Chemical Diversity of Medicinal Plants

Exploring new biologically active ingredients of plants are in the focus of medicinal plant researches. The chemicals of plants determine the healing properties of plants. This chapter deals with the active ingredients that can explain the applicability of medicinal plants or can help in the evaluation of the plants from chemical point of view. Rather difficult thing to classify the medicinal plants on the bases of their active chemical ingredients as in the same plants several compounds belonging to various chemical groups can be found and, in addition, in many cases they contribute to the effect and applicability of the plants. In other cases the same type of compounds is present in plants bearing different utilization from medical viewpoint. Exceptions are the plants having compounds of strong biological effect and the ingredients from them as pure compounds are used after their isolation. In this chapter the plants are discussed according to the classical, broadly applied grouping: based upon the biosynthetic pathways of the main active ingredients. Consequently, the classes of primary and secondary metabolites are used. Primary metabolites are as follows: carbohydrates, fatty acids, fats, proteins. The main groups of secondary metabolites discussed are the phenolics (including polyketides), terpenoids and alkaloids. Examples, most frequently occurring in medicinal plant handbooks illustrate the chemical diversity of these compounds.