Anti-inflammatory and Antinociceptive
activity of Pavonia zeylanica
Linn
Anitha Kumari1, K.G. Lalitha1, T. Venkatachalam2,
P. Kalaiselvi2, M.G. Sethuraman3
1Ultra
College of Pharmacy, Madurai – 625 020
2Annai JKK Sampoorani Ammal College of Pharmacy, B. Komarapalayam
- 638 183
3Gandhigram
Rural University, Gandhigram – 624 302
*Corresponding
Author E-mail:
ABSTRACT:
Pavonia zeylanica Linn.
(Family: Malvaceae) commonly known as Sittramutti (Tamil) is an herb distributed in the tropical
and sub-tropical regions of the world, and also found abundantly in India. It
has considerable reputation as a potent medicament in the treatment of various
ailments such as inflammation, fever and toothache. The anti-inflammatory
effect of the leaves of P. zeylanica, was evaluated using carrageenan induced paw oedema
and cotton pellet induced granuloma (chronic) in rat
models. The extract was also evaluated by hot plate and acetic acid induced
abdominal constriction assay to assess analgesic activity. The alcoholic
extract of P. zeylanica (AEPZ) exhibited
significant (P < 0.01) anti-inflammatory effect at the dose 50, 100 and 200
mg/kg. Maximum inhibition 46.16 % was noted at the dose of 200 mg/kg after 3 h
of drug treatment in carrageenan induced paw oedema, whereas the Indomethacin
10 mg/kg (standard drug) produced 65.38 % of inhibition. In the chronic model
(cotton pellet induced granuloma) the AEPZ (200
mg/kg) and standard drug showed decreased formation of granuloma
tissue by 40.30 % and 67.20 % (P < 0.01) respectively. The extract
also found to possess antinociceptive activity
against acetic acid-induced writhing and hot plate reaction in mice. In acetic acid-induced abdominal
constriction assay ) the AEPZ (200 mg/kg) and standard
drug aspirin showed reduction in abdominal constriction by 47.64% and 62.38% (P
< 0.01) respectively.Thus, the present study
revealed that the alcoholic extract of P. zeylanica
exhibited significant antinociceptive and
anti-inflammatory activity in the tested models.
KEYWORDS:
INTRODUCTION:
Herbal medicines derived from plant extracts are being
increasingly utilized to treat a wide variety of clinical diseases, though relatively
little knowledge about their mode of action is available. There is a growing
interest in the pharmacological evaluation of various plants used in Indian
traditional systems of medicine. P. zeylanica
Linn. (Family: Malvaceae)
commonly known as Sittramutti (Tamil) is a pubescent
herb distributed in the Deccan peninsula, parts of Bengal, Bihar, Orissa, Uttarpradesh and Rajesthan. It
has considerable reputation as a potent medicament in the treatment of various
ailments such as inflammation, fever and toothache. Leaves and young shoots are used as
emollient.
Roots are used as cooling, demulcent, carminative
diaphoretic, diuretic, astringent and tonic, to sort haemorrhage
and inflammation from internal organs1,2.
A saponins
pavophylline has been isolated from stem of this
plant3. However, fewer reports are available with
respect to the pharmacological properties of the plant. Thus, the present
investigation was carried out to evaluate the anti-inflammatory and antinociceptive potential of the alcoholic extract of P.
zeylanica (AEPZ) in experimental models.
MATERIALS AND METHODS:
Plant Material:
The plant P. zeylanica was collected from the Erode district, Tamilnadu, India during June 2010. The plant was
taxonomically identified by the Botanical survey of India, Coimbatore (Tamilnadu) and voucher specimen was deposited in our
laboratory for future reference. The leaves were dried in shade, pulverized by
a mechanical grinder and passed through a 40-mesh sieve to get the fine powder
and stored in an airtight container.
Preparation of extract:
The dried powdered plant material was extracted with
alcohol in a Soxhlet extraction apparatus. The solvent was removed under
reduced pressure and semi solid mass was obtained (yield 14.25 %). The extract
was subjected to preliminary phytochemical4The extract at the
different doses of 50, 100 and 200 mg/kg was suspended in aqueous Tween 80 solution (2 %), Pentazocin
(5mg/kg) Aspirin (100 mg /kg, i.p.) and Indomethacin (IPCA, Bombay)(10 mg/kg) in saline were used
for the present study.
Animals:
Swiss albino mice of both sexes weighing between 20 to
25 g and Albino Wistar rats of the either sex (180-200 g) were housed in
standard cages at room temperature (25±2
◦C) and relative humidity
45–55% at 12h light and 12h dark
cycle. The animals were fed with standard
pellet diet and water ad libitum. They were divided
randomly into groups of six animals each, before initiating the pharmacological
studies. The experiments were carried out during the light cycle. The
institutional animal ethics committee approved the experimental protocol (No. VM-10-02).
Toxicity Study:
Acute oral toxicity studies
were performed Ecobicon5 according to OECD(organization
for economic co-operation and department).Swiss albino male mice(n=6/each dose)
selected by random sampling technique were employed in this study.The
animals were fasted for 4 h with free access to water only. AEPZ(suspended
in 2% tween 80 were administered orally at a dose of
5mg/kg initially to separate groups of mice and mortality was observed for 3
days. If mortality
was observed in 4/6 or 6/6 animals, then the dose administered was considered
as toxic dose.
However, if the mortality was
observed in only one mouse of six animals, then the same dose was repeated with higher doses such as 50,300 and
1000,2000 mg/kg. the general behaviors such as motor
activity , tremors, convulsions, straub reaction,
aggressiveness piloerection, loss of lighting reflex,
sedation, muscle relaxation hypnosis,
analgesia, ptosis, lacrimation,
diarrhea and skin colour were observed for the first
one hour and after 24 h test drug administration.
Anti-inflammatory activity:
Carrageenan - induced rat paw oedema:
The rats were divided into 5 groups (n = 6). Acute
inflammation was produced by the sub plantar administration of 0.1 ml of 1 % carrageenan (S. D. Fine Chemicals Ltd, Bombay) in normal
saline in the right paw of the rats. The different groups were treated with
AEPZ (50, 100 and 200 mg/kg, p.o.), indomethacin (10 mg/kg, p.o.) and
control vehicle were administered orally. The paw volume was measured at 0 h
and 3 h after carrageenan injection using plethysmometer6
.The animals were pretreated with the extract 1 h before the administration of carrageenan. The extract and the standard used for this
study were prepared in the same manner as mentioned earlier. The ratio of the
anti-inflammatory effect of AEPZ was calculated and compared with control7.
Cotton pellets-induced granuloma:
The rats were divided into five groups (n = 6). After
shaving the fur, the rats were anaesthetized and 10 mg of sterile cotton
pellets were inserted, one in each axilla. The AEPZ
(50, 100 and 200 mg/kg, p.o) and indomethacin
(10 mg/kg, p.o.) and control vehicle were
administered orally for 7 consecutive days from the day of cotton pellet
implantation. The animals were anaesthetized on the eighth day and cotton
pellets were removed surgically and made free from extraneous tissues. The
pellets were incubated at 37°C for 24 h and dried at 60°C to constant weight.
Increment in the dry weight of the pellets was taken as measure of granuloma formation8.
Antinociceptive activity:
Acetic acid induced abdominal
constriction assay in mice:
For the abdominal constriction assay mouse
was administered intraperitoneally with 0.5 ml of 1%
acetic acid dissolved in 0.9% saline. The number of abdominal constriction was
counted during a 10 min period following the injection of acetic acid9. A significant reduction in
the number of abdominal constrictions by drug treatments as compared to vehicle
control animals was considered as a positive analgesic response and the
percentage inhibition of abdominal constriction was calculated. Aspirin (100 mg
/kg, i.p.) was used as reference standard.
Hot plate reaction time in mice:
Mice were screened by placing them on a hot plate
maintained at 55±1°C and recording the reaction time in seconds for forepaw
licking or jumping9. Only mice which reacted with in 15 sec and
which did not show large variation when tested on four separate occasions. Pentazocin (5 mg/kg, i.p.) was
used as reference standard. The time for forepaw licking or jumping on the
heated plate of analgesiometer was taken as the
reaction time.
Statistical analysis:
The experimental results were expressed as the mean ±
S.E.M. Data were assessed by the method of analysis of ANOVA followed by
student's t-test. P value of < 0.05 was considered as statistically
significant.
RESULTS AND DISCUSSION:
The extract showed positive test for steroids, triterpenoids and saponins.The
AEPZ was evaluated for anti-inflammatory and antinociceptive
activity in acute and chronic experimental animal models and the results are
tabulated in table 1 to 3. The AEPZ exhibited significant antinociceptive
and anti-inflammatory activity at the tested doses of 50, 100 and 200 mg/kg in
a dose dependant manner. The AEPZ for evaluated for its acute toxicity in mice.
The extract did not alter the general behavior and failed produce any mortality
even at highest dose of 2000 mg/kg, p.o. after 3 days
and found to be safe.
Table 1: AEPZ on carrageenin-induced rat paw edema and on cotton pellet granuloma in rats
|
Design of treatments (Group) |
Dose (mg/kg) |
Increase in paw vol.
after 3h (ml) |
% Inhibition |
Granuloma wt (wet wt in mg) |
% inhibition wet wt |
Granuloma wt (dry wt in mg) |
% inhibition dry wt |
|
I Control (saline) |
2ml/kg |
0.52±0.02 |
- |
226.0±1.20 |
- |
56.70±1.45 |
- |
|
II
Indomethacin |
10 |
0.18±0.02a |
65.38 |
80.20±1.14a |
64.51 |
18.60±1.45a |
67.20 |
|
III AEPZ |
50 |
0.38±0.16a |
26.92 |
146.92±1.52a |
34.99 |
40.52±1.27a |
28.53 |
|
IV AEPZ |
100 |
0.30±0.04a |
42.30 |
116.73±1.16a |
48.34 |
36.22±1.21a |
36.12 |
|
V AEPZ |
200 |
0.28±0.11a |
46.16
|
72.11±
2.12a |
59.23 |
30.33±1.42a |
40.30 |
All
values are given in mean ± SEM. N=6
a
p<0.01 are compared to control (ANOVA followed by Dunnett’s
t test)
Table 2: AEPZ
on acetic acid induced
abdominal constrictions
|
Treatment |
No. of abdominal Constrictions in 10 min |
% Inhibition |
|
Vehicle,
p.o. |
42.50
± 2.10 |
|
|
Aspirin,
100mg/kg p.o. |
16.00
± 1.80a |
62.38 |
|
AEPZ
50 mg/kg p.o. |
27.70
± 2.10a |
34.82 |
|
AEPZ
100 mg/kg p.o. |
25.10
± 1.36a |
40.90 |
|
AEPZ
200 mg/kg p.o. |
22.25
± 1.12a |
47.64 |
All
values are given in mean ± SEM. N=6
a
p<0.01 are compared to control (ANOVA followed by Dunnett’s
t test)
Table 3: Effect of AEPZ on hot plate test
in mice
|
Treatment |
Paw licking time in
seconds after |
|||
|
|
0
min |
60
min |
120
min |
180
min |
|
Vehicle |
4.66 ± 0.14 |
4.96 ± 0.24 |
5.24 ± 0.18 |
4.92 ± 0.26 |
|
Pentazotocin |
4.92
± 0.16 |
9.0
± 0.25 |
11.33
± 0.72a |
8.33
± 0.14a |
|
AEPZ
50 |
4.86
± 0.20 |
5.55
± 0.41 |
8.02
± 0.28a |
6.38
± 0.14a |
|
AEPZ
100 |
4.76
± 0.16 |
6.39
± 0.34 |
9.24
± 0.34a |
7.16
± 0.13a |
|
AEPZ
200 |
4.62
± 0.24 |
6.61
± 0.31 |
10.06
± 0.31a |
7.78
± 0.18a |
All values are given in mean ±
SEM. N=6
a p<0.01 are compared to control (ANOVA followed by Dunnett’s t test)
As shown in Table 1, the AEPZ showed maximum inhibition
of 46.16 % at the dose of 200 mg/kg after 3 h of drug treatment in carrageenan induced paw oedema,
whereas the standard drug showed 65.38 % of inhibition. Carrageenan
induced oedema is commonly used as an experimental
animal model for acute inflammation and is believed to be biphasic, of which
the first phase is mediated by the release of histamine and 5-HT followed by kinin release and then prostaglandin in the later phase10.
The extract effectively suppressed the inflammation produced by carrageenan.
As shown in Table 1, in the chronic model
(cotton pellet induced granuloma), the AEPZ (200
mg/kg) and standard drug showed decreased formation of granuloma
tissue at 40.30 % and 67.20 % (P < 0.01), respectively. Chronic
inflammation is a reaction arising when the acute response is insufficient to
eliminate proinflammatory agents. Chronic
inflammation includes a proliferation of fibroblasts and the infiltration of neutrophils and exudation11 .Chronic
inflammation occurs by means of the development of proliferative cells. These
cells can be either spread or in granuloma form. The
AEPZ showed significant anti-inflammatory activity in cotton-pellet induced granuloma and thus found to be effective in chronic
inflammatory conditions, which reflected its efficacy in inhibiting the
increase in the number of fibroblasts and synthesis of collagen and mucopolysaccharides during granuloma
tissue formation12.
Acetic acid-induced abdominal constrictions in mice:
The potential analgesic effects of the AEPZ were
investigated. The analgesic test used in the present study was chosen in order
to test different nociceptive stimuli, namely cutaneous thermic (hot plate) and
chemical visceral (abdominal constrictions) stimuli.
The results presented in Table 2, shows that AEPZ at
the doses of 50,100 and 200 mg/kg exhibited significant (P < 0.01)
inhibition of the control abdominal constrictions at the rate of 34.82 %, 40.90 % and 47.64%
respectively when compared to the effect of aspirin (100 mg/kg) which was
62.38%.
In acetic acid induced abdominal constrictions, which
is the viceral pain model, the processor the
release of arachidonic acid via cyclooxygenase
and prostaglandin via synthesis plays a role in the neoceptive
mechanism. Results of the present study show that all the doses of the AEPZ
produce significant antineoceptive effect and this
effect may be due to inhibition of the synthesis of the arachidonic
acid metabolite.
Hot plate reaction time in mice:
As shown in Table 3, the AEPZ produced significant (P
< 0.01) antinociceptive activity at all the
tested doses when compared with vehicle control. The results indicate that the
administration of AEPZ exhibit central analgesic properties, since it exerted a
significant and dose dependent effect on chemical (acetic acid induced) and thermic (heat) painful stimuli from the respective doses of
100 and 200 mg/kg such an efficacy on these two stimuli is characteristic of
central analgesic like morphine, while peripheral analgesic (paracetamol and
aspirin) and known to be inactive on thermic painful
stimuli.
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Received on 13.11.2011 Accepted
on 10.12.2011
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Asian J. Res. Pharm. Sci. 1(4): Oct.-Dec. 2011; Page 113-116