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

Vascular aging is a principal driver of cardiovascular morbidity and mortality, and effective prevention of age-related vascular pathologies depends on interventions that target fundamental molecular and cellular aging pathways. The present study investigated the anti-vascular aging activity of AL-VI10, a novel bioactive peptide derived from amphibian skin, together with the underlying mechanism. Notably, AL-VI10 exhibited excellent biosafety, with no detectable cytotoxic or hemolytic activity, and showed potent free radical scavenging capacity, enhanced antioxidant enzyme activity, and reduced reactive oxygen species (ROS) accumulation. In a D-galactose-induced mouse model of aging, AL-VI10 significantly attenuated vascular aging-associated phenotypes, including increased medial thickness, elevated expression of inflammatory cytokines, and up-regulation of matrix metalloproteinase levels, while simultaneously promoting autophagy. In hydrogen peroxide (H₂O₂)-induced senescent human umbilical vein endothelial cells, AL-VI10 reduced senescence-associated β-galactosidase (SA-β-gal) activity, down-regulated senescence markers p53 and p21, enhanced endothelial proliferation and migration, and increased endothelial nitric oxide synthase expression. Mechanistic analyses showed that AL-VI10 up-regulated silent information regulator 1 (SIRT1) and nuclear factor erythroid 2-related factor 2 (Nrf2). Pharmacological inhibition of SIRT1 suppressed AL-VI10-induced Nrf2 activation and weakened its anti-senescence effects, whereas inhibition of Nrf2 reversed ROS reduction and impaired endothelial recovery. Further analysis demonstrated direct binding of AL-VI10 to the extracellular domain of leukocyte differentiation antigen CD44 (CD44), and CD44 knockdown abolished activation of the SIRT1-Nrf2 axis and eliminated the anti-senescence activity of AL-VI10. These findings indicate that AL-VI10 alleviates vascular aging through CD44-dependent activation of SIRT1-Nrf2 signaling and identify amphibians as a promising source of bioactive compounds for anti-aging therapy.