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Afr. J. Biomed. Res.Vol.15 (January 2012); 29 - 34

Research Article
Anti-inflammatory and analgesic effects of methanol extract of
Stellaria media (L.) Vill leaf
1
Oyebanji B. O., 2, 3Saba A. B. and 2Oridupa O.A
1
Department of Animal Science, Obafemi Awolowo University, Ile-Ife, Nigeria.
2
Department of Physiology, Biochemistry and Pharmacology, University of Ibadan, Ibadan, Nigeria

ABSTRACT: The anti-inflammatory and analgesic effect of the methanolic extract of Stellaria media (L.) Vill leaf was
studied using albumen-induced paw oedema and formalin-induced paw lick in rats as the anti-inflammatory test models; acetic
acid-induced writhing, hot plate and tail flick tests in mice as the analgesic models. Three groups of five rats or mice each were
administered orally with the leaf extract of S. media at 100mg/kg, 300mg/kg or 500mg/kg body weight respectively. A fourth
group was administered with Indomethacin (5mg/kg b.w) and distilled water (10mls/kg b.w) for the control group. The extract
of S. media dose-dependently, significantly (p<0.05) inhibited egg albumen-induced paw oedema as effectively as
Indomethacin. The late phase of the formalin response was also inhibited. The extract at 300mg/kg body weight produced a
significant (p<0.05) inhibition of the acetic acid-induced abdominal constrictions in mice compared to the control group and
mice administered with indomethacin. The analgesic property of the extract was also exhibited in the tail flick test as the
extract significantly (p<0.05) increased the tolerance of the mice to pain relative to indomethacin-treated mice. The methanolic
extract of S. media showed potent peripherally and centrally mediated anti-inflammatory and analgesic properties. The
analgesic effect appears mediated through inhibition of release of histamine, serotonin and kinins, prostaglandin,
cyclooxygenase and slow reacting substance.

Keywords: Medicinal plant, anti-nociceptive, rat, mice

INTRODUCTION often raw in salads. There are several closely related

1
plants referred to as chickweed which lack the culinary
and medicinal properties of plants in the genus
Stellaria media (L.) Vill of the plant family Stellaria. S. media can easily be distinguished from
Carophyllaceae (Britton and Brown, 1913), commonly other members of its family. S. media has fine hairs on
known as chickweed, is a cosmopolitan plant found in only one side of the stem in a single band while other
most regions of the World including Britain and it members of the family which resemble the plant have
grows as a common garden weed (Chiej, 1984). In both hairs uniformly covering the entire stem.
Europe and North America, the plant is common in S. media is used medicinally as a tonic, diuretic,
gardens, fields, and disturbed grounds. It is very demulcent, expectorant, and mild laxative (Haragan,
competitive with small grains, and produces up to 80% 1991). It is traditionally recommended for treatment of
yield losses among barley (Davis et al., 2005). S. media asthma, bronchitis, or congestion and aids in the control
is edible and nutritious, and is used as a leaf vegetable, of obesity. S. media relieves itching and inflammation
and has soothing and moisturizing effects. It is used for
minor skin infections or irritations, and is an ingredient
in a number of commercial skin care products but most
of these traditional uses are not supported by scientific
data (Howard, 1987). This study was therefore
designed to investigate the anti-inflammatory and
*Address for correspondence:
bensaba2011@hotmail.com; Tel. Number: +2348054138127
analgesic activities of S. media leaves using laboratory
Received: September 2011; Accepted: December 2011) animal models.
 Antinociceptive effect of Stellaria media

MATERIALS AND METHODS administered to animals in the reference group (5mg/kg

p.o) and control animals received the vehicle (distilled
Experimental animals water at 10mls/kg b.w). One hour after treatment, an
Male Swiss mice (18 -20g) and Wistar rats (150 -180g) injection of 0.2ml (2% v/v) egg albumen was injected
of both sexes were used for the study. The experimental into the right hind paw of each rat under the sub plantar
animals were housed in a 12 hour light: dark condition region. The paw sizes were measured before and at
and maintained on standard rat and mouse diets and intervals of 30, 60, 90 and 120 minutes after egg
water ad libitum. Twenty five animals were randomly albumen injection by using the cotton thread method
and equally divided into five groups for each protocol. (Hess and Milonig, 1972, Olajide et al., 2000). Cotton
Three groups were administered with extract of 100, thread was wrapped around the paw and the
300 or 500mg/kg body weight. A group was circumference was measured with a meter rule. The
administered with 5mg/kg b.w of Indomethacin as the inhibitory activity was calculated according to the
reference drug and another was administered with following formula;
10ml/kg of distilled water. The Experimental Animal
Use and Ethical Committee of the Faculty of Percentage inhibition
Veterinary Medicine, University of Ibadan, Nigeria = (C1- C0) control – (C1-C0) treated X 100
approved the research protocols. (Ct-C0) control
Where Ct is paw size after albumen injection, C0 is paw
Plant materials size before albumen injection
Fresh leaves of S. media were collected from Mokuro,
Ile-Ife, Nigeria in September, 2008 by Mr. Ademoriyo Formalin paw lick: The method of Dubuission &
of Herbarium section, Department of Botany, Obafemi Dennis (1977) modified by Tjolsen et al, (1992) was
Awolowo University. Samples of the plant were adopted in this experiment. Formalin test is biphasic,
deposited at the Herbarium, Department of Botany, and measures pain of both neurogenic (first phase) and
Obafemi Awolowo University, Ile-Ife with voucher of inflammatory origin (second phase). The first phase
specimen number UHI 16380. The leaves were air- (0 – 5 minutes) being a result of direct stimulation of
dried for 72 hours after which they were pulverised into nociceptors measures centrally mediated effects and is
powdery form. A 500g of the powder was soaked in insensitive to anti-inflammatory agents. The second
methanol for 72 hours and thereafter filtered. The phase (20-30 minutes) is qualitatively different from
filtrate was concentrated in a rotary evaporator set at the first phase and is dependent on peripheral
400 C and freeze dried at -200 C. The extract obtained inflammation and changes in central procession due to
weighed 17.5 g (3.5% of the plant material) and this chemical mediators released from damaged cells that
was stored in a dessicator. stimulate nociception and thus induced pain.
Following an overnight fast, doses of the plant extract,
distilled water and indomethacin was orally
Acute toxicity administered to rats in the same pattern described
The acute toxicity and lethality (LD50) of the plant above. Thirty minutes after treatment, formalin was
extracts in rat were estimated using an Up-and-Down injected sub-cutaneously into the sub-plantar surface of
Method for Acute Toxicity testing described by Bruce rat left hind paw at the rate 50 μl of 2.5% solution.
(1985). 6 rats were administered with 3,000 mg/Kg Responses were measured 0-5 minutes after formalin
body weight of the extract. The rats were observed for injection, for the first phase and the second phase were
mortality for 2 days. No mortality was observed, after taken 20-30 minutes after the injection. The licking of
which 4 more rats were administered with 5,000 mg/Kg the injected paw and the duration was indicative of
b.w and observed for mortality for another 5 days. pain.
There was no death recorded for the first and second
groups within 7 days of observation. Analgesic study

Anti-inflammatory study Acetic acid writhing response in mice: Mice were

divided into five groups and administered with extract,
Albumen-induced paw oedema in rat: Pedal oedema Indomethacin or distilled water as earlier mentioned.
was induced according to the method described by One hour after, 1mg/kg b.w of 3% acetic acid was
Okoli et al., (2008). Following an overnight fast, doses injected intraperitoneally to each mouse. 5 minutes
of methanolic extract of S. media were orally following acetic acid administration, the number of
administered to rats in three groups Indomethacin was
30 Afr. J. Biomed. Res. Vol. 15, No.1, 2012 Oyebanji, saba and Oridupa
 Antinociceptive effect of Stellaria media

abdominal contractions that occurred within the next 20 toxicity test conducted therefore showed that the lethal
minutes were counted and recorded for each mouse. dose (LD50) of methanolic extract of S. media was
higher than 5000 mg/kg body weight.
Hot plate test: Twenty five rats were randomly and
equally divided into five groups and treated as Albumen induced paw edema
mentioned above. The animals were dropped gently on Rats administered with the extract recorded varying
the hot-plate (Ugo Basile, Socrel DS-37) set at 55±1°C degrees of inhibition of inflammation, with 500mg/kg
at 0, 30 and 60 minutes after. The reaction time was dose having the highest percentage inhibitions of 54%
recorded as the interval between placement of the at 90 and 120 minutes post administration. These were
animals on the hot plate and the time it either licks its comparable to rats administered with Indomethacin
fore-paws or jumps off the plate. which had 30% and 55% percentages of inhibition 90
or 120 minutes post administration. Rats in the control
Tail flick test: This experiment was conducted group had significantly (p<0.05) larger paw volumes
according to the modified method adopted by Sanchez- (0.8±0.05cm, 1.0±0.07cm, 1.1±0.07cm and
Mateo et al. (2006) using hot water bath. Groups of 1.1±0.08cm) compared to other rats in the study (Table
five mice each were administered with the extract at 1).
100, 300, 500mg/kg b.w. Indomethacin (5mg/kg b.w)
and distilled water respectively. Thereafter, the Formalin paw lick in rats
terminal 2 cm of the mice tail were immersed in hot The early (60.00±3.90 seconds) and late phase
water contained in a 500 ml beaker maintained at (18.25±8.00 seconds) reaction time of rats administered
55±1°C. A thermometer was placed inside the water to with 300mg/kg b.w and those administered with
monitor the temperature. Their responses to thermal 500mg/kg b.w (58.00±9.30 seconds and 18.25±8.00
pain were taken at 30, 60 and 90 minutes after seconds) of extract were comparable but significantly
administration of extract, Indomethacin or distilled (p<0.05) longer than that of Indomethacin-treated rats
water. (42.00±3.08 seconds and 7.00±4.60 seconds). Rats that
served as control animals recorded significantly longer
Statistical analysis reaction time to both the early and late phases of
Data were analysed using one way analysis of variance inflammatory pain in this experiment (Table 2).
(ANOVA) on GraphPad Prism 4.0 version. The result
obtained were expressed as mean values ± standard Acetic acid writhing response in mice
error of mean (SEM). The statistically significant The mean number of writhes recorded in the control
difference between the mean values were determined at mice was higher than in mice administered with 300
p<0.05. (p<0.05), 500 mg/kg b.w (p<0.05) of the extract or
5mg/kg b.w of Indomethacin (p<0.05). Indomethacin
treated mice had lower number of writhing movement
RESULTS with mice administered with 100 mg/kg (p<0.05), 300
mg/kg (p<0.05) or 500 mg/kg b.w (p>0.05) of the
Acute toxicity test extract (Table 3).
There was no mortality recorded for up to 5,000 mg/kg
body weight of the extract within 7 days. The acute

Table 1:
Changes in paw volume (cm) by methanolic extract of S. media or indomethacin in albumen induced paw oedema test in rats.
Treatment Groups 30 minutes 60 minutes 90 minutes 120 minutes
Extract (100mg/kg) 0.88±0.07a (0) 0.74±0.15ab (20) 0.64±0.18b(27) 0.7±0.03b (27)
Extract (300mg/kg) 0.86±0.15a (0) 0.86±0.0ab (10) 0.88±0.11ab (18) 0.76±0.08b(27)
Extract (500mg/kg) 0.90±0.13a (0) 0.62±0.14b (30) 0.6±0.09b (54) 0.6±0.13b(54)
Indomethacin (5mg/kg) 0.98±0.02a (0) 0.76±0.07ab (30) 0.86±0.1ab(30) 0.56±0.1b (55)
Control (Distilled water) 0.8±0.05a 1.0±0.07a 1.1±0.07a 1.1±0.08a
Values with different superscripts in a column are statistically significant (p<0.05); Values in bracket are percentage inhibitions.

31 Afr. J. Biomed. Res. Vol. 15, No.1, 2012 Oyebanji, saba and Oridupa
 Antinociceptive effect of Stellaria media

Table 2: The effect of methanolic extract of S. media or Hot plate test

Indomethacin on reaction time (in seconds) to pain in The time of 4.76±0.37 or 4.46±0.50 seconds taken to
Formalin paw lick test in rats react to thermal pain in mice group administered with
Treatment Groups Early phase (sec) Late phase (sec) 300mg/kg b.w at 30 or 60 minutes post administration
Extract (100mg/kg) 68.75 ± 13.10a 16.00 ± 9.68ab was non-significantly (p>0.05) longer than for those
administered with Indomethacin (4.06±1.10 or
Extract (300mg/kg) 60.00 ± 3.90ab 18.25 ± 8.00b 3.27±0.46 seconds) for the same period. The reaction
Extract (500mg/kg) 58.00±9.30ab 17.00 ± 7.80b time in mice administered with 500mg/kg b.w of
extract was non-significantly (p>0.05) different from
Indomethacin 42.00 ± 3.08b 7.00 ± 4.60b
values recorded for those mice in 300mg/kg dose.
(5mg/kg) However, the mice in 300mg/kg dose recorded the
Control 64.35± 6.67ab 65.00 ± 2.08a longest time taken to react to thermal pain (4.76±0.37)
at 30 minutes post administration (Table 4).
Values with different superscripts in a column are statistically
significant (p<0.05)
Tail flick test
Table 3: The onset of reaction to thermal induced pain was
The effect of methanolic extract of S. media or Indomethacin significantly (p<0.05) shorter in the control rats than in
on abdominal writhing in mice injected with acetic acid those administered with extract or Indomethacin for
intraperitonealy. any period of evaluation of pain. Indomethacin
Treatment Groups Average number of writhing administered mice exhibited longer reaction time to
pain than for mice administered with 100 mg/kg
Extract (100mg/kg) 36.3±9.9a
(p>0.05), 300 mg/kg (p<0.05) or 500 mg/kg (p>0.05)
Extract (300mg/kg) 19.6±4.3b body weight of extract at zero (0) minute post
Extract (500mg/kg) 26.0±3.3ab
administration. At 30 minutes post administration, the
time taken to react to pain was non-significantly
Indomethacin (5mg/kg) 16.4±2.7b (p>0.05) shorter in indomethacin treated mice than in
Control (Distilled water) 35.2±1.2a mice pre-treated with 100 or 300 but longer for 500
mg/kg b.w. At 60 minutes post administration, the
Values with different superscripts in a column are statistically value was significantly (p<0.05) shorter in
significant (p<0.05)
indomethacin treated mice than in mice pre-treated with
Table 4: 100 mg/kg or 300 mg/kg but non-significant (p>0.05)
The effect of methanolic extract of S. media or Indomethacin with 500mg/kg b.w. (Table 5).
on reaction (in seconds) to thermal pain induced in Hot plate
method in mice.
Treatment Groups Response Table 5:
The effect of methanolic extract of S. media or Indomethacin
0 30 60 on response (in seconds) to thermal pain induced by tail flick
Extract 3.55 3.33 2.99. method in mice
ab ab
Treatment Group 0 min 30 min 60 min
(100mg/kg) ± 0.20 ± 0.51 ± 0.42b
Extract 3.50±0.33ab 5.53±1.43b 6.11±0.90a
Extract 3.41 4.76 4.46 (100mg/kg)
(300mg/kg) ± 0.16b ± 0.37a ±0.50a Extract 2.89±0.92b 4.69±0.54b 6.37±1.08a
(300mg/kg)
Extract 3.40 4.18 3.19
Extract 3.60±0.24ab 3.66±0.44b 4.55±0.72b
ab a
(500mg/kg) ±0.17 ±0.64 ±0.26ab (500mg/kg)
Indomethacin 5.33±0.93a 4.10±1.09b 4.00±0.56b
Indomethacin 5.33 4.06 3.27
(5mg/kg)
(5mg/kg) ±0.90a ±1.10a ±0.46ab Control 2.00±0.20 2.00±0.23a 1.80±0.30
(Distilled water)
Control 3.96 2.89 1.92
Values with different superscripts in a column are
ab b
(Distilled water) ±0.52 ±0.16 ±0.30b statistically significant (p<0.05)
Values with different superscripts in a column are
statistically significant (p<0.05)
32 Afr. J. Biomed. Res. Vol. 15, No.1, 2012 Oyebanji, saba and Oridupa
 Antinociceptive effect of Stellaria media

DISCUSSION constrictions in mice compared with mice in the control

group. The inhibition produced by the extract was also
The animal models of inflammation and analgesia used comparable to that produced by Indomethacin. This
in this study showed that methanolic extract of Stellaria indicates a marked evidence of analgesic property.
media possesses potent anti-inflammatory and Acetic acid causes an increase in the peritoneal fluid
analgesic property, especially at 300mg/kg body weight level of prostaglandins (PGE2 and PGF2α) as well as
of the extract. lipooxygenase production, which partially involves
The extract of S. media dose-dependently inhibited peritoneal receptors and inflammatory pain by inducing
paw oedema induced by egg albumen as effectively as capillary permeability (Collier et al., 1968; Choi,
Indomethacin. Egg albumen induces inflammation in 2007). S. media therefore probably disrupt
body tissue with the release of serotonin, histamine and prostaglandins synthesis through inhibition of
prostaglandin from the tissue, resulting in oedema, lipoxoygenase and cyclooxygenase.
which has been shown to be inhibited by antihistaminic In this study S. media significantly (p<0.05)
agents (Mossa et al., 1995 Olaleye et al., 2004). prolonged the reaction time to thermal pain. The
Ilavarasan (2005) corroborated these submissions with reaction time to pain in mice administered with
the study of Cassia fistula bark which was concluded to 300mg/kg b.w of the extract was longer than in mice
have an anti-inflammatory effect in acute inflammatory administered with indomethacin. The hot-plate test of
conditions. These strongly point to the fact that the analgesia is considered selective for opioid-like
anti-inflammatory effect of S. media is mediated receptors. Although the central and peripheral
through inhibition of modulation of nociception by analgesics act by inhibiting the number of contractions
serotonin, histamine or prostaglandins. provoked by chemical pain stimuli, only the central
The anti-inflammatory effect of S. media obtained analgesics increase the time of response in the hot plate
from the egg albumen paw oedema test was test (García, et al, 2004). This test therefore suggests an
corroborated by the formalin paw lick test. This test is involvement of centrally mediated mechanism of
not only useful for assessing antinociceptive property, analgesic action of S. media, as well as peripheral
but also in understanding the mechanism of anti- mechanism as initially mentioned in the formalin
inflammatory action. The early (neurogenic) phase is as induced paw lick test.
a result of direct stimulation of nociceptors in the paw The analgesic property of the extract was also
which culminates in centrally mediated pain with exhibited in the tail flick test with the extract
release of substance P, while the late phase is due to the significantly (p<0.05) increasing the tolerance of the
release of histamine, serotonin, bradykinin and mice to pain, more than was observed for
prostaglandins (Zeashana et al., 2009). Drugs that act Indomethacin. Tail flick test is a standard method for
primarily on the central nervous system, such as investigating nociception and analgesia, with the
narcotics, inhibit both phases equally while peripherally measurement of the response to a brief, noxious
acting drugs such as non-steroidal anti-inflammatory stimulus which appears to be a spinal reflex, modulated
drugs (NSAIDs) and steroidal anti-inflammatory only by supraspinal inhibitory mechanism. The test is
inhibit the late phase (García et al., 2004; Zeashana et selective for centrally acting analgesics (Ramabadran et
al., 2009). S. media effectively inhibited the late phase al., 1989) indicative of morphine like effect (Domer,
of the formalin response similarly in this study thus 1990) and NSAIDs which inhibit cycloxygenase in
reinforcing inhibition of prostaglandin synthesis as its peripheral tissues, thereby interfering with the
possible mechanism of action. mechanism of transduction in primary afferent
The acetic acid-induced writhing is a visceral pain nociceptors (Fields, 1987). This test also confirms that
model and widely used for the evaluation of peripheral the mechanism of analgesia is both centrally and
antinociceptive activity (Du et al., 2007). The peripherally mediated.
intraperitoneal administration of an agent that irritates In conclusion, the methanolic extract of Stellaria
the serous membranes cause a stereotypical behaviour media has potent peripherally and centrally mediated
in mice which is characterized by abdominal anti-inflammatory and analgesic properties. The anti-
contractions, movements of the body as a whole, nociceptive property appeared mediated through
twisting of the dorsal abdominal muscles, and a inhibition of release of histamine, serotonin and kinins,
reduction in the motor activity and coordination prostaglandin, cyclooxygenase and slow reacting
(Zeashana, et al., 2009). Findings from the present substances. Further study is aimed at isolating and
study showed that the methanolic extract of S. media at elucidating the chemical structure of the bioactive
300mg/kg body weight produced a significant (p<0.05) principles responsible for the anti-inflammatory and
inhibition of the acetic acid-induced abdominal analgesic properties.
33 Afr. J. Biomed. Res. Vol. 15, No.1, 2012 Oyebanji, saba and Oridupa
 Antinociceptive effect of Stellaria media

Hess S.M., Milonig R.M. (1972). Assay for anti-

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34 Afr. J. Biomed. Res. Vol. 15, No.1, 2012 Oyebanji, saba and Oridupa