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Men, Medicine and Nature: An Overview.

1. INTRODUCTION

Sound health and sound mind is the primary concern of a man. Again good health helps

to maintain a happy mind. That’s why it is called that “health is wealth”. But very

usually man is facing obstacles in keeping his good health right from the very

beginning of his journey in this world. Naturally for the survival, man fights against

any disastrous happening with him and thus wants to overcome any obstacle. Suffering

from various ailments and injuries was the commonest occurrence for the ancient man.

And whenever man used to become helpless with this type of incidents he used to apply

his instinct and sixths senses to use something that were available in his surroundings

to allay his sufferings. In most cases it was the plant or plant parts that were used as

remedies. It is not certain when and how man learned to use the plant appropriately but

it is thought that animal was the first guide to show him the use of plants. Because

animals naturally know or feel how to get relief from the unusual internal conditions.

We still observe such incidents incase of our pets-it’s an example. On the other hand,

Muslim faith informs us that Adam was the first guide to make us understand about the

virtue of plants by self-taking of ‘Gandam’ fruit. But previous one has much more

logical and scientific basis. By and by, whether it was the guidance of animals or basic

instinct of man or sudden practices on assumptions, man came to know about the

therapeutic value of many plants or plant parts and thus their use are coming off from

generation to generation. On the starting there was no particular writing method to

preserve these experiences and verbally those were supplied to various persons and

continuous using on similar conditions made man to keep the experience in their mind.

Later these were written down and still these are being used as those were or in

somewhat modified form. The most important thing today is that those are now being

tried to prove scientifically and in this way synthetically development are being

advanced to meet the greater necessity or to conform the purity and specificity.

As for example, we can set some of our modern drugs like digitoxin, atropine and the

narcotic analgesics like morphine that have been developed from plants. Again

thousands of plant metabolites are being used in the treatment of variety of diseases. A

few interesting examples of plant metabolites include taxol from Taxus brevifolia,

vincristine and vinblastine from Vinca rosea Linn., all of which are important

anticancer agents being used clinically. In the current popular field of chemotherapy,

cepheranthine isolated from Stephania cepharantha and Stephania sasaki is being used

as a prophylactic in the management of tuberculosis. So it is clear that the primitive use

of plants or herbs played a great role in the development of modern medicine. Though

the plant or plant parts was the main concern of treatment, at that time whenever man

became unsuccessful to overcome any injuries or diseased conditions, he used to apply

religious beliefs and thus offered prayers for the relief.

Thus often happening of these types of situations created some verses or phrases or

words or prayers or tortures or other physical acts to reduce his sufferings. There was

another reason for the development of those rhythmic verses or words or prayers or

phrases-that was the intention of the religious chiefs to take or increase their power

over the general people, because they claimed that these religious facts were given to

them by the ancestral Gods. As a result this became confined in the hands of the

religious chiefs for many countries and it became a sort of secret magic and once it took

the secondary importance. However all those practices are collectively known as

traditional medicine as these were being practiced from generation to generation with

the traditional belief?

The basic concept of this system of medicine has been very comprehensively described

by the World Health Organization in this way: “Traditional medicine is the sum total of

all knowledge and practice, whether explicable or not, used in the diagnosis, prevention

and elimination of physical, mental, or social imbalance, relying exclusively on

practical experience and observations handed down from generation to generation

verbally or in writing”

1.2 Medicinal Plants-The Best Friend to Human Being in Nature

The universe is the greatest store that includes everything for the suitable survival of

animals and plants. For this reason, the greatest creation of God, man can enjoy a

comfortable and smooth life by using the plants and other animal as sources of food,

clothing, shelter and medicine.

The contributions of the plants are numerous in every sector of human life. It helps to

growing up of the human body and also protects human being from sickness by being

used as medicine. A large number of plants are used as medicinal agents in this world.

Specifically in Bangladesh about two hundred fifty species are used as medicinal

plants.

In nature plants of several varieties are available which are responsible for various

pharmacological actions. They are termed as medicinal plants. On the other hand, some

of them produce harmful effects on animal systems. They are termed as toxic or

poisonous plants. It has now been established that the plants which naturally synthesize

and accumulate some secondary metabolites like alkaloids, glycosides, tannins, volatile

oils and contain minerals and vitamins possess medicinal properties. A medicinal plant

may thus be defined as a plant which, in one or more of its organs contains substances

that can be used for therapeutic uses or which are precursors for the synthesis of useful

drugs.

However, ideally a definition of medicinal plants should include the following:

a) Plants or plant parts used medicinally in galenical preparation (e.g.

decoctions, infusions, etc).

b) Plants used for extraction of pure substances either for direct medicinal use

or for the synthesis of medicinal compounds (e.g. synthesis of sex

hormones).

c) Food, spice and perfumery plants used medicinally

d) Microscopic plants, e.g. fungi, actinomycetes, used for isolation of drugs,

especially antibiotics.

Fibre plants, e.g. cotton, flax, jute, used for the preparation of surgical dressings.

1.3 Historical Background of Medicinal Plants

Since disease, decay and death have always co-existed with life, the study of diseases

and their treatment must also have been contemporaneous with the dawn of human

intellect. The primitive man must have used as therapeutical agents and remedial

measures those things which he was able to procure most easily. There is no authentic

record of medicines used by the primitive man.

Illness, physical discomfort, injuries, wounds and fear of death had forced early man to

use any natural substance that he could lay his hand on, without any resistance, for

relieving the pains and sufferings caused by these abnormal conditions and for

preserving his health against disease and death.

Primitive peoples in all ages have had some knowledge of medicinal plants, derived as

the result of trial and error. These primitive attempts at medicine were based on

intuition, guesswork, superstition, or trial and error. Most savage people have believed

that disease was due to the presence of evil spirits in the body and could be driven out

by the use of poisonous or disagreeable substances calculated to make the body an

unpleasant place in which to remain. The knowledge regarding the source and use of

the various products suitable for this purpose was usually restricted to the medicine

men of the tribe. As civilization progressed the early physicians were guided in great

part by these observations.

Rig Veda (4500-1600 BC), which is the oldest book in the library of man supplies

various information on the medical use of plants in the Indian subcontinent. It was

noted that Indo-Aryans used the soma plant (Amanita muscaria, a narcotic and

hallucinogenic mushroom) as a medicinal agent. It is unfortunate that the Ayur Veda is

no more available in its original form but the most authentic and original texts

considered as the renowned representatives of the original Ayur Veda, are the

encyclopedic Agnivesha or Charaka Samhita and Sushruta samhita. The Indo-Aryans

used the plant for sacrificial purposes and its juice is described in the ancient Aryan

literature as stimulating beverage. The word oshadhi literally means heat -producer.

When the Indo-Aryans came to use the soma plant for therapeutic purposes, they came

to possess knowledge of the medicinal properties and uses of herbs and plants. Hence,

Oshadhi applied to all herbs and medicinal plants. The Vedas made many references to

healing plants including Sarpagondha (Rauwolfia serpentina), while a comprehensive

Indian herbal, the Charaka Samhita, cites more than 500 medicinal plants.

As far as records go, it appears that Babylonians (about 3000years BC) were aware of a

large number of medicinal plants and their properties. As evident from the Papyrus

Ebers (about 1500 BC), the ancient Egyptians possessed a good knowledge of the

medicinal properties of hundreds of plants. Many of the present day important plant

drugs like henbane (Hyoscyamus spp.), mandrake (Mandragora officinarum), Opium

(latex of Papaver somniferum fruit), pomegranate (Punica granatum), castor oil (oil of

Ricinus communis seeds), aloe (juice of Aloe spp.), onion (Allium cepa) and many other

were in common use in Egypt about 4500 years ago.

The Pen Tsao, the earliest known Chinese pharmacopoeia, appeared around 1122 BC

attributed to the legendary emperor Shen Nung, this authoritative work described the

use of Chaulmoogra oil (from the seed of Hydrocarpus kurzii ) to treat leprosy.

The practice of herbal medicine flourished most during the Greek civilization. When

historical personalities like Hippo crates (born in 460 BC) and Theophrastus (born in

370 BC) practiced herbal medicine as he was distinguished physician, practicing and

researching into herbal medicine. His materia medica consists of some 300 to

400medicinal plants. The far ranging scientific work of Aristotle (384-322 BC), a

Greek philosopher, included an effort to catalogue the properties of the various

medicinal herbs at that time. The Greek writer–physician Dioscorides (60 AD) who

wrote the famous treatise De Materia Medica, (published in78AD) which contained the

description of 600 medicinal plants. Two of the 37 volumes of books written by Pliny

De Elder (23-70 AD) which included a large number of medicinal plants. The great

Greek pharmacist-physician Galen (133-200 AD), who wrote about 500 volumes of

books describing hundreds of recipes and formulation of medicinal preparations

containing both plant and animal ingredients. Allopathic and Homeopathic systems of

medicine today are based on the doctrine expatiated by Galen.

After the dark ages were over, there came the period of the herbalists and

encyclopedists, and the monasteries of Northern Europe produced vast compendiums of

true and false information regarding plants, stressing in particular the medicinal value

and folklore. It was about this time that the curious “Doctrine of Signatures” came into

being. It was developed by Paracelsus (1490-1541 AD), a Swiss alchemist and

physician. According to this superstitious doctrine all plants possessed some sign, given

by the Creator, which indicated the use for which they were intended. Thus a plant with

heart-shaped leaves should be used for heart ailments, the liver leaf with its three lobed

leaves for liver troubles, and so on. Many of the common names of our plants of today

owe their origin to this curious belief.Such names as heartsease, Solomon’s-seal,

dogtooth violet, and liverwort carryon the old superstition.

From this crude beginning the study of drugs and drug plants has progressed until now

Pharmacognosy and Pharmacology are essential branches of medicine7.

1.4 Medicinal Plants Used In Traditional Medicine

Hakim Mohammed Said, a noted traditional medicine expert, advocates that Arab,

Chinese and Indian systems of medicines are not static but progressing from generation

to generation. Recent trend is to integrate the traditional medicine with modern

medicines. Best therapeutic results are said to be obtained often with the traditional

Chinese system.

We have seen that some manufacturers of traditional medicines use wrong parts of

medicinal plants in preparing their medicines. Medicinal plants used in traditional

medicine are often collected in the wrong season, at the wrong time of the day and at

the wrong stage of their growth due to ignorance on the part of the collectors. These

problems greatly affect the quality of traditional medicine, prepared from plant origin.

1.5 Contribution of Medicinal Plants to Modern Medicine

Plants and man are inseparable. The human race started using plants as a means of

treatment of diseases and injuries from the early days of civilization on earth and in its

long journey from ancient time to modern age the human race has successfully used

plants and plant products as effective therapeutic tools for fighting against diseases and

various other health hazards.

Scientists identified and isolated different chemical constituents from plants, which

have been used to prepare modern medicines. In course of time their synthetic

analogues have also been prepared. In this way, ancient uses of Datura plants have led

to the isolation of hyoscine, hyoscyamine, atropine and tigloidine; Cinchona bark to

quinine and quinidine, Rawolfia serpentina to reserpine and rescinnamine, Digitalis

purpurea to digitoxin and digoxin, Opium to morphine and codeine, Ergot to

ergotamine and ergometrine, Senna to sennosides, Catharanthus roseus to vinblastine

and vincristine4.

A recent survey by the United Nations Commission for Trade and Development

(UNCTAD) indicated that about 33% of drugs, produced in the developed countries,

are derived from plants (UNCTAD/GATT 1974: Annual Report, Geneva, Switzerland)

and that if microbes are added, 60% of medicinal products are of natural origin5.

According to some sources almost 80% of present-day medicines are directly or

indirectly derived from plants10. Surprisingly, this large quantity of modern drugs

comes from less than 15% of the plants, which are known to have been investigated

pharmacologically, out of an estimated 250000 to 50000 species of higher plants

growing on earth11. More than 47% of all drugs, used in Russia, are obtained from

botanical sources12.

At present, thousands of plant metabolites are being successfully used in the treatment

of variety of diseases11. A few striking examples of plant metabolites include taxol from

Taxus brevifolia13, vincristine and vinblastine from Vinca roseus14. All of which are

important anticancer agents being used clinically. In the current popular field of

chemotherapy, cepharanthine, isolated from Stephania cepharantha and Stephania

sasaki15 is being used as a prophylactic in the management of tuberculosis.

Even today 80% of the rural population of most developing countries of the world,

depends on herbal medicine for maintaining its health and well being16. The

consumption of medicinal plants is increasing in many developed countries, where 35%

of drugs contain active principles from natural origin17.

In China, about 15000 factories are involved in producing herbal drugs, herbal

medicines have been developed to a remarkable standard by applying modern scientific

technology in many countries, such as, China, India, Bangladesh, Srilanka, Thailand

and United Kingdom. In these countries, the dependence on allopathic drugs has been

decreased to greater extent18.

One hundred and seventy drugs from different plants, which are or once official in the

USP or NF, were used by the North American Indians. In 1960, 47% of drugs,

prescribed by physicians in the United States of America, were from natural sources19.

In 1967, 25% of the products, which appeared in 1.05 billion prescriptions filled in the

United States, contained one or more ingredients derived from higher plants20.

In the United States, in 1980, the consumers paid 8 billion dollars for prescription drugs

in which the active ingredients are still derived from plants5. 47% of some 300 million

new prescriptions written by physicians in America in 1961, contained as one or more

active ingredients, a drug of natural origin21. “Modern medicine still has much to learn

from the collector of herbs”, said Dr. Halfdan Mahler, Director General of the World

Health Organization. Many of the plants, familiar to the witch doctor, really do have

the healing power that tradition attaches to them. The age-old art of the herbalist must

be tapped10.

Thus it is apparent that whatever progress, science might have made in the field of

medicine over the years, plants still remain as the primary source of supply of many

important drugs, used in modern medicine. Indeed, the potential of obtaining new drugs

from plant sources is so great that thousands of substances of plant origin are being

studied for activity against such formidable foes as heart diseases, cancer, and aids6. In

this way, modern medicine will continue to be enriched by the introduction of newer

and more potent drugs from plant sources.

1.6 Chemical Constituents of Medicinal Plants

Plants have been serving the animal kingdom as its source of energy (food, fuel) as

well as its means of shelter and sustenance since the very beginning of its existence on

earth’s surface habitable for the animals.

In addition to providing the animal kingdom its food, fuel and shelter, each of these

plants has been synthesizing a large variety of chemical substances since their first day

of life on earth. These substances include, in addition to the basic metabolites, phenolic

compounds, terpenes, steroids, alkaloids, glycosides, tannins, volatile oils, contain

minerals, vitamins and a host of other chemical substances referred to as secondary

metabolites which are of no apparent importance to the plants own life. But many of

these compounds have prominent effects on the animal system and some possess

important therapeutic properties which can be and have been utilized in the treatment

and cure of human and other animal diseases since time immemorial. These secondary

metabolites differ from plant to plant. Thus, the plant kingdom provides a tremendous

reservoir of various chemical substances with potential therapeutic properties.

The chemical constituents, which are capable of influencing the physiological systems

of the animal body by exerting some pharmalogical actions, are designated as the active

chemical constituents or simply active constituents. In short, it may be said that the

chemical constituents present in the medicinal plants constitute the most important

aspect of all medicinal plants.

Green leaves are the sites of a great deal of such chemical activity. The chemical

substances with medicinal properties found in some plants are the products of such

chemical processes. The occurrence of the active chemical substances in all parts of the

plant body or they may be accumulated in higher concentrations in some specific part.

The types of chemical constituents are as follows:

A. Alkaloids and amides

Pyridine group

Tropane group

Isoquinoline group

Quinoline group

Quinolizidine group

Indole group

Steroidal group

Imidazole group

Phenylthylamine group

Alkaloidal amines

B. Antibiotic and Anti-inflammatory principles

C. Bitter and Pungent principles

D. Volatile oils and Fixed oils

E. Glycosides

Anthraquinone glycosides

Cardiac glycosides

Saponin glycosides

Thiocyanate glycosides

Other glycosides

F. Gum-resins and Mucilage

G. Vitamins and Minerals.

1.9 Inflammation – An Overview

Inflammation is the characteristic response of mammalian tissue to injury. Whenever

the tissue is injured there follows at the site of injury a series of events that tend to

destroy or limit the spread of the injurious agent.

Inflammation is fundamentally a protective response. It is closely intertwined with the

process of repair. Inflammation serves to destroy, dilute, or wall off the injurious agent,

but it in turn, sets into motion a series of events that, as far as possible, heal and

reconstitute the damage tissue. Without inflammation, infections would go unchecked,

wounds would never heal, and injured organs might remain permanent festering sores.

However, inflammation may be potentially harmful, causing life-threatening

hypersensitivity reactions, progressive organ damage, and scarring.

Etiology of inflammations:

The agents that injure tissue and therefore evoke the inflammatory response include:

1. Physical agents: e.g. Physical agents such as excessive heating or cooling,

ultraviolet or ionizing radiation or mechanical trauma.

2. Chemical agents: e.g. Chemical substances including toxins from various

bacteria.

3. Hypersensitivity: e.g. reaction of antibody or of sensitized lymphocytes with

bacterial or other antigens.

4. Infection: Microbial infection is a very important cause of inflammation.

Microorganism may injure tissue in several ways by release of exo- or endo-

toxins, by intracellular multiplication followed by cell death as seen in many

viral infections.

5. Necrosis: From almost any cause leads to release of substances, which induce

inflammation in adjacent living tissue.

Cardinal signs of inflammation:

1. Redness

2. Swelling

3. Heat

4. Pain

5. Loss of function

Types of inflammations:

According to its duration and predominant inflammation cell type, inflammation is

divided into acute or chronic pattern. The vascular and cellular responses of both acute

and chronic inflammation are mediated by chemical factors derived from plasma or

cells and triggered by inflammatory response.

Acute Inflammation:

Acute inflammation is the immediate and early response to an injurious agent. This is

relatively non-specific, its main role, being to clear away dead tissues, protect against

local infection, and allow the immune system access to the damaged area. The major

components of acute inflammation are:-

1. Alteration in vascular caliber that lead to an increase in blood flow.

2. Structural changes in the microvasculature that permit the plasma proteins and

leukocytes to leave the circulation.

3. Emigration of the leukocytes from the microcirculation and their accumulation

in the focus of injury.

i. Vascular changes

Inflammation causes change in vascular process in the affected areas. Such changes are

described in the following steps:

ii. Change in vascular flow and caliberFig 2: Blood pressure and plasma colloid osmotic forces in normal and inflamed microcirculation.

Change in vascular flow and caliber being very early after injury and develop at

varying rates, depending on the severity of the injury. The changes occur in the

following order:

Injurious agents cause an inconstant and transient vasoconstriction of arterioles then

follow the vasodilation. The first involves the arterioles and then results in opening of

new capillary bed in the area. Slowing of the circulation is brought about by increased

permeability of the microvasculature, with the outpouring of protein-rich fluid into the

extravascular tissues then leads to stasis. The increased permeability is the cause of

edema.

iii. Increased vascular permeability (vascular Leakage)

Increased vascular permeability is the hallmark of acute inflammation. The loss of

protein from the plasma reduces the intravascular osmotic pressure and increases the

osmotic pressure of the interstitial fluid. Together with the increased hydrostatic

pressure owing to vasodilation, this leads to a marked outflow of fluid and its

accumulation in the interstitial tissue. The mechanisms purposed for endothelial

permeability they are:-

i. Formation of endothelial gaps in venules (elicited by histamine, bradykinin,

leukotrienes, substance-P, and many other chemical mediators).

ii. Cytoskeletal reorganization. The endothelial cells undergo a structural

reorganization of the cytoskeleton, such that endothelial cells retract from one

another.

iii. Increased transcytosis across the endothelial cytoplasm: Transcytosis occurs

across channels consisting of clusters of interconnected, uncoated vesicles and

vacuoles called the vesiculovacuolar organelle, many of which are located close

to intercellular junctions.

iv. Direct endothelial injury, resulting in endothelial cell necrosis and detachment:

This effect is usually encountered in necrotizing injuries and is due to direct

damage to the endothelium by the injurious stimulus, as, for example, by severe

burns or lytic bacterial infections.

v. Delayed prolonged leakage is a curious but relatively common type of increased

permeability that begins after a delay of 2 to 12 hours, lasts for several hours or

even days, and involves venules as well as capillaries.

vi. Leukocytes-mediated endothelial injury: leukocytes adhere to endothelium

relatively early in inflammation. As seen subsequently, such leukocytes may be

activated in the process, releasing toxic oxygen species and proteolytic enzymes,

which then causes endothelial injury or detachment- resulting in increased

permeability.

vii. Leakage from new blood vessels: New vessels sprouts remain leaky until

endothelial cells differentiate and form intercellular junctions. In addition, certain

factors that cause angiogenesis also increase vascular permeability.

iv.Cellular events: Leukocyte Extravasation and Phagocytosis

A critical function of inflammation is the delivery of leukocytes to the site of injury.

The sequence of events in this journey called extravasatyion, includes: -----

1) Margination, rolling and adhesion of leukocytes in the lumen

2) Transmigration across the endothelium (also called diapedesis)

3) Migration in interstitial tissues toward a chemotactic stimulus

Fig 3: Sequence of leukocytic events in inflammation. The leukocytes first roll: then arrest and adhere to endothelium: and then transmigrate through and intercellular junction, pierce the basement membrane, and migrate toward chemo-attractants emanating from the source of injury. The roles of selectins, activating agents and integrins are also shown

v. Adhesion and transmigration

These occur largely due to interactions between complementary adhesions molecules

on the leukocytes and on the endothelium. Chemical mediator’s adhesion pairs include:

1) The selectins (E, P and L) which bind through their lectin (sugar binding) domains

to oligosaccharides (e.g. sialylated Lewis X), which themselves are covalently

bound to cell surface glycoproteins.

2) The immunoglobulin family, which includes the4 endothelial ICAM-1

(intercellular adhesion molecule-1) and VCAM-1 (vascular cell adhesion

molecule-1).

3) The integrins, which function as receptors some of the members of the

immunoglubin family and the extracellular matrix. The principal integrin reveptors

for ICAM-1 are the -integrins LFA-1 and MAC-1 (CD11a/CD18 and

CD11b/CD18), and those for VCAM-1 are the integrins 41 (VLA4) and 47.

It is now thought that neutrophils adhesion and transmigration in acute inflammation

occur by a series of overlapping steps: -

1) Endothelial activation: Mediators present at the

inflammatory sites increase the expression of E-selectin and P-selectin be

endothelial cells.

2) Leukocyte rolling: There is an initial rapid and

relatively loose adhesion, resulting from interactions between the selectins and

their carbohydrate ligands.

3) Firm adhesion: The leukocytes are then activated by

chemokines or other agents to increase the avidity of their integrins.

4) Transmigration: This is mediated by interaction

between platelet endothelial cell adhesion molecule-1 (PECAM-1 or CD31) on

leukocytes and endothelial cells.

vi. Chemotaxis and leukocyte Activation

Adherent leukocytes emigrate through interendothelial junctions, traverse the basement

membrane, and move towards the site of injury along a gradient of chemotactic agents.

Neutrophils emigrate first and monocytes follow. Chemotactic agents for neutrophils

include bacterial products, complement fragments, arachidonic acid metabolites (e.g.

Leukotriene B-4) and certain cytokines.

Chemotaxis involves binding of chemotactic agents to receptors on leukocytes,

phospholipase C activation, incteased intracellular calcium, activation of protein

kinase-C, protein phosphorylation leading to activation of intracellular contractile

proteins. Locomotion is controlled by the effects of calcium ions and phosphoinositols

on actin regulatory proteins such as gelsolin and filamin.

vii. Phagocytosis

Phagocytosis involves attachment of opsonized particles to Fe and C3b receptors on the

surface of leukocytes; Engulfment by pseudopods encircling the phagocytosed paricles,

creating a phagosome; Fusion of lysosomal granules with the phagosome, leading to

de-granulation; Killing and /degradation of bacteria.

viii. Extracellular Release

During phagocytosis, leukocytes release; Lysosomal enzymes by regurgitation during

feeding, reverse endocytosis and cytotoxic release; Oxygen derived active metabolites;

Products of arachidonic acid metabolism.

ix. Defects in Leukocyte function

MPO

MPO+Cl-

O2

O2

H2O2 OCl

OH

Fe2+

Active oxidaseNADPH

NADP+

Membrane oxidase

Cytoplasmic oxidase

Specific granule

Membrane

CYTOPLASM

PHAGOCYTIC VACUOLE

Fig 4: Summary of oxygen dependent bactericidal mechanism within phagocytic vacuole

These interfere with inflammation and inctease susceptibility to infection. They include

both genetic and acquired defects.

Deficiency in the number of circulating cells (neutropenia)

1) Defects in adherence (e.g. leukocyte adhesion deficiency) type I and II

2) Defects in migration and chemotaxis

3) Defects in phagocytosis (e.g. diabetes mellitus)

4) Defects in mivrobicidal activity. In chronic grnulomatous disease there are

ingerited defects in NADPH oxidase leading to a defect in the respiratory burst,

hydrogen peroxide production and the MPO-hydrogen peroxide halide

bactericidal mechanism.

x. Major events in inflammation

Hyperemia

Exudation of fluid

Cellular Exudation

Emigration of leukocytes

xi. Outcome of acute inflammation

Acute inflammation may results in:

1. Complete resolution, with regeneration of native cells and restoration of the site

acute inflammation to normal.

2. Healing by connective tissue replacement and scarring, which occurs after

substantial tissue destruction, when the inflammation occurs in tissues that do not

regenerate or when there is abundant fibrin exudation.

3. Abscess formation.

4. Progression to chronic inflammation.

Chronic Inflammation:

Chronic inflammation is of longer duration and is associated histologically with the

presence of lymphocytes and macrophages, the proliferation of blood vessels, fibrosis,

and tissue necrosis.

Chronic inflammation arises under the following settings:

1.Persistent infections by certain microorganism, such as tubercle bacilli having low

toxicity and evoke an immune reaction called delayed hypersensitivity.

i. Prolonged exposure to potentially toxic agents, either exogenous or endogenous.

ii. Autoimmunity: under certain conditions, immune reactions are set up against the

individual’ own tissues, leading to autoimmune diseases.

1.10. CENTRAL NERVOUS SYSTEM DEPRESSANT

Fig 5: Outcome of acute inflammation

Abscess formation

Damage neutralized, some tissue

damage

Marked neutrophilic response, with tissue

destruction

Tissue damage or injury

Acute inflammation

Damage neutralized, tissue damage minimal

Persisting, damaging agent, with tissue

destruction

Organization through phagocytosis and granulation tissue

formation

Re-growth of dead cells Organization with continued inflammation

ResolutionChronic inflammation

Healing by repair

Central nervous system depression or CNS depression refers to physiological

depression of the central nervous system that can result in decreased rate of breathing,

decreased heart rate, and loss of consciousness possibly leading to coma or death. CNS

depression often results from the use of depressant drugs such as alcohol, opioids,

barbiturates, benzodiazepines,general-anesthetics, and anticonvulsants such as

valproate semisodium used to treat epilepsy. Drug overdose is often caused by

combining two or more depressant drugs, although overdose is certainly possible by

consuming a large dose of one depressant drug. CNS depression can also be caused by

the accidental or intentional inhaling of certain volatile chemicals such as Butanone

(contained in Plastic Cement).

Other common causes of CNS depression are metabolic disturbances, such as

hypoglycaemia.

CNS depression is treated within a hospital setting by maintaining breathing and

circulation. Individuals with reduced breathing may be given supplemental oxygen,

while individuals who are not breathing can be ventilated with bag valve mask

ventilation or by mechanical ventilation with a respirator. Sympathomimetic drugs may

be used to attempt to stimulate cardiac output in order to maintain circulation. CNS

Depression caused by certain drugs may respond to treatment with an antidote.

2. OBEJECTIVE AND RATIONALITY OF THE PRESENT STUDY:

The use of plant products- crude extracts and metabolites in the treatment of various

diseases has not been yet abolished from the modern world. Rather in many parts of the

world, herbal medicine is being popular day by day and the usage rate is increasing.

Besides in underdeveloped and developed countries, traditional herb based therapy has

always got a significant contribution to the total health care system. Since Bangladesh

is enriched with medicinal plants, the present study may direct a significant way of

making best use of these resources. Majorities of our population, who are

impoverished, have to rely on the indigenous system of medication due to their

inability to meet the cost of modern medicine. Many of the indigenous plants of our

country don’t have any scientific bases behind their folklore use. Again plants do have

varied types of molecular entities within and it is not unlikely that a particular plant that

has got traditional indication for a particular disease may exhibit beneficial role in some

other ailments. That is why the present study- bioactivity guided phytochemical

investigation of Piper betle Linn. (Piperaceae) is primarily aimed at ---

1. Rationalization of the traditional use of the selected plant

2. Exploration of possible newer medicinal activities of the same plant and

3. Isolation of the bioactive principles.

2.1. Present Study Protocol

1. Extraction of the powdered plant parts of leaf of Mimosa pudica.

2. Preliminary biological screening of the crude extract for analgesic,anti-

inflammatory activity and CNS depressant for which the plant has popular

folklore usage.

3. Establishment of dose – response relationship.

4. Analysis of statistical significance of all the experiments conducted.

3. PLANT DESCRIPTION:

Mimosa pudica:

Mimosa pudica (from Latin: pudica "shy, bashful or shrinking"; also called sensitive

plant and the touch-me-not), is a creeping annual or perennial herb often grown for its

curiosity value: the compound leaves fold inward and droop when touched or shaken,

re-opening minutes later. The species is native to South America and Central America ,

but is now a pantropical weed.

3.2. Description:

Mimosa is a deciduous, small to medium-sized tree that can grow 20 to 40 feet tall. It is

a member of the legume (Fabaceae) plant family and is capable of fixing nitrogen. The

bark is light brown and smooth while young stems are lime green in color, turning light

brown and covered with lenticels. Leaves are alternately arranged and bipinnately

compound (6 to 20 inches long), having 20 to 60 leaflets per branch. The leaf

arrangement gives mimosa a fern-like or feathery appearance. The flowers are fragrant

and pink in color, about 1½ inches long. Fruits are flat and in pods, a characteristic of

many legumes. Pods are straw-colored and 6 inches long containing 5 to 10 light brown

oval-shaped seeds about ½ inch in length. Pods typically persist on the plant through

the winter months.

Mimosa reproduces both vegetatively and by seed. Seeds require scarification in order

to germinate. This characteristic allows the seed to remain dormant for many years.

Normally seeds are dispersed in close proximity of the parent plant; however, seeds can

also be dispersed by water. Wildlife may also contribute to the spread of mimosa

through the ingestion and excretion of the seeds. Vegetative reproduction occurs when

trees are cut back, causing quick resprouting and regrowth.

Extracts of the plant have been shown in scientific trials to be a moderate diuretic,

depress duodenal contractions similar to atropine sulphone, promote regeneration of

nerves, and reduce menorrhagia (Modern-natural 2001). Anitdepressant activity has

been demonstrated in humans (Martínez and others 1996). Root extracts are reported to

be a strong emetic (Guzmán 1975)."

 

The leaves are bipinnate, meaning that they are compound leaves consisting of many

leaflets arranged on side-branches off the main axis. These leaflets are called pinnae,

and these are sub-divided into many little leaflets called pinnules, thus giving the plant

a fern-like appearance. The pinnae are 2.5 to 5cm long and are made up of elliptical,

0.5cm long pinnules arranged in rows of opposite pairs.

3.4. Taxonomy and nomenclature

Scientific classificationKingdom: Plantae(unranked): Angiosprms (unranked): Eudicots

(unranked): Rosids Order: Fabales

Subfamily: Mimosoideae

Genus: Mimosa Species: M. pudica

Biological:

There are no known biological control agents for the control of mimosa. The plants like

a warm sunny position and a relatively humid atmosphere.

Chemical:  

Mimosa seedlings and small trees can be controlled by applying a 2% solution of

glyphosate or triclopyr plus a 0.25% non-ionic surfactant to thoroughly wet all leaves.

Systemic herbicides such as glyphosate and triclopyr can kill entire plants because the

chemicals travel through a plant from the leaves and stems to the actively growing

roots. Triclopyr is a selective herbicide for many broad-leaved plant species and should

be considered for sites where native or other desirable grasses are meant to be

conserved.

The cut-stump and basal bark herbicidal methods should be considered when treating

individual trees or where the presence of desirable species preclude foliar application.

Stump treatments can be used as long as the ground is not frozen. Horizontally cut

stems at or near ground level. Immediately apply a 25% solution of glyphosate or

triclopyr and water to the cut stump making sure to cover the outer 20% of the stump.

Basal bark applications are effective throughout the year as long as water is not

standing at time of application. Apply a mixture of 25% triclopyr and 75% basal oil to

the base of the tree trunk to a height of 12-15 inches from the ground. Thorough

wetting is necessary for good control; spray until run-off is noticeable at the ground

line. Applications should be made to cut stumps within one minute of cutting.

For larger trees stem injections of imazapyr or triclopyr can be used. For trees already

chopped down apply these herbicides to the stem and stump to prevent resprouting. For

saplings, apply triclopyr as a 20% solution in commercially available basal oil, diesel

fuel, or kerosene (2.5 quarts per 3-gallon mix) with a penetrant (check with herbicide

distributor) to young bark as a basal spray. For resprouts and seedlings thoroughly wet

all leaves with a surfactant in water with and triclopyr or glyphosate herbicide as a 2%

solution (8 ounces per 3-gallon mix between July to October) or clopyralid as a 0.2- to

0.4% solution (1 to 2 ounces per 3-gallon mix between July to September).

PLANT DESCRIPTION

Documented Properties& Actions:

Antibiotic, antimicrobial, anti-neurasthenic, antispasmodic, diuretic, nervine, poison, sedative

PlantChemicals Include:

Ascorbic-acid, crocetin, crocetin-dimethyl-ether, D-glucuronic-acid, D-xylose, linoleic-acid, linolenic-acid, mimosine, mucilage, norepinephrine, oleic-acid, palmitic-acid, sitosterol, stearic-acid

3.8. Chemical constituents

Mimosa pudica contains the toxic alkaloid mimosine, which has been found to also

have antiproliferative and apoptotic effects. The extracts of Mimosa pudica immobilize

the filariform larvae of Strongyloides stercoralis in less than one hour. Aqueous

extracts of the leaf of the plant have shown significant neutralizing effects in the

lethality of the venom of the monocled cobra (Naja Kaouthia). It appears to inhibit the

myotoxicity and enzyme activity of cobra venom.

4. MATERIALS AND METHODS

4.1 Preparation of the Plant Extract

Sample

The sample was the leaf of the plant, Mimosa pudica to study its analgesic,anti-

inflammatory activity and CNS depressant..

Collection of sample

The samples were collected from the Botanical garden of the Jahangirnagar University

and verified with Taxonomy Division of the Botany Department of the university.

Method of drying and pulverizing

The fresh leaf were washed with water immediately after collection. Then they were

dried in oven under 40-500C for 48 hours. When the roots were properly dried they

were ground by using a mechanical grinder to a coarse powder. Before grinding the

machine was cleaned to avoid contamination. The coarse powder was then taken in a

clean airtight container and prepared for extraction.

Method of extraction

The powdered leaves were weight (116gm) and filled in a clean extraction bag. The bag

was placed in a soxhlet extractor. Then petroleum ether (500mL) was used for

extraction. The extraction process was repeated for 10 cycles and in the same way

methanol was used subsequently.

The extracts were collected and dried separately on water bath. The dried extracts were

kept in desiccators.

Application of the extracts

Definite amount of the dried extract that was under study was weighed and dispersed in

suitable amount of alcohol to get suitable means to administer to the experimental

animals.

The experiments were carried out on albino mice (Swiss Strain). They were obtained

from animal house of the Department of Pharmacy, Jahangirnagar University, Savar,

Dhaka. Rats of 2-3 months old, weighing 200-250g, were used. The rates were housed

in plastic cages. They were maintained at room temperature under conditions of natural

light and dark schedule. The rats were fed with ‘rat chow’- prepared according to the

formula developed by the Bangladesh Council for Scientific and Industrial Research

(BCSIR), Dhaka. They were allowed to drink water ad libitum. The standard drug and

extracts were administered to the stomach with the help of feeding needle fitted to

syringe.

Standard Drug and its Solutions

Acetyl Salicylic Acid (Aspirin) (Purity 99.99%) was obtained from the store of the

Pharmacy Department of Jahangirnagar University and used as standard. Solutions of

the drug were prepared according to various dosages regimens in 0.2 ml of ethanol/100

g. B.W. Which were adjusted to a volume of 1 ml/100 g. B.W. with distilled water

during feeding. Doses of the drug were selected as reported in different literature and

pilot experiments were carried out in the study. All drugs were administered orally.

Inflammatory Agent

Among the many methods used for screening and evaluation of anti-inflammatory

drugs, one of the most commonly employed techniques is based upon the ability of

such agents to inhibit the acute inflammatory edema produced in the hind paw of the rat

following injection of a phlogistic agent. In this experiment, the phlogistic agent of

choice was carrageenin; a mucopolysaccharide derived from Iris sea moss, Chondrus

carrageenin (Sigma, Japan) was prepared as 1% solution in water for injection.

Experimental Design

The following experimental study was designed to demonstrate the anti-inflammatory

effect of Mimosa pudica extract and to compare the effect with a standard anti-

inflammatory drug (viz. Aspirin) on induced acute inflammation.

4.2.2 Carrageenin Induced Inflammation

Acute inflammation was induced as described by Winter et all (1962). A volume of

0.05 ml, 1% carrageenin was injected through a 26-gauge needle into the planter

aponeurosis of the right hind paw of the rats. The rats were pretreated with test drugs

before an hour of carrageenin injection. The maximum linear cross section of the joint

(between the central region of the planter aponeurosis and origin of the extensor

hallucis dorsis) was measured before carrageenin administration and similar

measurement were made 3 and 4-hours after the administration of carrageenin to assess

the progress of local inflammation edema. The mean increase in anterior posterior

diameter of paw of each group at 1st, 2nd and 3rd hour after carrageenin injection was

calculated to observe the dependent activity of drugs.

For standard drug testing, increase in paw-diameter 3 hours after carrageenin

administration was considered as a measure of effect. The percentage of edema with

test drugs at different doses compared to control group was calculated.

4.2.3 Formalin test

The antinociceptive activity of the drugs was determined using the formalin test

described by Dubuission and Dennis (1977). Control group received 5% formalin. 20

µl of 5% formalin was injected into the dorsal surface of the right hind paw 30 min

after administration of Mimosa pudica extract (100 and 200 mg/kg, p.o.) and 30 min

after administration of Diclofenac Na (10 mg/kg, i.p.). The mice were observed for 30

min after the injection of formalin, and the amount of time spent licking the injected

hind paw was recorded. The first 5 min post formalin injection is referred to as the

early phase and the period between 15 and 30 min as the late phase. The total time

spent licking or biting the injured paw (pain behavior) was measured with a stop watch.

Grouping of Animals and Their Treatment

The animals in which inflammation was induced by formalin and carrageenin injection

were grouped as follows. The animals were pretreated with the vehicle or drugs one

hour prior to formalin and carrageenin injection.

Group I: This group consists of 3 mice. They were received vehicle, i.e., ethanol in a

volume of 0.2 mo/100 g B.W. in dilute solution orally and served as control.

Group II: This group consisted of 3 mice, which Received indomethacin 10 mg/Kg.

B.W. orally.

Group III (Methanolic extrac): This group included 3 mice that received Mimosa

pudica 100 mg/mice orally.

Group IV (Methanol extract): This group included 3 mice that received Mimosa

pudica 200 mg/mice orally.

4.2.4 Analgesic Activity

Experimental Animal

Young Swiss-albino mice of either sex aged 7-8 weeks, average weight 20-35 gm were

used for the experiment. The mice were purchased from the animal Research Branch of

the International Centre for Diarrheal Disease and Research, Bangladesh (icddr, b).

They were kept in standard environmental condition (at 24.0±0°C temperature & 55-

65% relative humidity and 12 hour light/12 hour dark cycle) for one week for

acclimation after their purchase and fed (icddr, b) formulated rodent food and water ad

libitum. The set of rules followed for animal experiment were approved by the

institutional animal ethical committee.

Experimental Design

Twelve experimental animals were randomly selected and divided into four groups

denoted as group-I, group-II, group-III and group-IV, consisting of 3 mice in each

group. Each group received a particular treatment i.e. control, standard and the dose of

the extracts of the plant respectively. Prior to any treatment, each mouse was weighed

properly and the dose of the test sample and control materials was adjusted

accordingly.

Method of Identification of Animals

Each group consisted of three mice. As it was difficult to observe the biologic response

of three mice at a time receiving same treatment, it was quite necessary to identify

individual animal of a group during the treatment. The animals were marked as M-

1=Mice 1, M-2=Mice 2 and M-3=Mice 3,

Preparation of Test Materials

In order to administer the crude extract at dose of 100 mg/kg and 200mg/kg body

weight of mice, required amount of extract was measured and was triturated

unidirectional way by the addition of small amount of suspending agents (Tween-80).

After proper mixing of extracts and suspending agent, normal saline was slowly added.

The final volume of the suspension was made 5 ml. To stabilize the suspension, it was

stirred well by vortex mixture. For the preparation of Indomethacin at the dose of 10

mg/kg-body weight, required amount of Indomethacin was taken and a suspension of 5

ml was made.

Grouping of Animals and Their Treatment

The animals in which pain was induced by acetic acid injection for writhing test were

grouped as follows. The animals were pretreated with the vehicle or drugs half an hour

prior to acetic acid injection.

Group I: This group consists of 3 mice. They were received vehicle, i.e., ethanol in a

volume of 0.2 mo/100 g B.W. in dilute solution orally and served as control.

Group II: This group consisted of 3 mice, which Received diclofenac 10 mg/Kg.

B.W. orally.

Group III (Methanolic extrac): This group included 3 mice that received Mimosa

pudica root 100 mg/mice orally.

Group IV (Methanol extract): This group included 3 mice that received Mimosa

pudica root 200 mg/mice orally.

Grouping of Animals and Their Treatment

The animals in which pain was induced by formalin injection for licking test were

grouped as follows. The animals were pretreated with the vehicle or drugs half an hour

prior to formalin injection.

Group I: This group consists of 3 mice. They were received vehicle, i.e., ethanol in a

volume of 0.2 mo/100 g B.W. in dilute solution orally and served as control.

Group II: This group consisted of 3 mice, which Received diclofenac 10 mg/Kg.

B.W. orally.

Group III (Methanolic extrac): This group included 3 mice that received Mimosa

pudica root 100 mg/mice orally.

Group IV (Methanol extract): This group included 3 mice that received Mimosa

pudica root 200 mg/mice orally.

Procedure:

At zero hour test samples, and Diclofenac-Na were administered orally by means of a long needle with a ball-shaped end. For control group acetic acid was administered by means of a syringe at that time.

After 30 minutes acetic acid (0.7%) was administered intraperitoneally to each of the animals of all the groups.

30 minutes interval between the oral administration of test materials and intra-peritoneal administration of acetic acid was given to assure proper absorption of the administered samples.

Five minutes after the administration of acetic acid, number of squirms or writhing were counted for each mouse for fifteen minutes.

Figure 8: Schematic representation of procedure for screening of analgesic property on mice by acetic acid induced method for Mimosa pudica root extracts.

Counting of Writhing

Each mouse of all groups were observed individually for counting the number of

writhing they made in 15 minutes commencing just 5 minutes after the intraperitoneal

administration of acetic acid solution. Full writhing was not always accomplished by

the animal, because sometimes the animals started to give writhing but they did not

complete it. This incomplete writhing was considered as half-writhing. Accordingly

two half writhing were taken as one full writhing.

5. CNS depressant activity

5.1. Hole Cross Test

The method used was done as described by Takagi et al [19]. A steel partition was fixed

in the middle of a cage (30 cm×20 cm×14 cm h). A hole (diameter 3 cm) was made in

the steel partition at a height of 7.5 cm above the floor of the cage. The animals were

divided into control, standard and test groups (n = 3 per group). The control group

received vehicle (1% Tween 80 in water at the dose of 10 ml/kg b.wt, p.o.) whereas the

test group received the crude extract (at the doses of 100 and 200mg/kg b.wt, p.o.) and

standard group received diazepam at the dose of 1mg/kg body weight orally. Each

animal was then placed on one side of the chamber and the number of passages of each

animal through the hole from one chamber to the other was recorded for 3 min on 0, 30,

60, and 90 min during the study period.

5.2. Open Field Test

This experiment was carried out as described by Gupta et al [20]. The animals were

divided into control standard and test groups (n = 3 per group). The control group

received vehicle (1% Tween 80 in water at the dose of 10 ml/kg b.wt,p.o.). The test

group received the crude extract (at the doses of 100 and 200 mg/kg b.wt,p.o.) and

standard group received diazepam at the dose of 1mg/kg body weight orally. The

animals were placed on the floor of an open field (100 cm×100 cm×40 cm h) divided

into a series of squares. The number of squares visited by each animal was counted for

3 min on 0, 30, 60, and 90 min during the study period.

Grouping of Animals and Their Treatment

The animals in which experiment for central nervous system depressant were grouped

as follows:

Group I: This group consists of 3 mice. They were received vehicle, i.e., normal water

in a volume of 1ml/mice in orally and served as control.

Group II: This group consisted of 3 mice, which Received diazepam 5 mg/Kg. B.W.

orally.

Group III (Methanolic extract): This group included 3 mice that received Mimosa

pudica root 100 mg/mice orally.

Group IV (Methanol extract): This group included 3 mice that received Mimosa

pudica root 200 mg/mice orally.

6. RESULT AND DISCUSSION

6.1 Anti-inflammatory activity

Figure:1

To the carrageenan induced paw edema mice, the MeOH extract at dose 100 and 200

mg/kg b.wt, exerted a significant and dose dependent inhibition on paw edema

compared to the control group (table 1).

Carrageenan induced edema has been commonly used as an experimental animal model

for acute inflammation and is believed to be biphasic. The early phase (1-2h) of the

carrageenan model is mainly mediated by histamine, serotonin and increased synthesis

of prostaglandins in the damaged tissue surroundings. The late phase is sustained by

prostaglandin release and mediated by bradykinin, leukotrienes, polymorphonuclear

cells and prostaglandins produced by tissue macrophages.

Since the estract significantly inhibited paw edema induced by carrageenan in the

second phase and this finding suggests a possible inhibition of cyclooxygenase

synthesis by the extract and this effect is similar to the produced by non-steroidal anti-

inflammatory drugs such as indomethacin, whose mechanism of action is inhibition of

the cyclooxygenase enzyme.

6.2 Formalin test

Mimosa pudica root (100 and 200 mg/kg, p.o.) significantly (P<0.001) suppressed the

licking activity in either phase of the formalin-induced pain in mice in a dose

dependant manner (Table 2). Mimosa pudica root, at the dose of 200 mg/kg body

weight, showed the more licking activity against both phases of formalin-induced pain

than that of the standard drug diclofenac Na.

Figure:2

Values are mean ± SEM, (n = 3); * p<0.05, Dunnet test as compared to vehicle control.

Group I animals received vehicle (1% Tween 80 in water), Group II received

Diclofenac Na 10 mg/kg body weight, Group III and Group IV were treated with 100

and 200 mg/kg body weight (p.o.) of the Mimosa pudica root..

Acetic acid induced writhing response is a sensitive procedure to evaluate peripherally

acting analgesics and represents pain sensation by triggering localized inflammatory

response. Such pain stimulus leads to the release of free arachidonic acid from the

tissue phospholipid (Ahmed et al., 2006). The response is thought to be mediated by

peritoneal mast cells (Ribeiro et al., 2000), acid sensing ion channels (Voilley, 2004)

and the prostaglandin pathways (Hossain et al., 2006). The organic acid has also been

postulated to act indirectly by inducing the release of endogenous medFiators, which

stimulates the nociceptive neurons that are sensitive to NSAIDs and narcotics (Adzu et

al., 2003). It is well known that non-steroidal anti-inflammatory and analgesic drugs

mitigate the inflammatory pain by inhibiting the formation of pain mediators at the

peripheral target sites where prostaglandins and bradykinin are proposed to play a

significant role in the pain process (Hirose et al., 1984). In addition, it was suggested

that non narcotic analgesics produce their action by interfering with the local reaction

to peritoneal irritation thereby reducing the intensity of afferent nervous stimulation in

the acetic acid induced writhing test, a model of visceral pain (Vogel and Vogel, 1997).

Therefore, it is likely that Mimosa pudica root might have exerted its peripheral

antinociceptive action by interfering with the local reaction caused by the irritant or by

inhibiting the synthesis, release and/or antagonizing the action of pain mediators at the

target sites and this response in agreement with the previous studies with other parts of

Mimosa pudica root. The above findings clearly demonstrated that both central and

peripheral mechanisms are involved in the antinociceptive action of Mimosa pudica

root.. The analgesic activity of Mimosa pudica root could also be linked to the

mechanism of action either on central nervous system or peripheral nervous system.

Interestingly, compounds like flavonoids (Kim et al., 2004) and steroids, triterpenes in

part, have been shown to possess anti-inflammatory, analgesic activity and the claim

made by Pritam et al. (2011). Based on the slasses of compounds detected in Mimosa

pudica root extract, several mechanisms of action could be used ot explain the observed

activities of Mimosa pudica root extract.

The formalin model normally postulates the site and the mechanism of action of the

analgesic (Chau, 1989). This biphasic model is represented by neurogenic (0-5 min)

and inflammatory pain (15-30 min), respectively (Hunskaar and Hole, 1987). Drugs

that act primarily on the central nervous system such as narcotics inhibit both as

steroids and NSAIDs suppress mainly the late phase (Adzu et al., 2003). The

suppression of neurogenic and inflammatory pains by the extract might imply that it

contains active analgesic principle that may be acting both centrally and peripherally.

This is an indication that the extract can be used to manage acute as well as chronic

pain. The mechanism by which formalin triggers C-fibers activation remained unknown

for a relatively long time. Recently, however, McNamara et al., (2007) demonstrated

that formalin activates primary afferent neurons through a specific and direct on

TRPA1, a member of the transient receptor potential family of cation channels,

expressed by a subset of C-fiber nociceptors, and this effect is accompanied by

increased influx of Ca2+ ions. TRPA1 cation channels at primary sensory terminals

were also reported to mediate noxious mechanical stimuli (Kerstein et al., 2009). These

experiments suggest that Ca2+ mobilization through TRPA1cation channels is

concomitant with noxious chemicals and mechanical stimuli as they produce their

analgesic action. It is likely that the inhibitory effect of Mimosa pudica root to pain

response is due to inhibit the increase of the intracellular Ca2+ through TRPA1,

presumably evoked by formalin. So, the bark extract of Mimosa pudica root may

contain substances that affect the metabolism of Ca2+. Literature survey revealed that

tannins, triterpenoids and flavonoid are the major phytoconstituents of Mimosa pudica

root . Flovonoids, for example, have been found to suppress the intracellular Ca2+ ion

elevation in a dose dependent manner, as well as the release of proinflammatory

mediators such as TNFα (Kempuraj et al., 2005).

6.3 Analgesic Activity

Acetic acid-induced writhing test

Table 3 shows the effects of the extract of on acetic acid-induced writhing in mice. The

oral administration of both doses of Mimosa pudica roots significantly (p<0.001)

inhibited writhing response induced by acetic acid in a dose dependent manner.

Table 1: Effects of the Mimosa pudica leaf on acetic acid-induced writhing in mice

Sample Dose (mg/kg) No. of Writhing % inhibition

Vehicle   26.00Diclofenac Na 10 8.00 69.23MeOH 200 54.00 -107.69  400 23.00 11.54

Values are mean ± SEM, (n =3); * p<0.05, Dunnet test as compared to vehicle control.

Group I animals received vehicle (1% Tween 80 in water), Group II received

Diclofenac Na 10 mg/kg body weight, Group III and Group IV were treated with 100

and 200 mg/kg body weight (p.o.) of the Mimosa pudica root..

Table 2: Effect of Mimosa pudica leaf in hindpaw licking in the formalin test in mice

Sample Dose (mg/kg)

Early Phase (sec) % Protection Late Phase

(sec) % Protection

Vehicle   36.00   45.33  

Diclofenac Na 10 11.67 67.59 12.67 72.06MeOH 200 35.00 2.78 24.67 45.59  400 21.67 39.81 17.67 61.03

6.4. Neuropharmacological activity

6.4.1.Open-field test

In the open-field test, Mimusa pudica root extract exhibited a decrease in the

movements of the test animals at all dose levels tested. The results were statistically

significant for all doses and followed a dose-dependent response .

Table 5: Effect of methanolic extract of leaf of Mimosa pudica on Open Field test

in mice

    open field      

    Number of movements

GroupsDose (mg/kg) 0 min 30 min 60 min 90 min

Control Vehicle 119.4 114.80 111.80 104.20

Diazepam 10 114.6 74.00 50.20 20.80

test 1 200 122.8 96.20 82.80 66.20

test 2 400 113.6 88.00 69.20 49.80Values are mean ± SEM, (n = 3); * p<0.05, Dunnet test as compared to vehicle control.

Group I animals received vehicle (1% Tween 80 in water), Group II received diazepam

1 mg/kg body weight, Group III and Group IV were treated with 100 and 200 mg/kg

body weight (p.o.) of the Mimosa pudica root extract.

6.4.2 Hole-cross test

Results of the hole-cross test followed a similar trend to the ones observed in the open-

field test. They were statistically significant for all dose levels and followed a dose-

dependent response. The depressing effect was most intense during the second (60 min)

and third (90 min) observation periods .

Table 6: Effect of methanolic extract of leaf of Mimosa pudica on hole cross test in

mice

    hole cross

GroupsDose (mg/kg)

Number of movements0 min 30 min 60 min 90 min

Control Vehicle 15.80 18.60 17.80 16.60

Diazepam 10 16.00 6.20 2.60 1.40

test 1 200 16.60 10.20 8.40 6.60

test 2 400 17.00 8.80 6.00 4.00

Values are mean ± SEM, (n = 3); * p<0.05, Dunnet test as compared to vehicle control.

Group I animals received vehicle (1% Tween 80 in water), Group II received diazepam

1 mg/kg body weight, Group III and Group IV were treated with 100 and 200 mg/kg

body weight (p.o.) of the Mimosa pudica root extract..

6.4.3 DISCUSSIONS

Locomotor activity considered as an increase in alertness and decrease in locomotor

activity indicated sedative effect [28]. Extracts of Mimusa pudica root decreased

locomotor activity indicates its CNS depressant activity. Gamma-aminobutyric acid

(GABA) is the major inhibitory neurotransmitter in the central nervous system.

Different anxiolytic, muscle relaxant, sedative-hypnotic drugs are elucidation their

action through GABA, therefore it is possible that extracts of Mimusa pudica may acts

by potentiating GABAergic inhibition in the CNS via membrane hyperpolarization

which leads to a decrease in the firing rate of critical neurons in the brain or may be due

to direct activation of GABA receptor by the extracts Many research showed that plant

containing flavonoids, saponins and tannins are useful in many CNS disorders .Earlier

investigation on phytoconstituents and plants suggests that many flavonoids and

neuroactive steroids were found to be ligands for the GABAA receptors in the central

nervous system; which led to assume that they can act as benzodiazepinelike

molecules .Phytochemical investigations also showed the presence of alkaloids,

flavonoids, saponins and tannins in the extract, so might be this phytoconstituents are

responsible for its CNS depressant activity.

CONCLUSION

Our preliminary pharmacological studies on the methanol extract of Mimusa pudica

root provide in part scientific support for the use of this species in traditional medicine,

particularly in various ailments related to CNS disorders, analgesic, and anti-

inflamation . However, further pharmacological investigations are required to

understand its underlying mode of action on the CNS, mechanism of analgesic and

anti-inflamatory activity. In addition, future bioactivity-guided phytochemical work

should be carried out to identify any active constituent(s).

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