Artemisinin: From traditional Chinese medicine to modern day drugs

Rhinoceros horns, bear bile and seahorse? Medicine, but not as we know it today. Looking at the bizarre and sometimes unethical witches’ cauldron of ingredients used in traditional Chinese medicine, it’s hard to imagine how this can relate to the pills, syrups and lotions which we rely on to make us better today. Yet, as far-fetched as it seems, there was method in the ancient Chinese madness, and this age-old knowledge is proving extremely valuable for today’s scientists.

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Ancient medicine
Founded by Emperor Shen Nung, Tradtional Chinese Medicine (TCM) is one of the world’s oldest medical systems and is still widely practiced today. Different therapies, including acupuncture, massage and in particular the use of herbal medicines, are used to promote health and treat disease. Herbal remedies proposed to have medicinal properties, were derived from plants, minerals and animal products. Through centuries of trial and error, these remedies were classified by their perceived action in the body. This knowledge was compiled into a pharmacopoeia – a book containing a list of medicinal drugs with their effects, and directions for their use. This book was called the Materia Medica and it is still used by practitioners of TCM.

Two different views
The Traditional Chinese Medicine view of how the body works, what causes illness, and how the illness is treated is very different from the concepts that we accept in Western medicine. In TCM, the human body is seen as an organic entity in which the various organs and tissues have distinct functions but are all interdependent. In this view, health and disease relate to balance of the functions, and there is an emphasis on individualized treatment [1]. In comparison, western medicine applies health science, medical technology and biomedical research to diagnose and treat injury and disease. Instead of a trial and error method, proposed drugs are initially tested via computer modelling programs to see if the compound has the correct interactions with the target molecule to be effective and safe for human use. Unlike Chinese medicine, clinical trials are an important feature of the development of new Western medicines. Even though Chinese medicine is based more on theory and trial and error than scientific fact, it is known that many of the herbal remedies prescribed contain active ingredients (the part of the herbal remedy which can interact with our body).

From plant to pill
Many traditional herbal remedies have potentially beneficial active ingredients. Therefore research into traditional remedies is providing new inspiration for scientists for making new drugs. Recently, this research led to the discovery of a new anti-malarial drug artemisinin.

Chinese herbalists had been using a potent anti-malarial plant for more than 200 years but this was unknown to the Western world. Artemisia annua, or sweet wormwood, is a herb used in traditional Chinese medicine as a treatment for malaria and skin diseases. Artemisinin is the active ingredient in the plant extract. Studies on this compound have proved that artemisinin is indeed a strong anti-malarial agent. Most anti-malarial drugs act by rapidly killing parasites in the bloodstream. They are normally taken to prevent the disease by killing the parasites before they reach the liver to prevent them multiplying. Although the exact mechanism of artemisinin isn’t known, it is thought that the peroxide bridge (the O-O linkage shown in the above structure) is the part of the molecule that causes the anti-malarial action.

Artemisinin is thought to be a prodrug. A prodrug is a drug that is administered as an inactive compound and which is converted to the active agent in the body. Once activated in the body, artemisinin is thought to produce either carbon or oxygen centred radicals – reactive atoms with one or more unpaired electrons. These are ultimately responsible for the anti-malarial activity – the radicals attack the cell membrane of the parasite in the presence of high iron concentration.

Over one million malaria patients have been cured due to the treatment by artemisinin and its derivatives.