Medicine – natural molecules

There are natural molecules that are so well created evolutionarily that they don’t need human intervention. The 2015 Nobel Prize for the discovery of artemisinin is a nod from sometimes arrogant modern medicine to old knowledge whose path has sometimes been ridiculed. Today they are hidden in modern medicines, but their botanical origins must be keenly aware.
Some drugs are completely natural molecules, isolated from plants or microorganisms. Their pharmacological properties are such that it was not necessary to introduce additional chemical modifications of molecules. They are still obtained today by extraction from natural raw materials. Interestingly, some of them are strong-acting – microbiological or plant poisons. Here you can find a short story about several significant natural remedies that still mark medicine today, and sometimes form the main backbone in some groups of drugs, such as immunosuppressants.

Example 1: Artemisinin – natural antimalarial

artemizininArtemisinin is an unusual compound from the cyclic peroxide class, isolated from the plant Artemisia annua which is a wild plant from the Northern Hemisphere. Artemisia annua is not a new drug, the written data of its use dates back to the 4th century AD, and is probably used much longer.

In the book A Handbook of Formulas for Emergencies (肘后备急方), author Ge Hong explicitly recommends it for the treatment of malaria. It began to be developed by scientists of the Chinese army in the 60s of the 20th century, but until the late 70s the cure was almost unknown. It is believed that the Vietnam War greatly accelerated the development of this drug. Artemisinin became suitable for insulation after a 1,600-year-old method of water extraction was replaced by the extraction of artemisinin with diethyl-ether in 1971. When its structure and action was published in 1979, it was met with skepticism in the West, because it was thought that peroxide artemisinin could not be stable enough to produce an oral drug. By then, the Chinese had already clinically examined the drug. Only at the end of the century will it be more extensively clinically tested in the West; it is one of the few in water-soluble antimalaric drugs and is also used as an intravenous drug. Artemisinin is used in combination with other antimalarials to prevent the development of resistance. In 2006, the WHO included artemisinin as one of the drugs of choice for malaria, thus terminating the 150-year-old dominance of drugs based on the structure of another planetary-known natural antimalarial – quinine. Artemisinin is one of the most successful drugs for the treatment Plasmodium falciparum induced with malaria.

Until the discovery of artemisinin, ascaridole from essential oils of plants Mexican tea (Dysphania ambrosioides) and boldo (Peumus boldus) was one of the few isolated stable peroxides. Until recent times, ascaridole was a remedy against intestinal parasites, but it was replaced by drugs that show a better profile of side effects.

We are all extremely pleased that the discovery of artemisinin was awarded the Nobel Prize in 2015.

Example 2: Tubocurarine – from chemical hunting weapons to medicine

tubokurarinFor centuries, the local population of the Amazon rainforest has used real chemical weapons in hunting. From liana Chondrodendron tomentosum they extracted juice (curare). The word curare literally means “arrow poison.” Kurare is a poison – it paralyzes the willing muscles by inhibiting acetylcholine receptor.

The poison that entered into the victim’s body with an arrow would cause paralysis and made the hunting easier. The question remains – why weren’t the hunters poisoned? The answer lies in the very structure of tubocurarine – so-called quatric nitrogen atoms prevent the effective absorption of poisons, and meat would be completely safe for nutrition. When the Spanish conquistadors conquered much of South America, tubocurarine became famous in Europe as well. It was transported in tubes, for the safety of content, and hence the name tubocurarine. French physiologist Claude Bernard proved in 1848 that it only works if given in the form of injections and bypasses the digestive system, and claimed it acts on a neuromuscular connection. In 1850, George Harley proved his efficacy as muscle relaxant in strychnine and tetanus poisoning, since these diseases lead to uncontrolled spasms of willing muscles. But it will have to wait another century until Wintersteiner and Duthcer in 1935 isolate d- tubocurarine as an active substance of curare poison. The main meaning of tubocurarine, however, is recognized through anesthesia. Despite previous attempts at use in surgeries, Canadian doctors Harold Grifith and Enid Johnson were the first to use tubocurarine in appendicitis surgery in 1942. Until then, one of the big problems in surgery was the need to use muscle relaxants, and muscle relaxation was tried by increasing the dose of anesthetic, with sometimes fatal consequences. Tubocurarine was one of the major breakthroughs in modern anesthesiology, and although it has been replaced over time by other drugs, it is still approved and registered in the U.S. for the same use as 70 years ago.

Example 3: Poppy, opium and poppy alkaloids

The use of poppy (Papaver somniferum) in medicine has a tradition of several thousand years. It has been used for various purposes, but its use in symptomatic pain treatment remains as up-to-date as at the very beginning. Poppy seed juice, lachryma papaveris, i.e. poppy tears or opium, is primarily known as a prohibited drug from which heroin is obtained. But the contribution of poppy to medicine is much more than illegal trade and means of abuse. Opiate is obtained by notching seed bags of immature poppy seeds of several types of poppy (except P. somniferum, P. orientale and P. bracteatum). By cutting the juice flows out (latex) that is collected and processed. Opiate contains a whole range of medicinal compounds of alkaloids. Its meaning is so essential that it led as far as the Opium Wars, seemingly triggered by China’s ban on the use of opiates as a drug but essentially launched because of colonial pretensions by major powers. Opium was long known in pharmaceuticals as laudanum (laudare = praise, celebrate), but also as elixir paregoricum (pain reliever). Unaware of the side effects and dangers of addiction, it has been popular for a number of years. Separate compounds were isolated mostly in the 19th century. In 1804, German pharmacist Friedrich Sertürner isolated morphine, French chemist Pierre Robiquet isolated as many as two compounds, in 1817 noscapine and in 1832 codeine. Papaverine was discovered in 1848 by Georg Merck (founder of the famous Merck company).



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