Molecular tailoring and boosting of bioactive secondary metabolites in medicinal plants.

Although the production of most of the current medicines is based on chemical synthesis, more than 25% of the current prescribed drugs contains at least one active ingredient of plant origin (Kaufman et al 1999). Examples of important plant-derived pharmaceuticals include the antitumoral taxol and vinblastine, the antimalarial drug quinine and artemisinin, the analgesical morphine and codeine. In addition, it has been estimated that more than 80% of the world's population in developing countries depends primarily on herbal medicine for basic healthcare needs (Vines 2004). There is also a revival of traditional medicine in developed countries and an increase in the use of herbal remedies. The world market of herbal medicines, including herbal and raw material, has been estimated to have an annual growth rate between 5-15%. Total global herbal drug market is estimated as US $ 62 billion and it is expected to grow to US $ 5 trillion by the year 2050 (Joshi et al. 2004). At same time, there is a growing concern on loss of genetic diversity since about 75% of the 50,000 different medicinal plant species in use are collected from the wild (Edwards 2004). Moreover, to rely solely on wild spontaneous plants as a production system can be extremely dangerous, as shown recently by severe shortage problems of the antimalarial artemisinin (Scheindlin 2005). Additionally, bioactive plant compounds are produced generally at very low amount and, often, it is not economically convenient to extract them from natural sources.