Experimental animal studies on analgesic activity of two Bangladeshi plants-

Hydnocarpus kurzii and

Wedelia trilobata

Yesmin BegumSenior Lecturer

Department of Pharmacy

Southeast University

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.

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

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

We de l i a t r i l oba t a

H y dnoc ar pus kur z i i

Plant Review

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

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

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

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

MethodologyFresh 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.

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

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

Group Dose No. of writhingStandard 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

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

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……..

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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