Researchers at the John Innes Centre in the U.K. have created a genetically modified tomato that serves as a source for the amino acid l-3,4-dihydroxyphenylalanine (L-DOPA), which the brain converts into dopamine.
The discovery could provide an affordable source for the medicine, which first hit the market in the 1960s. Then touted as a “miracle drug,” L-DOPA showed promise for its ability to rouse patients who had been immobilized for years by Parkinson’s.
But access to the drug, which the World Health Organisation classifies as an essential medicine, is limited in developing nations.
The tomato-based source of L-DOPA could give more patients access to it globally. The cost of synthetic L-DOPA, roughly $2 daily, is prohibitive in many parts of the world.
The scientists were able to produce 150 mg of L-DOPA per kilogram of tomatoes.
The breakthrough could also benefit patients who suffer from L-DOPA side effects such as nausea and behavior disturbances.
The researchers at the John Innes Centre modified the tomato plant by incorporating a gene linked to L-DOPA synthesis in beets. In beetroot, the gene is responsible for producing betalains, a group of tyrosine-derived red and yellow pigments.
The source of L-DOPA is tyrosine, an amino acid found in several foods.
L-DOPA itself was first isolated in 1913 from broad beans (Vicia faba).
The velvet bean, Mucuna pruriens, is a more concentrated source of L-DOPA, containing up to 10% of the drug in its seeds, but the tropical legume is a problematic drug source. Velvet beans are difficult to harvest and contain high levels of tryptamines that can trigger hallucinations in patients with Parkinson’s disease.