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Journal of Ethnopharmacology 133 (2011) 345–352
Contents lists available at ScienceDirect
Journal of Ethnopharmacology
journal homepage: www.elsevier.com/locate/jethpharm
From the vasodilator and hypotensive effects of an extract fraction from
Agelanthus dodoneifolius (DC) Danser (Loranthaceae) to the active compound
dodoneine
M. Ouedraogoa,c,1, M. Ruiza,1, E. Vardelleb, H. Carreyreb, J.M. Coustardb, D. Potreaua,
L.L. Sawadogoc, C. Cognarda, F. Becqa, C. Vandebroucka, J. Besconda,∗
aInstitut de Physiologie et Biologie Cellulaires, Université de Poitiers, CNRS/UMR 6187, 40 avenue du Recteur Pineau F-86022 Poitiers Cedex, France
bLaboratoire de Synthèse et Réactivité des Substances Naturelles, Université de Poitiers, CNRS/UMR 6514, 40 avenue du Recteur Pineau, F-86022 Poitiers Cedex, France
cUniversité de Ouagadougou, 03 BP 7021, Ouagadougou 01, Burkina Faso
article info
Article history:
Received 12 May 2010
Received in revised form
23 September 2010
Accepted 2 October 2010
Available online 16 October 2010
Keywords:
Active fraction of Agelanthus dodoneifolius
Rat blood pressure
Hypotensive agent
Smooth muscle relaxation
Dodoneine
abstract
Aim of the study: Effects of the different fractions obtained by partition of ethanolic extract (EE) of Agelan-
thus dodoneifolius through column chromatography were investigated on rat blood pressure and aortic
relaxation and compared to those observed in the presence of crude EE.
Materials and methods: The acute hypotensive activity of EE, fractions and dodoneine, administrated
intravenously, was evaluated in anaesthetized rats using the invasive method of blood pressure recording.
Bioassay-guided fractionation using rat aorta pre-contracted by norepinephrine to monitor the relaxant
activity led to the isolation of dodoneine.
Results: In normotensive rats, injection of EE (0.01–10 mg/kg) produced a dose-dependent decrease in
both systolic and diastolic blood pressure without any significant change in heart rate. In a similar way, the
EE (0.001–3 mg/mL) caused relaxation of rat pre-contracted aorta in a concentration-dependent manner.
Fractionation of the EE afforded 14 fractions, F1–F14, that were tested on rat precontracted aortic rings.
At the concentration level of 1 mg/mL, a maximum relaxation effect was observed for fractions F2–F5.
F4 was the most effective to elicit a concentration-dependent relaxation effect with an ED50 = 160 ±1.1
g/mL (n= 5) and to decreased systolic and diastolic control pressure by 56.9% and 81.6% respectively.
F4 contains most of the dihydropyranone dodoneine, with 93% of the sample mass. Dodoneine separated
from this fraction was also able to decrease both systolic and diastolic arterial pressure by 32.5% and
38.7% at 100 g/kg, respectively.
Conclusion: For the first time, this study demonstrates the hypotensive property of the dodoneine present
in Agelanthus dodoneifolius.
© 2010 Elsevier Ireland Ltd. All rights reserved.
1. Introduction
Hypertension is one of the most common diseases in the
world. As it is a multiparametric pathology, its treatment gener-
ally involves a large panel of drugs. In developing countries where
it also affects a significant part of people (for instance 23% of the
population in Ouagadougou (Burkina Faso), Niankara et al., 2002),
hypertension is usually treated by plant decoctions or extracts
such as infusions of Agelanthus dodoneifolius. These natural prod-
Abbreviations: AE, aqueous extract; DE, dichloromethane extract; EE, ethanolic
extract; EtOAc, ethyl acetate; TLC, thin layer chromatography; DMSO, dimethylsul-
foxide.
∗Corresponding author. Tel.: +33 5 49 45 35 28; fax: +33 5 49 45 40 14.
E-mail address: Jocelyn.Bescond@univ-poitiers.fr (J. Bescond).
1These authors contributed equally to this work.
ucts recognized from the very beginning as an important source
of therapeutically effective medicines are still largely used since
approximately 60% of the present world population relies almost
entirely on plants for medication (Ajaikumar et al., 2005). Because
they contain a number of metabolites, these plants have generally
a wide spectrum of applications. From several decades, one of the
challenges of pharmaceutics is to isolate the active compounds and
to characterize their specific properties.
Agelanthus dodoneifolius (also called “African mistletoe”) from
the Loranthaceae family is one of these medicinal plants used in
African pharmacopeia. Agelanthus dodoneifolius (DC) Danser, the
most widespread specie of the family (Sallé et al., 1987; Boussim
et al., 2004) was shown to contain, tannins, anthracenosides,
anthraquinones, alkaloids, saponins, sterols and triterpenes (Deeni
and Sadiq, 2002; Traore et al., 2004) using simple group reagent
tests. So, it is used in traditional medicine as hypotensive, antispas-
modic, antiparasitic, in the treatment of wound infections, cancer,
0378-8741/$ – see front matter © 2010 Elsevier Ireland Ltd. All rights reserved.
doi:10.1016/j.jep.2010.10.002
346 M. Ouedraogo et al. / Journal of Ethnopharmacology 133 (2011) 345–352
Table 1
Scheme of bioassay-guided fractionation of the ethanolic extract (EE) from Agelanthus dodoneifolius.
cholera, asthma, diabetes and gastrointestinal, gynaecologic and
nervous disorders (Boussim, 2002, for review). It has also been
shown to have larvicidal and molluscidal activities (Cepleanu et al.,
1994). Moreover it was extensively used for treatment of cardio-
vascular diseases (Nacoulma/Ouedraogo, 1996).
Ouedraogo et al. (2005a,b) have shown that the crude aqueous
extract AE and the ethanolic extract EE of Agelanthus dodoneifolius
inhibited acetylcholine-induced bronchoconstriction on rat tra-
chea. It was also reported that the crude aqueous extract AE had
a vasorelaxant effect on rat aorta (Ouedraogo et al., 2005c).
The aim of the present study was (i) to fractionate the EE
of Agelanthus dodoneifolius by column chromatography and iden-
tify the fractions inducing vasorelaxant and hypotensive effects,
(ii) to determine the level of the active principle identified to be
dodoneine and (iii) to estimate its hypotensive property.
2. Materials and methods
2.1. Plant material and extraction
Agelanthus dodoneifolius was collected in the region close to
Ouagadougou (Burkina Faso) in June 2005. The plant was identified
by Prof. Boussim I.J., Taxonomist, Department of Biological Sciences,
University of Ouagadougou. A voucher specimen was deposited
in the herbarium of this institute with the reference no. 002. The
air-dried and powdered plant materials (750 g) were successively
macerated and extracted with CH2Cl2(2 ×2 L), 80% EtOH (2 ×2L)
and H2O(2×2L). Each extract was evaporated under reduce pres-
sure and/or lyophilized to dryness. The extraction afforded (i) 22.5 g
of a dark green gummy material with CH2Cl2(dichloromethane
extract or DE), (ii) then 125 g of ethanolic extract (ethanolic extract
or EE) and finally, (iii) 52.5 g of water extract (aqueous extract or
AE).
A sample of the EE (3 g) was fractionated by column chro-
matography (Acros Organics, Silicagel for column chromatography
0.035–0.070 mm, 60 ˚
A). Weight of silica: 75 g, column: ˚i2.9 cm,
length 30 cm. Eluent volume (400 mL each). The following frac-
tions were obtained: fraction F1: CH2Cl2; fraction F2: CH2Cl2/AcOEt
4/1; fraction F3: CH2Cl2/AcOEt 3/2; fraction F4: CH2Cl2/AcOEt
2/3; fraction F5: CH2Cl2/AcOEt 1/5; fraction F6: AcOEt; fraction
F7: AcOEt/EtOH 4/1; fraction F8: AcOEt/EtOH 3/2; fraction F9:
AcOEt/EtOH 2/3; fraction F10: AcOEt/EtOH 1/4; fraction F11: EtOH;
fraction F12: EtOH/H2O 4/1; fraction F13: EtOH/H2O 3/2; fraction
F14 (3 ×400 mL): EtOH/H2O 2/3, EtOH/H2O 1/3, H2O. Every fraction
was analyzed by TLC (Table 1).
2.2. Apparatus and chromatographic conditions
The chromatographic system (Dionex Ultimate 3000) consisted
of a gradient pump with degas option and gradient mixer, a
UV detector, and a Chromeleon®chromatography workstation
(Dionex Corporation, Sunnyvale, CA, USA). Chromatographic sepa-
rations were achieved on a C18 column (250 mm ×4.6 mm, 120 ˚
A,
Acclaim120, Dionex, USA) associated with a guard column packed
with the same phase. 20 L was injected through a loop injec-
tion valve (Rheodyne). The analyses were performed at 30 ◦C using
isocratic elution (water/acetonitrile 7/3) at 1.6 mL/min and UV
detection at 275 nm.
2.3. Determination of dodoneine
A set of calibrating standards at 0, 28, 55, 139, 277 and 555 mg/L
was prepared from the 1110 mg/L stock solution in acetonitrile.
A five-point calibration curve was constructed in the range of
22–555 mg/L with each batch of samples. The calibration curve was
linear with a correlation coefficient of 0.999 and an intercept value
not statistically different from zero.
The analytical chromatographic conditions were optimized for
the determination of dodoneine in the fractions F1–F14 obtained
by column chromatography of the EE, as describe in Table 1.
2.4. Animals
Wistar rats (250–300 g) were anaesthetized with intraperi-
toneal injection of sodium pentobarbital (30–50 mg/kg) for in vivo
studies, and with chloral hydrate (2 g/kg) for in vitro studies. All ani-
mal handling and procedures strictly conformed to the European
Community Guidelines (EEC Directive of 1986; 86/609/EEC).
2.5. In vivo experiments
Once animals were anaesthetized they were turned to a dorsal
decubitus position on a dissecting table under an overhead lamp
to maintain constant the body temperature. A longitudinal mid-
M. Ouedraogo et al. / Journal of Ethnopharmacology 133 (2011) 345–352 347
Fig. 1. Effects of EE of Agelanthus dodoneifolius on arterial pressure and heart rate in the anaesthetized rat. (A) Typical recording showing hypotensive effect of increasing
concentrations of EE on arterial pressure. (B) Dose-dependent effect of EE on heart rate (empty columns) compared to control (Ctrl, filled column). (C and D) Dose-dependent
effect of EE on diastolic (C) and systolic (D) arterial pressure (empty columns) compared to control (Ctrl, filled column). Data are expressed as mean ±SEM for N=3–4 animal
responses. * and ** indicate significant differences for P< 0.05 and P< 0.01, respectively, between test and control values.
tracheal incision approximately 20 mm long was made to expose
the right jugular vein and both common carotid arteries. The right
jugular vein was catheterized with a polyethylene tube (Biotrol
Diagnostic, Chennevières les Louvres, France) filled with a hep-
arin saline solution (50 UI/mL) containing (in mM, NaCl: 140; KCl:
5.4; CaCl2: 2.16; MgCl2: 0.24; NaHCO3: 11.9; glucose: 10; pH 7.4)
in order to administrate drugs. The catheterism of the left carotid
artery was performed by the introduction of a polyethylene tube
(internal diameter 0.86 mm, external diameter 1.52 mm, Biotrol
Diagnostic) filled with the same solution and connected to the
reusable blood pressure transducer (MLT0380, Powerlab, ADInstru-
ments). The transducer signal was amplified with a bridge amplifier
(ML301, Powerlab) connected to and controlled by a Powerlab.
From the blood pressure signal, the systolic and diastolic pressure
(mm Hg), as well as heart rate (beatsmin−1, bpm) were monitored
continuously during the experiment and calculated internally in
the Powerlab using the computed input feature of Chart software
(Chartv5.2, Powerlab). The parameters were equilibrated for at
least 30 min before starting the tests (Gilani and Aftab, 1992).
2.6. In vitro experiments
After the rat was deeply anaesthetized with chloral hydrate, its
chest was open by thoracotomy and the heart and the descending
thoracic aorta were quickly removed; then the aorta was placed
into Krebs solution containing (in mM): 120 NaCl, 4.7 KCl, 2.5 CaCl2,
1.2 MgCl2, 1.2 KH2PO4, 15 NaHCO3, 11.1 d-glucose, pH 7.4. The
aorta cleaned from connective tissues was cut into rings 3 mm in
length which were mounted between a fixed clamp and an ITI-25
isometric force transducer (Emka Technologies, Paris, France) in a
water-jacketed 5 mL organ bath containing oxygenated (95% O2and
5% CO2) Krebs solution (Robert et al., 2004, 2005). The rings were
rinsed three times and equilibrated in Krebs solution for 1 h and the
basal tension was monitored and adjusted to 2 g. Norepinephrine
348 M. Ouedraogo et al. / Journal of Ethnopharmacology 133 (2011) 345–352
Fig. 2. Effects of EE of Agelanthus dodoneifolius on aortic ring relaxation pre-
contracted by 1 M norepinephrine (NE). (A) Typical tracing showing the
concentration-dependent vasodilator effect of increasing concentrations of EE. (B)
Concentration–response curve for the relaxation induced by EE. Values indicate
the percentage of the residual contraction (normalized from the steady-state NE-
induced contraction value) and are plotted as a function of the concentration (g/mL)
of EE expressed as a logarithmic function. Data are mean ±SEM for n=5, N=3.
(NE; 1 M) was applied to induce a sustained contractile response
which was equilibrated for 30 min before cumulative addition of
increased concentrations of drugs.
2.7. Drugs and chemical reagents
Acetonitrile and water HPLC grade, chloral hydrate, nore-
pinephrine, heparin, indomethacin and l-NAME were purchased
from Sigma (Illkirch, France), and sodium pentobarbital from Sanofi
(Libourne, France).
The crude EE of Agelanthus dodoneifolius was dissolved in 10%
ethanol. Norepinephrine and the fractions F1–F14 of the EE were
dissolved in dimethylsulfoxide (DMSO). All the final solutions were
freshly prepared and used the day of experiment.
2.8. Data analysis and statistics
Blood systolic and diastolic pressures and heart rate changes
were expressed as percentage of control measurement recorded
after complete equilibration and just before injection of drugs. The
relaxant effect of the EE and its different fractions was expressed
as contraction percentage of the NE-constricted aorta rings.
Dose–response curves obtained for the EE and fraction 4 (F4)
were analyzed by a sigmoid non-linear regression method using
Graph Pad Prism software (San Diego, CA), allowing to calculate the
Fig. 3. (A) Vasorelaxant effects of fractions F1–F14 (1 mg/mL) obtained from EE of
Agelanthus dodoneifolius by column chromatography, on isolated rat aortic ring mus-
cle pre-contracted by 1 M NE. Bar graph represents the percentage of relaxation of
the steady state control contraction induced by 1 M NE, for each fraction of EE indi-
cated in abscissa. Note that the last column corresponds to the relaxation induced
by the maximal concentration of DMSO used to dissolve EE fractions. Values are
mean ±SEM from n= 4–8 experiments indicated in brackets (2< N< 3). (B) Effects of
F4 separated from EE of Agelanthus dodoneifolius by column chromatography on rat
smooth muscle contraction. Cumulative dose–response curves F4 (䊉) on isolated rat
aortic ring pre-contracted by 1 M NE, in the presence of F4 plus l-NAME, 100 M
() or in the presence of F4 plus indomethacin, 10 M(). Each point represents
the mean ±SEM from n= 3–5 rings; N=3.
concentration (g/mL) required to produce half maximum relaxation
of the NE-induced contraction (IC50).
Results were expressed as mean ±SEM of n observations. Sets
of data were compared with analysis of variance (One Way ANOVA,
Microcal Origin 5.0 software, Northampton, USA) or a Student’s
t-test. Differences were considered statistically significant when
P< 0.05, *P< 0.05, **P< 0.0l, ***P< 0.00l (n= experiment number;
N= animal number).
3. Results
We firstly tested the effect of the EE of Agelanthus dodoneifolius
on the basal blood pressure measured in normal anesthetized rat.
The successive intravenous injections of the EE (0.01, 0.1, 1 and
10 mg/kg respectively) produced an almost immediate and cumu-
lative reduction in systolic and diastolic blood pressure (Fig. 1A)
which was fully reversible within 6 min after the maximal response
was obtained. Control experiments with isotonic solutions with-
out drugs were performed in order to verify the absence of any
M. Ouedraogo et al. / Journal of Ethnopharmacology 133 (2011) 345–352 349
Fig. 4. Effects of F4 (from Agelanthus dodoneifolius) on blood pressure in the anaesthetized rat. (A) Typical recording showing the hypotensive effect of 1 mg/kg F4 (a) on
arterial pressure in anaesthetized rats. (Ba and Bb) Effect of F4 (1 mg/kg) on respective systolic and diastolic arterial pressure (empty columns) compared to control (Ctrl,
filled columns). Data are expressed as mean ±SEM for N=3 animal responses. ***Indicates significant differences for P< 0.001, between effect and control values.
effect on pressure following increased blood volume by these suc-
cessive injections. Heart rate following the EE injections did not
differ significantly (the maximum variation observed was close to
9%; Fig. 1B) whereas systolic and diastolic pressure values were
dose-dependently decreased as shown in Fig. 1C and D. At the max-
imal dose of the crude EE (10 mg/kg) injected, average systolic and
diastolic blood pressure were decreased significantly by 35.5 ±8.3
and 55.2 ±12.2% (N= 4), respectively.
Then, we performed experiments on rat aortic rings mounted
in an organ bath apparatus and measured their muscular activ-
ity. The NE-induced contraction reached a maximum, indicated
by a plateau phase, and then declined slowly during 4 h. The
vehicle DMSO (used at maximum 0.1%) had no effect on the
maximum response (data not shown). We applied the EE via cumu-
lative application into the organ bath (0.01–3 mg/mL). Clearly, EE
induced a concentration-dependent relaxation of rat aortic ring
pre-constricted by 1 MNE(Fig. 2A) that began at 10 g/mL and
was complete for 3 mg/mL. Half-maximal relaxation value ED50 for
the EE of 246 ±2g/mL was determined from five different aortic
rings (Fig. 2B).
The activities of the 14 fractions of the EE were tested for
their aortic relaxation properties (Fig. 3A). At the concentration
level of 1 mg of extract per mL, fractions F2–F5 led to a relaxation
effect higher than 70% of the steady state NE-induced contrac-
tion. Control experiments have shown that the DMSO used to
dissolve the fractions had no significant specific effect (Fig. 3A,
last column). The most active fraction, namely F4, elicits a dose-
dependent relaxation with an ED50 value of 160 ±1.1 g/mL (n=5;
Fig. 3B, filled circles). Pre-incubation of the rings with 100 MN
G-
nitro-l-arginine methyl ester (l-NAME), an inhibitor of nitric oxide
synthethase (NOS) before exposure to F4, did not prevent the relax-
ation (Fig. 3B, filled triangles). A similar result was obtained with
10 M indomethacin, an inhibitor of cyclo-oxygenase (Fig. 3B, filled
squares). These results suggest that, in our experimental condi-
tions, the relaxation of rat aortic smooth muscle cells by F4 was
independent of the NO synthetase and cyclo-oxygenase pathways.
Regarding to the most active effect of the fraction F4 on vascu-
lar reactivity, the blood pressure was recorded before and after the
injection of this fraction on normal anesthetized rat. As shown in
Fig. 4A, this fraction induced a strong and fast decrease of both sys-
tolic and diastolic blood pressure, without any significant change
in heart rate (307 ±12 bpm in control; 310 ±51 at maximal effect
for F4 on blood pressure and 321 ±25 after 10 min of F4 applica-
tion, N= 3). The maximal decrease in blood pressure was obtained
2 min after the injection of F4, followed by a progressive returned
to basal control values within 10 min. Fig. 4B shows that systolic
pressure value was decreased by 35.7% and 56.9% for F4 at 0.01 and
1 mg/kg, respectively. Fig. 4C shows that diastolic pressure values
were decreased by 48.2% and 81.6% with the fraction F4, respec-
tively at 0.01 and 1 mg/kg. Control experiments were performed to
verify that the DMSO used at maximum concentration of 0.1% has
no effect (data not shown).
Concomitantly, a TLC analysis of the methanolic extract
of the whole plant indicated the presence of a main com-
350 M. Ouedraogo et al. / Journal of Ethnopharmacology 133 (2011) 345–352
Fig. 5. Effects of dodoneine on arterial pressure and heart rate in the anaesthetized rat. (A) Typical recording showing hypotensive effect of increasing concentrations of
dodoneine on arterial pressure. (Ba and Bb) Dose-dependent effect of dodoneine on systolic (Ba) and diastolic (Bb) arterial pressure. Bc: Dose-dependent effect of dodoneine
on heart rate. Data are expressed as mean ±SEM for 3 < N< 4 animal responses. *Indicates significant differences for P< 0.05.
pound whose structure was determined from spectroscopic
and X-ray crystallographic analysis. A dihydropyranone, named
dodoneine or (R)-6-[(S)-2-hydroxy-4-(4-hydroxyphanyl)butyl]-
5,6-dihydropyran-2-one was isolated (Ouedraogo et al., 2007).
The bioassay-guided fractionation of the ethanolic extract (EE) is
reported Table 1. Dodoneine was only detected in the fractions
F2–F6 by TLC and determined by HPLC (Table 2). In the fraction
F4, dodoneine represents 93% of the weight sample.
As dodoneine induced a concentration-dependent aortic relax-
ation effect with an IC50 value of 81.4 ±0.9 M(Ouedraogo et al.,
2007), we recorded blood pressure on normal anesthetized rat
before and after the injection of dodoneine, in order to check
any effect on the whole body. As shown in Fig. 5A, dodoneine
induced a dose-dependent decrease of both systolic and diastolic
pressure. The systolic pressure was decreased by 17.4%, 19.8% and
32.5% by dodoneine at 0.01 g/kg, 1 g/kg and 100 g/kg con-
centrations, respectively (Fig. 5Ba). The diastolic pressure was
also decreased by 17.7% by dodoneine at 0.01 g/kg and signif-
icantly reduced by 27.4% and 38.7% at 1 g/kg and 100 g/kg,
respectively (Fig. 5Bb). Any significant change on heart rate was
M. Ouedraogo et al. / Journal of Ethnopharmacology 133 (2011) 345–352 351
observed (+9%, +0.006%, and −6.5% at the same concentrations)
(Fig. 5Bc).
4. Discussion
As suggested by the traditherapeutic use of Agelanthus
dodoneifolius in cardiovascular diseases, our results clearly con-
firm that the EE of the plant has both vasorelaxant and hypotensive
effects on rat cardiovascular system. In this study, we have been
able to isolate a fraction F4 from all the fractions of EE of Agelan-
thus dodoneifolius inducing the vasorelaxant effects and to observe
that F4 is the fraction with the highest level of this bioactive com-
pound, named dodoneine. In this paper and for the first time, the
hypotensive property of dodoneine has been demonstrated.
From previous results (Ouedraogo et al., 2005a,b), we have
already shown a bronchorelaxant effect of EE and AE of Agelan-
thus dodoneifolius on rat trachea precontracted by high potassium
solution or by acetylcholine. The vasodilatatory activity of Agelan-
thus dodoneifolius was also reported from experiments with AE of
the plant (Ouedraogo et al., 2005c) strengthening the idea that it
contains a compound with specific vasodilator and hypotensive
activity which would be worth to be isolated and identified. The
present results reveal that EE has also a significant hypotensive
effect on rat arterial blood pressure, and induces a concentration-
dependent relaxation of rat aortic rings, so that EE of Agelanthus
dodoneifolius has been considered to be a good candidate for the
research of a bioactive compound via chemical separation by chro-
matography.
The 14 fractions separated from the EE were tested on precon-
tracted aortic rings. A vasorelaxant effect similar to that observed
with the crude extract EE was obtained with fractions F2–F5, with
a maximum activity for fraction F4 (1 mg/mL). From data reported
in Fig. 3, F4 induces a relaxation effect higher than 100%, which
is confirmed from the dose response curve plotted in Fig. 4A. This
suggests that compound(s) contained in this fraction should have
their own effect on basal tension, which remains to be investigated
and elucidated.
It has been shown that the vasodilatory activity of the crude
AE of Agelanthus dodoneifolius could depend on nitric oxide (NO)
released from endothelium (Ouedraogo et al., 2005c), which is one
of the most important vasorelaxing mechanisms (Palmer et al.,
1987). Interestingly, our results show that the relaxing effect of F4
was neither affected in the presence of the NO synthetase inhibitor,
l-NAME, nor affected in the presence of the cyclo-oxygenase (COX)
inhibitor, indomethacin, suggesting that this relaxing effect is not
mediated by NO and COX metabolites, but probably by another
mechanism which remains to be investigated. Our results also show
that F4 decreases the systolic and diastolic blood pressure more
efficiently than the crude EE, confirming that the compound(s) con-
tained in EE of Agelanthus dodoneifolius is (are) contained in F4 (and
also fractions F2, F3 and F5).
The preponderant bioactive compound was identified as a dihy-
dropyranone, named dodoneine, with a vasorelaxant effect on
preconstricted rat aortic rings (Ouedraogo et al., 2007). The ana-
lytical studies by TLC and HPLC show that the dodoneine is mainly
Table 2
HPLC determination of dodoneine in the 2–6th fractions.a
Fraction F2 F3 F4 F5 F6
Mass sample (mg) 11.2 12 12.9 11.9 13.6
Quantification of dodoneine (mg) 0.04 1.38 11.99 5.55 0.55
Mass (%) – 12 93 47 0.4
aIn F1 no dodoneine was detected because of a too short elution time. In fractions
F7, F8 and further, polar compounds were eluted and dodonein was not detected by
TLC or HPLC where a more complex pattern was then observed.
present in F4, and to a lesser level, in F2, F3 and F5, in agreement
with their decreasing vasorelaxant effect observed on rat aortic
rings.
The vasorelaxant effect of the fraction F4 on aortic rings has
been confirmed by the observation of a hypotensive effect on anes-
thetized rats. In the same manner, our results show that the isolated
vasorelaxing compound dodoneine is able to decrease both systolic
and diastolic carotidal blood pressure by about 35% at the 100 g/kg
dose, without any significant effect on heart rate.
These results demonstrate clearly that dodoneine induces a
hypotensive effect. However this effect is lower than one observed
with the fraction F4, which contains 93% of dodoneine and 7% of
non-identified compounds. We cannot exclude that the unidenti-
fied compounds may have hypotensive effects by their own or a
potentializing effect on dodoneine activity. Dodoneine is probably
the main compound but not the only one causing the hypoten-
sive effect observed for the fraction F4. Moreover, such a decrease
demonstrating the hypotensive effect of dodoneine following an
acute administration on anaesthetized rats has also been observed
when the blood pressure has been measured after a chronic treat-
ment in a preliminary pharmacokinetic study.
5. Conclusion
We have demonstrated that the fractions F1–F14 of the EE of
Agelanthus dodoneifolius exert a vasorelaxant activity on rat aortic
rings in connexion with the presence of the isolated dihydropyra-
none dodoneine. The fraction F4 that contains 93% of dodoneine
have the most active relaxing effect and is effective to depress
the blood pressure recorded on anesthetized rats. Our results also
show that dodoneine which has been characterized to relax pre-
constricted aortic rings with half-maximal relaxation IC50 value of
81.4 ±0.9 M(Ouedraogo et al., 2007) induces an acute and chronic
hypotensive response on anaesthetized and vigil rats, respectively.
Then, we have identified for the first time that dodoneine can be one
of the major hypotensive compounds of Agelanthus dodoneifolius,in
agreement with the use of the plant decoction in traditional African
medicine. However, because of some fractions without dodoneine
have relaxing properties on aortic rings, further investigations are
needed to fully characterize the extracted material.
Acknowledgements
This work was supported by grants from the “Agence Univer-
sitaire de la Francophonie”, AUF (fellowships to M. Ouedraogo),
the “Université de Poitiers” (ACI 2006) and the “Centre National
de la Recherche Scientifique”. The authors wish to thank Danièle
Gauffreau for skilled technical assistance.
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