Plant Power That Shaped Modern Medicine: How Medicinal Plants Helped Us Understand the Brain
Some of our most important discoveries about how the brain works were made thanks to plants. Long before high-tech labs and brain scans, nature had already packed the answers into leaves, roots, resins and flowers. Many of today’s medicines, and even entire systems of pharmacology, owe their existence to humble, but sometimes highly potent, medicinal plants.
Here are just a few ways plant chemistry helped scientists unlock the secrets of the brain:
Opium Poppy & the Opioid System
When morphine was first extracted from the opium poppy (Papaver somniferum) back in 1806, it was used for its pain-relieving power. But its effects were so profound, scientists began to wonder how it worked. This led, in the 1970s, to the discovery of opioid receptors in the brain — specifically the mu (involved in pain and addiction), delta, and kappa receptors. These receptors are part of a built-in system in our bodies that responds to both plant-derived and naturally-made (endogenous) opioids. Five receptors (and subtypes) are now known.
Cannabis & the Endocannabinoid System
You’ve definitely heard of THC and CBD — the active compounds in Cannabis sativa subspecies. These were traditionally used for pain, nausea, and loss of appetite, but they also led to a huge breakthrough in neuroscience. In studying how these chemicals worked, scientists discovered the body’s cannabinoid receptors (CB1 and CB2), and with them, the endocannabinoid system — a network in the body that helps regulate mood, appetite, pain, memory, and more.
Henbane & Memory
Scopolia or henbane, contains scopolamine — a compound once used for sedation and anaesthesia. In 1974, researchers realised that scopolamine blocks acetylcholine, a key neurotransmitter for memory and consciousness. This helped uncover the cholinergic system (discovery of which is attributed to the physic garden’s very own curator and her team) and its role in everything from attention to learning.
Deadly Nightshade & the Parasympathetic Nervous System
Alkaloids from deadly nightshade (Atropa belladonna) and other Solanaceae plants (like mandrake and henbane) didn’t just inspire folklore with their mystery and poison — they led to the discovery of muscarinic acetylcholine receptors. These receptors help control the parasympathetic nervous system — our “rest and digest” functions like slowing the heart rate and relaxing muscles.
Coca Plant & Nerve Signals
Cocaine, extracted from the coca plant (Erythroxylum coca), was traditionally used to boost energy and relieve pain. When it was isolated in 1860, scientists realised it could numb tissues — leading to its use as a local anaesthetic. This discovery also helped researchers understand sodium ion channels, crucial for how nerves send signals.
Indian Snakeroot & Mental Health
The plant Rauvolfia serpentina, or Indian snakeroot, was traditionally used to treat ‘madness’. Its active compound, reserpine, became one of the first drugs to treat high blood pressure and psychosis. In the process, scientists discovered that it depletes brain chemicals like dopamine and serotonin — shedding vital light on how these neurotransmitters affect mood and mental health.
Foxglove & Heart Function
Digitalis purpurea—better known as foxglove – has long been used to treat heart failure. The compound digoxin, still extracted from foxglove today, improves heart function by affecting how the heart contracts. It also taught researchers a lot about ion channels and how they influence cardiac rhythm.
Fever Tree & Malaria
Quinine, the first effective treatment for malaria, was extracted from the bark of the Cinchona tree (fever tree or Peruvian bark). This bitter plant remedy not only saved countless lives, but it also kickstarted the field of antimalarial pharmacology, leading to modern synthetic drugs for malaria.
Nature: The Original Pharmacologist
These are just a few of the countless ways plants have illuminated our understanding of the brain, body, and medicine. At Dilston Physic Garden, we celebrate these natural pioneers—not just as historical footnotes, but as ongoing inspirations for healing and discovery.
Next time you pass a poppy, foxglove, or henbane in the garden, remember you’re walking among highly esteemed plants – the original chemists of the brain.
