A novel amino acid mixture containing isoleucine, glycine, and cystine improves insulin sensitivity with restoring mitochondrial oxygen consumption in C2C12 myotubes | Functional Foods in Health and Disease - Online ISSN: 2160-3855; Print ISSN: 2378-7007 Skip to main content Skip to main navigation menu Skip to site footer Open Menu Functional Foods in Health and Disease - Online ISSN: 2160-3855; Print ISSN: 2378-7007 Home Food Science Publisher Functional Food Center Current Archives About About the Journal Aims and Scope Contact Editing Services Editorial Team Express Peer Review Graphical Abstract Journal Insights Privacy Statement Submissions Announcements Search Search Register Login Home / Archives / Vol. 15 No. 4 (2025): April 2025 / Research Articles A novel amino acid mixture containing isoleucine, glycine, and cystine improves insulin sensitivity with restoring mitochondrial oxygen consumption in C2C12 myotubes Authors Kyoko Miura Mai Hasumura Yoshiro Kitahara Shinobu Nishitani Yoji Yamada DOI: https://doi.org/10.31989/ffhd.v15i4.1582 Abstract Background: Saturated fatty acids facilitate insulin insensitivity within peripheral tissues, which have been linked to the development of metabolic syndrome. Although some amino acids are involved in the regulation of lipid metabolism, their effect on insulin sensitivity remains unclear. This study investigated the effect of amino acids on the restoration of FFA-induced insulin insensitivity using C2C12 skeletal muscle cells.  Methods: C2C12 myotubes were treated with 0.5 mM palmitate overnight. Then, 1 mM of each amino acid was added, and the cells were incubated for an additional 18 hours. Akt phosphorylation was assessed with a western blot after stimulation with 100 nM insulin. Under the same conditions, glucose uptake was measured using a glucose uptake assay kit.  Mitochondrial function was measured using an extracellular flux analyzer. Results: Palmitate treatment reduced Akt phosphorylation to 40% of the control levels. However, among 17 amino acids evaluated, isoleucine (I), glycine (G), and cystine (C) restored Akt phosphorylation successfully. Under the same conditions, glucose uptake was reduced by palmitate.  A mixture of I, G, and C (IGC) were found to restore glucose uptake. In addition, palmitate decreased oxygen consumption and ATP production in C2C12 mitochondria, as determined by the Seahorse system, which is an extracellular flux analyzer. IGC was also found to restore mitochondrial function. Conclusions: The data collected in this study suggest that an appropriate amino acid mixture consisting of I, G and C may restore insulin signaling and glucose utilization suppressed by FFA. This was also found to restore mitochondrial oxygen consumption. Novelty: This study uniquely demonstrates that a novel amino acid mixture—comprising isoleucine, glycine, and cystine (IGC)—effectively restores insulin sensitivity and mitochondrial oxygen consumption in palmitate-induced insulin-resistant C2C12 myotubes. This conclusion could be used to identify a potential therapeutic strategy for metabolic dysfunction. Keywords: Insulin sensitivity, Mitochondrial function, C2C12 myotubes, Amino acid mixtures, Isoleucine, Glycine, Cystine Downloads [Abstract] [Full Article] Published 2025-04-12 Issue Vol. 15 No. 4 (2025): April 2025 Section Research Articles License Copyright (c) 2025 Functional Foods in Health and Disease This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License. Authors retain the copyright of their articles and grant the Functional Food Center (FFC) and its journals the right of first publication under the terms of the Creative Commons Attribution 4.0 International License. This license permits unrestricted use, distribution, and reproduction in any medium, including commercial use, provided the original author(s) and source are properly credited. Authors may post and share their published work freely, provided that the original publication in this journal is acknowledged. By submitting to this journal, authors confirm that their manuscripts are original, not under consideration elsewhere, and that they hold the necessary rights to grant this license. The Functional Food Center encourages open scientific exchange and allows derivative and extended works, provided attribution to the original publication is maintained. About the Journal      Editing Services      Graphical Abstract      Journal Insights        Submissions        Editorial Team       Privacy Statement        Contact        Current        Archives   Open Journal Systems Hosting and Support by: OpenJournalSystems.com