What is phytotherapy?

15. February 2021 — von Daniela Diepold

Plants play an important role for us: as foods, spices, delicacies, or remedies. Modern phytotherapy uses the natural healing powers of plants (phyton, Gr. = plant) in medicinal preparations based on scientific principles.

Over millennia, the principle of trial and error has led to important insights into the effects that plants can have, and traditional recipes and remedies have continuously been refined.

The origins of morphine, atropine and digitoxin

It was not until the 19th century that a scientific approach to medicinal plants and their ingredients began in today’s sense. With the help of Chemistry, individual active ingredients were isolated from the plants. That’s how it was possible to isolate morphine from opium, atropine from deadly nightshade and digitoxine from foxglove. These substances have become an indispensable part of modern medicine. By chemically isolating pure active ingredients from poisonous plants, the problem of risky and unprecise dosage could be avoided. Instead, it became possible to dose isolated active ingredients in tablets, drops or ointments and use them in the same way as synthetically produced medicine.

The definition of phytotherapy

Phytotherapy stands for therapy and prophylaxis with medicinal products of plant origin, so-called phytopharmaceuticals. Phytopharmaceuticals only contain plants, parts of plants or products of plants origin such as essential oils, balsams and ole-gum-resins as active ingredients. These can be substances that are monoprepared or combined, but isolated pure substances are never used in medicine.

What are the parts of plants?

Here’s a little botany:
herba = herb: all the parts of the plant that are above ground
flos = flower
folium = leaf
semen = seeds
fructus = fruit
cortex = bark
lignum = wood
radix = root
rhizoma = rootstalks

The dose makes the poison

Phytopharmaceuticals usually have a wide therapeutic range. There is a difference between the dose that achieves the desired effect and the (over)dose that cause undesirable side effects. Herbal medicines usually cause fewer side effects than synthetically produced medicines, but they are not free of side effects.

Phytopharmaceuticals make up combinations of different active ingredients that together form a unit. Combined, the active ingredients are more effective than pure substances, as this increases the target areas, with substances being either synergistic or antagonistic.

Lead compounds are crucial for effectivity

Lead compounds are specific chemical compounds that define the drug ingredients, and are most crucial for the effectivity of the substance. The amount of the lead compound effectively controls the preparation of the pharmaceutical. In terms of the therapeutic quality, the following applies: substances with the same lead compounds have comparable effects.

Active ingredients in medicinal plants and phytopharmaceuticals

The chemical substance classes responsible for the diverse effects of medicinal plants are not many. Within these, the smallest differences in chemical structure of the compounds often decide which primary effect it will have on the organism.

Essential oils give many plants their characteristic scent. Applied externally, they stimulate blood flow, while internally their effects differ. Some promote the secretion of digestive juices (spices!), while others affect the lungs, stimulating bronchial secretion (coughing).

Bitter substances and bitter taste increase the formation of digestive juices. They make you feel hungrier, which in turn means that food is put to better use and processed better. So-called tannins are an example of these. These were historically used to tan animal hides into leather. In medicine, the tannins make inflamed superficially insensitive to bacteria, relieving diarrhoea and inflammation of mucous membranes.

Saponins’ chemical structure give them soap-like properties (sapo = Latin for soap). Depending on the complex structure of these substances, they can be either used to treat cough (e.g. primula and ivy), or to stimulate kidney activity (e.g. goldenrods, onosis or restharrows), or else to strengthen veins (horse chestnut).

Mucilage covers inflamed mucous membranes, forming a protective layer. For this reason, plants with mucus are used to relieve coughing (e.g. marshmallow). Strongly swelling plant mucilage (e.g. flea seeds) can also be used as mild laxatives.

Flavonoids are yellow-coloured substances (flavus = Latin for yellow) that can be found in almost all plants. Only in some plants, however, are they used therapeutically as it is only there that we find the particular kinds of flavonoids in the right amount: flavonoids in hawthorn for heart failure, in milk thistle for liver damage, in chamomile for an antispasmodic effect and in birch leaves for a diuretic effect.

Often, several of these substance groups are found in one plant, with the effects complimenting one another. For example, the particular digestive effect of chamomile flowers comes from the interplay of anti-inflammatory essential oils and relaxing flavonoids.

At a glance

  • The effect of phytopharmaceuticals comes from the particular make-up of the plants: the chemical active substances found in the plants connecting to certain receptors in the animal that eats the plant, leading to a physical effect.
  • The relationship of dosage and effect: a minimum dose is required to achieve a therapeutic effect; underdosing gives no effect, while extreme overdosing can cause undesirable effects.
  • Herbal medicines, even when they come from a single plant, are always made up of a combination of different substances.
  • The quality of herbal medicine can be checked with medical and scientific methods.

In the next article on phytotherapy, we’ll speak about individual medicinal plants in more detail.