Plant Constituents: The Chemistry of Plants

To a pharmacist, these are the active ingredients of the plant, the chemicals that have a marked, definable physiological and therefore, possibly medical activity upon the body. These constituents and their actions within the body are also referred to as their pharmacology. 

These active ingredients are not of immense interest to a medical herbalist, because the focus is on using whole plants for whole people. Knowing chemical components and actions in isolation from the rest of the plant, does not tell us much about the activity of the plant itself. This does not deny the value of studying such plant constituents, as long as it takes its place within a holistic context of therapeutics.

Plant chemistry includes the miracle of photosynthesis, plant respiration, structure, growth, development, and reproduction. Much of the chemical basis of life is common to both plants and animals. From a holistic perspective the whole of the plant must be respected as an integrated biologically evolved unit that is beyond the analytical comprehension of science.

Plant Constituents

Physiologically active plant constituents are usually classified by their chemical structure rather than specific actions. The list here will assumes a certain degree of chemical knowledge:

• Acids
• Alcohols
• Carbohydrates
• Phenols & phenolic glycosides
• Tannins
• Coumarins & their glycosides
• Anthraquinones & their glycosides
• Flavones & Flavonoid glycosides
• Volatile Oils
• Saponins
• Cardioactive glycosides
• Cyanogenic glycosides
• “Bitter Principles”
• Alkaloids

Recommended Resources:

• Lisa Ganora, Herbal Constituents
• Dr. Andrew Pengelly, The Constituents of Medicinal Plants
• Dr. Kerry Bone, The Principles and Practice of Phytotherapy