Journal of Medicinal Plants Research Vol. 4(2), pp.

072-081, 18 January, 2010

Available online at http://www.academicjournals.org/JMPR
DOI: 10.5897/JMPR09.005
ISSN 1996-0875 2010 Academic Journals

Review

Current phytotherapy - A perspective on the science

and regulation of herbal medicine
Sunday J. Ameh1*, Obiageli O. Obodozie1, Uford S. Inyang1, Mujitaba S. Abubakar2 and
Magaji Garba3
1

Department of Medicinal Chemistry and Quality Control, National Institute for Pharmaceutical Research and
Development (NIPRD), P. M. B. 21, Garki, Idu Industrial Area, Abuja, Nigeria.
2
Department of Pharmacognosy and Drug Development, Ahmadu Bello University, Kaduna State, Zaria.
3
Department of Pharmaceutical and Medicinal Chemistry, Ahmadu Bello University, Kaduna State, Zaria.
Accepted 15 October, 2009

Phytotherapy is the use of plant materials to prevent and treat ill health or promote wellness. The
practice dates to antiquity, yet remains current. It began in Mesopotamia, and subsequently spread to
the rest of the Old World. The primacy of herbalism in medicine is evident from the large number of
modern drugs that owe their origin to ethnobotanical remedies. This review traces the origins, the
science and breakthroughs, and the effort of the World Health Organization to regulate herbal medicine.
It notes three instruments as decisive in that effort: the Alma-ata Declaration of 1978; the manual on
quality control of medicinal plant materials of 1998; and the general guidelines for methodologies on
research and evaluation of Traditional Medicine of 2000. This review notes that while plants synthesize
a large variety of secondary metabolites for various ecophysiological causes, most of such metabolites
originate from a relatively few biosynthetic pathways. The pathways include those for alkaloids;
terpenes/ terpenoid/ steroids; shikimic acid/ aromatics; and polyketides. These secondary metabolites,
better called phytochemicals, affect man in ways that require that their production, quality, distribution
and use be regulated. The review comments on the impact of World Health Organization on the
regulation of herbal medicine.
Key words: Phytotherapy, world health organization (WHO), traditional medicine, Alma-ata declaration,
ecophysiological causes, biosynthetic pathway, phytochemical, quality control, regulation.
INTRODUCTION
Three decisive events connected with the current
popularity of herbal medicine include: the Alma-ata
Declaration (WHO, 1978); the manual on quality control
methods for medicinal plant materials (WHO, 1998); and
the general guidelines for methodologies on research and
evaluation of Traditional Medicine (WHO, 2000).
Currently, medicinal plant research is one of the fastest
growing areas of biomedical research. This is illustrated
by the following observation: The number of citations in
PubMed from 1990 - 2007 containing the word phytotherapy was less than 100 in 1990, but rose to over 1, 000
in 1998, then to 12, 000 in 2005, and to over 15, 000 in
2007 (Wikipedia-phytotherapy, 2008). In 1999, the world

*Corresponding author.
2348053691277.

E-mail:

sjitodo@yahoo.com.

Tel:

market for herbal remedies was US$19.4 billion, with

Europe in the lead (US$6.7 billion), followed by Asia
(US$5.1 billion), North America (US$4.0 billion), Japan
(US$2.2 billion) and the rest of the world (US$1.4 billion).
As at 2003 over 50, 000 plants were in use for medicinal
purposes worldwide (Mapdb.com, 2003). This trend or
outlook for phytotherapy is assumed to result partly from
the failure of chemical agents to fully realize the hope it
raised when Paul Ehrlich introduced Salvarsan in 1909.
Ehrlich had coined the term chemotherapy to refer to
the use of chemical agents (pharmaceutical medicines) to
treat illnesses. The prevailing conception of chemotherapy had led biomedical scientists to imagine that
someday there will be for every disease a magic bullet
(Albert, 1981).

However, owing to the supposed failure of pharmaceutical medicine, phytotherapy, which had begun to gain
more ground after the Alma-ata Declaration in 1978,

In the New World, especially North America, herbal

medicine became a blend of two separate traditions:
European herbalism, brought by Europeans; and the
herbal traditions of Native Americans. During the 1800s
Ameh et al.
073

entered a new phase of rapid growth in the early 1990s.

Aim of the review
Three decades after the Alma-ata Declaration of 1978,
the time has come to take stock of the historical development of phytotherapy. This review will attempt to do
this by examining issues or queries such as:
(1) Why has phytotherapy become so popular today?
(2) How have the advances in the science of medicinal
plants facilitated the rise and popularity of phytotherapy?
(3) What are phytochemicals and why do plants produce
them in the first place?
Why did the WHO take the bold step of regulating the use
of phytochemicals in health and disease?
(4) This review aims to draw the attention of scholars to
the vast literature on this subject, with a view to sharpening the focus of research in medical herbalism.
HERBALISM AS AN ANCIENT PRACTICE
It is generally agreed that herbalism is an ancient practice
worldwide. Lietava (1992) provided evidence that
Neanderthals, living thousands of years ago in presentday Iraq, used plants for medicinal purposes, similar to
those described some 3,000 years ago in 2 Chronicles
16:13 - 14: Asa ....died in the one and fortieth year of his
reign. And they buried him in his own sepulchres, which
he had made for himself in the city of David, and laid him
in the bed which was filled with sweet odours and divers
kinds of spices prepared by the apothecaries art. It is
notable that the word apothecary or apothecaries,
meaning pharmacist, occurs six times in the Scofield
Study Bible (1996), indicating that pharmacy is as old as
religion.
It is also generally agreed that from time immemorial,
people practiced herbal medicine as an integral part of
religious art, and that from such origins, the systems of
herbalism developed in the Middle East (Green, 2006),
Africa (Elujoba, 2005), Asia (Ninivaggi, 2001)
and
Europe (herbplace.com, 2009). Among the earliest
reports of herbalism is that of Emperor Shen Nung of
China (3000 - 2700 BC) who had a pharmacopoeia that
included chaulmoogra oil for treating leprosy (Sofowora,
1982). Other reports include: Ebers papyrus, dated 1550
BC, describing plants used in Egypt; a classification of
medicinal plants by Theophrastus (370 - 285 BC); De
Materia Medica (77 AD), listing over 600 remedies,
mostly of plants; list of over 1400 drugs and medicinal
plants in Corpus of Simples (people.vcu.edu, 2009a).

the most effective American healers combined European

and Native American herbalism. By the 1850s the influx
of Chinese immigrants added Chinese herbal traditions to
the mix. However, this triple heritage began to decline
after the American Civil War, partly because conventional
medicine improved during that war, and because of the
highly influential Flexner Report of 1910, which favoured
conventional medicine, but was critical of herbal medicine
and other alternative approaches (Pelletier, 2008) In
South and Central America, where Native American and
European herbal traditions had been in vogue, there
came a third factor - Yoruba herbalism (Grotte, 2008),
made possible by the Atlantic Slave Trade.
BIOCHEMISTRY OF HERBAL DRUGS
Herbal drugs are the secondary metabolites of plants.
They are better called phytochemicals, to differentiate
them from primary metabolites because they are needed
for growth and maintenance. By contrast, phytochemicals
are required only indirectly, to enable plants survive and
reproduce in a given competitive ecosystem. Medicinally
useful phytochemicals fall into a relatively few broad
groups, but perform several functions. Some are toxins,
used to deter predation; some are pheromones, used to
attract insects for pollination; others are phytoalexins,
which protect against microbial infections; and yet others
are allelochemicals, which inhibit rival plants competing
for soil and light (Lai, 2004; Tapsell, 2006; Taiz and
Zeiger, 2006). Thus, although plants synthesize a large
variety of phytochemicals, most are derivatives of a
relatively few biosynthetic pathways (people.vcu.edu,
2009a). These are briefly outlined.
Biosynthesis of alkaloids from amino acids
In nature, alkaloids represent a diverse group of compounds that are related only by the occurrence of one or
more atoms of nitrogen in a heterocyclic ring. Plants
produce about 12,000 alkaloids that are organized into
groups according to their carbon skeleton (Ziegler and
Facchini, 2008). The nitrogen makes the compounds
basic, so that they exist as salts in the plant. Plant alkaloids are often toxic to animals; have a complex structure;
and are widely distributed in plants. The structures of
some are given in Figure 1.
Among the most famous alkaloids are: the cinchonines,
of which quinine is an example; the tropane alkaloids, of
which hyoscyamine and cocaine are examples. Others
include: the ergot alkaloids, of which the most famous is
lysergic acid diethylamide (LSD) - a synthetic derivative
of the ergot alkaloid, ergine. Others include opium

alkaloids, of which morphine is an example. The well

known drug of addiction, heroine, is a synthetic derivative
074
J. Med. Plant. Res.

of morphine obtained by acetylation. The structures of the

four examples are shown in Figure 2).

HO

COOMe

MeO

O
OH

N
Quinine

Cocaine

Hyoscyamine

Figure 1: Plants produce 12, 000 alkaloids representing a diverse group related only by the
occurrence of 1 or 2 atoms of nitrogen in a heterocyclic ring as shown in the 3 examples above.
NH2

NEt2
O

AcO

HO
N

O
N

N
LSD - Lysergic Acid Diethylamide

HO

Ergine - natural LSD Morphine

N
AcO
Heroine

Figure 2: Above are examples of drugs of addictions, lysergic acid diethylamide (LSD) an ergot
alkaloid derived from ergine; and heroine an opium alkaloid derived from morphine.

CHO

Myrcene

Citral

Menthene

Carvone

Figure 3: Above are examples of acyclic monoterpenes - myrcene and citral; and of
cyclic monoterpenes menthene and carvone.

Some alkaloids are not so easily classified, however.

An example is vincristine - an extremely complex alkaloid
isolated from Catharanthus roseus, along with vinblastine, a homologue in which the N-methyl group is
oxidized to an aldehyde.
The precursors of most alkaloids are L-amino acids.
For example cocaine and coniine are derived from
ornithine and lysine respectively, while noradrenalin and
mescaline are derived from phenylalanine and tyrosine
respectively. Strychnine and LSD are derived from
tryptophan, while morphine is from tyrosine (Ziegler and
Facchini, 2008).
Biosynthesis of terpenes, terpenoids and steroids
from isoprene
Terpenes are a large and varied class of hydrocarbons,
produced by a wide variety of plants. Each terpene
(C10H16) consists of a pair of isoprenes (C5H8). The
names monoterpenes (C10H16), sesquiterpenes (C15H24),

diterpenes (C20H32) and triterpenes (C30H48) are based on

the number of isoprene units. The mono- and sesquiterpenes are the so called essential oils, and have been
utilized in perfumery since ancient times (people.vcu.edu,
2009c).
A few examples of essential oils are indicated in the
structures in Figure 3. Myrcene and Citral are examples
of acyclic monoterpenes, while menthene and carvone
are cyclic monoterpenes.
The name "terpene" is derived from "turpentine". Terpenes, as biosynthetic precursors, are found in all living
things. For example, steroids are derivatives of the triterpene, squalene. Terpenes and their oxidation products
are the main constituents of the essential oils of plants
used widely as food colorants and flavorants; and as
fragrances in perfumery, and as agents in aromatherapy.
When terpenes are modified by oxidation with or without
rearrangement of the carbon backbone, the resulting
compounds are called terpenoids. Citral and carvone are
examples of acyclic and cyclic monoterpenoids respectively. Some authors however, use the term terpene to

include all terpenoids. Included among the terpenoids are

also the carotenoids, which are the attractive colorants of

tomatoes, oranges, yellow corn, pumpkin and grape.

They are tetraterpenoids.
Ameh et al.
075

OH

O
OH

(+) Camphor

Menthol

Thujone

Tetrahydrocannabinol

Figure 4: Menthol, camphor, thujone and the cannabinoids found in Cannabis sativa are typical of the terpenoids.

OH

CHO

COOH
HO

OH

OMe

OH

OH

OH

Shikimic acid

Vanilin

Salicyclic acid

OH

MeO
HO

Scopoletin

Hydroxyquinone

Figure 5: Aromatics derived from shikimic acid vary in complexity from the simple vanillin, salicylic acid,
hydroxyquinone and scopoletin; to the more complex podophyllotoxin.

COOH
pyruvic acid
HO

COOH

+
O

OH

HO

OH
OH

HO
OH

erythrose

shikimic acid

Figure 6: Shikimic acid, a precursor of many medicinal phytochemicals secondary metabolites,

is formed from two primary metabolites - pyruvic acid and erythrose.

Other important derivatives of isoprene are: vitamin A, a

diterpenoid; quinones, such as vitamin K; alcohols, such
as vitamin E; and sterols, such as vitamin D. Terpenoids
are responsible for the aroma of eucalyptus and the
flavors of cinnamon, cloves and ginger. Other well-known
terpenoids include menthol, camphor, thujone and the
cannabinoids found in Cannabis sativa (Figure 4).

ted (people.vcu.edu (2009d). The acid is a precursor of

many important compounds, including:
(1) Two key aromatic amino acids - phenylalanine and
tyrosine.
(2) Indole containing aromatic derivatives - for example,
tryptophan.
(3) Many alkaloids and other aromatic derivatives.
(4) Tannins, flavonoids, and lignin.

Biosynthesis of aromatics and other products of

shikimic acid pathway

Aromatics contain at least one benzene ring. Included

among them are the flavones and isoflavones and their
substituted products, collectively called anthocyanins that give flowers, fruits and seeds their various colours.
Quercetin is a substituted flavone, or a flavinoid. Also
included are the tannins that give teas their astringency
(people.vcu.edu (2009d) (Figure 7).
Tannins are mostly colorless, widespread in nature,
and many are glycosides. They are non-crystalline, form
colloids with water, precipitate alkaloids and proteins, and
form dark blue complexes with ferric chloride - a property
exploited in ink production. The name tannins derives
only from their ability to tan leather.

Aromatics and other natural products derived from

shikimic acid vary in complexity from the simple, such as
vanillin, salicylic acid hydroxyquinone and scopoletin; and
to the more complex, such as podophyllotoxin
(people.vcu.edu (2009d) (Figure 5).
Shikimic acid is formed from two primary metabolites pyruvic acid and erythrose (Figure 6).
It is an important intermediate in plants and microorganisms. The name comes from the Japanese flower
shikimi - Illicium anisatum, from which it was first isola-

There are two groups of tannins:

(1) Hydrolysable tannins, which are esters of gallic acid
(structure below) and their glycosides.
076
J. Med. Plant. Res.

(2) Condensed tannins, which are polymers derived from

OH

O
OH

HO

O
OH

Flavone

Isoflavone

Quercetin

OH

Figure 7: Aromatics contain at least one benzene ring. Included among them are the
flavones and isoflavones and their substituted products, collectively called anthocyanins,
such as quercetin.

OH

OH

Aromatization

HO

OH
OH

Shikimic acid

HO

OH
OH

Gallic acid

Figure 8: Gallic acid from which many medicinally important phytochemicals are derived is
formed from enzymatic aromatization of shikimic acid in plant cells.

various flavonoids, such as quercetin (structure in Figure

7).
It should be noted that gallic acid results from aromatization of shikimic acid (Figure 8).
Biosynthesis of polyketides
The polyketide pathway is major biosynthetic pathway for
several medicinally important products. The compounds
are derived from poly-b-keto unit, formed by the coupling
of acetate or substituted acetate units via a condensation
reaction catalyzed by polyketide synthetase complex
(people.vcu.edu, 2009d; Robinson, 1991).
As would be expected, poly-b-keto units are the building blocks for a wide range of natural products,
collectively called polyketide. They include polyketide
antibiotics, antifungals, cytostatics, anticholesterolemics,
antiparasitics, coccidiostatics, insecticides and other
economical important compounds. A few examples are
given below (people.vcu.edu, 2009d).
(1) Macrolide antibiotics - an example is erythromycin-A,
produced by Streptomyces erythreus.
(2) Polyene antibiotics - an example is amphotericin-B,
produced by Streptomyces nodosus.
(3) Tetracycline antibiotics - an example is
oxytetracycline, produced by several different species of
Streptomyces. The antitumor agent, doxorubicin, is a
polyketide glycoside similar in structure to the
tetracyclines.

(4) Anticholesterolemics - an example is Lovastatin,

isolated from Aspergillus terreus.
(5) Other economically important polyketides include the
carcinogenic mycotoxins, called aflatoxins.
Among the simplest compounds derived from the
polyketide pathway are the essential fatty acids present
in all living organisms. A key example is arachidonic acid
- the precursor of the prostaglandins, which mediate in
several physiological activities (people.vcu.edu, 2009d).
A comment on glycosides
A large number of medicinal compounds exist as
glycosides - they do not constitute another class of
phytochemicals, and many of the phytochemicals already
mentioned exist as glycosides (Tapsell, 2006). By
definition, glycosides consist of a glucose moiety or some
other sugar attached to an aglycone. The aglycone is the
portion of the molecule that is bioactive in its free form
but inert until the glycoside bond is broken by water or
enzymes. This mechanism allows the plant to defer the
availability of the molecule to an appropriate time, similar
to a safety lock on a gun. An example is the cyanogenic
glycosides in cherry pits that release toxins only when
bitten (Taiz and Zeiger, 2006). Other examples of
glycosides include: andrographiside, one of the bitter
principles present in Andrographis paniculata; rutin, one
of the antimicrobial principles of Mitracarpus scaber; and
strictosamide, one of the many alkaloid glycosides
present in Nauclea latifolia.

Selected examples of scientific exploitation of natural

molecules

instance, Farnworth (1990) showed that some 119

medicinal compounds in use today arose from about 90
plant species. The now popular antimalarial, artemisinin,

It is amazing how so many of todays most patronized

drugs are synthetic analogues of natural products. For

Ameh et al.

CH2OH

COOH

COOH

O-glycoside

OH

OCOMe

Salicin

Salicyclic acid

077

Aspirin - acetylsalicyclic acid

Figure 9: Introduction of sodium salicylate and aspirin to medicine in 1875 and 1899 followed the
discovery of salicin - a glycoside of salicyl alcohol, found to be the analgesic agent in willow bark.

COOMe

N
O

HN

O
O

O
NH2

Lidocaine

Procaine

Cocaine

Figure 10: Attempts to synthesize compounds as beneficial as cocaine, but without its
undesirable effects, led to such drugs as procaine and lignocaine.

Et
+

Et

OH

CH3SO4-

HO
Atropine

Oxyphenonium

Benztropine mesylate - tropane derivative

Figure 11: Attempts to modify DL-hyoscyamine, a belladonna alkaloid, led to such drugs as adephenine,
oxyphenonium and benztropine mesylate.

was developed from a Chinese herbal medicine

(Klayman and Bingel, 1977). Here a few examples
selected from Finar (1970), Albert (1981) and Sofowora
(1982) is presented with comments:
Salicin: The introduction of sodium salicylate and aspirin
to human medicine in 1875 and 1899 respectively,
followed the discovery that salicin, the analgesic agent in
willow bark. Salicin is a glycoside of salicyl alcohol
(Figure 9).
Cocaine: As soon as the structure of cocaine, an active
principle from coca leaves, became known, attempts
began to synthesize related compounds in the hope of
finding a molecule that would be as beneficial as cocaine,
but without its undesirable effects. This led to drugs such

as procaine and lignocaine, which like cocaine contain

tertiary nitrogen (Figure 10).
Atropine: From knowing the structure of this compound,
also called DL-hyoscyamine, a belladonna alkaloid,
attempts were made to modify its structure, leading to
several important synthetic drugs, such as: adephenine,
oxyphenonium and benztropine mesylate (Figure 11).
Morphine: Although the structure of this opium alkaloid
had been known since 1806, it was not until 1938 that
pethidine was introduced as an analogue. After 1938
however, other synthetic opiates rapidly followed.
Examples are: nalorphine, methadone or amidone,
pentozocine, butorphanol, and etonitazine - an extremely
addictive substance, which is claimed to be 1,500 times
more potent that morphine. The presence of tertiary

nitrogen in the following structures of morphine, pethidine

and codeine are notable (Figure 12).
Cinchonine: This alkaloid, along with quinine and others,
occurs in the bark of various species of cinchona. Their
synthetic analogues include: Mepacrine, Quinacrine, and
078
J. Med. Plant. Res.

chloroquine. Note that both quinine and chloroquine

contain the quinoline nucleus (Figure 13).
It is quite clear from the foregoing that medicinal plants,
have not only been the major source, but have largely
been the inspiration for many synthetic remedies.

MeO

HO

CO

HO

HO
Codeine

Pethidine - Meperidine

Morphine

Figure 12: Morphine was known in 1806, but only in 1938 was pethidine introduced as its analogue.
After 1938 however, many synthetic opiates including codeine rapidly followed.

Et
Et

NH

NH

HO

NH

N
Quinine

Et

Et

MeO

MeO

Cl

N
Quinacrine - Atabrine

Cl
Chloroquine

Figure 13: Cinchonine, along with quinine and others, occurs in the bark of various species of
cinchona. Their synthetic analogues include: Mepacrine, Quinacrine, and chloroquine.

RISING PROFILE OF HERBAL MEDICINE THE

CORE OF TRADITIONAL MEDICINE
Spread of patronage
Up to 80% of the Third World relies on traditional medicine (WHO, 2003). In many industrialized countries, 70 80% of the populations have used some form of
alternative or complementary medicine (WHO, 2008).
The herbal aspect of the practice is the most popular
form, and is highly lucrative in the international
marketplace. In the EU annual revenues from herbal
medicines surpassed US$ 6 billion in 2003 (Current
status of medicinal plants, 2003). In China sales of the
same fetched US$ 14 billion in 2005, while in 2007;
herbal medicine boosted the Brazilian economy by US$
160 million (WHO, 2008). In 2006, a US-based company,
Xechem Incorporated, commenced commercial production of Niprisan, an herbal medicine for sickle cell
disorder developed in Nigeria (Wambebe et al., 2001).
Issues arising from the rising patronage
Globalization of practices that developed over centuries
in certain communities, without a concurrent internationalization of standards for their evaluation and
regulation is bound to produce challenges (WHO, 2003).

Since many countries are yet to adopt national policies

on traditional medicine, it is difficult to regulate such
practices globally. Secondly, the means to test the safety,
efficacy and quality of traditional therapies are highly
limited for both raw and finished products. The suitability
of products depends on the quality of their raw materials,
which often include several natural constituents. Thirdly,
since medicinal plant materials are mostly collected from
the wild, the expanding herbal medicine market could
threaten biodiversity. Thus efforts must be made to
preserve wild plants and the indigenous knowledge for
their utilization in medicine. Fourthly, many erroneously
believe that since herbal medicines are natural, they are
safe and free of risks. This, according to WHO (2003),
calls for increased public awareness of the true situation namely, that herbal medicines do have potentials to
harm, especially if used wrongly. Since the early 1980s
WHO had steadily responded to these issues by
promoting the integration of traditional medicine into the
national health systems (WHO, 2005a; 2005b; 2007).
WHO GUIDELINES
MEDICINES

FOR

ASSESSING

HERBAL

Some key definitions and objective of the guidelines

Since the Alma-ata Declaration, WHO has been promoting traditional medicine, inclusive of herbal medicine.
This has led to the upsurge in global demand, leading to
many countries seeking WHOs advice in identifying safe
and effective herbal remedies. In response the WHO
published the requirements for clinical trials of herbal

products (WHO, 2005b), which contains the following

definitions:
(1) Herbal substance - material derived from the plant(s)
by extraction, mechanical manipulation or some other
process.
(2) Herbal product - the herbal material administered to
Ameh et al.
079

Table 1. Documentation of safety based on experience.

Condition
No toxicological data exist

Action needed
Documented experience of long-term use ( at least 20-30
years) without problems should form the basis of risk
assessment

Some toxicological data exist

The period during which the drug had been in use should
be noted.
The health disorder treated with the drug should be noted.
The number of patients so treated should be noted.
The location in which the treatment was carried out should
be noted.

There is toxicity

Attempts must be made to establish its dose-dependency.

Attempt must be made to explain (a) above

There is potential for misuse

All cases of abuse or dependence must be documented

Long-term tradition cannot be proved

Attempts must be made to conduct toxicity studies

clinical subjects.
(3) Herbal product synonyms - herbal remedy, herbal
medicine, herbal drug, botanical drug.
The objective of the guidelines (WHO, 2000) is: To
define basic criteria for evaluating quality, safety and
efficacy of herbal medicines; and to thereby assist
national regulatory authorities, scientific organizations
and manufacturers to undertake an assessment of documentations submitted in respect of such products (WHO,
2000) . Traditional experience with a given product is a
key factor is assessing such a product. As a general rule,
traditional experience must take the following into
consideration: Long-term experience in the use of the
product; Medical indications of the product; Ethnographic
background of the product; and Historical background of
the product. The definition of long-term may vary from
culture to culture, but must be at least 20-30 years.
Another general rule is that: Prolonged and apparently
uneventful use of a substance usually offers testimony of
its safety (WHO, 2000).
Assessment of quality
In assessing the quality of medicinal plant materials or
their preparations (WHO, 2000), the issues that foremost
are: whether the item is supported by a monograph;
whether the item is a crude plant material or a defined

finished product; and the conditions under which the item

is stable. For imported items, the regulatory status in the
country of origin must be declared.
Assessment of safety
Long-term usage: The guiding principle is that: if the
product has been in use traditionally for at least 20 - 30
years, but usually more, without demonstrated harm, no
specific restrictive regulatory action need be undertaken,
unless new evidence demands a revision of risk-benefit
assessment (WHO, 2000). A review must be made of all
literature pertaining to the subject matter. This should, as
much possible, include original articles and references.
Available oral traditions should also be taken note of. If
official monographs or review articles exist, they must be
perused and assessed.
Pharmacovigilance and routine toxicological studies
Known side-effects are to be documented according to
normal pharmacovigilance practices. Similarly, results of
any toxicological studies carried out should feature in the
assessment of safety (WHO, 2000).
Documentation of safety based on experience: The key
points are shown in the Table 1.

Assessment of efficacy
The issues raised (WHO, 2000) in assessing the
efficacies of an herbal medicine are:
(1) Whether the ingredients and their pharmacological
actions are known, and whether these have any relations
with observed clinical results.
(2) Whether the indications for use of the medicine are
specified. Evidence that such indications are evidencebased must be rigorously sought, unless they relate to
minor disorders, unspecific complaints or prophylactic
use.
(3) If long-term traditional use has not been established, it
is needful to seek fresh clinical evidence.
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J. Med. Plant. Res.

WHO GUIDELINES FOR LABELING AND PROMOTION

Product information for the user
These refer to product labels and package inserts. They
are designed to be understood literate consumers, and
should contain information necessary for correct usage.
The following are called for: name of the product;
quantitative list of active ingredients; dosage form; and
indications. Information under indications include: dosage
(if appropriate, specify for children and the elderly); mode
of administration; duration of usage; major adverse
effects, if any; over-dosage information; contraindications, warning, precautions and major drug interactions;
and use during pregnancy and lactation. Others include
expiry date; lot number; and holder of marketing
authorization, or manufacturer. Active ingredients are to
be identified by their botanical names, in addition to the
common names. Where all the above information cannot
be supplied, the minimum required must be determined
by the national drug regulatory authority (WHO, 2000).
Promotion
Advertisements and other promotional materials directed
to health workers and the general public must be
consistent with the elements of information approved for
labels and inserts (WHO, 2000).
Conclusion
The World Health Organization had over time produced a
large corpus of data on how medicinal plant materials
and their products should be handled, starting from the
collection of materials, through manufacturing, to clinical
trials. These dossiers, better called guidelines, are
intended to facilitate the work of regulatory authorities,
scientific academies, industries and interregional
agencies concerned with the regulation and trade of
herbal medicines. It is intended that assessments by
these agencies would reflect current scientific knowledge,
and that such assessments would form the basis for
classifying herbal medicines for the purpose of regulation

and trade. Since effective control of herbal medicines

moving in international commerce requires close liaison
between national agencies, such agencies should be
able to monitor the production and use of these products.
Such an exercise requires common terms of reference,
which the WHO guidelines represent. Familiarity of
governments and businesses with these guidelines
should stimulate and facilitate sponsorship of researches
designed to evaluate the efficacy, acceptability, cost and
relative value of herbal medicines as compared with other
remedies.
ACKNOWLEDGMENT
We gratefully acknowledge the study fellowship granted

for this review by the Research and Development

Planning Committee (RDPC) of the National Institute for
Pharmaceutical Research and Development; and the
library facilities provided by the US National Institute of
Health.
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