The Promise of Traditional Medicines
The usage of plants, plant extracts or plant-derived pure chemicals to treat disease become a therapeutic modality, which has stood the test of time. Today several pharmacological classes of drugs include a natural product prototype. Aspirin, atropine, ephedrine, digoxin, morphine, quinine, reserpine and tubocurarine are a few examples of modern drugs, which were originally discovered through the study of traditional cures and folk knowledge of indigenous people. A team work amongst ethnobotanists, ethnopharmacologists, physicians and phytochemists is must for the fruitful outcome on medicinal plants research. While the ethnopharmacologists have a greater role in the rationalization of combination of activities, the phytochemists role will slightly shift towards standardization of herbal medicines.
Received: March 28, 2010;
Accepted: May 02, 2010;
Published: August 13, 2010
Traditional or herbal medicine is in an evolutionary process as communities
and individuals continue to discover new techniques that can transform practices
in the field of medical sciences. Traditional medicine and drug discovery using
natural products still important issues in the current target-rich, lead-poor
scenario (Patwardhan et al., 2004).
According to the World Health Organization (WHO), about three-quarters of the
world population depends upon traditional remedies (mainly herbs) for the health
care of its people. In fact, herbs/plants are the oldest friends of human being.
They not only provided food and shelter but also served the humanity to cure
different dysfunctions. The traditional medicines also sometime called as, herbal
or natural medicine existed in one way or another in different cultures/civilizations,
such as Egyptians, Western, Chinese, Kampo (Japan) and Greco-Arab or Unani/Tibb
(South Asia). Historians from all around the world have produced evidence to
show that apparently all primitive peoples used plants often in a sophisticated
way. Quinine from Cinchona bark was used to manage the symptoms of malaria long
before the disease was identified and the raw ingredients of a common or garden
aspirin tablet have been a popular painkiller for far longer than we have had
access to tablet-making machinery. By the middle of the nineteenth century at
least 80% of all medicines were derived from plants. Then came the revolution
inspired by the development of the pharmaceutical industry and synthetic drugs
dominated, though traditional medicine has never been out of scene. Even today
if you visit to any pharmacy in the West, you will find at least 25% plant derived
drugs. Moreover today many pharmacological classes of drugs include a natural
product prototype (Gilani et al., 1992).
Traditional medicines have given us very useful synthetic clues of modern drugs
in the past (Table 1) (Gregory, 2004).
Most of these plant-derived drugs were originally discovered through the study
of herbal cures and folk knowledge of traditional people and some of these could
not be substituted despite the enormous advancement in synthetic chemistry (Gilani
et al., 1998).
Herbal products are also commonly used patients with certain chronic medical
dysfunctions, including breast cancer (12%), liver disease (21%), human immunodeficiency
virus (22%), asthma (24%) and rheumatological disorders (26%) (Inamdar
et al., 2008). A lot of traditional medicines have been reported
with different pharmacological actions (Table 2) (Gregory,
Traditional medicine safety and standards: Figure 1
a flow chart for the study of plants used in traditional medicine , the
most important feature of all health care is to do no harm (Oath of Maimonides);
assuring that whatever is being taken by humans for medicinal purposes is safe.
Effectiveness is a secondary consideration. Many users of herbal medicines consider
that they are safe for human consumption; an assumption based, in part, on extensive
prior field experience.
|| Few examples of plant-derived modern drugs
||Examples of well known herbs and their proposed pharmacological
If this concept ever had validity, it is now no longer correct. In different
parts of the world, phytotherapeutical products are frequently used with over-the-counter
(OTC) and prescription products (Anonymous, 2000).
Various formulations of traditional drugs are available in the market Worldwide
(Table 3). In the US market, tablet and capsule formulations
the famous one, while overseas, teas or infusions of herbs are the most popular
(Gregory, 2004). The WHO has issued a set of some guidelines
for the study of traditional medicines (Anonymous, 2000).
|| List of traditional drug formulations
On a batch-to-batch basis there must be botanical, chemical and biological
standardization of products and collateral studies which would establish both
the safety of the product and a demonstration of its efficacy and meaningful
shelf-life. Real time PCR (polymerase chain reaction) analysis on a microchip
will become a standard procedure for the authentication of phytotherapeutic
constituents (Carles et al., 2001). Multi component
analytical systems will have a significant stress in the area of routine chemical
standardization. Quick, cheap, accurate and clinically relevant biological systems,
usually microarray-based, will demonstrate (verify) the level of biological
activity for each batch of marketable product (Prasad et
Synergistic (side-effects nullifying) combinations in plants: The presence
of synergistic and/or side-effects neutralizing combinations in medicinal plants
is a long-established concept put forth by the Hippocrates and strengthened
by Ibn Sina and others; however, this concept remained dormant and lacks sufficient
scientific evidence mainly due to scarcity of ethnopharmacologists with wider
background (Gilani et al., 2000, 2005c).
An alternate approach to bring about cholinergic effect is through inhibition
of an endogenous enzyme (ACE), responsible for the breakdown of endogenous Ach,
thus making availability of enhanced level of Ach at the desired site, as is
the case for the use of ACE inhibitors in myasthenia gravis, senile dementia
and Alzheimers Disease (AD). ACE inhibitor potential has been reported
in medicinal plants (Rahman and Choudhary, 2001; Khalid
et al., 2004; Gilani et al., 2004,
2005a) and thus provided scientific basis for some of
the traditional uses of the respective medicinal plants.
Khalid et al. (2004) and Gilani
et al. (2005a) reported the presence of a unique combination of
activities (ACE inhibitory and calcium antagonist) in Sarcococca saligna
with active chemicals identified Similarly, juliflorine from Prosopis
juliflora and Withanolides from Withania somnifera were found to
possess this special combination of activities (Choudhary
et al., 2005a, b).
|| A flow chart for the study of plants used in traditional
Turmeric (rhizome of Curcuma longa) has been traditionally used as antispasmodic
and bronchodilator along with other multiple uses (Gilani
et al., 2005b). St. Johns Wort (Hypericum perforatum) is
a well known botanical having already being used for mild to moderate depression
and its antidepressant actions are said to be mediated through multiple modes,
such as inhibition of monoamine oxidase, catechol-o-methyltransferase and dopamine
hydroxylase (Thiede and Walper, 1994; Kleber
et al., 1999; Ron et al., 2000), by
blocking synaptic reuptake of 5-HT (5-hydroxy tryptamine), nor adrenaline, dopamine,
GABA (Gamma Amino Butyric Acid) and L-glutamate (Muller,
2003), inhibiting nitric oxide synthetase (Luo et
al., 2004) .
These examples indicate that the herbs in their crude form show interesting combination of activities and there is a huge potential of medicinal plants not only as a source of new drugs but also their use in the form of botanicals both in developing countries and the industrialized world.
If humanity is going to survive, let alone continue to evolve, major shifts
in the consumption of renewable versus non renewable resources are required.
What we must strive for is an open vision of the ways in which current resources
and technologies and those to be developed, can be utilized most favourably
for the future health care. We must develop and continually reaffirm a vision
that, few decades (30-40 years) from now, for some of the reasons outlined above,
that there will be a well defined requirement for safe, effective, standardized
and sustainable natural products in global health care (Cordell,
2000, 2004; Cordell et al.,
2001). There must be a willingness on both sides, those who have the resources
and those who wish to assist in the investigation and potential development
of those resources, to initiate and maintain innovative agreements for the training
of local personnel, for the establishment of local herbaria and research laboratories
and for the distribution of royalty and licensing income (Soejarto
et al., 2002).
Future impact: The time has come to now to evaluate what the future
impact of natural products must be in global health care as single agent drugs
and as standardized traditional medicines. Nearly 5750 different natural product
skeletal, from the perspective of interactions with enzymes and receptors, represent
substantially greater chemical diversity space and is more reflective of the
chemical diversity space of drugs, as compare to the known range of combinatorial
compounds (Feher and Schmidt, 2003).
Comparatively, there are relatively limited numbers of natural products and
of those, very few have been given even cursory biological evaluation (Cordell
et al., 2001). While considering the development of single drug agents,
one could make the case for enhanced structure diversification through a number
of pathways including combinatorial chemistry, combinatorial biosynthesis, chemistry
on plant extracts, find alternative, previously untapped sources (e.g., endophytic
fungi, extremophile microbes, or those difficult to culture. There is the future
potential of having available the full biosynthetic capacity of an organism,
rather than only that present at a particular point in time. Genetically controlling
natural product biosynthesis is challenging at the core of enhancing the consistent
availability of biologically significant natural products, either as single
agents or as a multiple component mixtures (Cordell, 2004).
If plants are to be effective and reproducible factories for the production
of medicinal agents for whole world, the molecular switches which command the
overall pathway and the specific enzymes involved in secondary metabolite formation,
must be profoundly clear and understood (Boonstra et
al., 2001). Biocatalysis, using isolated enzyme systems is another criterion
to improve natural product structural diversity and to conduct reactions which
have no parallel in organic synthesis (Rathbone et al.,
2002). Approximately 21,200 alkaloids, 76% have never been evaluated in
a single bioassay (Cordell et al., 2001).
We should continually evolve the vision of the role of traditional medicine and the natural product sciences for the future, when the pressures on available resources, including land use, water and oil, will be quite different. We should completely integrate all of the available technologies into developing the societal role of traditional medicine in global health care. It is duty to create these visions and maintain them for the creative growth of the health care of individuals and for the security and stability of societies. The future of traditional medicine needs that you be a visionary global scientist. Innovative strategies employing all of the associated sciences and technologies must be created in order that the natural product sciences, including traditional medicine, can help in the development, in a sustainable manner, of the foods and the health care products, including drugs, for a dramatically expanding worldwide population. Finally, we must promote the development of multidisciplinary, international, collaborative research programs which will encourage the local and global scientific development of our natural resources. A team work amongst ethnobotanists, ethnopharmacologists, physicians and phytochemists is must for the fruitful outcome on medicinal plants research. While the ethnopharmacologists have a greater role in the rationalization of combination of activities, the phytochemists role will slightly shift towards standardization of herbal medicines.
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