounds could give insight about potential of the traditionally used medicinal plants for
development of antibacterial drugs.
Data Availability
NMR data of compounds 1–4 are included in the Supplementary Materials.
Conflicts of Interest
The authors declare that they have no conflicts of interest.
Acknowledgments
Mr. Tamirat.T was thankful to Wollega University, Ethiopia,
for financial support for his PhD study. This work was
supported by the International Foundation for Sciences,
Stockholm, Sweden, through a grant to Negera Abdissa (IFS,
grant no.: F/5778-2)
Supplementary Materials
NMR data of compounds 1–4 are provided in the supplementary information. (Supplementary Materials)
References
[1] G. M. Rukunga and P. G. Waterman, “New macrocyclic
spermine (budmunchiamine) alkaloids from Albizia gummifera: with some observations on the Structure−Activity
relationships of the budmunchiamines,” Journal of Natural
Products, vol. 59, no. 9, pp. 850–853, 1996.
[2] M. Abdel-Kader, J. Hoch, J. M. Berger et al., “Two bioactive
saponins from Albizia subdimidiata from the Suriname
rainforest,” Journal of Natural Products, vol. 64, no. 4,
pp. 536–539, 2001.
[3] H. J. Beentje, Kenya Trees, Shrubs and Lianas, National
Museums of Kenya, Nairobi, Kenya, 1994.
[4] K. Kokila, S. D. Priyadharshini, and V. Sujatha, “Phytopharmacological properties of Albizia species: a review,”
International Journal of Pharmacy and Pharmaceutical Sciences, vol. 5, no. 3, pp. 70–73, 2013.
[5] L. M. Simo, O. P. Noté, J. N. Mbing et al., “New cytotoxic
triterpenoid saponins from the roots of Albizia gummifera
C.A. Smith,” Chemistry and Biodiversity, vol. 14, no. 10,
pp. 01–22, 2017.
[6] Z. P. Mahlangu, F. S. Botha, E. Madoroba, K. Chokoe, and
E. E. Elgorashi, “Antimicrobial activity of Albizia gummifera
(J.F.Gmel.) C.A.Sm leaf extracts against four Salmonella
serovars,” South African Journal of Botany, vol. 108, pp. 132–
136, 2017.
[7] M. Tefera, A. Geyid, and A. Debella, “In vitro anti-Neisseria
gonorrhoeae activity of Albiziagummifera and Croton macrostachyus,” Pharmacology Oline, vol. 1, pp. 75–83, 2012.
[8] D. Nigussie, G. Tasew, E. Makonnen et al., “In-vitro investigation of fractionated extracts of Albizia gummifera seed
against Leishmania donovani Amastigote Stage,” Journal of J
Clinical & Cellular Immunology, vol. 6, no. 6, pp. 01–06, 2015.
[9] S. Cao, A. Norris, J. S. Miller et al., “Cytotoxic triterpenoid
saponins of Albizia gummifera from the Madagascar rain
Forest,1,” Journal of Natural Products, vol. 70, no. 3,
pp. 361–366, 2007.
[10] M. Meshesha, T. Deyou, A. Tedla, and N. Abdissa,
“Chemical constituents of the roots of Kniphofia isoetifolia
Hochst and evaluation for antibacterial activity,” Journal of
Pharmacy & Pharmacognosy Research, vol. 5, no. 6,
pp. 345–353, 2017.
[11] M. Kumara, R. Agarwala, K. Deyb, V. Raib, and B. Johnsonc,
“Antimicrobial activity of aqueous extract of Terminalia
chebula Retz. on gram positive and gram negative microorganisms,” International Journal of Current Pharmaceutical
Research, vol. 1, no. 1, pp. 56–60, 2009.
[12] H. Tedila and A. Assefa, “In vitro antibacterial activity of
Rumexnervosusand Clematis simensisplants against some
bacterial human pathogens,” African Journal of Microbiology
Research, vol. 13, no. 1, pp. 14–22, 2019.
[13] M.-Y. Baek, J. G. Cho, D. Y. Lee, E. M. Ahn, T. S. Jeong, and
N. I. Baek, “Isolation of triterpenoids from the stem bark of
Albizia julibrissin and their inhibition activity on ACAT-1
and ACAT-2,” Journal of the Korean Society for Applied Biological Chemistry, vol. 53, no. 3, pp. 310–315, 2010.
[14] G. A. Meshram and S. S. Khamkar, “Effect of oleanolic acid
isolated from garlic leaves on carbohydrate metabolizing
enzymes, in Vitro,” International Journal of Pharma Sciences
and Research, vol. 5, pp. 988–991, 2014.
[15] M. Endo, K. Shigetomi, S. Mitsuhashi, M. Igarashi, and
M. Ubukata, “Isolation, structure determination and structure–activity relationship of anti-toxoplasma triterpenoids
from Quercus crispula Blume outer bark,” Journal of Wood
Science, vol. 65, no. 3, pp. 01–11, 2019.
[16] M. Zanger, “The determination of aromatic substitution
patterns by nuclear magnetic resonance,” Organic Magnetic
Resonance, vol. 4, pp. 1–25, 1971.
[17] I. S. Okoro, T. A. Tor-Anyiin, J. O. Igoli, X. S. Noundou, and
R. W. M. Krause, “Isolation and characterisation of stigmasterol and β–sitosterol from Anthocleista djalonensis
Journal of Chemistry
[18]
[19]
[20]
[21]
[22]
A. Chev,” Asian Journal of Chemical Sciences, vol. 3, no. 4,
pp. 1–5, 2017.
K. M. Kumari, “Isolation and characterization of bio active
triterpenes and phytosterols from Alysicarpus monilifer L,”
International Journal of Current Microbiology and Applied
Sciences, vol. 5, pp. 60–66, 2017.
M. Haque, N. Sultana, S. Abedin, and S. Kabir, “Stigmasterol,
rengyolone, 2-phenylethyl β-D-glucopyranoside and n-tetradecyl-β-D-glucopyranoside from the flowers of Nyctanthes
arbor-tristis Linn,” Bangladesh Journal of Scientific & Industrial Research, vol. 54, no. 3, pp. 275–282, 2019.
G. Tesfamaryam, B. Tsegaye, T. Eguale, and A. Wubete, “In
vitro screening of antibacterial activities of selected Ethiopian
medicinal plants,” International Journal of Microbiological
Research, vol. 6, no. 1, pp. 27–33, 2015.
O. Gabay, C. Sanchez, C. Salvat et al., “Stigmasterol: a phytosterol with potential anti-osteoarthritic properties,” Osteoarthritis and Cartilage, vol. 18, no. 1, pp. 106–116, 2010.
M. Aurang, S. U. Khan, T. U. Rahman, M. Sajid, and S. Seloni,
“Isolation and biological activity of β-sitosterol and stigmasterol from the roots of Indigofera heterantha,” Pharmacy
& Pharmacology International Journal, vol. 5, no. 5,
pp. 204–207, 2017.
7