Medicinal Plants Classification Biosynthesis and ... - Index of

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S.M.M. Vasconcelos, J.E.R. Honório Júnior, R.N.D. Cavalcante de Abreu et al.
these plants. The chemical potential of living organisms is of interest to pharmaceutical
industries as a source of new drugs (e.g. taxol, ephedrine), agrochemical by providing natural
fungicidal and insecticide (e.g. rotenon), food industries by providing natural substances for
food flavor and color (e.g. menthol, benzoic acid), and cosmetics by natural perfumes (e.g.
camphor, linalol, coumarin) (Buckingham, 1993; Braz-Filho, 2007).
According to Pereira (1993), there are about 12.000 known secondary metabolites,
including terpenes, alkaloids, acetogenins, aromatics, and others used to intoxicate or
dissuade insects or herbivore mammals of their predator action (e.g.: camphor, psoralen,
florizin). Many of these insect-plant interactions cause clear evolutionary reflexes, which are
responsible for different reactions that some plants present against their predators.
Medicinal plants are the ones that exert pharmacologic actions when administered to men
or animals in any route or preparation (Brasil, 2001). They play important role in modern
medicine, because they provide extremely important drugs that could hardly be obtained by
chemical synthesis, as the alkaloids of Papaver somniferum and cardiotonic glycosides of
Digitalis spp (Turolla, Nascimento, 2006). Although there is a clear development of huge
pharmaceutical laboratories and synthetic drugs, medicinal plants remain as an alternative
treatment in some parts of the world.
The World Health Association (WHO), through the Traditional Medicine Program,
sponsors and encourages many countries to study the potential utility of traditional medicine,
including the evaluation of efficacy and security of drugs derived from medicinal plants
(WHO, 1993).
According to WHO estimates, a big part of the population, even in rich countries, still
uses traditional medicaments, especially medicinal plants. Although it is easy to have access
to modern medicine in these countries, the use of medicinal herbs remains popular for
historic and cultural reasons. About 25% of all medical prescriptions have at least one
product obtained from plants. On the other side, in developing countries, 65-80% of the
population depends exclusively on medicinal plants for basic health care. This means that
almost 4 billion of people trust in plants as sources of drugs (Agra et al., 2007; Raven et al.,
2001).
There are about 500 thousand species of plants in the world. Brazil is one of the 12
nations that have 70% of the planet biodiversity and is the country with the biggest vegetal
cover of the Earth. This fact has economic importance and also requires the conservation of
such biodiversity (Brasil, 2001).
Nowadays, although the free official health system reaches the country, it cannot
provide, in an adequate manner, the demand for health care. Furthermore, these people
cannot afford health professional or industrialized drugs. Thus, they use medicinal plants,
which are sometimes cultivated in their garden (Pilla, Amorozo, Furlan, 2006).
A great part of medicinal flora does not have its chemical and pharmacological properties
well studied, and the popular knowledge about these plants exists predominantly in developing
countries. The Brazilian Health Ministry has encouraged researches with traditional plants
looking for possible new compounds and effects of these plants (Brasil, 2001).
In Brazil, especially in Northeast, about 80% of the population has low purchasing power
and finds the cure for health problems in folk medicine, most of the time using plants