In this guest blog, Dr Ffyon Davies, an A&E and PHEM doctor based in North Wales, writes about the historic and future importance of plants within medicine.
It might surprise you to know that over 1/3 of modern medicines are derived from plants, microorganisms and animals, with 60-80% of antibiotics and anticancer drugs originating from chemical compounds that originated in the natural world.
In the USA, nearly 80% of prescribed medications are derived from plants and fungi.
I first became interested in the medicinal properties of plants and fungi during the covid pandemic lockdowns. When we were confined to walking within 5 miles of our houses, my local dog walk started to get dull... but it allowed me to start noticing all the little things, and that included the various plants and fungi that were growing in my local patch of woodland.
I started doing some reading and identifying as many different species as I could, and was surprised and amazed at how many modern medicines are derived from plants and fungi!
At first, I struggled to reconcile my interest in the medicinal properties of plants and fungi with the potential lack of a valid evidence base. Indeed, many herbal and traditional medicines may lack this, and have little more than a placebo effect. Similarly in some cases, the passage of time can lead to symptom resolution despite the use of herbal medicines, and not because of them, however there are also a significant number of plants and fungi that have a strong evidence base from which we have derived many modern-day medicines.
Ethnobotany, the study of a region’s plants through the traditional knowledge and culture of indigenous people, originated in the early 20th century and links traditional medicine with modern pharmaceutical medicine.
Medicines such as the chemotherapy drugs paclitaxel from yew trees, and vincristine from Madagascan periwinkle were discovered this way.
A lot of potential knowledge may still exist with indigenous communities, which has been handed down over centuries. Sometimes, local healers and shamans can be reluctant to share this knowledge, as historically medicinal plants have been exploited to the point of extinction. The Encephalartos Woodii, whose bark and leaves have traditional medicinal properties, was once widespread in South Africa, however over-harvesting and habitat loss has all but removed this plant from the wild and it is now an endangered species.
Modern Medicines and their Ethnobotanical Histories
Aspirin is derived from the bark of willow trees. Native American Indians had known about this for centuries, and when this was further investigated by pharmaceutical companies, we discovered aspirin.
Opium is derived from poppies and has long been recognised to have strong analgesic properties before we synthesised morphine and diamorphine from it.
Penicillin is another famous example- discovered by Alexander Fleming, penicillin was derived from a fungi that commonly grows on oranges and has arguably been one of the most important discoveries in the history of medicine. More recently, a chemical was isolated from the European Chestnut tree that has potential to treat MRSA.
Atropine is derived from deadly nightshade (atropa belladonna). Prostitutes in Italy used to put drops made from the plant in their eye, which would dilate their pupils and make them look more beautiful and alluring, hence the latin name bella – beautiful – donna – lady. Its antimuscarinic properties have also meant it was an effective treatment for asthma.
Digoxin Dr William Withering is credited with the first trials of foxglove extract in 1785 to treat ‘dropsy’, the fluid retention associated with heart failure. One interesting story is that Van Gogh perhaps suffered from digoxin toxicity, resulting in the strong yellow hues in a lot of his paintings.
Warfarin A Canadian vet noticed that large numbers of cattle were dying from haemorrhagic illnesses after minor procedures, such as dehorning or castration. He noticed that the cattle had been feeding on silage made from sweet clover and tested his theory that the sweet clover was thinning the blood of the cattle by feeding it to rabbits. Sure enough, the rabbit that had ingested sweet clover died of a haemorrhagic illness, and warfarin was discovered.
Quinine and hydroxychloroquine The Quechua people of Peru had long used the bark of the cinchona tree for muscle shaking, diarrhoea, and other illnesses. This was discovered by colonialists and became very popular in the 18th century as a tonic.
It was particularly popular amongst the officers of the British army, who drank it in gin and tonic. It was noticed that much fewer of the officers were dying of malaria in India, and quinine was discovered to be a treatment (and preventative) for malaria. Hydroxychloroquine was also later synthesis from the cinchona tree.
Theophylline was discovered from the tea leaf in 1888, but was primarily used as a diuretic and cardiac drug until its potential in treating asthma was discovered in 1992.
There are thought to be between 50,000 and 80,000 medicinal plant species worldwide. We don’t know the exact number, as many have not yet been formally discovered, however approximately 15,000 of these plants are already threatened by extinction.
A recent report conservatively estimated that we are losing one potential major new drug every 2 years.
This is for a variety of reasons including: more land being used for agricultural purposes, plants being used for biological resources, residential development, loss of biodiversity and habitat, and climate change. In some areas, 20% of the wild resources of medicinal plants have already been exhausted.
Rapid habit destruction and loss of biodiversity means that we are at risk of losing some species before we even discover them.
If we do discover new medications before we lose these species, pharmaceutical companies often patent and exploit the natural resources of the medicinal plant in question. Many low resource settlements still depend on traditional medicines, as they may not have access to other healthcare options or they may have different health and cultural beliefs.
There is much more that we can learn from indigenous communities and traditional medicine: just look at how much we have learned already.
References and Further Reading
Medicinal Plants by Kew Gardens
Hedgerow Medicine by Julie-Bruton Seal and Matthew Seal
Dr Ffyon Davies is an FY4 A&E Doctor based in North Wales. She has worked as chief medical officer on board the Tall Ship Pelican of London (Seas Your Future), sailing from Germany to Tenerife, and the Bahamas to Bermuda, and as a trail medic supporting ultramarathons in Wales and the Azores islands.
Later this year she is looking forward to supporting a 3 week expedition to the Canadian Yukon with the British Exploring Society, and an expedition to climb Kilimanjaro with Dig Deep charity. She is also part of the WEM faculty and will be speaking at the World Extreme Medicine conference in Edinburgh later this year.