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Corresponding author: Mei-Jung Chen, Ph.D., Department of Biomedical Engineering, School of Health, Ming Chuan University, No. 5,
De-Ming Road, Gui-Shan Taoyuan 333, Taiwan, ROC. Tel: +886-2-28824564 ext. 3657, Fax: +886-2-28213938, E-mail: meijungchen@
gmail.com
Received: November 3, 2010; Revised: January 31, 2011; Accepted: February 17, 2011.
2012 by The Chinese Physiological Society and Airiti Press Inc. ISSN : 0304-4920. http://www.cps.org.tw
Chinese Journal of Physiology 55(1): xxx-xxx, 2012 1
DOI: 10.4077/CJP.2012.AMM104
Attenuation of the Extract from Moringa
Oleifera on Monocrotaline-Induced
Pulmonary Hypertension in Rats
Kang-Hua Chen1, 2, Yi-Jui Chen3, 4, Chao-Hsun Yang5, Kuo-Wei Liu6,
Junn-Liang Chang7, 8, Shwu-Fen Pan9, Tzer-Bin Lin10, and Mei-Jung Chen8
1Department of Surgery, Keelung Hospital, Department of Health, Executive Yuan, Keelung
2Department of Nursing, Ching Kuo Institute of Management and Health, Keelung
3Department of Pharmacy, Min-Sheng General Hospital, Taoyuan
4Department of Nursing, Cardinal Tien College of Healthcare and Management, New Taipei City
5Department of Cosmetic Science, College of Science, Providence University, Taichung
6Department of Electronic Engineering, School of Information Technology, Ming Chuan University
7Department of Pathology and Laboratory Medicine, Taoyuan Armed Forces General Hospital
8Department of Biomedical Engineering
9Department of Biotechnology, School of Health, Ming Chuan University, Taoyuan
10Department of Physiology, School of Medicine, China Medical University, Taichung
Taiwan, Republic of China
Abstract
The purpose of this study was to determine the effects of an extract from Moringa oleifera (MO) on
the development of monocrotaline (MCT)-induced pulmonary hypertension (PH) in Wistar rats. An
ethanol extraction was performed on dried MO leaves, and HPLC analysis identified niaziridin and niazirin
in the extract. PH was induced with a single subcutaneous injection of MCT (60 mg/kg) which resulted in
increases in pulmonary arterial blood pressure (Ppa) and in thickening of the pulmonary arterial medial
layer in the rats. Three weeks after induction, acute administration of the MO extract to the rats decreased
Ppa in a dose-dependent manner that reached statistical significance at a dose of 4.5 mg of freeze-dried
extract per kg body weight. The reduction in Ppa suggested that the extract directly relaxed the pulmonary
arteries. To assay the effects of chronic administration of the MO extract on PH, control, MCT and
MCT+MO groups were designated. Rats in the control group received a saline injection; the MCT and
MCT+MO groups received MCT to induce PH. During the third week after MCT treatment, the MCT+MO
group received daily i.p. injections of the MO extract (4.5 mg of freeze-dried extract/kg of body weight).
Compared to the control group, the MCT group had higher Ppa and thicker medial layers in the pulmonary
arteries. Chronic treatments with the MO extract reversed the MCT-induced changes. Additionally, the
MCT group had a significant elevation in superoxide dismutase activity when normalized by the MO extract
treatments. In conclusion, the MO extract successfully attenuated the development of PH via direct
vasodilatation and a potential increase in antioxidant activity.
Key Words: pulmonary hypertension, Moringa oleifera, monocrotaline, superoxide dismutase
Introduction
Moringa oleifera (MO) belongs to the species
Moringaceae. MO contains several phytochemicals
some of which are of high interest for their medicinal
value. The leaves of MO contain nitrile glycosides
2Chen, Chen, Yang, Liu, Chang, Pan, Lin and Chen
such as niazirin and niazirinin, and mustard oil glyco-
sides such as 4-[(4'-O-acetyl-alpha-L-rhamnosyloxy)
benzyl] isothiocyanate, niaziminin A, and niaziminin
B (5). These glycosides are reported to have hypoten-
sive (5) and antioxidant activities (9). Animal studies
have shown that administration of an extract from
MO for two weeks elevates the level of glutathione
(GSH) in the liver (7) and prevents acetaminophen-
induced liver injury (7). Niaziridin, a nitrile glycoside,
is a bioenhancer for drugs and nutrients, including vi-
tamins A and C (15). Clinically, co-administration of
niaziridin is useful for reducing drug toxicities. There-
fore, in this study we sought to determine the medici-
nal properties of the MO extract.
Pulmonary hypertension (PH), a severe and life-
threatening disease in humans, is characterized by a
significant increase in pulmonary arterial blood pres-
sure (Ppa). To investigate this ailment, animal models
of PH induced by chronic hypoxia exposure (23) or
monocrotaline (MCT) administration (18) have been
established. MCT is a pyrrolizidine alkaloid that is
metabolized in the liver producing a toxic metabolite.
Pulmonary endothelial injury is evident within one
week of MCT administration (11, 12). This pathologic
lesion induces proliferation of smooth muscle cells in
the pulmonary arterial tree (12). Remodeling is the
critical step in the development of PH (12) as smooth
muscle proliferation increases the resistance in the
pulmonary circulation to elevate Ppa (12). Ppa is sig-
nificantly increased two weeks after MCT treatment
and is more severe three weeks post-MCT (2). Pro-
longed elevation of Ppa leads to compensatory right
ventricular hypertrophy (16).
Analysis of lung tissue homogenate has shown
that reactive oxygen species contribute to the de-
velopment of PH (2, 3). Reducing the production of
reactive oxygen species, either in the early or late pe-
riod of MCT-induced PH, successfully attenuates the
development of PH (2, 3). This effect reflects the fact
that oxygen radical scavengers are effective either in
the prevention or in the treatment of PH. The major
consideration of the clinical treatment of PH shall
be in vasodilation. Many of the vasodilators that are
useful for systemic hypertension work poorly for PH.
Inhalation of nitric oxide gas is a common clinical
therapy for PH, but tolerance by patients is poorly
(20). PH is not well understood and is not easily de-
tected or treated. Therefore, one of the purposes of
this study is to find a useful treatment for PH.
Considering the role of reactive oxygen species
in enhancing PH and both the antioxidant and va-
sodilatory properties of the MO extract (7, 9), we hy-
pothesized that the MO extract could reverse the
development of PH. In this study, we examined the
effects of an MO extract on MCT-induced PH. Our
results suggest that the MO extract attenuates PH in
rats via an elevation in antioxidant activity. As far as
we are aware of, this report is the first to demonstrate
the pharmacological benefits of the MO extract in
PH.
Materials and Methods
MO Extract
The extract was prepared by Dr. Chao-HsunYang
of Providence University in Taichung, Taiwan. In
brief, fresh leaves of MO were collected from Nan-
tou, Taiwan. Soon after collection, the leaves were
freeze-dried, ground into powder, and stored at -18°C
until further use. The bioactive components of the
herbal powder were then isolated by hexane extraction
(powder:solvent = 1:2 w/v) with constant shaking (50
rpm) at room temperature overnight. The extract was
filtered, and the residue was suspended in hexane to
repeat the extraction process. The filtered fluids were
mixed well and were concentrated under vacuum at
50°C. The concentrate was then freeze-dried as a
powder form and stored at -18°C. Before usage, the
extract was dissolved in ethanol (stock solution was
3 g freeze-dried MO extract/100 ml ethanol). The
working solution was further diluted with double-
distilled H2O.
High Performance Liquid Chromatography (HPLC)
The compounds in the extract from MO were
determined by HPLC (Agilent 1100 series, USA)
using a pre-packed RT 250-4.6 MIGHTYSIL RP-18
GP 5 mm column (4.6 × 250 nm, Kanto Chemical,
Tokyo, Japan) and a 220-nm UV detector. The mobile
phase, composed of methanol:sodium dihydrogen
phosphate-acetic acid buffer (0.1 M, pH 3.8; 20:80),
was used as the eluant at a flow rate of 1.0 ml/min.
Animal Preparation
All the animals were cared for in accordance
with the Guide for the Care and Use of Laboratory
Animals (1996, published by National Academy Press,
2101 Constitution Ave. NW, Washington, DC 20055,
U.S.A.), and experiments were approved by the
Laboratory Animal Care Committee of the School of
Health, Ming Chuan University, and by the Taiwan
Council on Animal Care. We obtained the experi-
mental animals from the animal center of National
Taiwan University.
The schedule of acute treatments and functional
assays is depicted in Fig. 1A. To understand the acute
vasodilatory effects of the MO extract on PH, 6-
week-old male Wistar rats were divided into two
groups: control (n = 26) and MCT (n = 22). Rats in
Moringa Oleifera and Pulmonary Hypertension 3
the control group received a saline injection. For the
MCT group, one bolus of MCT (60 mg/kg) was given
subcutaneously to each rat to induce PH. Neither
activity nor food was restricted in either group of rats.
Various doses of the MO extract were administered
3 weeks following MCT treatment to determine its
acute effects on Ppa.
The schedule of chronic animal treatments and
functional evaluation is depicted in Fig. 1B. To ex-
amine the chronic effects of the MO extract on the de-
velopment of PH, 6-week-old male Wistar rats were
divided into three groups: control (n = 7), MCT (n =
7) and MCT+MO (n = 8). Rats in the control group
each received a saline injection. Rats in the MCT and
MCT+MO groups each received a subcutaneous MCT
injection (60 mg/kg). Rats in the MCT+MO group
received daily i.p. administrations of the MO extract
(4.5 mg of freeze-dried MO extraction/kg) on days
14-20 following MCT injection. All rats were freely
mobile and fed ad libitum. Functional studies were
carried out when the rats were 9 weeks old.
Functional Studies
Acute Vasodilatory Effects of the MO Extract on PH
Ppa was used as the index for PH. Measurements
of Ppa and systemic hemodynamics were carried out
3 weeks after the MCT or saline treatment. Rats in the
control group were monitored for the same period of
time as the MCT group. On the day of the measure-
ments, rats were anesthetized with urethane (1.2 g/kg,
i.p.). After insertion of an endotracheal cannula and
a femoral arterial catheter, a saline-filled catheter
was introduced into the right jugular vein and then ad-
vanced to the right atrium, right ventricle, and finally
to the pulmonary artery. The catheter monitored
acute changes in Ppa. Ppa was measured with a Grass
pressure transducer (P23XL, Grass technologies,
Rhode Island, USA), with its diaphragm located at the
level of the heart, and Ppa was recorded on a Biopac
System (MP35, Biopac, Goleta, CA, USA) (Fig. 2).
Mean Ppa was further calculated according to the
following formula: diastolic pressure + 1/3 pulse
pressure. The systemic mean blood pressure and
heart rate were measured through the right femoral
arterial catheter with a Grass pressure transducer and
Biopac MP35 System recorder, as described for Ppa
measurement and recording. The measurements were
collected when values stabilized after the surgical
procedures. After recording the baseline hemody-
Fig. 1. Time schedules of treatments with the MO extract for analyzing acute and chronic effects of the extract on MCT-induced
pulmonary hypertension (PH). (A) 6-week-old rats in the control and monocrotaline (MCT) groups received saline or an MCT
injection on day 0. Functional studies to test the vasodilatory effects of an extract from moringa olifera (MO) were carried
out on day 21. (B) The control, MCT and MCT+MO groups were designed to analyze the chronic effects of the MO extract on
MCT-induced PH. The injection of saline in the control group, or MCT in the MCT and MCT+MO groups, was carried out
on day 0. The MO extract was given to the MCT+MO group from day 14 to day 20.
(A) Acute effects of the MO extraction on PH
(B) Chronic effects of the MO extract on PH
Groups
Control
MCT
Animal preparation Functional studies
To collect Ppa data and
tissue samples for
morphological
examination and
analysis of SOD activity
071421
MCT+MO
MO extract
MCT treatment
MCT treatment
Saline injection
Groups
Control
MCT
Animal preparation Functional studies
Saline injection
MCT treatment
To test the Ppa responses
to the incremental doses of
MO
071421
Time (days)
Time (days)
4Chen, Chen, Yang, Liu, Chang, Pan, Lin and Chen
namic parameters and the mean Ppa, the effects of
incremental doses of the MO extract (1.5, 4.5 and
15.0 mg of freeze-dried MO extract/kg, i.v.) were
then studied. Each animal received two different
doses. The second dose was always higher than the
first one and was administered at least one hour after
all parameters had recovered to their initial level.
Chronic Effects of the MO Extract on PH
To evaluate the chronic effects of the MO ex-
tract on PH, three weeks after the MCT treatment, we
measured Ppa, conducted morphologic examinations,
and determined superoxide dismutase (SOD) activity
in the control, MCT and MCT+MO groups. On the
day of the measurement, rats were anesthetized with
urethane (1.2 g/kg, i.p.). After insertion of an endo-
tracheal cannula and a right femoral arterial catheter,
artificial ventilation with a respirator at a rate of 60
breaths/min and a tidal volume of 6-8 ml/kg was ap-
plied. The chest of the rat was then opened via a
midline sternotomy. A 22-G needle filled with hep-
arinized saline was inserted through the wall of the
right ventricle and advanced into the pulmonary artery
(15). Ppa, systemic mean blood pressure and heart
rate were measured, and mean Ppa was calculated as
the sum of diastolic pressure and 1/3 pulse pressure.
After the measurements were obtained, the heart was
removed and the right ventricle (RV) was separated
from the left ventricle and septum (LV+S). Both por-
tions were weighed, and the weight ratio RV/(LV+S)
was calculated and used as the index of right ventricular
hypertrophy. Finally, the right lung tissue was dissected
and frozen at -80°C for subsequent determination of
superoxide dismutase (SOD) activity. The left lung
was dissected for morphological examinations.
Morphological Examinations
Lung samples were taken from each experi-
mental group for morphological examinations. The
left lung was excised after the functional study and
was inflated for 30 min with 4% formaldehyde to
maintain a pressure of 25 cm H2O. Then, the trachea
was tied, and the lung lobe was immersed in a 4%
formaldehyde solution. Tissue blocks were taken
from rostral, middle and caudal portions of the
formaldehyde-immersed lung. These blocks were
washed, fixed and vacuum-embedded in paraffin.
From each block, at least three nonconsecutive 2-µm
sections were cut, stained with hematoxylin and eosin,
and examined by light microscopy for the thickness
of pulmonary arteries according to the method of
Zhou and Lai (24).
SOD Activity Assay
The endogenous SOD activity in the lung tissue
was measured by an SOD assay kit (cat 7500-100K;
Trevigen Int, Gaithersburg, MD, USA). Aliquots of
supernatants from the homogenized lung tissues were
used for determining SOD activity by both the xanthine/
xanthine oxidase (X/XOD) (8) and the NitroBlue
Tetrazolium (NBT) assays. In brief, homogenized lung
tissue (0.05 g) was added to 60 µl of cold PBS for 5
min. The insoluble components were separated by
centrifugation. The supernatant was then removed into
a clean cuvette and deionized water was added to 42.5
Ppa (mmHg)
30
20
10
0
SBP (mmHg)
120
100
80
60
0.5 sec
Fig. 2. Tracing curves of pulmonary arterial blood pressure (Ppa) and systemic blood pressure (SBP) in the control rats.
Moringa Oleifera and Pulmonary Hypertension 5
µl. The 25x Reaction Buffer (60 µl), X Solution (7.5
µl) and NBT Solution (30 µl) were then mixed well
with the homogenized tissue extract. At the absor-
bance at 550 nm, each sample was measured for 330
seconds immediately after addition of 10 µl XOD.
Displacement of tissue extract by deionized water was
used as a negative control, and SOD was used as a
positive control. Superoxide anion, generated from the
conversion of X/XOD, converted NBT to NBT-
diformazan which absorbed light at 550 nm (A550).
SOD reduced superoxide anion concentrations and
thereby lowered the rate of NBT-diformazan formation.
Determinations of the rate of increase in absorbance
units (A) per minute for the negative control and samples
were calculated as (A550330 sec. – A55030 sec.)/5 min =
∆A550/min. Thus, the % inhibition of SOD in the lung
tissue was calculated as [(∆A550/min)negative control –
(∆A550/min)sample]/(∆A550/min)negative control × 100 =
% inhibition. This value increased with the con-
centration of SOD in the lung tissue. All measure-
ments were performed in duplicates.
Statistical Analysis
Data are presented as means ± SEM. Using
Student’s t test, the acute Ppa responses to the MO
extract were analyzed by comparison to baseline data
before MO extract administration. To evaluate the
chronic effects of the MO extract, the systemic hemo-
dynamic parameters, Ppa, pulmonary arterial medium
thickness, RV/(LV+S) and % inhibition of SOD were
analyzed as follows: a one-way analysis of variance
was used to establish the statistical significance of
differences among groups; if there was a significant
difference among groups, statistical differences
between any two groups were analyzed with Newman-
Keuls multiple group comparisons. Differences were
considered significant if P < 0.05.
Results
The HPLC fingerprint of the crude 3% MO
extract is shown in Fig. 3. The fingerprint was similar
to that reported by Shanker et al. (17). Two peaks
representing niaziridin and niazirin were identified
in the spectrum from the MO extract (Fig. 3).
The acute responses of Ppa to the MO extract
are summarized in Fig. 4. In the control rats, there
was no significant difference in Ppa at any dose used.
In addition, vehicle did not alter Ppa either in the con-
trol or MCT-treated rats. Ppa decreased immediately
after the administration of the MO extract to MCT-
treated rats (data not shown). The MO extract caused
a dose-dependent decrease in Ppa in the MCT groups.
Low doses of the MO extract (e.g. 1.5 mg/kg) caused
a small non-significant decrease in Ppa. Administra-
tion of 4.5 mg/kg of the MO extract reduced Ppa to
approximately 80% of that of the MCT control and
reached statistical significance. The highest dose, at
15.0 mg/kg, significantly reduced Ppa to 51.4% of
that of the MCT control.
The effects of chronic administrations of the
MO extract to MCT-treated rats are summarized in
Table 1 and Figs. 5-9. There were no significant dif-
ferences in either body weight or systemic blood
pressure among the groups (Table 1). Notably, the
MO extract increased the heart rate of the rats (Table
1). The chronic effects of treatment with the MO ex-
tract on Ppa are shown in Fig. 5. In comparison to
the control group, MCT administration increased Ppa
indicative of PH (Fig. 5). Repeated administrations
of the MO extract during the latter stages (third week)
significantly reversed the MCT-induced increase in
Fig. 3. Analysis of the 3% Moringa oleifera (MO) crude extract
by HPLC identified two components, niazirin and
niaziridin.
Niaziridin
Niazirin
0102030405060 min
Fig. 4. Pulmonary arterial pressure (Ppa) in rats. Abscissa: log
of dose (mg of freeze-dried MO extract per kg of body
weight). Open circles indicate the Ppa changes caused by
the acute Moringa oleifera (MO) extract in the control
group. Solid circles indicate the Ppa changes affected
by acute treatment with the MO extract in the monocro-
taline (MCT)-treated group. Bars indicate 1 SE. The MO
extract caused a significant decrease in Ppa at the dose
of 4.5 (#P < 0.05) and 15.0 (##P < 0.01) mg of freeze-
dried MO extract/kg.
Log dose (mg/kg)
Ppa (mmHg)
0
5
10
15
20
25
30
35
MCT
Control
##
#
Baseline
0.176 0.653 1.176
6Chen, Chen, Yang, Liu, Chang, Pan, Lin and Chen
Ppa to a level similar to that of the control group (Fig.
5). This finding reflected treatment, but not pre-
vention, of progression of MCT-induced PH by the
MO extract.
Photomicrographs of histological sections also
supported the results from measurements of Ppa (Fig.
6). Compared to the control group, MCT administra-
tion induced thickening of vessel walls with luminal
narrowing (Figs. 6A and 6B). Administration of the
MO extract for one week reduced the MCT-induced
thickening of vessel walls (Figs. 6B and 6C). The
statistical results of pulmonary arterial medium thick-
ness are summary in Fig. 7. Consistent to the Ppa re-
sults (Fig. 5), the MCT-induced morphologic change
was attenuated by administration of the MO extract
(Fig. 7).
The effects of the MO extract on right ventricular
hypertrophy are summarized in Fig. 8. MCT adminis-
tration significantly elevated the weight ratio of RV/
(LV+S) indicating right ventricular hypertrophy. The
MCT and MCT+MO groups had a similar degree of
right ventricular hypertrophy (Fig. 8).
The results from the SOD activity assay on the
tissue samples from the three groups are summarized
in Fig. 9. There was no significant difference in the
SOD activity between the control and the MCT groups.
The MO extract treatments caused a significant in-
crease in SOD activity (Fig. 9).
Discussion
We sought to determine the acute and chronic
effects of an extract from MO on MCT-induced PH.
Acute administration of the extract reduced Ppa in
a dose-dependent manner (Fig. 4). To determine
whether the MO extract is able to treat MCT-induced
PH, we administered the extract in the third week
after MCT treatment. Chronic administrations of the
MO extract significantly attenuated the MCT-induced
increase in Ppa (Fig. 5) and thickening of pulmonary
arterial walls (Figs. 6 and 7). The extract also in-
creased SOD activities (Fig. 9). These effects are
further discussed below.
Two important components, niaziridin and
niazirin, were identified by HPLC analysis of the MO
extract in ethanol (Fig. 3). The HPLC pattern analysis,
so-called the “fingerprint” method, provides a useful
means of identifying crude drugs and of preparatory
batches of pharmacologically active standardized
extract. Our results were consistent with those of
Shanker et al. (17): two peaks representing niaziridin
and niazirin were identified in the spectrum from the
MO extract (Fig. 3). Niaziridin has been demonstrated
to be a bioenhancer for antioxidative nutrients such as
vitamin A and vitamin C (15), and hypotensive effects
of niazirin on spontaneous hypertension in rats have
also been documented (6). The hypotensive activity
of the MO extract on the systemic circulation has
been demonstrated in several studies (5, 6). Bioactive
Table 1. Body weight (BW) and systemic hemodynamic parameters in three groups of rats
Group Control MCT MCT+MO
(n = 7) (n = 7) (n = 8)
BW (g) 259.3 ±3.5 247.9 ±3.5 245.6 ±7.7
SBP (mmHg) 89.0 ±5.1 79.1 ±4.1 84.3 ±4.9
DBP (mmHg) 55.7 ±5.2 60.9 ±6.0 65.9 ±3.8
MBP (mmHg) 66.8 ±4.8 67.0 ±5.3 72.0 ±3.8
HR (beats/min) 313.5 ±14.0 315.1 ±12.8 387.6 ±12.8*, #
Values are means ± SE. n, number of rats; SBP, systolic blood pressure; DBP, diastolic blood pressure; MBP, mean blood
pressure; HR, heart rate; MCT, monocrotaline; MO, Moringa oleifera (MO) extract was injected once daily during the
third week post MCT. MO extract caused an increase in HR when compared to control group (*P < 0.05) or MCT group
(#P < 0.05).
Fig. 5. Pulmonary arterial pressure (Ppa) in three groups of rats.
MCT, monocrotaline. MO, Moringa oleifera extract
administered at 4.5 mg/kg once daily during the third
week post MCT. Bars indicate 1 SE. MCT administra-
tion caused a significant increase in Ppa (**P < 0.01)
that was attenuated by the MO extract (#P < 0.05).
Ppa (mmHg)
0
10
20
30
40
#
**
Control MCT MCT+MO
Moringa Oleifera and Pulmonary Hypertension 7
components extracted from the leaves of plants such
as thiocarbamates (5) and niazirin (6) have shown hy-
potensive activity. However, there are many differences
between the systemic and pulmonary circulations. The
hypotensive agents used in the clinic to control systemic
hypertension often do not induce similar reductions
in PH thereby limiting the treatment and worsening
the severity of PH. In this study, the hypotensive ac-
tivity of the extract from MO was evaluated by measure-
ments of Ppa (Fig. 4). The extract we used for this
study was from the leaves of MO, similar to that used
by Faizi et al. (6). We also identified the active com-
Fig. 6. Photomicrograph of histologic sections from the three
groups of rats. MCT, monocrotaline; MCT+MO,
monocrotaline treatment followed by MO extraction
injections within the third week post MCT. Arrows
indicate the smooth muscular layers in pulmonary
arterioles. Arrow head in (B) indicates red blood
cells. All the imaged fields are amplified 100-fold.
(A) Control
(B) MCT
(C) MCT+MO
Fig. 7. Differences in pulmonary arterial medium thickness
among different experimental groups. MCT, mono-
crotaline; MCT+MO, monocrotaline treatment followed
by the MO extract injections within the third week post
MCT. Bars indicate 1 SE. MCT administration caused
a significant increase in the muscularization (*P < 0.05)
that was attenuated by the MO extract (#P < 0.05).
Pulmonary arterial
medial thickness (%)
0
20
40
60
80
100
*
#
Control MCT MCT+MO
Fig. 8. Weight ratio of the right ventricle (RV) to the sum of the
left ventricle and septum (LV+S) in three groups of rats.
MCT, monocrotaline; MO, Moringa oleifera extract
(MO) administered at 4.5 mg/kg once daily during the
third week post MCT. Bars indicate 1 SE. MCT adminis-
tration caused a significant increase in this ratio (**P <
0.01).
RV/(LV+S)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
**
Control MCT MCT+MO
**
8Chen, Chen, Yang, Liu, Chang, Pan, Lin and Chen
ponent, niazin (Fig. 3). Pulmonary hypotensive activity
was observed only in MCT-treated rats immediately
after injection of the MO extract, and this activity was
dose-dependent (Fig. 4). According to our results,
the acute hypotensive effect is attributable to the bio-
active component, niazin. Moreover, the MO extract
caused a slight, but not statistically significant, increase
in Ppa in control rats (Fig. 4), consistent with previous
findings (4, 19) that tonic pressure plays an important
role in vasodilation and contraction in pulmonary
circulation. The only difference between our results
and those of Faizi et al. (6) was the lack of systemic
hypotensive effects. We used the low-dose MO treat-
ment (4.5 mg/kg) in contrast with the high dose (30
mg/kg) used in Faizi’s study (6). This most likely ex-
plains the absence of systemic hypotension in our study
(Table 1). Many reagents have acted as systemic vasodi-
lators, but few have affected pulmonary circulation.
To our knowledge, our study is the first to demon-
strate hypotensive activity of the MO extract on the
pulmonary circulation.
We suggest that the effects of the prolonged MO
extract treatment in attenuating MCT-induced PH
occur via its anti-oxidant properties. Pharmaco-
logically-induced PH in rats is due to inflammatory
damage of the pulmonary endothelium (11, 12) fol-
lowed by remodeling of the pulmonary arterial tree
and subsequent elevation of Ppa (12, 14). This pro-
gression has been associated with the appearance
of reactive oxygen species (2). Administrations of
antioxidants, dimethylthiourea and hexa(sulfobutyl)
fullerenes during the late phase of vascular injury
reduced the MCT-induced increases in Ppa and reac-
tive oxygen species, indicative of the ability of ROS
scavengers to treat MCT-induced PH (2). Further-
more, inducing SOD expression via gene transfer
increased oxygen radical scavenging in MCT-treated
rats and successfully prevented the development of
MCT-related PH (13). Notably, the MO extract has
previously been reported to have antioxidant properties
(13). Our data, which show that treatment with the
MO extract during the third week following MCT
successfully attenuated both the MCT-induced in-
crease in Ppa (Fig. 5) and the thickening of pulmonary
arterial walls (Fig. 6), support this claim. Additionally,
the MO extract increased SOD activity (Fig. 9). Ac-
cordingly, we hypothesize that modulation of PH by
the MO extract is due to its antioxidant effects.
The MCT-induced right ventricular hypertrophy
was not improved by treatment with the MO extract
(Fig. 8). Two possibilities might explain its ineffec-
tiveness. First, the length of administration of the
extract was long enough to reduce Ppa but not long
enough to decrease right ventricular hypertrophy, which
is a compensatory mechanism occurring subsequent
to high Ppa. Second, the MO extract might affect car-
diac tissue directly. The bioactive components of the
MO extract are purported cardiac stimulants (1). Time-
course studies in MCT-induced PH suggest the oc-
currence of right ventricular hypertrophy as soon as 10
days post-MCT treatment (10), with severity increasing
until 3 weeks (21, 22). We administered the MO extract
only in the third week by which point the right ven-
tricular hypertrophy might have already manifested.
Although both the MCT-induced increase in Ppa and
the thickening of the pulmonary arterial walls were
reduced by treatment with the MO extract (Figs. 5, 6
and 7), evidence revealed that MCT-induced right
ventricular hypertrophy was not affected by this ex-
tract (Fig. 8). Additionally, the heart rate was also
significantly accelerated by the MO extract in com-
parison to the MCT group (Table 1). Given these results,
we attributed the appearance of right ventricular
hypertrophy following treatment with the MO extract
to our second hypothesis, a direct stimulatory effect of
the MO extract.
There are limited clinical agents to treat PH;
thus, it is necessary to develop a new source of phar-
macological agents. We demonstrated that the MCT-
induced increase in Ppa was reduced by treatment
with an extract from MO acting through the antioxidant
properties and vasodilatory effect of the extract. The
MO extract is readily available and might be a novel
drug candidate. More studies are needed, however,
to examine therapeutic applications of the MO extract
in the future.
Acknowledgments
This study was supported by grants from the
Fig. 9. The SOD activity in three groups of rats. MCT, mono-
crotaline; MO, Moringa oleifera extract (MO) adminis-
tered at 4.5 mg/kg once daily during the third week post
MCT. Bars indicate 1 SE. The MO extract caused
a significant increase in SOD activity when compared
with the control group (**P < 0.01) and the MCT group
(#P < 0.05).
Inhibition rate (%)
0
10
20
30
40
50
60
Control MCT MCT+MO
**
#
Moringa Oleifera and Pulmonary Hypertension 9
National Science Council (NSC93-2320-B254-001)
and from Keelung Hospital.
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