Introduction

During the 20th century many plants have been investigated in order to assess their potential value as new medicinal agents or as sources of new organic molecules that could be used in contemporary medicine or could act as templates for the synthesis or semi-synthesis of potentially useful therapeutic compounds. Examples include Catharanthus roseus G.Don., the Madagascan periwinkle, source of the indole alkaloids vinblastine and vincristine which have been successfully used in the treatment of Hodgkin’s disease (malignant lymphadenoma), Rauvolfia serpentina Benth., the Himalayan snakeroot, source of the alkaloids reserpine and ajmaline that have been employed in the medication of stress, hypertension and cardiac oedema and Taxus spp., certain yews, that are the source of taxol, a compound of potential use in the treatment of cancers and especially breast cancer.