Plants for colds and aches

Another example of the importance of medicinal plants for medicine is the story of acetylsalicylic acid which is also known as aspirin. Here,  two plants played major roles in its development. Both have been used for thousands of years, since long before chemical substances were isolated from them. The two main role players were the white willow, Salix alba and meadowsweet, Filipendula ulmaria. A substance was successfully isolated from willow bark in 1830 and since the generic name for willows in Latin is Salix, it was named salicin. Eight years later it was discovered that it was a glycoside, i.e., it consisted of one part sugar and one part aglycon. The aglycon could be oxidised into an acid, which was called salicylic acid. Similar substances were also found in other plants, e.g., meadowsweet. The substance from meadowsweet was named spirin since the plant’s scientific name at that time was Spiraea ulmaria.

In 1876 it was discovered that salicylic acid was effective against rheumatic pain. A common side effect was stomach problems. A German chemist, Felix Hoffman, whose father suffered from both rheumatic pain and stomach problems which were associated with the salicylic acid, started to experiment. In 1897 he modified the substance chemically to acetylsalicylic acid whereupon his father’s stomach problems were eased. At the pharmaceutical company where Hoffman was employed, they tested the substance on animals and this is thought to be the first time that animal trials were used in the pharmaceutical industry. Later, when tests were carried out on human beings, they found that the substance was not only effective against rheumatic pain but also other kinds of pains, e.g., headaches. When it was time to launch the substance on the market they needed a good name for it. Aspirin was chosen. “A” from acetyl and spirin from spiraea.

Acetylsalicylic acid is one of today’s most common medicines against pain. In many products, the substance is combined with caffeine, which is another well-known plant substance. Caffeine has been refined from coffee since 1820. In recent years there has emerged an alternative use for acetylsalicylic acid. It is known to be an anticoagulant and, in low doses, it prevents blood clots.

Linnaeus gave the plant the scientific name Rudbeckia purpurea, to honour Olof Rudbeck – his predecessor in the post of professor of medicine. But nowadays purple coneflower bears the scientific name Echinacea purpurea.The plant originates in North America but was brought to Europe during the latter part of the 17th century. It was cultivated as early as 1699 in the botanical gardens at the University of Oxford in England.

In Linnaeus’ time the purple coneflower was not known to have medicinal effects but was cultivated as an ornamental plant. A physician in Nebraska in the USA learnt from Indians in 1871 that the plant could be crushed and used on open sores. He recommended it as a means of cleansing the blood as well as against eczema, haemorrhoids, malaria, migraine, snake bites and rheumatism. Between 1885 and 1935 the plant was used against bacterial infections but that was discontinued with the discovery of sulfonamide – a synthetic antibiotic. In Germany, much work was carried out on the plant during the period 1940–1955 where it was found that it was not as effective killing bacteria as had at first been believed and during the same time penicillin was beginning to be used widely.

Recent research has shown that the purple coneflower has interesting medicinal effects, as does its relative blacksamson, Echinacea angustifolia. Extracts from these plants are considered to stimulate the immune defence and are therefore recommended for treating mildly infectious diseases as well as common colds.

Preparations such as these are now big sellers on the market of herbal remedies and research is still continuing on their effects. They have been shown to have local bactericidal effects and speed up the healing process of sores that are hard to treat, all of which motivates the Indians’ use of the plant. There have also been many clinical trialsthat have shown that extract of echinacea probably has a positive effect on the immune defence system and therefore should be useful against colds and similar problems.

Liquorice is not just a kind of sweet – there is also a plant called liquorice, Glycyrrhiza glabra. It grows to 1-1.5 metres high and is found, for example, around the Mediterranean. The root at first tastes sweet, but is followed by a bitter after-taste. The sweet taste is due to its content of 2-12% glycyrrhizin, which is a triterpenoid saponin. The evaporated extract from the root is called liquorice and is used for confectionary and as a taste improver in drugs.

Glycyrrhizin and many other saponins work as expectorants for coughs since they reduce surface tension. Liquorice is therefore used as a product for treating coughing. Glycyrrhizin is about 50 times sweeter than sucrose – cane sugar. However, if you eat too much of it, you will experience the laxative effect of liquorice, and if you consume large quantities over long periods of time, you will get high blood pressure and heart problems. So when you eat liquorice, it’s not just your teeth you have to worry about.

Another plant substance which plays a big part in the confectionary industry is Gummi arabicum or gum Arabic which is the resin from an African tree, an acacia, Acacia Senegal. It is a carbohydrate which is used, among other things, as a thickening agent in many cough sweets.

The Ginkgo or maidenhair tree, Ginkgo biloba, has been called a living fossil. The tree evolved around 250 million years ago and has no close living relative. A characteristic of the young leaves is that they have two lobes which is why Linnaeus gave the tree the epithet biloba – the two-lobed. The tree is originally from China and Japan. In 1730 the first samples came to Utrecht but the tree soon spread to the rest of Europe. Linnaeus didn’t use gingko medicinally, but it has been used for centuries in China.

In the 1930s a group of substances called ginkgolides was isolated. However, it took until 1967 to discover their chemical structure. Ginkgolides have been shown to increase the blood flow in the brain which helps old people symptoms such as memory loss, tiredness and tinnitus. They have also been shown to have positive effects treating shock, burns and inflammatory skin diseases.

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Referens:
Bruhn, J G 1996. Ginkgo biloba – en översikt. Svensk Farmaceutisk Tidskrift 100(2):42-45.