The 21st century is witnessing serious scientific effort to discover major
active ingredients in medicinal plants through research and development (R and
D). This perhaps may be sequel to the inability of orthodox medicine to comprehensively
address most disease conditions plaguing mankind or it may be a response to
the clarion call by the World Health Organization that developing countries
should endeavour to develop and utilize local medications that are most appropriate
to their local circumstances especially for Primary Health Care (PHC) in order
to cut down on huge cost associated with incessant drug importation (WHO,
1996). However, in the academia, the widely held view for the sudden rise
in research work in herbal medicine has been linked to the quest to meet research
mandates and perhaps earn routine promotion.
Whatever reason that may be ascribed to this increase in R and D activities in medicinal plants, one thing is instructive which is that herbal medicine is beginning to take the center stage in the management of health-related problems in the Nigerian health care system. Continuous R and D may be on the increase due to incessant changes in and the quest for new technology especially in this era of globalization.
Technological R and D therefore has been defined as that complex process of
activities aimed at acquiring new knowledge, improving new engineering designs
and functions and creating new products, all with a view to some ultimate application
(Girifalco, 1991). In fact, the results of most research
outputs from R and D are beginning to form the basis for measuring the degree
of industrial, technical and economic development of any nation (Koleosho,
Through technological R and D, countries of the Far East Asia such as China,
South Korea and India have been able to develop and upgrade the quality of their
herbal medicine. China for instance is the World leading producer and exporter
of herbal medicine. In 1993 the total sales of herbal medicine in China amounted
to $2.5 billion. In Japan, there was a 15 fold increase in herbal medicine sales
when compared to 2.5 fold increase of pharmaceutical products between 1974 and
1989 (WHO, 1996). The countries of the Far East Asia
have been able to meet 75% of their health care needs through the development
and utilization of herbal medicine and traditional medicine practice.
Meanwhile, only 40% of herbal medicines consumed in Nigeria are produced locally
and the remaining 60% are imported from foreign countries. Again, the commercial
interest to mass produce herbal medicine through R and D and make them available
for local and international use is lacking (Ohuabunwa, 1998)
and it would probably take a longer time for this to improve and grow significantly.
In Nigeria, effort at local herbal medicine R and D is yet to yield the desired
benefits due to low funding of R and D activities, lack of adequate infrastructural
facilities, non-commercialization of most research results, low demand that
constraints R and D investment and problems faced by herbal medicine researchers
(Oyelaran-Oyeyinka, 1996; Ilori et
The main aim of this study is to chronicle the trend of research results in herbal medicine from published scientific studies in Nigeria. The specific objectives are to examine the pattern of such research outputs; highlight some technical developments in herbal medicine production with emphasis on barriers to herbal medicine research and recommend policy changes that would guide and improve future research effort especially in areas where much research appears not to have been adequately carried out.
Literature review: Nigeria is a rich gene developing country for medicinal
plants and the country is home to approximately 5, 000 plant species thus making
it the 11th largest in terms of plant genetic diversity in Africa. Around 205
of these species are endemic in nature with Northern, Western, Central and Eastern
Zones of the country being home to most of the endemic species (FEPA,
Herbal medicine in the simplest form are medicines or drugs made from herbs
or plants and can be said to process several synonyms all of which refer to
plants as the raw materials for medicine namely, phytomedicines, plant medicines,
green medicines, traditional medicine portions, traditional remedies plant drugs
and forest health products among others (Elujoba, 1998).
The World Health Organization also defined herbal medicine as finished labeled
medicinal products that contain as active ingredients aerial or underground
parts of plants or other plant materials or combinations thereof whether in
crude juices, gums and fatty oils and other substances of this nature. Herbal
medicine may contain standard excipients in addition to the active ingredients.
Medicines containing plant material combined with chemically defined active
substances including chemically defined isolated constituents of plants are
not considered to be herbal medicine. Exceptionally, in some countries herbal
medicine may also contain by tradition, natural organic or inorganic active
ingredients which are not or plant origin (WHO, 1996).
A Traditional Medical Practitioner (TMP) has been defined as a person who is
recognized by the community in which he lives as competent to provide health
care by using vegetable, animal and/or mineral substances and certain other
methods based on the social, cultural and religious background as well as the
knowledge, attitudes and beliefs that are prevalent in the community regarding
physical, mental and social well-being and the causation of diseases and disability
The production techniques or processing or herbal medicine in Nigeria is still
largely antediluvian and therefore, benefit of the use of modern technology.
Hence, the current debate in academic circle on the safety, efficacy and quality
of herbal medicine. Before now, bare hands were used to pick dirt and separate
unwanted parts of plants (Garbling) and grind herbs into powdery forms.
These have been replaced by special machines that help pick or sort the desired
herbs and mill them with the aid of hammer, knife or teeth mills (Trease
and Evans, 1978).
An overview of some of the processes employed in the production of herbal medicine
and the equipments (machines) that perform these functions are becoming more
scientific and complex (Tsumura, 1991). The use of analytical
techniques is employed to collect plants from their natural habitats in order
to ensure that only the desired plants are collected.
The seasons for collecting active ingredients in medicinal plants are a matter
of considerable concern and importance. Research has shown that rubarb contains
no anthraquinone derivatives in winter but contains anthranols which on the
arrival of warmer weather are converted by oxidation into anthraquinones. Daily
variations of the alkaloids of the poppy, hemlock, the solanaceous plants and
ergot have been reported (Trease and Evans, 1978). So,
plants should be harvested when the part of the plant being used contains the
highest possible level of active compounds (Sofowora, 2008).
Extraction process for making tinctures, fluid and solid extracts has been technologically
improved upon. The old technique of maceration has been replaced for example
with a counter-current extraction process, fluid extracts are concentrated by
thin layer evaporations while freeze-drying and spray drying (atomization) are
modern drying techniques that are in vogue.
Research in the development of drugs from herbs has enable scientists to manufacture
potent preparations that aided the recovery of man from a state of chemical
and structural unbalance (Odukoya, 1998). This feat
was achieved by identifying and isolating bioactive compounds from plants and
their co-generic species with the use of modern methods such as chromatographic
separation, use of paper and silica gel, High Performance Liquid Chromatograph
(HPLC) and spectrometer for on-line measurement among others. For example, a
semi-purified herbal preparation may be assayed for a particular group of constituents
e.g., total alkaloids in Belladonna or Cinchona bark or total glycosides of
digitalis. Also specific identifiable components may be evaluated or assayed
e.g., reserpine content as distinct from the total alkaloid content of Rauwolfia
species or morphine in opium (Olaniyi, 1998). Therefore,
quality assessment that covers the three areas of quality assurance of herbal
medicine i.e., quality, safety and efficacy are now possible through the use
of modern technology-base analytical techniques. This has helped to broaden
the frontiers of knowledge in herbal medicine standardization and evaluation.
However, intense debate surrounds the issue of how to conduct clinical trials
of herbal medicine according to Western Pharmaceutical Clinical Standards. Also
there is an inherent problem with the single-active-ingredient approach preferred
by pharmaceutical companies that are actively involved in herbal medicine research.
Isolating a single compound may not be the most appropriate approach in situations
where a plants activity decreases on further fractionation (separation of active
ingredients by using solvents) or where the plants contain two or three active
ingredients that must be taken together to produce full effect (Chaudhurry,
1992). Beckstrom-Sternber and Duke (1994) have documented
several cases where synergy has been lost by using the single ingredient approach
to developing drugs from plants.
Evidence reveals that there are a host of barriers to herbal medicine research
in general. In Nigeria, Sofowora (2008) identified other
barriers to scientific research in herbal medicine namely:
||Cost of acquiring information
||Distrust of researchers by practitioners
||The desire to pass down information only to off springs
||Restrictions due to cult/trade membership
||A lot of unwritten knowledge resides in the hands of healers in many societies
In addition, most healers bring in some other elements of traditional medicine practice such as incantation into herbal medicine practice. Sometimes healers may claim that to enhance the efficacy of their herbal medicine, some funny parts of an animal are to be used in preparing medicines. Such things may include legs of a worm, the bones of fly, the penis of a snake, fatty tissue of a female mosquito, breast of a chamelon among others. At times, the healer will claim to have used or direct the patient to provide as part of the ingredients for preparing a potion, hardly accessible materials such as the teeth of a virgin leopard, saliva of a young bat, sperm of a fertile lion and egg of a crocrodile. Such a mix-up of herbal medicine practice with traditional medicine tends to mar effort in herbal medicine research.
The above restrictions Adesanya noted, actually affected the level and type
of information revealed to researchers to the extent that in most books, only
the plants are mentioned, the methods of preparation are often missing. In addition,
most of the herbalists that would have given useful information to herbal medicine
researchers are getting older and vital information is being lost (Elujoba,
1998; Sofowora, 2008).
Even traditional medicine knowledge which is mostly tacit in nature is passed on from one person to another based on rules of age, gender or lineage. These restrictions are mainly in place to ensure that the knowledge remains an aspect of group identity.
In spite of the above mentioned barriers, a lot of progress in herbal medicine
research has been recorded in China, Japan and other countries of the Far East
Asia where in the past 20 years have witnessed a tremendous increase in herbal
research into the use of standardized, semi-purified herbal extracts called
phytomedicines (WHO, 1996). Scientific researchers over
the years have been conducting researches on Nigerian medicinal plants along
various disease states with the available infrastructural facilities at their
MATERIALS AND METHODS
Data for this survey were generated from the book of abstracts of published research findings on Nigerian medicinal plants and traditional medicine practices for 35 years (1970-2005). Out of a total of 1050 abstract of published research findings, 702 research works were on biological areas. These were then categorized along disease states where the efficacies of the herbal preparations were established. Then the number of research findings in each disease area was determined and computed as a percentage of all research outputs for the period under review. The percentages were ranked in a decreasing order of magnitude.
RESULTS AND DISCUSSION
As shown in Table 1, the high points in herbal medicine R and D activities within the period under investigation are in anti-infective drugs or anti-microbial drugs (32.48%), Gastro-Intestinal Tract (G.I.T) drugs (9.69%), analgesics, antipyretics and non-steroidal anti-inflammatory agents (8.69%) cardiovascular agents (5.41%), toxicity studies (5.27%), hypoglycemic agents (4.27%) and molluscicidal (3.85%).
Other areas where research activities were moderately undertaken are in oxytocic agents (2.85%), dermatological agents (2.71%), insecticide (2.42%), anesthetics (2.28%), drugs affecting the blood (2.28%) and tranquillizers (2.14%).
Areas that were least researched into are anti-convulsants (1.57%) anti-viral
agents (1.57%), hypatoprotective agents (1.28%), psychotherapeutic drugs (1.00%),
anti oxidants (1.00%), hormones (0.85%), respiratory system drugs (0.43%), diuretics
(0.43%) dental agents (0.43%) and hemorrhoids (0.14%). The above three classified
research levels with respect to research intensities represent the biological
However, the isolation and characterization of natural products from Nigerian medicinal plants without biological testing yielded several compounds of novel structure and constituents which could serve as templates or precursors for the development of new drugs in the areas where much research in terms of drug development has not been adequately carried out.
In Table 1, the pattern of research outputs is skewed in
favour of anti-infective drugs, G.I.T drugs among others. This may be due to
the rate of occurrence or the preponderance of certain diseases that are common
or endemic among Nigerian population. This may also have triggered a plethora
of research interests into such areas with the hope of finding new and improved
method of obtaining lasting cure.
||Categorization of herbal medicines discovered through scientific
research on medicinal plants and traditional medicine practices in Nigeria
|Computed from book of abstracts of published research findings
on Nigerian medical plants and traditional medicine practices. Vol. 1 (2005)
Secondly, it would be as a result of inadequate infrastructural facilities
needed to conduct researches in other areas. Again, the nature and type of in-house
R and D, the availability of funds, chemicals, analytical materials and even
technical know-how of research personnel may limit the scope of research activities
too. The wisdom in treading along known part or by concentrating research activities
within or around certain established areas may be informed by the need to minimize
risk or failure, gain time and perhaps increase the probability of achieving
better results by improving on past performances. Meanwhile, in doing so the
possibility of duplicating research effort or results is indeed high. Lack of
mentorship could also pose a big challenge. If there were no personnel to teach,
guide and direct researchers on how to conduct researches into unfamiliar areas
that are posing big health problems such as HIV/AIDS then not much research
activities would take place in such areas.
This study is set out to establish the trend in research into Nigerian medicinal plants and traditional medicinal practices. An understanding of this trend is critical for the design of policies guiding research in herbal medicinal plants and traditional medicinal practices. However, there is need for further study especially in vital areas that have recorded less research outputs.