First identification of an amphibian-derived peptide with anti-vascular aging activity

Vascular aging is a principal driver of cardiovascular morbidity and mortality. Effective prevention of age-related vascular pathologies requires interventions that modulate core molecular and cellular aging pathways. This study evaluated the anti-vascular aging effects and underlying mechanisms of AL-VI10, a novel amphibian skin-derived bioactive peptide. Notably, AL-VI10 exhibited excellent biosafety, with no cytotoxicity or hemolytic activity, coupled with potent free radical scavenging capacity, enhanced antioxidant enzyme activity, and reduced reactive oxygen species (ROS) accumulation. In a D-galactose-induced aging mouse model, AL-VI10 significantly attenuated vascular aging phenotypes, including increased medial thickness, inflammatory cytokine expression, and matrix metalloproteinase levels, while promoting autophagy. In hydrogen peroxide (H₂O₂)-induced senescent human umbilical vein endothelial cells, AL-VI10 decreased senescence-associated β-galactosidase (SA-β-gal) activity, down-regulated senescence markers p53 and p21, stimulated endothelial proliferation and migration, and increased endothelial nitric oxide synthase expression. Mechanistic investigations showed that AL-VI10 up-regulated silent information regulator 1 (SIRT1) and nuclear factor erythroid 2-related factor 2 (Nrf2) expression. Inhibition of SIRT1 suppressed AL-VI10-induced Nrf2 activation and diminished its anti-senescence effects, while Nrf2 inhibition reversed ROS reduction and impaired endothelial recovery. Moreover, AL-VI10 bound to the extracellular domain of leukocyte differentiation antigen CD44 (CD44), with CD44 knockdown shown to abolish SIRT1-Nrf2 activation and neutralize the anti-senescence activity of AL-VI10. These results demonstrate that AL-VI10 alleviates vascular aging via CD44-mediated activation of the SIRT1-Nrf2 signaling pathway, highlighting amphibians as a valuable source of novel bioactive compounds for anti-aging therapies.