18-09-2017, 02:38 PM
Pharmacognosy is the study of drugs derived from plants or other natural sources. The American Society of Pharmacognosy defines pharmacognosy as "the study of the physical, chemical, biochemical and biological properties of drugs, drugs or potential drugs or medicinal substances of natural origin, as well as the search for new drugs from natural sources" . It is also defined as the study of raw drugs.
All plants produce chemicals as part of their normal metabolic activities. These phytochemicals are divided into
(1) primary metabolites such as sugars and fats, found in all plants; and
(2) secondary metabolites-compounds that are found in a smaller range of plants, fulfilling a more specific function.
For example, some secondary metabolites are toxins used to discourage predation and others are pheromones used to attract insects for pollination. These are secondary metabolites and pigments that may have therapeutic actions in humans and which can be refined to produce drugs. Examples are inulin of dahlia roots, quinine of cinchona, THC and CBD of cannabis flowers, morphine and poppy codeine, and digoxin of foxglove.
