Plant screening by chemical and chromatographic procedures under field conditions

The plant kingdom constitutes an invaluable source of new chemical products which may be important due to their biological properties and in particular because of their potential use in medicine. In many countries, mainly in the Tropics, systematic surveys of plants are currently in progress. It is therefore important to have a simple and universal method available for preliminary chemical screening of plants under field conditions. The procedure suggested here is based on the identification in raw plant extracts of some chemical groups of substances (alkaloids, quinones, saponins, polyphenols, anthranoids) by precipitation and colour reactions. To obtain more accurate results, a second stage, based on thin-layer chromatographic separation of extracts of plant material, can be applied. Solvent systems, specific spray reagents and reference substances are proposed. A number of groups of products, including flavonoids, coumarins, cardenolides and steroids can be rapidly identified in plants by this method.