According to the American Society of Pharmacognosy, pharmacognosy is the study of the physical, chemical, biochemical, and biological properties of drugs, drug substances, or potential drugs of natural origin (plants, animals, and microbes), as well as the search for new medicinal substances from nature. The term ‘pharmacognosy’ is far broader than the concept of medicinal plants; it encompasses all natural sources, including microorganisms such as archaea and bacteria, as well as fungi and animals. The number of chemical compounds found in plants is far smaller than the total number found in all other life forms on Earth.

Pharmacognosy also studies drugs such as heparin and its derivatives, which are obtained from animal sources. Drugs obtained from human blood, such as albumin and immunoglobulins, also fall within the remit of pharmacognosy, although their clinical applications are covered in other university courses. Insulin from animal sources and the antibiotics erythromycin and gentamicin, which are derived from bacteria, are also part of pharmacognosy. The dominance of plant compounds and herbal drugs in pharmacognosy studies at pharmaceutical faculties is a legacy of the past, dating back to the publication of the book Lehrbuch der Materia Medica in Vienna in 1811. Modern 21st-century pharmacognosy textbooks are slowly rectifying this.

But where do compounds obtained by the chemical modification of natural compounds belong? Examples include the antibiotic azithromycin, produced from erythromycin through a few chemical steps, and ivermectin, obtained by the chemical modification of avermectins, which do not occur naturally. Some classify such compounds in pharmacognosy, while others classify them in medicinal chemistry, but this debate is not important. The most important thing is that they are taught in a structured way somewhere.

All plants that can be used as medicine are medicinal plants. This seemingly circular definition requires adding a definition of “drug”. I prefer the FDA’s definition: any substance recognised by an official pharmacopoeia or formulary, intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease, or any substance (other than food) intended to affect the structure or function of the body. This seemingly dull definition is essential for understanding pharmacology, and failing to grasp it can lead to manipulation and imprecision. Since the FDA definition excludes food, the question arises as to how plants that can be used as both food and medicine, which are dual-defined in European Union legislation (such as flax seeds), should be classified. The regular consumption of certain plants, such as broccoli, statistically reduces the risk of several diseases. Such plants are usually the remit of nutritional science, although their mechanisms are part of pharmacognosy.

At first glance, phytotherapy need not be defined: it is simply the use of medicinal plants and plant-derived substances for treatment, including prevention, diagnosis, and symptom alleviation. In the rich history of medicinal plants, stretching back hundreds of thousands of years, it would seem that nothing has changed. However, a great deal has changed. Throughout history, as is the case today, numerous plants with a narrow therapeutic window have been used. This means that the difference between an effective (efficient) dose and a toxic dose is relatively small. One example is deadly nightshade (Atropa belladonna), belonging to a pharmacological class of plants used since the Neanderthal era. You won’t find it in the form of herbal material or over-the-counter capsules in pharmacies or online shops because, given the supplement industry and human mentality, there would be thousands of deaths. Extracts from this plant are used extensively in medicine, but only under the supervision of medical professionals and at very specific doses for specific conditions.

Since the 20th century, the use of plant-based substances has been more restricted. The first of these were plants such as deadly nightshade, autumn crocus (Colchicum autumnale) and foxglove (Digitalis). These are not used for self-medication and cannot be obtained without a prescription. Since the 19th century, phytotherapy has been defined as the use of relatively non-toxic plant species, where errors in dosage and indication do not pose a significant risk. This risk always exists, but it is statistically significantly lower than with plants such as autumn crocus.

This is also why the scope of pharmacognosy and herbal medicines is far broader than that of phytotherapy. In Europe alone, over a hundred plant species are used for self-medication and over-the-counter sales, but this list is exhaustive. To conclude, multiple herbal medicines are used in medicine but, in regulatory, semantic, and practical terms, are not part of phytotherapy.

For many years, I thought the concept of aromatherapy was consistent worldwide. It involves the use of essential oils to treat, alleviate, provide therapy for or prevent disease. However, a conversation with Robert Tisserand in France called my certainty into question. He asked a simple question: ‘Is Gelomyrtol forte really aromatherapy?’ For those who are unaware, Gelomyrtol is a herbal drug used to treat respiratory conditions and contains several essential oils in an oral formulation. So, is every application of essential oils aromatherapy, or does it simply refer to the inhalation and local application of essential oils on a person, primarily in the context of mood?

A second important question arises. Essential oils are just one of the many forms of diverse plant extracts. On what grounds do we justify the existence of this discipline separately from the use of whole plants? If so, we could also have ‘tincture therapy’, ‘supercritical therapy’ and ‘infusion therapy’. This question may seem heretical to aromatherapy enthusiasts, but it is worth asking periodically to gain a broader understanding of the world of medicinal plants. The answer is simple: it exists for historical and cultural reasons, which can be read about in the history of aromatherapy on Plantagea.

Phytopharmacy is a term favoured by my profession in the pharmaceutical world. Medicinal plants are also a domain of self-medication, with many non-medical professionals involved in the field. The term was coined to lend credibility, implying that the recommendation comes from a professional who, by virtue of their training, understands the wider context, from pathophysiology to potential drug interactions. Phytopharmacy suggests an evidence-based approach. Although it is taught and practised by nutritionists and doctors, the term originates from the fact that pharmaceutical faculties are among the last to clearly integrate medical subjects with pharmacognosy and botany.

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