PROCESS OF MODERN DRUG DISCOVERY USING ETHNOPHARMACOLOGY
The discovery process using ethnopharmacology is composed of several stages which are as follows:
1. Information source: There should be a reported medical use of a naturally occuring material. Most reliable information arises from in depth studies carried out by field workers living in a particular community of a particular ethnic group, on the use of local plants and other materials. The information provided needs clarification and translation into scientific terms. Data on the part of the plant used, time of collection, methods of preparation, formulation and applications are necessary. Any restrictions on the use due to time of the year should be clearly specified as it may lead to high or low concentration of the active constituent.
2. Scientific investigation:
The material is collected for experimental studies. Extracts used for testing should be as close as possible to the traditional process.
Tests for activity: Long term use of a material in traditional medicine is good indicator of therapeutic efficacy. To be of most value, a range of tests should be chosen which is closely related to the possible underlying causes of the disease. For example tests for the efficacy of a preparation for an antiinflammatory disease such as arthritis should encompass key mechanisms associated with the formation of various mediators like lipoxygenase, cycloxygenase etc. Most test systems for biological activity utilise invitro systems using animal tissue, cultured cells, cloned receptors or enzyme systems.
3. Chemical examination:
It should be linked with the tests for biological activity. Chemotaxonomic considerations can provide a hint to the nature of active compounds and a short cut to their isolation. The active compounds are usually discovered by several cycles of fractionation of the extract linked with testing for activity of each fraction, until pure compounds are isolated from the active fractions, a process known as Bioassay guided fractionation. Separation is done using TLC, GC, LCMS etc.