Study on Analgesic activity of two Bangladeshi medicinal plants

1. Experimental animal studies on analgesic
activity of two Bangladeshi plants-
Hydnocarpus kurzii
and
Wedelia trilobata
Yesmin Be gum
Senior Lecturer
Department of Pharmacy
Southeast University

2. Abstract
 Natural remedies can defeat pain without relying on the risky
drugs. At present, plant parts are widely used traditionally or medicinally to
avoid the life threatening side effects of steroids, NSAIDs and opiates. The
aim of the present study was to evaluate the analgesic activity of two
medicinal plants Wedelia trilobata (Asteraceae) and Hydnocarpus kurzii
( Achariaceae) in animal model. Both plants possess great medicinal value
in folklore medicine. The analgesic activity of the methanolic leaf extracts of
both plants was investigated by acetic acid induced writhing and formalin
induced hind paw licking (chemical induced) method at the doses of 100
and 200 mg/kg of body weight. The leaf extract of W. trilobata showed
statistically significant analgesic effect (p<0.001) in acetic induced writhing
and formalin induced hind paw licking swiss albino mice model at both
dose levels. The leaf extract of H. kurzii also demonstrated statistically
significant (p<0.05) analgesic effect in both model. These results suggest
that the methanolic extract of both plants possess potential peripheral and
centrally acting analgesic activity. Hence, the bioactive compounds of both
plants would be evaluated to develop as potent analgesic and anti-
nociceptive agent free from side effects and addiction.

3. A medicinal plant is any plant which in one or more of its organs,
contains substances that can be used for therapeutic purposes or
which is a precursor for synthesis of useful drugs” (1). In Bangladesh,
about 406 medicinal plants are identified and documented with the
utilized part in different health problems in districts. There are about
297 Unani, 204 Ayurvedic and 77 Homeopatheic drug manufacturing
industries in Bangladesh where the medicinal plants are extensively
used in both raw and semi– processed forms of medicine in various
pharmaceutical dose formulations. These plants also serve as
important raw materials for many modern medicinal preparations. The
market value of drugs produced by these industries from medicinal
plants is about Tk. 300 crores. (The Daily Jugantor, 21 June, 2003).
Ethnopharmacological studies are continued to validate the medicinal
uses of plants in folklore medicine.
Background

4. Pain is an unpleasant sensory and emotional experience associated
with actual or potential tissue damage. Most pain resolves once the
noxious stimulus is removed and the body has healed, but it may persist
despite removal of the stimulus and apparent healing of the body. Pain is
the most common reason for physician consultation in most developed
countries. Simple pain medications like analgesics are useful in 20% to
70% of cases. Analgesics are one of the most prescribed drugs in
Bangladesh. Rational or Irrational use of analgesics as paracetamol,
NSAIDs, opoids may lead to potentially life threatening liver damage,
kidney damage, peptic ulcer, renal disease, hemorrhage etc with various
unwanted effects. The present study was focused to manage pain
without any side effects by using two important Bangladeshi plants.
Study Justification

5. Wedelia trilobata
Hydnocarpus kurzii
Plant Review

6. Hydnocarpus kurzii or Chaulmugra belonging to the family
Achariaceae, widely distributed through out the forests of
Chittagong, Chittagong Hill Tracts, Cox's Bazar and Moulavi Bazar.
it’s seeds yield chaulmoogra oil, which is used in leprosy and other
skin diseases, also used to treat rheumatism, sprains and bruises,
sciatica and chest complaints, and for dressing wounds.
Wedelia trilobata belonging to the family Asteraceae, native to Central
America, now widely distributed in Bangladesh. This species has
been found as an ornamental herb grown in the islands of Dhaka
city streets and in the private gardens. It has long been used as
traditional herbal medicine in South America, China, Japan, India
for the treatment of a variety of ailments like reproductive problems,
amenorrhea, dysmenorrhea, colds ,flu , fevers and inflammations.
Plant Review

7.  Many bioactive compounds have been identified and isolated from
both plants. H. Kurzii has many potential secondary metabolites
as hydnocarpic acid, chaulmoogric acid, gorlic acid , oleic acid
and palmitic acid. W. trilobata has a number of bioactive
compounds as α -phellandrene, germacrene D, D-limonen, 1,5,5-
trimethyl-6-methylene- cyclohexene, caryophyllene, α-pinene, D-
limonene, germacrene D and phytol (2) .
 W. trilobata hold great ethnopharmacological, phytochemical and
therapeutic potential that reveals antioxidant, analgesic, anti-
inflammatory, antimicrobial, wound healing, larvicidal,
trypanocidal, uterine contraction, antitumor, hepatoprotective
activities(3).
 Pharmacological reports also revealed its use in the treatment of
diabetes, menstrual pain and reproductive problems in women.
 H. kurzii also possesses wound healing , anti microbial.,
thrombolytic, analgesic, antioxidant, antihyperglycemic
activities(4-10).
Literature Review

8. Collection and authentication of plant
and the plant parts
Extraction of plant materials with
methanol
Evaluation of Analgesic activity using
experimental animal by acetic acid
induced writhing
Evaluation of Analgesic activity using
experimental animal by formalin
induced hind paw licking method
Statistical analysis of the
pharmacological data
Study Design

9. The analgesic property of both extracts was evaluated by acetic
acid induced writhing and formalin induced hind paw licking
method in swiss albino mice. The extracts were administered per
orally. Indomethacin and saline water were used as standard
and normal control respectively.
Rotary Evaporator
Methodology
Fresh leaves of H. kurzii & W. trilobata were collected and extracted
using methanol by maceration. 17.67gm & 15.9gm of extract
residue were obtained from W. trilobata and H. kurzii respectively
after evaporation by Rotary evaporator.

10. Mice(25 -30) were selected and divided into standard,
test and normal control group respectively
At beginning, appropriate concentration of saline water,
Indomethacin & extracts samples were administered
orally to normal, standard and test group respectively
After 30 minutes acetic acid was administered
intraperitoneally to each of the animals of all the groups.
After 5 minutes the no. of writhing was counted for 30
minutes
Acetic acid induced writhing method

11. Mice(25 -30) were selected and divided
into standard, test and normal control
group respectively
At beginning, appropriate
concentration of saline water,
Indomethacin & extracts samples
were administered orally to normal,
standard and test group respectively
After 30 minutes formalin was
administered to each of the animals
of all the groups
The number of paw licking was
measured in each mouse from 0-5
minutes and 20-30 minutes.
Formalin induced hind paw licking method

12. Group Dose No. of writhing
Standard 10mg/kg 9.00 ± 1.20 ***
W. Trilobata 100mg/kg 15.75 ± 0.85***
W. Trilobata 200mg/kg 11.25 ± 0.75***
H. kurzii 100mg/kg 24.75 ± 1.30*
H.kurzii 200mg/kg 24.25 ± 1.40*
Data Analysis for Analgesic Activities
The effect of the methanolic extract of H.kurzii and W.trilobata on
acetic acid induced writhing in mice is shown in the following table.
All values are Mean ± SEM, n = 4 One way Analysis of Variance
(ANOVA) followed by Dunnett’s test was performed as the test of
significance. The minimum value of p < 0.001 and p<0.05 were
considered significant with control group

13. Group Dose No. of licking
in Early
phase
No. of
licking in
Late phase
Standard 10mg/kg 9.25±0.8*** 11.5 ± 0.2***
W. Trilobata 100mg/kg 24.7±2.1*** 15.75±0.55***
W. Trilobata 200mg/kg 19.25± 0.75*** 11.5 ±0.64***
H. kurzii 100mg/kg 31.5±4.4* 15 ±1.2*
H.kurzii 200mg/kg 27.5± 2.4* 12 ±1.4*
Continued…….
The effect of the methanolic extract of H. kurzii & W. trilobata on
formalin induced pain in mice is shown in the following table. All
values are Mean ± SEM, n = 4 One way Analysis of Variance
(ANOVA) followed by Dennett's test was performed as the test
of significance. The minimum value of p < 0.001 and p<0.05
were considered significant with control group

14.  Acetic acid induced writhing is a sensitive method in evaluating for
peripheral analgesic activity. Writhing is an overt response to the
intense pain induced by irritant principles via nociceptors
characterized by episodes of retraction of abdomen and stretching
of hind limb. The experimental result of this method recommend
that prostaglandin synthesis might be inhibited by the extracts of
both plant, a peripheral mechanism of pain reduction.
 Formalin induced paw licking test produces a distinct biphasic
response including early phase and late phase. Pain sensation
observed during early phase is supposed to reflect the neurogenic
pain while late phase is believed to represent inflammatory pain. In
this test the delay in paw licking time in both phases further
approve that the extracts have analgesic activity with both pathway
involving inflammatory and non-inflammatory analgesia.
Continued……..

15. In summary, present pharmacological study
results of leaf extracts of W. trilobata and H.
kurzii verifies the previous reports and also
correlates with the medicinal uses. Further
investigation should be carried out to identify
the responsive compounds and evaluate the
possible mechanisms of analgesia.
Conclusion

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