Table of Contents
Mucuna pruriens, also known as cowitch and velvet bean [1; 2] is a traditional medicinal plant belonging to the Leguminosae family . M. pruriens is notable as a climbing legume, found in southern China and eastern India . Benefits of Mucuna pruriens have been documented as anti-diabetic, anti-neoplastic, anti-microbial, aphrodisiac, along with enhancing learning and memory [1; 3]. In addition, parts of the M. pruriens plant used in medicinal treatment include the seeds, leaves and roots , where it has the potential as a neuroprotective through its naturally occurring L-DOPA content.
As all parts of the Mucuna plant has the ability to treat certain ailments, M. pruriens extracts contain substances that showcase a variety of pharmacological effects . In addition, Mucuna seeds contain around 5% of L-dopa content [6; 7], which is converted to dopamine in the brain . Besides L-dopa, Mucuna contains alkaloids, flavonoids, tannins, saponins and carbohydrates . In addition, an alcohol extract of M. pruriens seeds was demonstrated to have anti-lipid peroxidation properties . The ‘on effect’ of Mucuna in patients has been documented as being active after 23-27 minutes, and thus is quick acting (using a 30 gram dose). In addition, researchers noted that it remained ‘active’ for over 200 minutes .
Amino acid composition
Seeds of M. pruriens contain essential amino acids, which are in line with the recommended FAO/WHO requirement pattern  – Figure 2. Amino acids are vital as they serve many important functions, such as regulating metabolic pathways, along with having effects on other cellular components, such as DNA and protein synthesis and nutrition .
Benefits and effects
Interestingly, the Mucuna plant has been found to contain L-Dopa, along with other hallucinogenic tryptamines . From this high source of L-Dopa, velvet bean (M. pruriens) has been widely used in the treatment of Parkinson’s disease . M. pruriens beans have been described as a possible and useful therapeutic agent for disease of the central nervous system (CNS) and also reproductive system . Leaves of M. pruriens have been documented as remedy for diabetes, arthritis, dysentery and cardiovascular disease . One report has described that compared to synthetic L-DOPA contained in Sinemet, L-DOPA derived from Mucuna is twice as powerful in controlling Parkinson disease symptoms .
Oxidative stress is one mechanism which eventually leads to the development of Parkinson’s disease . Mucuna pruriens has been found to exhibit antioxidant effect; thereby, validating its neuroprotective and anti-parkinson properties . Seeds from M. pruriens have long been used to treat Parkinson’s disease patients, in ancienter Indian ethnotherapeutics . Parkinson’s disease, causing disorder of the nervous system, could be due to oxidative stress, with a role of reactive oxygen species . A randomised, controlled double-blind crossover trial was carried out in order to compare the anti-parkinsonian effects of a mucuna seed powder formulation against synthetically produced L-DOPA . 30g of powdered M. pruriens extract formulation showed a longer duration of therapeutic response when compared to a dose of manufactured L-DOPA. Further, the mucuna dose did not increase dyskinesia or cause dopaminergic damage. Authors of this study noted that the rich, natural abundance of L-DOPA in the mucuna powder could potentially have advantages over L-DOPA preparations . M. pruriens contains prurienine, which is reported as being a remedy for constipation in Parkinson’s disease patients .
Figure 4. Mucuna pruriens (box) prevents mitochondrial dysfunction (modified from )
Mucuna pruriens depression and stress
Assessing the anti-depressant effects of M. pruriens in a validated depression animal model, a 10mg/kg of M. pruriens seed powder extract showed a reduction of depressive-like activity . This work was within the context of both an acute and chronic depression modal . M. pruriens has also been attributed to reducing stress-induced oxidative damage in rat brains . M. pruriens was investigated for its ability to counteract the effects of psychological stress in 60 men undergoing fertility screening (infertile men) . A 5g M. pruriens seed powder treatment was taken orally over a 3-month period, and results showed improvements in psychological stress . Remarkably, treatment with M. pruriens also improved sperm count and motility. Conclusions drawn from this data indicates that M. pruriens is not only able to circumvent and manage stress, but also regenerates the anti-oxidant system of infertile men . In rats, Mucuna pruriens was shown to dramatically alleviate stress-induced oxidative damage in the rat brain . In humans, stress-induced depression is resulted from free radical damage via reactive oxygen species (ROS).
L-DOPA [L-3,4-dihdroxy phenyl alanine], is a non-protein amino acid precursor of dopamine (DA) . Recently, a study assessing 0.5mM L-DOPA and a 3g aqueous extract of velvet bean seeds (M. pruriens) was carried out to assess their effects . Similar findings were found between both L-DOPA and the velvet bean extract; and, both compounds reduced phenylalanine ammonia lyase (PAL) and cinnamyl alcohol dehydrogenase (CAD) activities  – Figure 2. Evaluating the L-DOPA content across four varieties of Mucuna found that M. pruriens contained the highest L-DOPA content, which varied roughly between 4-7% .
Figure 5. An aqueous extract of M. pruriens, compared to a control and a single dose of L-DOPA, was found to have an effect on the enzymatic activity of PAL and CAD. These results indicated that root, shoot and leaf components had an effect.
Breast cancer is indeed one of the most common causes of cancer death in woman around the world . Using a methanol extract of M. pruriens to test its effectiveness against proliferating breast cancer cells, results confirmed that M. pruriens inhibited cancer cell growth . Surprisingly, this study also revealed that M. pruriens was more effective against breast cancer than L-DOPA on its own. As M. pruriens contains other phytochemical constituents, these may also influence the inhibition of breast cancer cells .
A methanol extract of M. pruriens seeds was tested in rats to assess the extracts effects on androgenic activity . Doses of 1000mg and 1500mg were administered to rats, and testis, blood and prostate were tested for analysis. Results indicated that the M. pruriens extract significantly increased relatives weights of testis and testicular testosterone levels; along with protein levels in the testis . Results confirmed that M. pruriens, in an animal model, elicited effects on testosterone.
Safe doses of M. pruriens have been evaluated using animal models. In particular, 500mg/kg and 750mg/kg treatment of M. pruriens root extract caused significant increases in serum urea and creatinine levels . Elevated levels of both urea and creatinine is usually indicative of kidney dysfunction and animals exhibiting these concentrations suggests that M. pruriens extract – at high doses – might cause kidney damage . Conversely, smaller doses – 125mg/kg and 25mg/kg – in animals did not cause structural changes in the liver. With this information, caution should be exercised with M. pruriens at high doses. On measuring M. pruriens effect on Parkinson Disease (PD) motor deficits, an acute dose of 16mg/kg (~2mg/kg L-DOPA) was shown to assist in step initiation, compared to 6mg/kg stand-along L-DOPA . 48mg/kg was also shown to be effective in antagonising jaw tremors. Large doses, between 15 to 30 grams have been used in clinical studies, however these are too high and should be avoided .
Safety and Side Effects
Individuals should not use M. pruriens if they have hypersensitivity to M. pruriens or its components . One report found that a patient suffered from gastrointestinal problems. Additionally, M. pruiens should be avoided in patients with psychosis or schizophrenia . The toxicity of Mucuna pruriens has been studied on the basis of whether or not its consumption has negative effects on kidneys . In a dose-dependent manner, 50-200mg/kg of M. pruriens methanol extract was administered to adult rats. Results demonstrated that high doses of the M. pruriens extract caused cell degeneration in kidney tissue compared to control groups . In mucuna beans, excessive consumption of these beans results in increased serum L-DOPA levels in peripheral tissue. This can cause harmful side effects such as nausea, vomiting, anorexia, delusions and depression . However, no adverse effects have been described at both chronic and acute doses . Lastly,
Assessments of the effectiveness of Mucuna pruriens on five healthy human volunteers – in a single dose regiment of a 30mg powder extract – was evaluated. This study found that L-DOPA was absorbed from the M. pruriens extract given . The pharmacokinetic profile of the extract showed features similar to synthetically produced L-DOPA .