Molecules 2013, 18, 9207-9218; doi:10.3390/molecules18089207
OPEN ACCESS
molecules
ISSN 1420-3049
www.mdpi.com/journal/molecules
Article
In Vitro Antiprotozoal Activity of Triterpenoid Constituents of
Kleinia odora Growing in Saudi Arabia
Nawal M. Al Musayeib 1,*, Ramzi A. Mothana 1,2, Ali A. El Gamal 1, Shaza M. Al-Massarani 1
and Louis Maes 3
1
2
3
Department of Pharmacognosy, College of Pharmacy, King Saud University, Riyadh 11451,
Saudi Arabia; E-Mails:aelgamal00@yahoo.com (A.A.-G.); salmassarani@ksu.edu.sa (S.M.-M.)
Department of Pharmacognosy, Faculty of Pharmacy, Sana’a University, P.O. Box 33039, Sana’a,
Yemen; E-Mail: rmothana@ksu.edu.sa
Laboratory for Microbiology, Parasitology and Hygiene (LMPH), Faculty of Pharmaceutical,
Biomedical and Veterinary Sciences, Antwerp University, Antwerp B-2610, Belgium;
E-Mail: louis.maes@ua.ac.be
* Author to whom correspondence should be addressed; E-Mail: nalmusayeib@ksu.edu.sa;
Tel./Fax: +966-11-2914-842.
Received: 15 July 2013; in revised form: 28 July 2013 / Accepted: 29 July 2013 /
Published: 31 July 2013
Abstract: Two lupane and four ursane triterpenes, namely epilupeol (1), lupeol acetate (2),
ursolic acid (3), brein (4), 3β 11α-dihydroxy urs-12-ene (5) and ursolic acid lactone (6)
were isolated from aerial parts of Kleinia odora and identified. Compounds 1 and 3–6 were
isolated for the first time from K. odora. The triterpene constituents were investigated for
antiprotozoal potential against erythrocytic schizonts of Plasmodium falciparum,
intracellular amastigotes of Leishmania infantum and Trypanosoma cruzi and free
trypomastigotes of T. brucei. Cytotoxicity was determined against MRC-5 fibroblasts to
assess selectivity. The ursane triterpenes were found to be active against more than one
type of the tested parasites, with the exception of compound 6. This is also the first report
on the occurrence of ursane type triterpenes in the genus Kleinia and their antiprotozoal
potential against P. falciparum, L. infantum, T. cruzi, and T. brucei.
Keywords: Kleinia odora; triterpenes; antiplasmodial; antileishmanial; antitrypanosomal
Molecules 2013, 18
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1. Introduction
Protozoal infections are a worldwide health problem, particularly in developing countries [1–4], and
approximately 14% of the World population are at risk of infection. Various studies have been
conducted on leishmaniasis, malaria, Chagas and sleeping sickness which are considered major killing
diseases [5]. The drugs currently in use mostly lack adequate efficacy, are toxic or show other
liabilities, such as the need for parenteral application or high cost [6]. This reflects the need to continue
searching for new and better antiprotozoal drugs. Natural products may offer good sources of leads for
new drug design and discovery.
The genus Kleinia is a flowering plant comprising 40 species that are distributed in Somalia, the
Middle-East, Madagascar and India [7,8]. Three species of this genus are commonly distributed in the
Southern regions in Saudi Arabia: K. odora (Forssk) DC, K. deflersii (O.Schwartz) and K. pendula
(Forssk) Sch. Bip. [9–11]. Several species of Kleinia are known to be rich sources of oxygenated
sesquiterpenoids such as germacrane and oplopane abrotanifolon derivatives and lupane-type
tri-terpenoids [12–14]. Triterpenes comprise one of the most interesting groups of natural products
due to their high potential as pharmacological agents, including leishmanicidal, trypanocidal and
antiplasmodial activity [15].
As part of our ongoing research on Saudi medicinal plant metabolites with antiprotozoal potential,
triterpenoid constituents from K. odora were isolated, structurally analyzed and evaluated for antiprotozoal
potential against the protozoan parasites Plasmodium falciparum, Leishmania infantum, Trypanosoma
cruzi and T. brucei. To assess selectivity, cytotoxicity was determined on MRC-5 fibroblasts.
2. Results and Discussion
2.1. Phytochemistry
Compound 1 was isolated as a white powder. Its 13C-NMR and DEPT spectrum (Table 1) exhibited
30 carbons, including seven singlet methyl groups, eleven methylenes, six methines one of which is
oxygenated, and six quaternary carbons, which taken together revealed the basic skeleton of a
pentacyclic triterpene. NMR spectra include signals for isopropenyl group (olefinic quaternary carbons
at δc 150.9, methylene carbon at δc 109.3, protons singlets at δH 4.69 and 4.57, and methyl singlet at
δH 1.64) suggesting lupane type triterpene. The 1H-NMR spectrum (Table 1) showed one oxymethine
proton at C-3 as a broad singlet (δH 3.39). The proton signal at δH 2.38 (1H, td, 11.0, 10.0, 5.5 Hz)
further revealed a typical H-19β lupane structure [16]. By comparing these NMR data with previously
published data [17], compound 1 was characterized as epilupeol.
Compound 2 was also isolated as white crystals. The NMR data (Table 1) suggested a lupane
skeleton. The NMR data were identical with those of epilupeol, except for the ring A signals.
Compound 2 displayed a double doublet at δH 4.47 confirming the α-orientation of the C-3 proton [18].
It also showed additional signals attributed to the presence of an acetoxy group (carbonyl signal at δC
171.0 and methyl signals at δC 27.9 and δH 2.04). By comparison with previously reported data [19],
compound 2 was identified as lupeol acetate.
Compound 3 was isolated as a white powder. The 1H- and 13C-NMR spectra (Table 1) revealed the
presence of five tertiary methyls, two secondary methyls, nine methylenes, seven methines, one of
Molecules 2013, 18
9209
which was oxygenated, and six quaternary carbons, which indicated a pentacyclic triterpenoid. The
NMR spectrum showed a double bond (δC 124.5, 138.2 ppm) and a carboxyl group (δC 178.6) signals.
The positions of the carboxy group and double bond were confirmed by a HMBC correlation study. By
comparison with previously reported data [20] compound 3 was identified as ursolic acid
(3β-hydroxy-urs-12-en-28-oic acid).
The proton and carbon signals in the 1H- and 13C-NMR spectra (Table 1) of compound 4 were very
similar to those of compound 3, except for the signals of ring D. The carboxy group signals in the
NMR spectrum disappeared and it showed one additional oxymethine signal (δH 4.19; δC 67.4) and an
additional methyl singlet at δH 0.80. The hydroxyl and methyl groups were positioned at C-16 and
C-17 based on a HMBC correlation study. Comparing the spectral data with those reported in the
literature [21], compound 4 was identified as brein (urs-12-ene-3β,16β-diol).
The 13C-NMR data of compound 5 (Table 1) were very similar to those of compound 4 and differed
in the signals for rings C and D. This was attributed to the presence of an α-hydroxy at C-11 and the
disappearance of the β-hydroxyl at position 16. Spectral data of 5 are reported for the first time based
on DEPT, HMBC and HSQC evaluation and comparison of NMR data of structurally related
compounds [21] and the published 1H-NMR data of its acetate form [22]. Compound 5 was identified
as 3β, 11α-dihydroxy urs-12-ene.
The NMR spectral data of compound 6 (Table 1) exhibited characteristic signals of an
oleanan-28,13β-olide. The 13C-NMR spectrum displayed resonances for a double bond at δC 129.9 and
135.0 for C-11 and C-12, in addition to an oxygenated quaternary carbon at 91.9 and a carbonyl at
182.6 for C-13 and C-28, respectively. These data confirmed the olean-11-en,28,13β-olide structure.
These results are in agreement with previously reported [23] data for ursolic acid lactone 6.
Compounds 1 and 3–6 were isolated for the first time from K. odora. To the best of our knowledge,
this is also the first report on the occurrence of ursane type triterpenes in the genus Kleinia. The
structures are summarized in Figure 1.
2.2. Antiprotozoal Activity
Petroleum ether and chloroform extracts of K. odora exhibited potent activity against T. brucei with
IC50 values of 0.5 µg/mL (Table 2). The chloroform extract gave slightly higher selectivity (SI = 63)
compared to the petroleum ether extract (SI = 39). The chloroform extract also displayed moderate
activity against P. falciparum schizonts and intracellular amastigotes of L. infantum (IC50 8 µg/mL). In
comparison, the petroleum ether extract showed similar activity against P. falciparum, L. infantum and
T. cruzi (IC50 8.6, 6.8 and 5.7 µg/mL) but with lower selectivity. This motivated us to investigate the
antiprotozoal activity of the isolated and identified triterpenoids from the chloroform extract.
Brein (4) and 3β, 11α-dihydroxy urs-12-ene (5) were found to be active and selective against more
than one of the investigated protozoa. Brein (4) showed selective and potent activity against T. brucei
(IC50 2.3 µM, SI >27.8), with moderate side-activity against P. falciparum, L. infantum and T. cruzi
(IC50 9.3–9.9 µM) and acceptable selectivity (SI > 6.5). Compound 5 showed potent and selective
activity against L. infantum (IC50 3.2 µM, SI > 20) with some side-activity against T. cruzi and
T. brucei (IC50 8.1 and 7.9 µM, respectively, SI > 7.9).
Molecules 2013, 18
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Figure 1. Structures of the triterpenoid compounds 1–6.
19
R3
12
25
26
17
CH3
1
28
R2
15
10
8
5
3
R1
21
R1
27
HO
R2
23
24
1. R1 = H, R2 = OH
2. R1 = OCOCH3, R2 = H
3. R1 = H, R2 = COOH, R3 = H
4. R1 = OH, R2 = CH3, R3 = H
5. R1 = H, R2 = CH3, R3 = OH
O
O
HO
6
Although ursolic acid (3) showed efficacy against T. brucei (IC50 2.2 µM) comparable to that of
brein (4), its effect against T. cruzi and L. infantum (IC50 8.8 and 7.4 µM) was associated with low
selectivity. Meanwhile, ursolic acid lactone 6 was devoid of any antiprotozoal activity at the highest
concentration tested (64 µg/mL). The antitrypanosomal and antileishmanial activity of urosolic acid
obtained herein is in consistent with the data found in literature. It has been shown to be active against
T. brucei at IC50 1.0 ± 0.2 µg/mL (2.2 µM) [24,25]. In addition, it was also claimed active against
T. cruzi with IC50 21 µM [26] and L. donovani (IC50 = 3.5 µg/mL) (7.6 µM) [27]. It is worthy of
pointing out that in our investigation, the antiplasmodial activity of this compound (IC50 29.7 µM) is
not in agreement with previously reported data which lists IC50 values of 3.1 µg/mL (6.8 µM) [28] and
4.9 µg/mL (10.7 µM) [29].
Molecules 2013, 18
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Table 1. 1H- and 13C-NMR data for compounds 1–6.
#
Compound 1 in CDCl3
δC
δH
Compound 2 in CDCl3
δC
δH
Compound 3 in DMSO
δC
δH
Compound 4 in MeOD
δC
δH
Compound 5 in CDCl3
δC
δH
Compound 6 in MeOD
δC
1
33.2
38.4
38.2
40.1
39.7
39.4
2
25.1
21.3
28.2
27.9
27.4
27.7
3
76.3
76.8
79.7
4
37.5
38.0
38.8
39.9
39.1
40.0
5
49.0
55.4
54.8
56.7
55.3
56.1
6
18.3
18.2
18.0
19.5
18.4
18.8
7
34.1
34.2
32.7
31.8
33.5
32.3
8
41.0
40.8
40.0
41.0
43.3
41.5
3.39 (br s)
81.0
4.47 (dd, 5.5, 10.5 Hz)
3.18 (d, 7.5 Hz)
78.8
3.23 (br s)
3.2 (dd, 6.5, 10 Hz)
9
50.1
50.3
47.1
48.5
55.8
10
37.2
37.8
36.7
36.8
38.1
11
20.8
20.9
22.9
24.2
68.3
4.26
129.9
5.61 (d, 8.5 Hz)
12
25.3
23.7
124.5
128.6
5.18 (d, 2 Hz)
135.0
6.07 (d, 10 Hz)
13
38.0
37.1
138.2
139.7
143.0
91.9
14
42.9
42.8
41.6
45.1
42.1
42.0
15
27.4
25.1
27.2
36.4
27.9
26.6
16
35.6
35.6
25.6
67.4
27.4
23.9
17
43.0
43.0
46.7
39.5
33.6
46.6
18
48.3
48.3
52.4
62.4
58.0
61.8
38.4
40.9
39.3
41.5
5.16 (br s)
2.11
126.3
5.23 (br s)
4.19 (d, 6.5 Hz)
2.2 (d, 10 Hz)
79.5
δH
54.0
37.5
(d, 11.5 Hz)
19
48.0
2.38 (td, 11, 10,
48.0
20
150.9
151.0
38.1
40.0
39.4
39.4
21
29.8
29.8
30.4
31.8
31.1
32.3
22
40.0
40.0
36.5
36.8
41.3
32.4
23
28.3
0.82 (s)
27.4
0.85 (s)
21.1
0.90 (s)
28.8
0.82 (s)
28.7
24
22.2
0.93 (s)
16.5
0.84 (s)
16.9
0.68 (s)
16.3
1.02 (s)
23.1
5.5 Hz)
2.38 (td, 11, 10,
5.5 Hz)
1.29 (s)
28.3
0.96 (s)
15.6
0.80 (s)
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Table 1. Cont.
Compound 1 in CDCl3
Compound 2 in CDCl3
Compound 3 in DMSO
Compound 4 in MeOD
Compound 5 in CDCl3
Compound 6 in MeOD
#
δC
δH
δC
δH
δC
δH
δC
δH
δC
δH
δC
δH
25
16.0
0.84 (s)
16.2
1.05 (s)
15.1
0.87 (s)
16.4
1.02 (s)
16.8
0.90 (s)
19.4
1.05 (s)
26
15.9
1.03 (s)
16.0
0.83 (s)
16.9
0.76 (s)
18.3
1.10 (s)
18.0
1.26 (s)
18.4
0.98 (s)
27
14.6
0.96 (s)
14.5
0.79 (s)
23.3
1.10 (s)
25.1
1.20 (s)
23.1
1.30 (s)
16.6
1.25 (s)
28
18.0
0.78 (s)
18.0
0.94 (s)
178.6
22.1
0.80 (s)
28.2
1.10 (s)
182.6
-
29
109.3
4.69 (br s), 4.57 (br s)
109.3
4.69 (br s), 4.57 (br s)
16.9
0.82, (d, 6.5 Hz)
17.0
0.84 (d, 6.5 Hz)
17.6
0.90 (d)
18.3
1.05 (d, 7.5 Hz)
30
19.3
1.64
19.3
1.68 (s)
21.1
0.92, (d, 7.0 Hz)
21.1
0.97 (d)
21.4
0.95 (d)
19.6
0.98 (d, 6.0 Hz)
1’
171.0
2’
27.9
2.04 (s)
Table 2. Antiprotozoal activity and cytotoxicity of triterpenoid constituents isolated from the plant K. odora.
Sample
Petroleum ether extract
Chloroform extract
Cmpd. 3
Cmpd. 4
Cmpd. 5
Cmpd. 6
Chloroquine
Miltefosine
Benznidazole
Suramine
Tamoxifen
P. falciparum
IC50
SI
8.6 ± 2.1
2.3
8.2 ± 1.9
4
29.7 ± 5.9
<1
9.7 ± 3.2
> 6.6
23.9 ± 5.7
2.7
>64.0
0.3 ± 0.05
-
L. infantum
IC50
SI
6.8 ± 1.6
3
8.1 ± 2.3
4
7.4 ±1.9
1.5
9.3 ± 2.2
> 6.9
3.2 ± 0.9
> 20
>64.0
-
T. cruzi
IC50
5.7 ± 1.6
31.0 ± 4.9
8.8 ± 2.3
9.9 ± 2.6
8.1 ± 1.8
>64.0
T. brucei
SI
3.4
1.3
> 6.5
> 7.9
-
IC50
0.5 ± 0.1
0.5 ± 0.1
2.2 ± 0.6
2.3 ± 0.4
7.8 ± 1.8
40.9 ± 8.1
SI
39
63
5.2
> 27.8
> 8.2
-
MRC-5
IC50
19.4 ± 3.4
31.3 ± 4.2
11.4 ± 2.1
>64.0
>64.0
>64.0
10.4 ± 2.1
1.9 ± 0.3
0.03 ± 0.01
11.4 ± 3.2
IC50 μg/mL for extracts; µM for pure compounds.
Molecules 2013, 18
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These divergent results may be attributed to the diversity of parasite strains, parasite load, stages of
parasite life cycle or be related to differences in the experimental conditions [30]. Ursolic acid lactone
6 was reported to have activity against L. donovani (IC50 191.52 µM) without cytotoxicity towards
peripheral blood mononuclear cells [31]. In our opinion, this result was misinterpreted by the authors
since the standard miltefosine under the same experimental conditions showed an IC50 of 9.31 µM [31];
hence, the compound should be considered as inactive. To the best of our knowledge, this is the first
report on the antiprotozoal evaluation of compounds 4, 5 and 6 against P. falciparum, L. infantum,
T. cruzi, and T. brucei.
3. Experimental
3.1. General
The 1D-NMR and 2D-NMR spectra were recorded on a Bruker AMX-400 spectrometer with
tetramethylsilane (TMS) as an internal standard. Thin layer chromatography (TLC) was performed on
precoated silicagel F254 plates (E. Merck, Darmstadt, Germany). All chemicals were purchased from
Sigma Chemical Company (St. Louis, MO, USA).
3.2. Plant Materials
The plant Kleinia odora was collected from the South of Saudi Arabia in February 2011 and
identified at the Pharmacognosy Department, College of Pharmacy, King Saud University. A voucher
specimen was deposited at the Pharmacognosy Department, College of Pharmacy, King Saud
University (Voucher # P-15129).
3.3. Extraction and Isolation
The air-dried and powdered aerial part of K. odora (1 kg) was extracted by maceration with 70%
ethanol (4 × 2 L) at room temperature. The combined obtained ethanolic extract was filtered and
evaporated at 40 °C using a rotary evaporator. The dried ethanolic extract (50 g) was subsequently
redissolved in water (200 mL) and partitioned successively for several times with petroleum ether
(3 × 200 mL), chloroform (3 × 200 mL) and n-butanol (3 × 200 mL) to provide the corresponding
extracts. The petroleum ether extract (6 g) was subjected to column chromatography on pre-packed
silica gel columns (35 mm i.d. × 350 mm) to give nine fractions. The elution was performed with a
gradient of hexane-ethyl acetate (10:1) to pure ethyl acetate. TLC analysis of the fractions with
anisaldehyde/sulfuric acid and heating at 100 °C allowed the analysis of the nine fractions. Fraction 1
was further purified by using a chromatotron (Harrison Research, Palo Alto, CA, USA) (silica gel 60
F254, layer thickness 2 mm, Merck, Darmstadt, Germany) to give compound 2 (27 mg). The elution
was performed with a mobile phase composed of hexane–dichloromethane (60:40, v/v). The
chloroform extract (4 g) was applied on a silica gel column and eluted with a gradient of
dichloromethane-ethyl acetate (9:1) to pure ethyl acetate to give seven fractions. Fraction 1 was
rechromatographed on a silica gel column (dichloromethane-acetone, 9:1) and on a RP-18 column
(MeOH–H2O, 90:10) to produce compound 4 (48 mg) and compound 6 (21 mg). Direct crystallization of
fraction 2 eluted by 30% acetone-dichlormethane gave compound 3 (35 mg). Fraction 5 was purified on a
Molecules 2013, 18
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RP-18 column (MeOH–H2O, 90:10) to give compound 5 (8 mg). Fraction 7 (80 mg) was subjected to
RP-18 column chromatography with MeOH–H2O (90:10) as a solvent to produce compound 1 (20 mg).
Epilupeol (1). Amorphous powder; m.p. 205 °C; NMR (CDCl3): see Table 1.
Lupeol acetate (2). White crystals; m.p. 215–218 °C; NMR (DMSO): see Table 1.
Ursolic acid (3). White powder; m.p. 236 °C; NMR (DMSO): see Table 1.
Urs-12-ene-3β,16β-diol (4). Solid; m.p. 221 °C; NMR (MeOD): see Table 1.
3β,11α-Dihydroxyurs-12-ene (5). Amorphous powder; NMR (CDCl3): see Table 1.
3-Hydroxy-13,28-epoxyurs-11-en-28-one (6, ursolic acid lactone). White powder; m.p. 268 °C; NMR
(MeOD): see Table 1.
3.4. Antiprotozoal Assay
3.4.1. Standard Drugs
For the different tests, appropriate reference drugs were used as positive control: tamoxifen for
MRC-5, chloroquine for P. falciparum, miltefosine for L. infantum, benznidazole for T. cruzi and
suramin for T. brucei. All reference drugs were either obtained from the fine chemical supplier
Sigma-Aldrich, Taufkirchen, Germany (tamoxifen, suramin) or from WHO-TDR, Geneva, Switzerland
(chloroquine, miltefosine, benznidazole).
3.4.2. Biological Assays
The integrated panel of microbial screens and standard screening methodologies were adopted as
previously described [32]. All assays were performed in triplicate at the Laboratory of Microbiology,
Parasitology and Hygiene at the University of Antwerp (Belgium). Plant extracts were tested at 5
concentrations (64, 16, 4, 1 and 0.25 μg/mL) to establish a full dose-titration and determination of the
IC50 (inhibitory concentration 50%). The final in-test concentration of DMSO did not exceed 0.5%,
which is known not to interfere with the different assays [32]. Selectivity of activity was assessed by
simultaneous evaluation of cytotoxicity on a fibroblast (MRC-5) cell line. The criterion for activity
was an IC50 <10 μg/mL and a selectivity index (SI) of > 4.
3.4.3. Antiplasmodial Activity
Chloroquine-resistant P. falciparum K 1-strain was cultured in human erythrocytes O+ at 37 °C
under a low oxygen atmosphere (3% O2, 4% CO2, and 93% N2) in RPMI-1640, supplemented with
10% human serum. Infected human red blood cells (200 μL, 1% parasitaemia, 2% haematocrit) were
added to each well and incubated for 72 h. After incubation, test plates were frozen at −20 °C. Parasite
multiplication was measured using the Malstat assay, a colorimetric method based on the reduction of
3-acetyl pyridine adenine dinucleotide (APAD) by parasite-specific lactate-dehydrogenase (pLDH) [32,33].
Molecules 2013, 18
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3.4.4. Antileishmanial Activity
L. infantum MHOM/MA(BE)/67 amastigotes were collected from the spleen of an infected donor
hamster and used to infect primary peritoneal mouse macrophages. To determine in vitro
antileishmanial activity, 3 × 104 macrophages were seeded in each well of a 96-well plate. After 2 days
outgrowth, 5 × 105 amastigotes/well, were added and incubated for 2 h at 37 °C. Pre-diluted plant
extracts were subsequently added and the plates were further incubated for 5 days at 37 °C and 5%
CO2. Parasite burdens (mean number of amastigotes/macrophage) were microscopically assessed on
500 cells after Giemsa staining of the testplates, and expressed as a percentage of the blank controls
without plant extract.
3.4.5. Antitrypanosomal Activity
Trypanosoma brucei Squib-427 strain (suramin-sensitive) was cultured at 37 °C and 5% CO2 in
Hirumi-9 medium [34], supplemented with 10% fetal calf serum (FCS). About 1.5 × 104
trypomastigotes/well were added to each well and parasite growth was assessed after 72 h at 37 °C by
adding resazurin [35]. For Chagas disease, T. cruzi Tulahuen CL2 (benznidazole-sensitive) was
maintained on MRC-5 cells in minimal essential medium (MEM) supplemented with 20 mM
3
L-glutamine, 16.5 mM sodium hydrogen carbonate and 5% FCS. In the assay, 4 × 10 MRC-5 cells and
4 × 104 parasites were added to each well and after incubation at 37 °C for 7 days, Parasite growth was
assessed by adding the alpha-galactosidase substrate chlorophenol red alpha-D-galactopyranoside [36].
The color reaction was read at 540 nm after 4 h and absorbance values were expressed as a percentage
of the blank controls.
3.4.6. Cytotoxicity against MRC-5 Cells
MRC-5 SV2 cells were cultivated in MEM, supplemented with L-glutamine (20 mM), 16.5 mM
sodium hydrogen carbonate and 5% FCS. For the assay, 104 MRC-5 cells/well were seeded onto the
test plates containing the pre-diluted sample and incubated at 37 °C and 5% CO2 for 72 h. Cell
viability was assessed fluorimetrically after 4 h of addition of resazurin. Fluorescence was measured
(excitation 550 nm, emission 590 nm) and the results were expressed as % reduction in cell viability
compared to control.
4. Conclusions
Two lupane and four ursane triterpenes were from isolated aerial parts of K. odora and identified.
Ursane type triterpenes from the biologically active chloroform extract were investigated for their
antiprotozoal potential. All were found to have activity against more than one type of the tested
parasites, with exception of compound 6.
Acknowledgments
The authors extend their appreciation to the NPST program by King Saud University for funding
the work through the project number (10-MED1288-02). The authors gratefully acknowledge that
Molecules 2013, 18
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financial support. An Matheeussen and Margot Desmet are acknowledged for performing all the
in vitro assays.
Conflict of Interest
The authors declare no conflict of interest.
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Sample Availability: Samples of the compounds are available from the authors.
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