Did you know that a lot of our most common medicines are plant-based in origin?

Today most of our everyday medicines are made via chemical processes. However, what a lot of people don’t know is that a lot of these drug compounds were not thought up or discovered by clever scientists. They were made by clever plants- and then scientists found a way to make them synthetically for large scale production. Plants are the medical geniuses here, and they don’t even know it!

Even though we have categorised many plant compounds for their medical uses- plants still represent a huge untapped resource for undiscovered medicines. It is estimated that there are 400,000 plant species in the world– meaning we have only scratched the surface in terms of drug discovery from plants.

Here are a couple of our commonly used medicines, which have their roots in plants:

Aspirin (Acetylsalicylic acid)

Millions of people rely on Aspirin for treatment of fevers, headaches and general aches and pains. But a lot of people don’t know that aspirin was first discovered in plants.

336px-Aspirin-skeletal.svg

Strutcure of Aspirin source: Wikipedia

For thousands of years people from all over the world have been using aspirin-containing plants for the treatment of their aches and pains. For example, Hippocrates himself used to talk about the virtues of a tea made from willow bark for the treatment of fevers- all the way back in 400BC!

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The willow tree: Via pixabay

We now know that the fever-treating properties of willow bark tea was due to high levels of the plant compound salicylic acid. In 1897 a chemist at the company Bayer added an acetyl group to salicylic acid thus creating what we now know as Aspirin.
Did you know? Salicylic acid whilst acting as a medicine in humans, is actually a plant hormone. In plants salicylic acid helps to regulate several processes, maybe most importantly, the plant immune response.

Quinine

L0058850 Samples of cinchona bark, Quinquina Route Equateur, prepared

Wellcome blog post via wikimedia

Quinine is a medication used to treat malaria- and for many years was the drug used for the ‘first line’ of treatment. The Quechua people, who are indeginous to peru, ground the bark of the cinchona tree and added it to sweetened water (forming tonic water) which they used as a muscle relaxant to treat shivers. This tonic water was subsequently found to also be an effective treatment for malaria, leading to Cinchona tree bark (or Peruvian bark) becoming the most valuable commodities shipped out of Peru in the 17th century. The active compound of the cinchona tree: Quinine, was first extracted in 1820, with bark extracts being a common treatment of malaria since the 17th century.
Did you know? Quninine is what makes tonic water bitter. British colonials drinking tonic water in India didn’t like the bitter taste and so mixed it with Gin- making one of my favourite drinks Gin and Tonic.

Paclitaxel (Taxol)

Paclitaxel is a chemotherapy medication used to treat a range of cancers. It works by stopping cancer cells splitting into two new cells thereby preventing the growth of cancer.

Pacific_yew_tree

Pacific Yew tree source: Wikimedia

Paclitaxel was first isolated from the Pacific Yew tree, a conifer tree native to North America. By the 1950s it was realised that we needed treatments to destroy cancer cells that had spread to other parts of the body. This led to a huge search by the National Cancer Insitute for new cancer drugs, and the creation of the Cancer Chemotherapy National Service Center (CCNSC). The CCNSC at first only analysed known and synthetic compounds for anti-cancer activity, but by the 1960s it had also starting searching for treatments from plant sources. When an extract from the bark of the Pacific yew tree was analysed it was found to be toxic to living cells. The most cytotoxic compound in the bark extract was named paclitaxel.

Unfortunately, there was no easy way to get this anti cancer-drug from Pacific yew trees sustainably. Pacific yew trees are extemely slow growing, and a large amount of bark was required to make a therapeutic dosage of paclitaxel. In addition, the extraction of the bark from the tree would destroy it, and as numbers of the tree were already dwindling….

Luckily, after a lot of very hard work, a effective synthetic version of this compound was successfully made. Taxol is now used for the treatment of many cancers, and is still one of the best plant-based cancer treatments around!

Where next for plant medicines?

There is now a huge effort being undertaken to look back at ‘natural traditional’ plant based medicines used around the globe to identify plants, and the active plant compounds, for the development of future medicines.

But, there is a darker side to all of this which I want to touch on briefly… Plants offer a huge potential for medicines, and we now know how to effectively harness this potential. However, not all plant ‘medicinal compounds’ are good for us. In the case of paclitaxel- its a good cancer drug because it kills cells- this highlights the requirement of plant medicines to be tested and researched. Just because medicinal compounds are being produced naturally in plants, does not mean they will be good for us.. and just because a compound its good via diet doesn’t mean it is good topically.

Additionally, plants do not tend to naturally make these ‘medicinal’ compounds in ‘therapeutic’ doses. There is a dangerous trend where people grab on to the idea of plant containing a ‘medicinal compound’ and eating huge volumes of said plant. The most flawed and disturbing extreme of this has been seen promoted by some ‘health gurus’, saying copious amounts of a fruit/vegetable/tea containing a compound can cure cancer.

Whilst there are a lot of potential medicinal compounds in plants which we need to investigate futher, often these compounds will need some fine-tuning to make them the most effective for our use.
References:

https://kids.frontiersin.org/article/10.3389/frym.2017.00014

https://en.wikipedia.org/wiki/Quinine

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3121651/

https://www.cancer.gov/research/progress/discovery/taxol

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