1.0 Introduction
Plants had been used for medicinal purposes long before recorded history. Ancient Chinese and Egyptian papyrus writings describe medicinal uses for plants as early as 3000BC. Indigenous cultures(such as African and Native Americans) used herbs in their healing rituals, while others developed traditional medical systems in which herbal therapies were used. Researchers found that people in different parts of the world tended to use the same or similar plants for the same purposes.Traditional medicine is the sum total of knowledge, skills and practices based on theories, beliefs and experiences indigenous to different cultures that are used to maintain health, as well as to prevent, diagnose, improve or treat physical and mental illnesses (Pretty,2011).
Herbal medicines include herbs, herbal materials, herbal preparations, and finished herbal products that contain parts of plants or other plant materials as active ingredients. (W.H.O., 2008).Recently, the World Health Organization estimated that 80% of people worldwide rely on herbal medicines for some part of their primary health care. The remaining 20% of individuals living in industrialized countries uses, in at least 25% of cases, pharmaceuticals which have been directly derived from plant products.
The use of medicinal plants in complementary and alternative medicine has seen a great increase in recent years especially in Asia and Europe. One of the main reasons for the increasing use of traditional medicine is a growing trend for patients to take a more proactive approach to their own health and to seek out different forms of self-care. In the process, many consumers have turned to natural traditional medicinal products and practices, under the assumption that “natural means safe”(W.H.O, 2004).
A vast family of plant kingdom has been explored from time immemorial for their medicinal values. These include: Euphorbiaceae, Fabaceae, Rubiaceae, Apocynaceae, Solanaceae, Sterculiaceae and many others. Many of these plants used as medicine were derived from ethnomedicinal plant sources.Plants have diverse pharmacological roles they play in the health of people, these pharmacological roles have depended on the occurrence of varieties of chemical components in the plants (Duke and Wain, 1981). Medicinal plants are sources of a number of novel chemical compounds(Boret al., 1998). The metabolites that have effects on human health are known as phytochemicals. Phytochemicals are compounds derived from plants which possess vast biological properties. They are divided into two major types: primary and secondary plant metabolites. Examples of primary plant metabolites include: carbohydrates, amino acids, fatty acids, lipids, steroids and phenolics.Secondary metabolites are responsible for the medicinal effects of plants (Deyu, 2007).Examples of such chemicals include alkaloids, flavonoids, saponins, phenol compounds, steroids and proteins (Negemet al., 1980)
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