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Ethnobotanical Leaflets 12: 373-387. 2008. Origins of Plant Derived Medicines M.
Maridass* and A. John De Britto Animal Health Research Unit & Plant Molecular biology
Research Unit St.Xavier’s College (Autonomous) Palayamkottai-627002 Email: orchideyadass@yahoo.com Issued Abstract This review article describes the origins of plant
derived medicines that have been developed as a result of traditional
knowledge being handed down from one generation to the next. Various
industries are now searching into sources of alternative, more natural and
environmentally friendly antimicrobials, antibiotics, diabetics, antioxidants
and crop protection agents. Medicinal plants have provided a good source of a
wide variety of compounds, such as phenolic compounds, nitrogen compounds,
vitamins, terpenoids and some other secondary metabolites, which are rich in
valuable bioactivities, e.g., antioxidant, anti-inflammatory, antitumor,
antimutagenic, anti-carcinogenic, antibacterial, or antiviral activities.
Medicinal plants have become the main object of chemists, biochemist, and
pharmaceutics. Their research plays an important role for discovering and
developing new drugs that hopefully have more effectiveness and no side
actions like most modern drugs. Origin of Medicine Fossil records revealed that the human use of plants as
traditional medicine date back to middle Paleolithic age, approximately
60,000 years ago (Solecki et al., 1975). The plants were used as flavors,
foods, insect deterrents, ornamentals, fumigants, spices, and cosmetics
(Kunin et al., 1996; Pieroni et al., 2004). Generally, the
medicinally useful plants are sold as commodities in the market, and those
that are sold for medicinal purposes dominate the market (Runner et al., 2001). At present, natural products (and
their derivatives and analogs) represent over 50% of all drugs in clinical
use, in which natural products derived from higher plants represent ca. 25%
of the total (Alandrin et al., 1998). The World Health
Organization estimated that over 80% of the people in developing countries
rely on traditional remedies such as herbs for their daily needs (Tripathi et al., 2003), and about 855
traditional medicines include used crude plant extracts. This means that about 3.5 to 4 billion of
the global population rely on plants resources for drugs (Farnsworth, 1988). Many infectious diseases are
known to be treated with herbal remedies throughout the history of mankind. The maximum therapeutic and minimum side
effects of herbal remedies have demonstrated or verified in numerous
scientific investigations. Even today,
plant materials continue to play a major role in primary health care as
therapeutic remedies in many developing countries (Czygan, 1993; Ody,
1993). Market
Demands of Medicinal Plants Nearly 95 percentage of
plants used in traditional medicines are collected from forests and other
natural sources. The plants collected from different sources show wide disparity
in therapeutic values and also much variation in market rates. In the recent
years there has been greater expansion of indigenous drug industry in New medicines have been discovered with traditional,
empirical and molecular approaches ( Table 1. Currently
used Drugs in the United States that are obtained from flowering Plants.
Natural products have provided many
effective drugs. These include a wide
range of older drugs such as quinine (Kremsner et al., 1994) and morphine (Benyhe et al., 1994) and newer drugs such as paclitaxel (TaxolTM) (Wani et al., 1971), camptothecin (Wall et al., 1966), etoposide (Endo et al., 1976), mevastatin
(Keller-Juslén, et al., 1971), and
artemisinin (Klayman, 1985). Further evidence of the importance of natural
products is provided by the fact that almost half of the world’s 25 best
selling pharmaceuticals in 1991 were either natural product or their
derivatives (O’Neill, 1993).
The number of higher plant species (angiosperms and
gymnosperms) on planet earth is estimated around 250,000 (Ayensu et al., 1978),
with a lower level at 215,000 (Cronquist, 1981) and an upper level high as
500,000 (Tippo et al., 1977; Schultes, 1972). Of these, only about 6%
have been screened for biological activity, and only 15% have been
pharmacologically screened. Moreover, plant extracts contain up to several
thousands of secondary metabolites. The major types of compounds identified
in Indian medicinal herbs include alkaloids, saponin, flavonoids,
anthroquinones, terpenoids, coumarins, lignans, polysaccharides, polypeptides
and proteins. Efficient detection and rapid characterization of these
components on a molecular basis offer better understanding of the
pharmacological application of Indian herbal medicines. Plant-Derived Drugs from Traditional Systems of Medicine For thousands of years, plant-derived (herbal) remedies
have remained a vital part of traditional Chinese medicine, and even today it
constitute about a 30% to 50% proportion of the total drug therapy for a
fifth of the world’s population who live in the People’s Republic of The drugs commonly used in People’s
Republic of China PRC include tropane alkaloids anisodamine and anisodine
from Scopolia tangutica, which are employed as a mild, naturally
acting anticholinergic agent for
septic shock in cases of bacillary dysentery, and in the treatment of migrane
headache. An isoquinoline alkaloid, racemic tetrahydropalmatine, from Corydalis
ambigua is used as an analgesic and tranquilizer, and indirubrin, a
nitrogen-containing metabolite produced by Indigofera tinctoria, is
effective in the treatment of chronic myelocytic leukemia (Xiao and Fu, 1987;
Han et al., 1988). Plant-Derived Antibacterial Chemotherapeutants Infectious disease is the number one cause of death
accounting for approximately one-half of all deaths in tropical countries.
Death from infectious diseases, ranked 5th in 1981, has become the
3rd leading cause of death in 1992, with an increase of 58%
(Pinner et al., 1996). More than hundreds of plants world wide are used in
traditional medicine as treatments for bacterial infection (Martin et al.,
2003). Although many have been treated by conventional pharmaceutical
approaches, there is a growing interest in the use of natural products by the
general public. In addition the pharmaceutical industry continues to examine
their potential as sources novel growth factor, immunomodulatory and
antimicrobial activity (Ghose et al., 2003). Plant-Derived Wound Healing Agents Wound healing occupies an
important field of research in modern biomedical sciences. Wound
healing involves cellular, physiological, biochemical and molecular processes
which result ultimately in connective tissue repair and the formation of a
fibrous scar (Peacock, 1988). Wound healing process uses a combination of
three mechanisms. Contraction is the major method by which wound healing
occurs at an amputation site, such as the tip of a finger. Epithelisation predominates
in the healing of abrasions and connective tissue deposition occurs when
lacerations are sutured and closed (Cockbill et al., 2000). Healing of wound is an important part of the reparative process.
A detailed pathophysiology of wound was better understood following the
establishment of the theory of a cell signal cascade system involved in the
formation of new tissues repairing the wound. Like the alchemist’s dream of
turning base metal into gold, efforts aimed at achieving a perfect wound
healing has inspired many researchers in trying various therapeutic options
which were thought to aid or accelerate the wound healing process. The
cheaper and more effective the agent, may be better
for the patient. Durodola (1977) demonstrated the effectiveness of crude extract of Ageratum conyzoides in inhibiting the growth of Staphylococcus aureus, a major wound pathogen in in-vitro cultures of
the organism. Much work has recently been done on the wound healing effect of
several medicinal plants (Oladejo et
al., 2003; Biswas et al., 2003; Abo et al., 2004; Biswas et
al., 2004). Plant-Derived
Anti-Diarrhoeal Agents Diarrhoea is a major health
problem especially for children under the age of 5 years and up to 17% of all
death in the indoor pediatric patients is related to diarrhoea. Worldwide incidence of diarrhoeal death
account for more than 5-8 million each year in infants and small children
less than 5 year especially in developing countries (Fauci et al., 1998). According to WHO estimate for the year
1998, there were about 7.1 million deaths due to diarrhoea (Park et al., 2000).
A range of medicinal plants with anti-diarrhoeal properties has been widely
used by the traditional healers; however, the effectiveness of many of these
anti-diarrhoeal traditional medicines have not been scientifically evaluated
(Chitme et al., 2004). Plant-Derived
Anti-Diabetic Agents There are 143 million people worldwide
suffering from diabetes, almost five times more than the estimates ten years
ago. This number may probably double by the year 2030. Therefore, the global
human population appears to be in the midst of an epidemic of diabetes.
Reports from the World Health Organization (WHO) indicate that diabetes
mellitus is one of the major killers of our time, with people in Diabetes mellitus is a
metabolic disorder characterized by hyperglycemia. It may be secondary to a
deficiency or disturbance in the secretion of insulin or to an abnormal
response of peripheral tissues to insulin. The resulting metabolic
derangement of the intermediary metabolism of carbohydrate, lipid, and
protein affects all organ systems but most prominent in the arteries,
arterioles, and capillaries (Damjanov et
al., 1996). There are two main categories of this disease. Type 1
diabetes mellitus also called insulin-dependent diabetes mellitus (IDDM) and Type 2, the non-insulin-dependent diabetes mellitus (NIDDM). IDDM
represents a heterogenous and polygenic disorder, with a number of non-HLA
loci (about 20) contributing to the disease susceptibility. Though this form
of diabetes accounts for 5 to 10% of all cases, the incidence is rapidly
increasing in specific regions. It is
estimated that incidence of Type 1 diabetes will be about 40% higher in the
year 2010 than in 1997, and yet there is no identified agent substantially
capable of preventing this type of disease. NIDDM is far more common and
results from a combination of defects in insulin secretion and action. This
type of disease accounts for 90 to 95% of all diabetic patients. Treatment of
type 2 diabetes is complicated by several factors inherent to the disease
process, typically, insulin resistance, hyperinsulinemia, impaired insulin
secretion, and reduced insulin-mediated glucose uptake and utilization
(Tiwari and Madhusudana Rao, 2002). The recommended use of plants in the treatment for
diabetes needs to be evaluated. Plants are important not only for the control
of type 2DM but also for its prevention, especially for people with elevated
levels of blood glucose and blood intolerance who have a greater risk of
developing diabetes (Anderson et al.,
2004).
Botanical products can improve glucose metabolism and the
overall condition of individuals with diabetes not only by hypoglycemic
effects but also by improving lipid metabolism, antioxidant status, and
capillary function (Bailey et al., 1989). A number of medicinal/culinary
herbs have been reported to yield hypoglycemic effects in subjects with
diabetes. These include cinnamon, cloves, bay leaves,
turmeric (Khan et al., 1990), bitter melon (Srivastava et al.,
1993; Raman and Lau, 1996), gurmar (Basakaran et al., 1990; Shanmugasundaram
et al., 1990; Bishayee and Chatterjee, 1994), Korean ginseng (Sotaniemi et al., 1995), onions and
garlic (Koch and Lawson, 1996), holy basil (Rai et al.,
1997). Table 2. Chemical drugs and drugs from medicinal plants.
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