Active substances in medicinal herbs

The medicinal plant contains substances capable of treating a disease or preventing its start (Moravcová, 2006).

The first group of active substances in plants are products of primary metabolism – sugars (carbohydrates) and fats (lipids). Herbal carbohydrates are obtained for example from common wheat (Triticum aestivum) whose sprouted and dried caryopses containing starch, which transforms into maltose during sprouting, are used. Maltose is then applied as a strengthening agent in various diseases.

Children commonly known lipids from home cooking. We can divide them into fats, oils and waxes. A number of vegetable oils have pharmaceutical use, e.g. olive oil is obtained by pressing drupes of the European Olive Tree (Olea europaea) and is used for example as emulsion for injections, in nasal drops (Pinosol) and it has a subtle laxative effect.


The other group of active substances are tannins which were originally used to tan skins (removing the remnants of tissues and softening) and for the production of inks. These are substances that precipitate in the presence of proteins so that they are used as antidotes against poisons of the protein-origin, and they also precipitate in the presence of heavy metals or alkaloids. Therefore, if there was a suspicion of poisoning by these substances, a strong tea containing tannins was administered. Tannins are mostly found in leaves, fruits (their contents are reduced with the ripening of the fruit), bark (spruce, oak, willow), and rhizomes. They are found in the families of: Polygonaceae, Rosaceae, Fagaceae or Ericaceae. They have astringent effects, calm wounds (but must not be used on large wounds as tannin can be reabsorbed and liver damage can occur). They are used for the treatment of burns and frostbite and as gargles; they suppress sweating and are used for diarrhea, etc.


A huge group of glycosides follows. They are active substances containing carbohydrate and non-sugar component aglycon. These include cardioactive glycosides, saponins, thioglycosides and many others with specific effects on the organism. Saponins in contact with water lather and are used for the production of soaps, for example the root of common soapwort (Saponaria officinalis). They are very toxic to fish. Thioglycosides are commonly consumed in the diet, plants from the family of Brassicaceae, e.g. cabbage, kale, kohlrabi, cauliflower, mustard, radish, horseradish, etc. contain thioglycosides. All are characterized by bitter substances of pungent taste which act disinfectantly. However, a number of glycosides require precise dosing and are therefore not intended for domestic use, e.g. cardioactive glycosides (e.g. Lily of the Valley – Convallaria majalis).


Plants also contain poisonous alkaloids, such as capsaicin in peppers (Capsicum), which causes local congestion and provokes a feeling of warmth or a variety of addictive substances that are available only on prescription , as there is a risk of addiction, for example ephedrine that joint-pine (Ephedra) contains, opioid alkaloids, e.g. morphine that poppy (Papaver somniferum) contains in its latex or is found in greater celandine (Chelidonium majus), nicotine in tobacco (Nicotiana tabacum), etc. A number of alkaloids are considered stimulants, e.g. caffeine in the tea plant (Thea), and Coffea.

Essential oils

Another significant group of substances are volatile substances of terpenic character which cause the smell of plants and the lure of insects – essential oils. A high content of essential oils are characterized by the families of pine (Pinaceae), ginger (Zingiberaceae), laurel (Lauraceae), deadnettle (Lamiaceae), or umbellifers (Apiaceae). The essential oils are stored in different parts of the plant. Lastly, we mention amara which are substances that have a very bitter taste.