ABSTRACT
Plant secondary metabolites represent an enormous value from economical point of view. First of all quite a few are used as specialty chemicals, such as drugs, flavours, fragrances, insecticides and dyes. Of all drugs used in western medicine about 25% is derived from plants, either as a pure compound or as derived from a natural synthon (Verpoorte 2000). Examples of the former are morphine, codeine, paclitaxel, vinblastine, vincristine, scopolamine, atropine, pilocarpine, physostigmine, digoxin and artemisinin. With a total world market for
medicines of about 250 billion US $ per year, it is obvious that natural products from plants are a valuable commodity. A much more diffi cult group to assess in terms of economical terms, at least in value of money, is that of the medicinal plants (Balick et al. 1996). It is estimated that about 80% of the world population depends on traditional medicinal plants for their primary health care. Though in most cases no scientifi c studies have been made to confi rm their activity, of those studied quite a few showed activities related to their use. Traditional medicines are very important in primary health care, where they can be used instead of expensive western medicines. Their potential value is in the possibility that they may contain new biologically active compounds, which can be further developed into drugs for the international market. The other major group of economically important natural products is that of fl avours and fragrances. This group comprises both pure chemical entities and mixtures of compounds (e.g. various essential oils). These compounds are on the market as such, but of course they are also of great importance for the quality of our food and spices. For example the bitter taste of beer is dependent on the bitter acids from hops. Moreover, food plants also contain all kinds of other compounds which are very much quality determining, such as caffeine. Presently there is much interest in health promoting effects of secondary metabolites in food. Anthocyanins, fl avonoids and carotenoids are now well known examples, but certainly one may expect others that will be discovered in the coming years.
