Amino Acids

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Cell death and mitochondrial dysfunction induced by the dietary non-proteinogenic amino acid l-azetidine-2-carboxylic acid (Aze)

  • Kate Samardzic
  • Kenneth J. RodgersEmail author
Original Article


In addition to the 20 protein amino acids that are vital to human health, hundreds of naturally occurring amino acids, known as non-proteinogenic amino acids (NPAAs), exist and can enter the human food chain. Some NPAAs are toxic through their ability to mimic protein amino acids and this property is utilised by NPAA-containing plants to inhibit the growth of other plants or kill herbivores. The NPAA l-azetidine-2-carboxylic acid (Aze) enters the food chain through the use of sugar beet (Beta vulgaris) by-products as feed in the livestock industry and may also be found in sugar beet by-product fibre supplements. Aze mimics the protein amino acid l-proline and readily misincorporates into proteins. In light of this, we examined the toxicity of Aze to mammalian cells in vitro. We showed decreased viability in Aze-exposed cells with both apoptotic and necrotic cell death. This was accompanied by alterations in endosomal–lysosomal activity, changes to mitochondrial morphology and a significant decline in mitochondrial function. In summary, the results show that Aze exposure can lead to deleterious effects on human neuron-like cells and highlight the importance of monitoring human Aze consumption via the food chain.


Non-protein amino acid Azetidine-2-carboxylic acid Mitochondria Multiple sclerosis 



Centre for Health Technologies, University of Technology Sydney.


This study was partly funded by the Centre for Health Technologies, University of Technology Sydney.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Research involving human participants and/or animals

This article does not contain any studies with human participants or animals performed by any of the authors.

Informed consent

This article does not contain individual participants requiring informed consent.

Supplementary material

726_2019_2763_MOESM1_ESM.docx (3 mb)
Supplementary material 1 (DOCX 3106 kb)


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© Springer-Verlag GmbH Austria, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Neurotoxin Research Group, School of Life Sciences (04.06.340)University of TechnologySydneyAustralia

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