title: The folic acid analogue methotrexate protects frog embryo cell membranes against damage by the potato glycoalkaloid alpha-chaconine.
abstract: As part of an effort to improve the safety of plant foods, a need exists to more clearly delineate the mechanisms of toxicities of glycoalkaloids, which may be present in Solanum plant species such as potatoes, tomatoes and eggplants. Alpha-chaconine is a major glycoalkaloid present in potatoes. To assess the possible influence of structure of pteridine derivatives on toxicity of potato glycoalkaloids, a previous study that demonstrated the protective effects of folic acid against the Solanum glycoalkaloid alpha-chaconine-induced toxicity on Xenopus laevis frog embryo cell membranes was extended to two folate analogues--a synthetic compound widely used as a therapeutic agent methotrexate, and naturally occurring L-monapterin. Adverse effects on embryos were evaluated by observing changes in membrane potentials with an electrochromic dye, di-4-ANEPPS, as a fluorescent probe for the integrity of the membranes. Methotrexate decreased alpha-chaconine-induced polarization, as did folic acid. This decrease may result from an alteration of membrane conformations that prevents the binding of the glycoalkaloid to the membrane receptor sites, and/or from effects on folic acid metabolism. In contrast, L-monapterin did not significantly reduce the alpha-chaconine-induced toxicity. The possible significance of these results to food safety is discussed.
authors.affiliation: Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater 74078, USA.
authors.forename: M L
authors.initials: ML
authors.lastname: McWilliams
authors.forename: J T
authors.initials: JT
authors.lastname: Blankemeyer
authors.forename: M
authors.initials: M
authors.lastname: Friedman
mesh_terms: D000818:Animals; D002240:Carbohydrate Sequence; D002462:Cell Membrane / Q000187:drug effects*; D004625:Embryo, Nonmammalian / Q000187:drug effects / Q000502:physiology; D005493:Folic Acid Antagonists / Q000494:pharmacology*; D008727:Methotrexate / Q000494:pharmacology*; D008969:Molecular Sequence Data; D019798:Neopterin / Q000494:pharmacology; D012992:Solanine / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000633:toxicity; D011198:Solanum tuberosum / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D014982:Xenopus laevis
chemical_list: D005493:Folic Acid Antagonists; D012992:Solanine; C011860:alpha-chaconine; D019798:Neopterin; D008727:Methotrexate