Multi-Targeted Effects of Novel Cycloastragenol Derivatives: Enhancing NRF2, Proteostasis, and Telomerase Pathways with p53 Modulation to Delay Replicative Senescence

Abstract

Aging is a complex, multifactorial process driven by various cellular and molecular mechanisms, including telomere shortening, oxidative stress, and the decline of proteostasis, all of which contribute to replicative senescence and age-related diseases. Cycloastragenol (CA), a triterpenoid saponin derived from Astragalus membranaceus, has shown potential for its ability to activate telomerase, suggesting therapeutic benefits in delaying cellular aging. In this study, we explored the effects of novel CA derivatives, obtained through biotransformation as telomerase activators, on the NRF2/proteasome/telomerase axis and their potential to delay replicative senescence in human primary epidermal keratinocytes (HEKn). Our findings reveal that these CA derivatives significantly enhance NRF2 nuclear activity, leading to the upregulation of key cytoprotective enzymes essential for mitigating oxidative stress. Notably, these derivatives exhibited efficacy at much lower concentrations compared to CA, demonstrating their potential for enhanced therapeutic application. The derivatives also markedly increased proteasome activity, particularly in the {beta}1 and {beta}5 subunits, thereby preserving proteostasis--a critical factor in preventing the accumulation of damaged proteins associated with aging. Furthermore, continuous treatment with these derivatives sustained stimulatory effects, which was evidenced by increased NRF2, proteasome, and hTERT protein levels even in senescent cells and extended cellular lifespan. Additionally, we explored the impact of CA derivatives on p53-mediated pathways, demonstrating that these compounds effectively modulate the p53/p21 axis, reducing cell cycle arrest and promoting cellular proliferation. Moreover, the derivatives exhibited neuroprotective properties by attenuating glutamate-induced excitotoxicity, further underscoring their potential as multi-targeted anti-aging agents. In conclusion, our study provides strong evidence that novel CA derivatives act on multiple fronts to enhance NRF2 activity, maintain proteostasis, and modulate telomerase and p53 pathways, most at lower doses compared to CA. These actions collectively contribute to the delay of replicative senescence and the promotion of cellular longevity, positioning CA derivatives as potent candidates for developing multi-targeted anti-aging therapies that address the complex interplay of aging-related cellular processes. HighlightsO_LITelomerase-active CA derivatives enhance NRF2 activity and proteasome activity, leading to cytoprotection at lower doses than CA. C_LIO_LICA derivatives modulate the p53 pathway and cell cycle, prolonging cellular lifespan and delaying replicative senescence. C_LIO_LICA derivatives protect cells against glutamate-excitotoxicity along with decreased p53 protein levels. C_LI