Background: Sulphur is an abundant element in biological systems, which plays an
important role in processes essential for life as a constituent of proteins, vitamins and other crucial
biomolecules. The major source of sulphur for humans is plants being able to use inorganic
sulphur in the purpose of sulphur-containing amino acids synthesis. Sulphur-containing amino
acids include methionine, cysteine, homocysteine, and taurine. Methionine and cysteine are classified
as proteinogenic, canonic amino acids incorporated in protein structure. Sulphur amino acids
are involved in the synthesis of intracellular antioxidants such as glutathione and N-acetyl
cysteine. Moreover, naturally occurring sulphur-containing ligands are effective and safe detoxifying
agents, often used in order to prevent toxic metal ions effects and their accumulation in
Methods: Literature search for peer-reviewed articles was performed using PubMed and Scopus
databases, and utilizing appropriate keywords.
Results: This review is focused on sulphur-containing amino acids – methionine, cysteine,
taurine, and their derivatives – glutathione and N-acetylcysteine, and their defense effects as antioxidant
agents against free radicals. Additionally, the protective effects of sulphur-containing
ligands against the toxic effects of heavy and transition metal ions, and their reactivation role towards
the enzyme inhibition are described.
Conclusion: Sulphur-containing amino acids represent a powerful part of cell antioxidant system.
Thus, they are essential in the maintenance of normal cellular functions and health. In addition
to their worthy antioxidant action, sulphur-containing amino acids may offer a chelating site
for heavy metals. Accordingly, they may be supplemented during chelating therapy, providing
beneficial effects in eliminating toxic metals.