Pharmacognosy is the study of plants or other natural sources as a possible source of drugs. The American Society of Pharmacognosy defines pharmacognosy as "the study of the physical, chemical, biochemical, and biological properties of drugs, drug substances, or potential drugs or drug substances of natural origin as well as the search for new drugs from natural sources".Originally—during the 19th century and the beginning of the 20th century—"pharmacognosy" was used to define the branch of medicine or commodity sciences (Warenkunde in German) which deals with drugs in their crude, or unprepared, form. Crude drugs are the dried, unprepared material of plant, animal or mineral origin, used for medicine.

As late as the beginning of the 20th century, the subject had developed mainly on the botanical side, being particularly concerned with the description and identification of drugs both in their whole state and in powder form. Such branches of pharmacognosy are still of fundamental importance, particularly for pharmacopoeial identification and quality control purposes, but rapid development in other areas has enormously expanded the subject. A typical protocol to isolate a pure chemical agent from natural origin is bioassay-guided fractionation, meaning step-by-step separation of extracted components based on differences in their physicochemical properties, and assessing the biological activity, followed by next round of separation and assaying.

A typical protocol to isolate a pure chemical agent from natural origin is bioassay-guided fractionation, meaning step-by-step separation of extracted components based on differences in their physicochemical properties, and assessing the biological activity, followed by next round of separation and assaying. Typically, such work is initiated after a given crude drug formulation (typically prepared by solvent extraction of the natural material) is deemed "active" in a particular in vitro assay.

If the end-goal of the work at hand is to identify which one(s) of the scores or hundreds of compounds are responsible for the observed in vitro activity, the path to that end is fairly straightforward:

1. Fractionate the crude extract, e.g. by solvent partitioning or chromatography.
2. Test the fractions thereby generated with in vitro assay.
3. Repeat steps 1) and 2) until pure, active compounds are obtained.
4. Determine structure(s) of active compound(s), typically by using spectroscopic methods.

In some countries in Asia and Africa, 80% of the population relies on traditional medicine (including herbal medicine) for primary health care. Native American cultures have also relied on traditional medicine such as ceremonial smoking of tobacco, potlatch ceremonies, and herbalism, to name a few, prior to European colonization. Knowledge of traditional medicinal practices is disappearing, particularly in the Amazon.

Regards
Rutherford
Managing Editor
Journal of Pharmacy Practice and Education