A large number of important modern drugs and natural products and most of the traditional medicines are derived from medicinal plants. It is thus expected and also desirable that the students of pharmacy and traditional medicine should possess a good knowledge of the various aspects of medicinal plants. In this perspective various aspects of medicinal plants are discussed in the following pages.
Definition of Medicinal plants:
The plants that possess therapeutic properties or exert beneficial pharmacological effects on the animal body are generally designated .as MedidI)al plants. Although there are no apparent morphological characteristics in the medicinal plants that make them distinct from other plants growing with them, yet they possess some special qualities or virtues that make them medicinally important. It has now been, established that the plants, which naturally synthesize and accumulate some secondary metabolites like alkaloids, glycosides, tannins and volatile oils and contain minerals and vitamins, possess medicinal properties. Accordingly, the WHO consultative group on medicinal plants has formulated a definition of medicinal plants in the following way: “A medicinal plant is any plant which, in one or more of its organs, contains substances that can be used for therapeutic purposes· or which are precursors for the synthesis of useful drugs.”
However, this definition of the WHO consultative group includes only the medicinal plants whose therapeutic properties and active chemical constituents have been established scientifically. It does not take into consideration the vast majority of the medicinal plants, which have been used in traditional medicine for hundreds of years with a reputation as efficacious remedies, but have not yet been subjected to thorough scientific studies, or their uses have not yet been substantiated by scientific data. Since some of the wonder drugs of modern medicine have their roots in the traditional uses of medicinal plants, it would be unfair to ignore this vast treasure of knowledge, built through costly endeavours and experiences of the people of different cultures and civilizations, sometimes at the cost of human lives. Thus all the uninvestigated medicinal plants used in traditional medicine should also be recognized as medicinal plants.
Medicinal plants may therefore be broadly defined as a group of plants. which are used for medicinal purposes, based on scientifically validated data or traditional knowledge of their medicinal properties or virtues.