CHAPTER 1 INTRODUCTION Evaluation of some plant constituents for immunomodulatory effect 1 Mankind has, throughout its existence, used plant material not only as a source of nutrition but also for numerous other purposes. The plants provided food, clothing, shelter, and medicine. Plants are considered to be medicinal if they possess pharmacological activities of possible therapeutic use. Medicinal plants have been a rich source of medicines because they produce a host of bioactive molecules, most of which probably evolved as chemical defenses against predation or infection. Plant derived drugs are used to cure mental illness, skin diseases, tuberculosis, diabetes, jaundice, hypertension and cancer. Medicinal plants play an important role in the development of potent therapeutic agents. Plant derived drugs came into use in the modern medicine through the uses of plant material as indigenous cure in folklore or traditional systems of medicine. Over the past decade, herbal medicines have been accepted universally, and they have an impact on both world health and international trade. Hence, medicinal plants continue to play an important role in the healthcare system of a large number of the world’s population (Akerele, 1988). Traditional medicine is widely used in India. Even in USA, use of plants and phytomedicines has increased dramatically in the last two decades. A National Centre for Complementary and Alternative Medicine has been established in USA. The herbal products have been classified under ‘dietary supplements’ and are included with vitamins, minerals, amino acids and ‘other products intended to supplement the diet’ (Rao et al., 2004). Use of plants as a medicinal remedy is an integral part of the South African cultural life (Brandt et al., 1995). It is estimated that 27 million South
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CHAPTER 1 INTRODUCTION
Evaluation of some plant constituents for immunomodulatory effect 1
Mankind has, throughout its existence, used plant material not only as a
source of nutrition but also for numerous other purposes. The plants
provided food, clothing, shelter, and medicine. Plants are considered to
be medicinal if they possess pharmacological activities of possible
therapeutic use. Medicinal plants have been a rich source of medicines
because they produce a host of bioactive molecules, most of which
probably evolved as chemical defenses against predation or infection.
Plant derived drugs are used to cure mental illness, skin diseases,
tuberculosis, diabetes, jaundice, hypertension and cancer. Medicinal
plants play an important role in the development of potent therapeutic
agents. Plant derived drugs came into use in the modern medicine
through the uses of plant material as indigenous cure in folklore or
traditional systems of medicine. Over the past decade, herbal medicines
have been accepted universally, and they have an impact on both world
health and international trade. Hence, medicinal plants continue to play
an important role in the healthcare system of a large number of the
world’s population (Akerele, 1988). Traditional medicine is widely used in
India. Even in USA, use of plants and phytomedicines has increased
dramatically in the last two decades. A National Centre for
Complementary and Alternative Medicine has been established in USA.
The herbal products have been classified under ‘dietary supplements’
and are included with vitamins, minerals, amino acids and ‘other
products intended to supplement the diet’ (Rao et al., 2004). Use of
plants as a medicinal remedy is an integral part of the South African
cultural life (Brandt et al., 1995). It is estimated that 27 million South
CHAPTER 1 INTRODUCTION
Evaluation of some plant constituents for immunomodulatory effect 2
Africans use herbal medicines from more than 1020 plant species (Meyer
et al., 1996).
Plants have been the basis of many traditional medicine systems
throughout the world for thousands of years and continue to provide
mankind with new remedies. Plant based medicines initially dispensed
in the form of crude drugs such as tinctures, teas, poultices, powders,
and other herbal formulations (Samuelsson, 2004). The plant based
indigenous knowledge was passed down from generation to generation in
various parts of the world throughout its history and has significantly
contributed to the development of different traditional systems of
medicine. The use of plants as medicines has involved the use of crude
plant drug or the isolation of active compounds, beginning with the
isolation of morphine from opium in the early 19th century (Kinghorn,
2001) and subsequently led to the isolation of early drugs such as
cocaine, codeine, digitoxin and quinine, of which some are still in use.
Numerous molecules have come out of ayurvedic experiential base,
examples include Rauwolfia alkaloids for hypertension, psoralens in
vitiligo, holarrhena alkaloids in amoebiasis, guggulsterones as
hypolipidemic agents, Mucuna pruriens for Parkinson’s disease,
piperidines as bioavailability enhancers, bacosides in mental retention,
picrosides in hepatic protection, phyllanthins as antivirals, curcumin in
inflammation, withanolides, and many other steroidal lactones and
glycosides as immunomodulators (Patwardhan, 2000).
Herbal medicines are currently in demand and their popularity is
increasing day by day. About 500 plants with medicinal use are
CHAPTER 1 INTRODUCTION
Evaluation of some plant constituents for immunomodulatory effect 3
mentioned in ancient literature and around 800 plants have been used
in indigenous systems of medicine. India is a vast repository of medicinal
plants that are used in traditional medical treatments (Chopra et al.,
1956). The WHO (world health organization) estimated that about 80% of
the populations living in the developing countries rely almost exclusively
on traditional medicines for their primary health care needs. In almost
all the traditional medicines, the medicinal plants play a major role and
constitute the backbone of the traditional medicines. Indian Materia
Medica includes about 2000 drugs of natural origin almost all of which
are derived from different traditional system and folk fare practices
(Narayana et al., 1998). India has an ancient heritage of traditional
medicine. The various indigenous systems use several plant species to
treat different ailments in which Ayurveda is the important and most
primitive system of medicine. The Ayurvedic system of medicine
developed an extensive use of medicines from plants dating from at least
1000 BC.
1.1. AYURVEDA
Ayurveda is the oldest system of medicine, which came in to existence
during Vedic times (about 900 BC). It is an upveda (part) of Atharva
Veda. The word Ayurveda is derived from ‘Ayur’ meaning life and ‘Veda’
meaning science. Thus, ayurveda literally means science of life.
Ayurveda deals with the physical, as well as spiritual health. It is based
on the concept of strengthening the host defenses against different
diseases (Thatte and Dahanukar, 1986). The medicinal form is governed
CHAPTER 1 INTRODUCTION
Evaluation of some plant constituents for immunomodulatory effect 4
by the laws of nature, which suggest that life is a combination of senses,
mind, body and soul. It was the first holistic system of diagnosis and
treatment integrating nutrition, hygiene, rejuvenation, and herbal
medicine. It reveals the potential of various herbs generally in polyherbal
formulations as drugs (Dash and Kashyap, 1980). One of the main
approaches in Ayurvedic medicine is to “increase the body’s natural
resistance to the disease/stress” known as “Rasayana” (Rejuvenation)
(Pallabi et al., 1998).
Ayurvedic medicine considers the human body to be in balance
with nature. The body is believed to be a dynamic and resilient system
that can cope with all stresses from its environment while maintaining
the ability to heal itself.''' The main objectives of Ayurveda are to
maintain and promote health by preventing physical, mental, and
spiritual ailments and to cure disease through natural medicine, diet,
and a regulated lifestyle. According to ayurveda, the structural aspect of
every individual comprises five elements - earth, water, fire, air and
space. According to Ayurvedic theory a harmonious balance between
three humors of the body viz,. 'Vayu', 'Pitta' and 'Kaf' is needed for positive
health; imbalance of these may cause disease. A significant part of
Ayurvedic therapeutics is preventive in nature. It aims to promote positive
health so that individuals do not suffer from disease. This is the concept
of "Vyadhirodhak chamatav", i.e. capacity of the body to resist disease
(Katiyar et al., 1997). The practice of Ayurveda therapeutics consisted of
8 sections divided into 180 chapters and listed 314 plants, which are
used as medicines in India.
CHAPTER 1 INTRODUCTION
Evaluation of some plant constituents for immunomodulatory effect 5
In the ayurveda literature, there was much stress on the collection
of plant material during a particular season, from a particular locality
and at a certain time of day. It is now well established that the
concentration and profile of secondary metabolites in a plant depend on
environmental, nutritional and photoperiodic factors. Thus, the correct
type of plant material is essential. Around 1,250 plants are currently
used in various Ayurvedic preparations (Chatterjee and Pakrashi, 1991;
Mills and Kerry, 2000).
Ayurveda remains an important system of medicine and drug
therapy in India. Plant alkaloids are the primary active ingredients of
Ayurvedic drugs. Today the pharmacologically active ingredients of many
Ayurvedic medicines are being identified and their usefulness in drug
therapy being determined. Ayurvedic medicines generally come in the
form of powders, tablets, decoctions, and medicated oils, that are
prepared from natural herbs, plants and minerals. In addition, the
diseases treated and cured by Ayurvedic medicines do not cause any
side effects.
1.2. HERBAL MEDICINE
Medicinal plants play an important role in the development of potent
therapeutic agents. About 500 plants with medicinal use are mentioned
in ancient texts and around 800 plants have been used in indigenous
systems of medicine. Indian subcontinent is a vast repository of
medicinal plants that are used in traditional medical treatments (Chopra
et al., 1956), which also forms a rich source of knowledge. The various
CHAPTER 1 INTRODUCTION
Evaluation of some plant constituents for immunomodulatory effect 6
indigenous systems such as Siddha, Ayurveda, Unani and Allopathy use
several plant species to treat different ailments (Rabe and Staden, 1997).
In India around 20,000 medicinal plant species have been recorded
recently (Dev, 1997), but more than 500 traditional communities use
about 800 plant species for curing different diseases (Kamboj, 2000).
Plant derived drugs are used to cure mental illness, skin diseases,
tuberculosis, diabetes, jaundice, hypertension and cancer. These drugs
provide outstanding contribution to modern therapeutics; for example:
serpentine isolated from the root of Indian plant Rauwolfia serpentina in
1953, was a revolutionary event in the treatment of hypertension and
lowering of blood pressure. Vinblastine isolated from the Catharanthus
roseus (Farnsworth et al., 1967) is used for the treatment of Hodgkins,
choriocarcinoma, non-hodgkins lymphomas, leukemia in children,
testicular and neck cancer. Vincristine is recommended for acute
lymphocytic leukemia in childhood advanced stages of hodgkins,
lymphosarcoma, cervical and breast cancer (Farnsworth and Bingel,
1977). Medicinal herbs as potential source of therapeutics aids has
attained a significant role in health system all over the world for both
humans and animals not only in the diseased condition but also as
potential material for maintaining proper health.
1.3. PLANT AS A SOURCE OF MEDICINE
The plants are of great importance in human’s life. They provide food,
clothing and shelter and besides these plants are the major sources of
medicines. Medicinal plants have been a major source of cure of human
CHAPTER 1 INTRODUCTION
Evaluation of some plant constituents for immunomodulatory effect 7
diseases since time immemorial. Much of the medicinal use of plants
seems to have been developed through observations of wild animals, and
by trial and error. As time went on, each tribe added the medicinal
power of herbs in their area to its knowledge base. A great variety of
plants are used for medicinal treatment.
The whole plant or from different organs, like leaves, stem, bark,
root, flower, seed, etc may be used as herbal drugs. Some drugs are
prepared from excretory plant product such as gum, resins and latex.
These parts taken as whole or compressed as tablets or made into pills,
used to make infusions (teas), extracts, tinctures, etc., or mixed with
excipients to make lotions, ointments, creams, etc.
Rather than using a whole plant, pharmacologists identify, isolate,
extract, and synthesize individual components, thus capturing the active
properties. The medicinal properties of a plant are due to presence of
active ingredients or active constituents or phytochemicals. The activity
of these phytochemicals depends upon the solvent used and the method
of extraction (Eloff, 1998). In addition to active ingredients, plants