Fabaceae

Mucuna pruriens

Velvet bean · Kapikacchu · Cowitch

Trial support Serious Yielded a drug

Part used: seed
Native range: Tropical Africa and Asia; naturalised across the tropics
Morphology: A vigorous climbing annual legume with three-part leaves and dark purple flowers, followed by S-shaped pods covered in orange hairs that cause intense itching on contact.

What is in it

non-protein amino acids L-DOPA

tryptamines

serotonin in the pod hairs

Evidence

The seed contains L-DOPA, the standard treatment for Parkinson disease, at several per cent by weight. Small controlled trials show it produces genuine antiparkinsonian effects, with a faster onset than standard levodopa preparations. This is real, and it is not a reason to use the plant.

Safety

An uncontrolled dose of an active drug. L-DOPA content varies with variety, growing conditions and processing, so a preparation of unknown strength is being taken for a condition that requires careful titration. Dyskinesia, psychosis, nausea and hypotension are all documented risks of levodopa. The pod hairs cause severe contact dermatitis and are used as an itching powder.

Interactions: Serious with monoamine oxidase inhibitors — hypertensive crisis; Interacts with prescribed levodopa and with dopamine antagonists; Contraindicated with antipsychotics

Regulatory: Not a permitted listed-medicine ingredient in Australia. Levodopa is a prescription medicine.

How the traditions classify it

Ayurvedic Sweet and bitter; heating in potency. Used for what the tradition calls kampavata — a trembling disorder that maps closely onto Parkinson disease — and as an aphrodisiac and nervine.

Three systems, rating the same plant. Where they disagree, none of them is correcting the others — they are separate frameworks that arrived at their categories independently.

Historical use

Recorded in Ayurvedic texts for a trembling disorder, which is one of the more striking correspondences between a traditional indication and a modern diagnosis. Also grown as a cover crop and famine food, requiring extensive processing to be edible.

Recorded as history and attributed where possible. Long use establishes that a plant was widely used, not that it worked, and not that it was safe.

Worth knowing

Mucuna is the most remarkable correspondence in this collection between a traditional indication and a modern one. Ayurveda prescribes it for kampavata, a trembling disorder, and the seed contains several per cent L-DOPA — the drug used to treat Parkinson disease, discovered independently in the West in the 1960s.

That is a genuine hit. A tradition identified a plant for a movement disorder, and the plant contains the specific molecule that treats it.

It is also the strongest argument in this whole collection for isolating and measuring. Levodopa has a narrow therapeutic window; too little does nothing and too much causes dyskinesia and psychosis. Neurologists titrate it in small increments. A bean of unknown potency, taken by someone with Parkinson disease, is the same drug without any of the control that makes it usable.

Nomenclature verified against GBIF backbone taxonomy.