Plants affecting stomach, kidneys and liver

Many bitter tasting plants affect the digestive system. They have often been used to increase appetite and it has been proven that some bitter substances affect the kidney function.

Chamomile is calming and also has an anti-inflammatory effect, which means that chamomile extract can be used for example for disorders of the stomach and intestines, and for menstrual problems.

Saint Mary's thistle, a species from the Mediterranean area, has fruits which contain a liver protecting substance. The same substance also has an effect on stomach ulcers.

Bogbean – a bitter for the stomach

The leaves and rhizomes of
bogbean have been used in
medicine for stomach complaints.
Photo: Håkan Tunón.

Bogbean, Menyanthes trifoliata, is commonly found in Sweden in marshy areas. It has had a high incidence of use as a medicinal plant for many hundreds of years, principally because of its bitter taste. Even in our times the bogbean is used in traditional medicine to treat, among other things, inflammation of the kidneys. In Linnaeus’ book Materia medica (1749), he recommends it for inflammation of the kidneys, rheumatism as well as for stomach complaints. Linnaeus’ disciple and successor as professor of medicine in Uppsala, Carl Peter Thunberg, wrote a thesis about the use of bogbean which was published in 1797.

Many bitter tasting plants have been used for increasing the secretions in the stomach and thus improving the appetite which affects condition in general. Scientific studies have shown that bogbean contains several different bitter tasting substances which affect the stomach and intestinal system. Loganin is the bitter tasting substance which occurs in the greatest quantities in the plant. Apart from bogbean, absinth, yarrow and yellow gentian have also been used. Earlier, plants were graded for quality according to their bitterness. Stidies in systematic botany have shown that bogbean is closely related to yellow gentian (Gentiana lutea).

Pharmacological and chemical studies of the bogbean have been carried out at the Department of Medicinal at Uppsala University. A decoction of the plant has been shown to reduce inflammation and to have a protective effect against kidney damage. Here too, the bitter substances are at least partly responsible for the medicinal effects. However, more scientific studies are needed before it can be recommended to patients.

Chamomile for the stomach

Chamomile tea is a classic
calming product for people under
stress. It is also good for the
Photo: Håkan Tunón

Chamomile (Chamomilla recutita) is one of our oldest and most well-known medical plants. It has been used for healing since the time of the Ancient Greeks and it was included in the Stockholm Pharmacopoeia [1686] as well as in the Swedish pharmacopoeias from the first to the eighth edition [1775–1901]. Nowadays the chamomile flower has a place in the European pharmacopoeia.

Many different substances have been identified from chamomile over the years, but it is now thought that the effects are due to essential oils and flavonoids.

The flavonoids constitute the water-soluble, the non-volatile part of the chamomile’s active substances, whereas essential oils principally consist of substances which are hard to dissolve in water but easy to dissolve in alcohol and other organic solvents. Essential oils also have the property of accompanying the steam from a hot-water solution making the effect better from an alcohol infusion than from tea. Chamomile and its constituent substances have been the topics of many scientific studies and the medical effects are considered to be a result the various components which have both similar and partially different effects.

Among other things, chamomile has shown anti-inflammatory activity and to heal wounds. It has a mildly calming effect on mice and the substance apigenin inhibits panic and has a mildly sedative effect which also induces the relaxation of muscles. The calming effects are considered to result from a flavonoid binding to certain receptors in the brain and thus explains the relaxing effect of chamomile. Essential oils have demonstrated anti-inflammatory effects, the ability to reduce fever and act as antispasmodics, all of which are important for ailments of the stomach and intestinal tracts.

The anti-inflammatory effect is explained by the chamomile extract inhibiting the release of substances that causes inflammation. These effects are caused by essential oils and flavonoids. Chamomile tea is prepared from dried flowers and used for fortifying the stomach, the release of gases, strengthening nerves and for relieving cramp. Its main use is internal for stomach and intestinal problems as well as against menstrual discomfort, but it can also be used externally for inflammation and irritation of skin and mucous tissues.

Many different substances have been identified from chamomile over the years, but it is now thought that the effects are due to essential oils and flavonoids.

Thistles protect against liver damage

The milk thistle contains
substances that protect the liver.
Photo: Håkan Tunón.

The milk thistle, Silybum marianum, is native to the Mediterranean and the Orient and has long been used in medicine. Dioscorides in Ancient Rome recommended the plant for use against various illnesses. The fruits have been used against stitch, as well as problems of the spleen and liver. Research has shown that the medically interesting substances in the fruits of the milk thistle are of a type known as flavonolignans.

Originally it was believed that there was one substance, silymarin. However modern research shows that silymarin consists of several closely related substances. Several of these can protect the liver. The fruits contain 1.5-3% silymarin.

According to the authorities within medicinal plant research, the flavonolignans from the milk thistle are the most studied natural products for protection against liver damage. Since 1969 more than 100 scientific articles have been written about their pharmacology and clinical use. One example from a two year clinical study showed that treatment with silymarin reduced deaths in patients with severe liver damage. Half of the patients were treated with silymarin three times a day and the other half were given placebos – sugar pills. After two years, the proportion of survivors in the placebo group was 53% and in the silymarin group 76%.

Silymarin is also used in the treatment of poisoning by destroying angel or death cap (Amanita phalloides and Amanita virosa) amanita mushrooms. It has also been claimed that silymarin has an effect on stomach ulcers and this has been confirmed in tests on sores produced in the mucous membrane of the stomach.

Mayapple – a many facetted healing herb

Mayapple in blossom
PHoto: Håkan Tunón.

Mayapple, Podophyllum peltatum, is a low herb that grows in the woods of Eastern USA and Canada. The plant has a rhizome that can grow up to one meter long. Previously, an extract from the root was produced by using alcohol. The extract was then concentrated and diluted hydrochloric acid was added. Precipitation forms which was washed, dried and subsequently ground to a powder. This powder, which is known in the pharmaceutical world as podophyllum, contains 20% podofyllotoxin, 10% beta-peltatin, and 5% alfa-peltatin.

In early 20th century podophyllum was mainly used as a laxative. Its laxative effects are principally due to the presence of peltatin. Podophyllin was used for venereal warts, but in modern medicine we use podophyllin instead in its refined form, podophyllotoxin. Both peltatin och podophyllotoxin have inhibiting effects on tumours and have therefore been thoroughly studied. Various derivatives of podophyllotoxin have been produced, e.g., teniposid which is mainly used against cancer of the bladder, and etoposid against other types of cancer.

A Mayapple plant with fruit in the
Botanical Garden, Uppsala University.
Photo: Håkan Tunón.

Another species Podophyllum hexandrum (synonymous: P. emodii) is native of the Himalayas. Podophyllin, produced from this species, contains up to 40% podophyllotoxin and no peltatins. Therefore it is much less of a laxative than podophyllin from P. peltatumP. hexandrum is used today for the refinement of podophyllotoxin for drug manufacture. Modern research has shown that podophyllotoxin is not only effective against cancer but is also useful in the treatment of genital warts and other viral illnesses. Clinical tests have shown that podophyllotoxin or structurally similar compounds have positive effects on other diseases, such as psoriasis, rheumatoid arthritis, Alzheimer and malaria.

Suggested Reading:
Bohlin, L. and Rosén, B., Podophyllotoxin derivatives: drug discovery and development. Drug Discovery Today 1:343-351, 1996.

Last modified: 2022-03-08