Dopamine is a neurotransmitter that carries messages about pleasure, pain and muscle movements between nerve cells. A lack of dopamine in the brain is a major symptom of Parkinson's disease and other neurodegenerative diseases. Many of the drugs currently used to treat dopamine deficiencies are derived from herbs. Natural plant chemicals increase dopamine in several ways: inhibiting the enzymes that break down dopamine; increasing L-dopa, the precursor of dopamine; or stimulating dopamine receptors in the brain.
Ayahuasca
Ayahuasca (Banisteriopsis caapi) is a climbing vine found in the tropical areas of South America and the West Indies. It is used in combination with other herbs to make a hallucinogenic beverage called ayahuasca. The plant affects dopamine through its alkaloids and flavonoids. A study reported in the 2010 issue of the Journal of Ethnopharmacology found that the harmala alkaloids in ayahuasca, known as harmaline and harmine, showed strong MAO-A and MAO--B inhibition, and the flavonoids epicatechin and procyanidin showed moderate MAO-B inhibition. The MAOs, or monoamine oxidases, are enzymes that break down dopamine and terminate its messaging action. They come in two forms, A and B, both of which can reduce dopamine levels. Inhibiting these enzymes allows dopamine levels in the synapses to increase.
Broadbean
Broadbean (Vicia faba) was one of the first plants involved in the discovery of levodopa, or L-dopa, the precursor to dopamine. L-dopa is found in the leaves, flowers and shoots of broadbean, and is the major treatment for dopamine deficiency diseases. The neurotransmitter dopamine cannot cross the blood-brain barrier, but L-dopa can. Once in the brain, L-dopa is converted to dopamine.
Cowage
Cowage (Mucuna pruriens) is a climbing tropical vine with white, lavender or purple flowers. It is a popular Ayurvedic medicine for nervous disorders. Cowage leaves contain genistein, an MAO inhibitor, but the seeds provide the primary medicinal value of the plant. Cowage seeds contain L-dopa, the precursor to dopamine, and the plant has become the major commercial source for L-dopa. A study in the 2009 issue of Neurotoxicity Research compared an extract of cowage seeds, containing L-dopa and other components, to an equivalent dose of pure L-dopa. The researchers found that higher doses of pure L-dopa were needed to be as effective as the cowage seed extract.
Baikal Skullcap
Baikal skullcap (Scutellaria baicalensis) is an important herb in traditional Chinese medicine. It is used to treat a range of disorders, including diabetes and hypertension. The root contains the flavonoids chrysin and baicalein, which are MAO inhibitors. A study published in the 2006 issue of the Journal of Food and Drug Analysis tested the effect baicalein had on animals treated with methamphetamine, which depletes dopamine in the brain. The researchers found that baicalein restored levels of dopamine that were reduced by methamphetamine. When the animals were pretreated with baicalein, their dopamine levels did not drop.
References
- Journal of Ethnopharmacology; Banisteriopsis caapi, a unique combination of MAO inhibitory and antioxidative constituents for the activities relevant to neurodegenerative disorders and Parkinson's disease; Samoylenko V, Rahman MM, Tekwani BL, Tripathi LM, Wang YH, Khan SI, Khan IA, Miller LS, Joshi VC, Muhammad I; Feb. 2010
- Neurotoxicity Research; Assessment of symptomatic and neuroprotective efficacy of Mucuna pruriens seed extract in rodent model of Parkinson's disease. Kasture S, Pontis S, Pinna A, Schintu N, Spina L, Longoni R, Simola N, Ballero M, Morelli M; Feb. 2009
- Journal of Food and Drug Analysis; Baicalein reverses the methamphetamine-induced striatal dopaminergic neurotoxicity in mice; Liu YY, Yeh PH, Wang GJ, Huang SW, Chi CW, Ho LK, Pan WHT; Dec. 2006
