Neopterin extends C. elegans lifespan in an ATFS-1-dependent manner.

Neopterin, a byproduct of tetrahydrobiopterin synthesis, is commonly used as a biomarker for immune system activation. In addition to its role in immune responses, neopterin levels are known to increase with age. Its impact on longevity, however, remains unclear. Here, we demonstrate that neopterin supplementation extends lifespan in Caenorhabditis elegans . Additionally, neopterin shows moderate activation of the mitochondrial unfolded protein response (UPR ^mt ), and that the neopterin-mediated lifespan extension is dependent on ATFS-1 , the primary transcription factor regulating UPR ^mt . These findings highlight the need for further investigation into the biological functions and health-promoting effects of neopterin.