Levodopa, a direct precursor of dopamine, is the main medication for Parkinson’s disease. Patients are treated with “synthetic” levodopa in different doses or combinations in tablets of Sinemet, Madopar and Stalevo.
The largest natural source of levodopa is Mucuna, a legume (such as common beans, peas, lentils, peanuts). Extracts from the variety of Mucuna pruriens, especially the seeds, display a very interesting biochemical profile. These have been used for three thousand years in more than 200 recipes from India medicine.
Extract of mucuna seed powder contains large amounts of levodopa and a little serotonin and nicotine along with other ingredients that are only partially known. In the treatment of Parkinson’s disease such extracts seem to be more effective and less toxic than the synthetic preparations1.
FURRY BEAN GROWING IN THE TROPICS
Mucuna pruriens is a kind of “hairy” or furry bean, native to Southeast Asia, especially the plains of India, but also widely distributed in tropical regions of Africa and the Americas (particularly in the Caribbean).
The wide dissemination of the plant explains its variety of names, depending on the location: velvet beans, cowhage, itch bean, picapica, Fogareté, Kapikachu, sea bean, deer eyes, yerepe, Atmagupta, nescafe, chiporazo.
A SHRUB AS A VINE
This annual plant grows as a climbing shrub with long tendrils that enable it to reach more than fifteen feet in height.
Young plants are almost completely covered by a diffuse orange hair that disappears as they age. It grows or is cultivated as fodder to enrich the soil (adding a lot of nitrogen) or for its medicinal qualities.
Since its discovery2, in 1937, and due to its high content of levodopa, interest has grown and now it is produced in much larger quantities.
ITS FLOWERS ARE POLLINATED BY BATS
The velvet bean leaves are of the trifoliate type, with leaflets of 5 to 12 cm (4 in.) in width and 7-15 cm (3-5 “) long.
The white or purple flowers are in axillary racemes up to 32 cm long. They are self-fertile, though in some places they are pollinated by bats which, while trying to eat nectar of the plant, carry pollen from flower to flower in their ears3.
PODS AND SEEDS
The pods are produced in groups of 10 to 14, measure 4-13 cm long and 1-2 cm wide, and are covered with fine white or light brown hairs.
Each capsule contains 3 to 7 seeds, which are from 8 to 13 mm wide and 10 to 19 mm long4.
The seeds can be black, white, red, brown or mottled.
NAMED “PRURIENS” BECAUSE OF THE ITCH
It is called “pruriens” because of the intense itching produced by their contact.
The orange “hairs” of flowers and pods of Mucuna pruriens contain chemicals (including serotonin) that, when they come in contact with the skin, cause intense irritation and itching, and sometimes very troublesome injury including allergies and severe swelling.
FOOD, FORAGE OR GREEN MANURE
Velvet bean or mucuna is mainly used as a cover crop or green manure, which provide organic matter and nitrogen to the soil. Fresh biomass yields are high.
Mucuna pruriens produces nematicidal compounds and can reduce the population of worms when combined with other crops. This also has allelopathic effects that suppress weed growth.
Another use of mucuna is as a high quality forage. In fields where the pods are mature sheep and goats can graze.
Its leaves, pods and seeds are high in protein, much more so than any of the other pasture grasses. Interestingly, if the proportion of mucuna is high the animals reach a slightly lower weight5 6suggesting some toxic or disnutritive element.
The roasted seeds are used as a substitute for coffee in areas of Central America. The buds and young pods are used as food after being cooked several times.
The dried seeds can be consumed after being soaked in water for 24-48 hours and then cooked4, changing the water several times to reduce the content of toxic and antinutritive compounds.
AN ANCIENT MEDICINE
In India, mucuna has been the main healing herb for three thousand years. All parts of the plant are used in more than 200 indigenous medicinal preparations. The seeds contain up to 7% levodopa, which is used in the treatment of Parkinson’s disease.
In the Ayurvedic medicine, velvet bean is recom-mended as an aphrodisiac, and studies have shown that its use causes a rise in testosterone levels, increased muscle mass and strength, and also improves coordination and attention.
TOXICITY OF MUCUNA AND OTHERS LEGUMES
The difference between a drug and a poison is a matter of dosage. The appropriate dose of levodopa improves Parkinson’s and other diseases, but when taken in excess it may cause problems.
Ingestion of large amounts of vegetables (of the Fabaceae type) by any person may induce intoxication because an excess of levodopa, when converted into dopamine, provokes abdominal symptoms (pain, vomiting) and cardiovascular abnormalities (tachycardia, flushing, etc.). These symptoms have been described in common beans and also in different varieties of mucuna, e.g. Mucuna gigantea 8, originally from Hawaii.
LEVODOPA AND MORE
The interest in mucuna increased after 1937 when it was discovered2 that the variant contained large amounts of levodopa. However, this amino acid alone does not justify the many medical applications of this interesting plant.
Extracts from the seeds or other parts of the plant have many numerous healing properties that cannot be explained only by levodopa.
In the treatment of Parkinson’s disease some results in groups of patients and in experimental animals show that, apart from natural levodopa, Mucuna pruriens has other ingredients that show outstanding features. It must contain other substances that improve the absorption of levodopa and metabolic efficiency, as explained below.
50 KNOWN INGREDIENTS, OTHERS REMAIN
Mucuna pruriens is an amazing plant. In addition to levodopa, it contains other natural ingredients that influence their particular properties, although some are found in small quantities.
To date, 50 substances have been identified in the powder of its seeds10 11 1213.
. Other still unidentified components must exist in mucuna, such as portions or mixtures of alkaloids, proteins, peptides, polysaccharides, glycosides, glycoproteins and several phytochemicals including tryptamine, alanine, arginine, glutathione, isoquinolone, mucunine, nicotine. prurienine, serotonin, tyrosine, etc. 14
These substances, identified or not, confer special powers on mucuna, perhaps boosting the levodopa or adding some kind of dopamine agonism and even extended its effects. We need to continue investigating them.
OTHER PLANTS THAT CONTAIN LEVODOPA
It was thought that levodopa was only present in Mucuna (Vicia species), but it can also be found, although less concentrated, in plants like Phanera, Cassia, Pileostigma, Canavalia, Dalbergia, etc.15 This extends the horizon for new therapies.
However the differences among these are striking. It has been well known for a long time that beans contain natural levodopa, although in small quantities, and may improve some parkinsonian symptoms. Our beans, when they are green, including pod and seeds, contain 0.6% concentration of levodopa.
The whole fruit of Mucuna pruriens, contains a concentration of 4.02 %, and if you select the white variant of its seed, it contains 6.08 % levodopa (ten times higher than in common beans).
MUCUNA CONTAINS MORE LEVODOPA
Trials have been conducted in which mucuna seeds are germinated in darkness or in different conditions of light and providing varied nutrients (oregano, proteins from fish, etc.).
Results showed that by adding oregano to seeds germinated in darkness, mucuna sprouts containing 33% more levodopa have been obtained 16.
In an attempt to increase the proportion of levodopa in mucuna, researchers selected some cells from the ground, and then grew them grow in a medium that allow nutrients to be supplied.
In this way they have managed successfully to increase the concentration17 18 19.
MUCUNA CAN PROVIDE OTHER BENEFITS
This is a question of common sense. If, apart from levodopa, Mucuna pruriens naturally contains certain substances that make it more effective, the same can happen with other varieties of mucuna (there are many) or with other vegetables that have been capable of modifying the proportions of levodopa, antioxidants and other ingredients20 21.
This opens up a horizon of new therapeutic possibilities.