Biological and pharmacological approaches to the screening and evaluation of natural products.

Many traditional herbal remedies contain active principles, the effects of which can be demonstrated pharmacologically; the biological activity of the whole plant extract is usually related to the constituents that have been identified. Thus, active extracts detected by screening methods are often subjected to more elaborate bioassays to determine their specific pharmacological activity. This paper aims to elucidate the biological, pharmacological and clinical approaches used in the screening of bioactive natural substances. In addition, a scientific process with the goal of finding substances with useful pharmacological activity in plant extracts is rigorously investigated.