1. Introduction
The natural extracts of plants are an important source for the identification of new biologically
active compounds with possible applications in the pharmaceutical field. Phytotherapy
embraces especially the isolation from herbs, of compounds with unique chemical structures,
which are considered to be pharmacologically active. Recent statistics show that, on an annual
basis, there are identified over 1500 new compounds from different species of plants, and
about one quarter of prescription drugs contain substances of plant origin.