title: β-N-methylamino-L-alanine (BMAA) metabolism in the aquatic macrophyte Ceratophyllum demersum.
abstract: The cyanobacterial neurotoxin, β-N-methylamino-l-alanine (BMAA) bioaccumulates and biomagnifies within the environment. However, most reports on the environmental presence of BMAA focus on the presence of BMAA in animals rather than in plants. Various laboratory studies have reported that this neurotoxin, implicated in neurodegenerative disease, is rapidly taken up by various aquatic and terrestrial plants, including crop plants. In this study the metabolism of BMAA in the aquatic macrophyte, Ceratophyllum demersum, was investigated using stable isotopically labelled BMAA. Data show that the toxin is rapidly removed from the environment by the plant. However, during depuration cellular BMAA concentrations decrease considerably, without excretion of the toxin back into the environment and without catabolism of BMAA, evidenced by the absence of label transfer to other amino acids. This strongly suggests that BMAA is metabolised via covalent modification and sequestered inside the plant as a BMAA-derivative. This modification may be reversed in humans following consumption of BMAA-containing plant material. These data therefore impact on the assessment of the risk of human exposure to this neurotoxin.
authors.affiliation: Department of Biochemistry and Microbiology, Nelson Mandela Metropolitan University, PO Box 77 000, Port Elizabeth 6031, South Africa. Electronic address: Simone.Downing@nmmu.ac.za.
authors.forename: Simoné
authors.initials: S
authors.lastname: Downing
authors.affiliation: Department of Biochemistry and Microbiology, Nelson Mandela Metropolitan University, PO Box 77 000, Port Elizabeth 6031, South Africa. Electronic address: maranda.esterhuizen2@nmmu.ac.za.
authors.forename: Maranda
authors.initials: M
authors.lastname: Esterhuizen-Londt
authors.affiliation: Department of Biochemistry and Microbiology, Nelson Mandela Metropolitan University, PO Box 77 000, Port Elizabeth 6031, South Africa; The Institute for Ethnomedicine, 240E Deloney Ave, Jackson, WY 83001, United States of America. Electronic address: Tim.Downing@nmmu.ac.za.
authors.forename: Timothy
authors.initials: T
authors.lastname: Grant Downing
mesh_terms: D000599:Amino Acids, Diamino / Q000378:metabolism*; D000818:Animals; D000458:Cyanobacteria / Q000378:metabolism*; D000087522:Cyanobacteria Toxins; D004785:Environmental Pollutants / Q000378:metabolism*; D019684:Magnoliopsida / Q000378:metabolism; D009498:Neurotoxins / Q000378:metabolism*
chemical_list: D000599:Amino Acids, Diamino; D000087522:Cyanobacteria Toxins; D004785:Environmental Pollutants; D009498:Neurotoxins; C001824:beta-N-methylamino-L-alanine
keywords: Aquatic; BMAA; Macrophyte; Metabolism; β-N-methylamino-l-alanine