Extraction Technologies for Medicinal and Aromatic ... - Capacity4Dev

EXTRACTION TECHNOLOGIES FOR MEDICINAL AND AROMATIC PLANTS
tions of plant materials include macro- and microscopic descriptions, tests
of identity, and analytical and physicochemical determinations. The expected
results of these tests and measurements are presented as numerical limits
or as a range or discretely observable result.
While fixing the limits of specifications, naturally met variations
in plant drugs need to be accommodated. A plant material conforming to the
prescribed specifications should be considered acceptable for intended use.
Several factors contribute to variation in the content and composition of raw
materials. These factors can broadly be grouped in four categories of climatic,
nutritional, collection and post-harvest factors. Climatic factors include prevailing
temperature, rainfall, humidity, daylight and altitude of the growing region.
The nutritional factors are those which affect the health of a growing plant and
are reflected in the production of biomass and its composition; several soil factors
such as availability of micro- and macronutrients, pH and cation exchange
capacity are important for optimal growth of plants. Collection factors control
the content of active components by giving due attention to the age, season,
collection time and part of the plant collected. Post-harvest factors are important
as the collected material is still live and carries out metabolic processes
and respires; the enzymatic processes continue after collection until they are
deactivated by drying or other suitable treatment; the crushing and cutting of
material leads to de-compartmentalization of reactive chemical constituents of
plants which were naturally located in intact cells; and the collected material
faces direct impact of oxidation by air and light besides physical loss of some
components.
The World Health Organization, in its volume Quality control methods
for medicinal plant materials, has listed several parameters which are valuable
in assuring quality of plant drugs. These include identification, visual inspection,
sensory characters, macro- and microscopic characteristics, moisture content,
foreign matter, fingerprint by thin layer chromatography (TLC), ash values,
extractive values, volatile matter, microbial load, heavy metals and pesticide
residues, radioactive contaminants and, according to the nature of the drug,
one or more determinations for bitter value, tanning test, foaming, hemolytic
and swelling indices. The European Medicines Agency’s “Guideline on quality of
herbal medicinal products” and “Guideline on specifications” more precisely describe
the quality-related issues of medicinal plants. These documents define
and differentiate herbal substances (equivalent to herbal drugs), herbal preparations
(equivalent to herbal drug preparations) and herbal medicinal products
(equivalent to traditional herbal medicinal products). The guidelines emphasize
the quantification of active or analytical markers and describe procedures to
ensure quality of raw material, semifinished and finished products.
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