Sulphur Amino Acids: How Important is it to Set Reference Ranges for Each Population?

Helena Caldeira Araújo; Cristina Florindo; Alexandra Gomes; João Caio; Rita Castro; Isabel Rivera

doi:10.2174/0118715303282774231128053723

Sulphur Amino Acids: How Important is it to Set Reference Ranges for Each Population?

Endocr Metab Immune Disord Drug Targets. 2024 Jan 12. doi: 10.2174/0118715303282774231128053723. Online ahead of print.

Authors

Helena Caldeira Araújo^{1

2}, Cristina Florindo³, Alexandra Gomes³, João Caio³, Rita Castro^{3

4}, Isabel Rivera³

Affiliations

¹ Faculdade de Ciências da Vida, Projeto Medicina, Universidade da Madeira, Funchal, Portugal.
² Centro Química da Madeira, Universidade da Madeira, Funchal, Portugal.
³ Laboratory of Metabolism and Genetics, Department of Pharmaceutical Sciences and Medicines, Faculty of Pharmacy, Universidade de Lisboa, Lisbon, Portugal.
⁴ Department of Nutritional Sciences, The Pennsylvania State University, University Park, PA 16802, USA.

PMID: 38243971
DOI: 10.2174/0118715303282774231128053723

Abstract

Introduction: Metabolism of sulfur amino acids requires an optimal interplay between nutritional demand, enzymes, transporters, and adequate dietary intake of B vitamins. Insufficient intake and excess are detrimental, and concentrations depend on health status. However, plasma aminothiol concentrations, previously reported in healthy subjects using highly sensitive methods, vary considerably, and age- and gender differences were observed. Therefore, defining age- and gender-specific ranges for each population is crucial to evaluate the meaning of plasma thiol redox state in health and disease.

Methods: A healthy Portuguese pediatric population (n=90), aged 9- (n=38) and 17-year-old (n=52), was evaluated. Plasma aminothiols, total homocysteine (tHcy), cysteine (tCys), glutathione (tGSH) and γ-glutamylcysteine (tγ-Glu-Cys), were analysed as SBD-F derivatives by HPLC with fluorescence detection.

Results/case report: Mean plasma concentrations (SD) for the 9- and the 17-year-old groups, were as following: tHcy = 4.58 (0.98); 8.13 (3.27) µM, p <0.001; tCys = 207.34 (32.07); 198.59 (21.24) µM, p = 0.274; tGSH = 4.54 (1.08); 5.20 (1.84) µM, p = 0.123 and tγ-Glu-Cys = 1.47 (0.30); 1.06 (0.28) µM, p < 0.001, respectively. No statistically significant differences were found between males and females in the 9-year-old group. However, in the 17-year-old group, significant differences between genders were observed for tHcys (p < 0.001) and tγ-Glu-Cys (p = 0.039), with males presenting the highest concentrations. When correlating the four thiols' plasma concentrations, only the precursors of glutathione, tγ-Glu-Cys and tCys, were positively correlated (r = 0.450, p < 0.001).

Conclusion: Our results showed significant differences in tHcy and tγ-Glu-Cys levels across both age groups, which increased and decreased with age, respectively. It is interesting to highlight that in the 17-year-old group, tHcy and tγ-Glu-Cys levels were higher in males than in females. These observations showed that age and gender influence plasma levels of thiols, which may impact cellular oxidative status. In conclusion, setting age and gender distinct ranges for each specific population is of utmost importance for understanding disease mechanisms and the effectiveness of therapeutic interventions.

Keywords: Sulphur amino acids; age; nutrition; pediatric.