AMHERST, Mass. – In a new study, plant scientist Fatemeh Etemadi at the University of Massachusetts Amherst’s Stockbridge School of Agriculture, who promotes faba bean as a cold-hardy crop that can thrive in New England’s short growing season with a ready market among many immigrant groups, has now characterized the amount of L-DOPA found in samples of the bean plant’s leaves, stems, roots and seeds.
This work was conducted in response to requests from people with Parkinson’s disease who told Etemadi that they have been looking for sources of natural L-DOPA to ease their symptoms. The phenolic component can elevate the level of L-DOPA in the bloodstream, a precursor of a neurotransmitter used for the relief of Parkinson’s disease symptoms.
The plant scientist says that previous research was mainly focused on L-DOPA accumulated in the seeds but her recent experiments show that other plant parts have L-DOPA in impressive amounts, especially the leaves. Results showed that “all tested varieties had the highest amount of L-DOPA before pod ripening,” she reports. Levels were lowest in stem and root samples. Details appear in the online “just published” section of the Journal of Crop Science and will be in the September print edition.
Etemadi says she was not only scientifically interested, but also moved by patients’ requests for natural, plant-based alternatives to synthetic drugs. She notes, “We are not physicians or nutritionists and we don’t recommend a specific dose for Parkinson’s treatment, but in responding to public interest, we try to provide sound scientific data.”
Etemadi, whose doctoral work at UMass Amherst has allowed her to conduct research in plant physiology, vegetable production and sustainable agriculture systems, adds, “It is important to me to conduct a kind of research which has benefit to people’s health and the environment.”
“My original research goal was to integrate this cool-season legume to extend the growing season in New England conditions. We found that many ethnic groups such as Portuguese, Chinese, Middle Eastern and people from Central Asia use this bean in their various recipes. It is also very common in the diets of African peoples. There is a high market for the fresh faba bean pods, especially in the eastern part of the state.”
Her doctoral advisor, professor Masoud Hashemi, adds that faba beans, also spelled fava, currently sold in urban markets are imported from Mexico. He says, “We thought that if we could help farmers to grow this crop in New England, we could create a new market for them and decrease the cost for consumers.” A legume crop, the beans add significant amounts of nitrogen to the soil and thus contribute to the nitrogen needs of the next crop grown in that soil.
Etemadi and Masoud have received funding from the Massachusetts Department of Agricultural Resources and from Northeast Sustainable Agriculture Research and Education program to advance these ideas. Further, the two are co-authors of the booklet, “Faba Beans: Growers Guide in New England,” with professor Frank Mangan and technical assistant Sarah Weis of UMass Extension. Etemadi also has made a YouTube video on how to grow faba beans in New England.
Her work related to L-DOPA content in different parts of the bean was conducted at the UMass research farm in South Deerfield, where Etemadi planted seeds of eight faba bean varieties in two seasons, 2014 and 2015, harvesting them at five growth stages including early and late seedling, flowering, pod rising and maturity. After harvesting, she divided the plants into roots, stems, leaves, pods and seeds. She then chemically digested these tissues separately and analyzed them using high-performance liquid chromatography, a precise method for measuring trace chemical concentration in each plant organ.
She also conducted experiments on whether L-DOPA levels change with processing methods such as freezing, boiling or drying, and how environmental factors such as drought and nitrogen stress affect L-DOPA levels. As for why faba beans contain L-DOPA, Masoud says, that it is a secondary metabolite, which in plants is usually related to a defense mechanism. More research is needed to explore further how this mechanism exactly works, he adds.