Aging Research

Cellular Senescence: The FOXO4-DRI Story

Senescence is one of the better-mapped hallmarks. FOXO4-DRI is a designed D-retro-inverso peptide that disrupts the FOXO4-p53 interaction at the protein-protein interface. The mechanism, established by the Peeper lab at the Netherlands Cancer Institute (Baar et al., Cell 2017), exploits a vulnerability specific to senescent cells: they express high levels of FOXO4, which binds and sequesters p53 to prevent apoptosis. Disrupting this interaction releases p53, which then triggers selective apoptosis in senescent cells while healthy cells remain largely unaffected. The original work showed restoration of fitness, hair density, and renal function in aged and progeroid mice. Translation to humans has been slower than the mouse data suggested it might be, and the compound remains preclinical.

A structural caveat: FOXO4-DRI activates p53-mediated apoptosis. Because telomerase and p53 dysregulation are central to most cancers, any compound that modulates these pathways requires careful consideration in any research context. The risk profile of senolytic peptides is not the same as standard small-molecule senolytics like dasatinib + quercetin, and head-to-head selectivity data is still developing.

Telomere Attrition: The Epitalon Question

Epitalon (Ala-Glu-Asp-Gly, AEDG) sits on telomere attrition as its primary mapped hallmark. The Khavinson group reported in 2003 that the peptide induces hTERT expression in telomerase-negative human fibroblasts and extends telomeres past the Hayflick limit (Khavinson et al., Bulletin of Experimental Biology and Medicine). A 2025 independent study by Al-Dulaimi et al. (Biogerontology) replicated key findings in additional cell lines and confirmed telomere elongation, marking the first significant Western laboratory replication. Most of the broader Epitalon literature still originates from the St. Petersburg Institute of Bioregulation and Gerontology — a structural asymmetry that the field acknowledges. The telomerase-cancer relationship is itself unresolved: roughly 85–90% of human cancers express telomerase, which is one reason telomerase activation in any research context carries unresolved long-term questions.

Mitochondrial Dysfunction: MOTS-c, Humanin, SS-31

Three peptides cluster around mitochondrial dysfunction, with different origins. MOTS-c is encoded within the 12S rRNA of mitochondrial DNA — a mitochondrial-derived peptide (MDP) in the literal sense — discovered by Pinchas Cohen's lab at USC in 2015. It signals through AMPK to regulate metabolic homeostasis under stress. Humanin, also mitochondrial-derived, acts through formyl peptide receptor-like 1 (FPRL1) and IGFBP-3 binding pathways, with roles in cytoprotection and apoptosis modulation. SS-31 (Elamipretide) is synthetic, not mitochondrial-derived — it's a Szeto-Schiller peptide that binds cardiolipin on the inner mitochondrial membrane to stabilize membrane potential and cristae structure. The three compounds occupy the same hallmark but address it through distinct molecular mechanisms.

Where Peptide Research Doesn't Reach

Several hallmarks remain thinly covered by available research peptides. Loss of proteostasis is dominated by small-molecule chaperone inducers, not peptide-based interventions. Disabled macroautophagy is most often studied through pharmacological autophagy inducers (rapamycin, spermidine), not peptides. Dysbiosis belongs to the microbiome research field rather than the peptide field. Stem cell exhaustion is approached primarily through cell-based therapies. This isn't a gap to apologize for — it's a description of where the chemistry currently sits. Peptide research engages aging biology unevenly across the twelve hallmarks, and the catalog reflects that.

Research Models Commonly Used

Standard aging research models include senescence-accelerated mouse prone (SAMP) strains, naturally aged C57BL/6 mice (typically 20–24 months), progeroid models (Zmpste24 knockout, BubR1 hypomorphic, Ercc1 mutants), and worm/fly models (C. elegans, Drosophila) for high-throughput longevity screens. For cellular work, replicative senescence in human dermal fibroblasts (passage-induced) and induced senescence (irradiation, oncogene activation, oxidative stress) are the workhorse in vitro systems. Biomarker endpoints have expanded substantially since 2020 — DNA methylation clocks (Horvath, GrimAge, PhenoAge), epigenetic age estimators, and SASP (senescence-associated secretory phenotype) profiling are increasingly standard.

Frequently Asked Questions

Reference Points for Further Reading

López-Otín et al.'s 2023 Cell paper on hallmarks of aging is the standard framework reference. The 2022 Copenhagen meeting summary (Schmauck-Medina et al., Aging) proposes additional hallmarks (mechanical properties, splicing dysregulation) for those interested in framework evolution. For senolytics specifically, the Kirkland group at Mayo Clinic publishes the most-cited clinical translation work. For mitochondrial-derived peptides, the Cohen lab at USC is the foundational source on MOTS-c and Humanin. For Epitalon and Khavinson peptide chemistry, the 2025 Al-Dulaimi paper in Biogerontology represents the most recent independent Western replication work. For epigenetic clocks, Horvath's original 2013 Genome Biology paper remains the entry point.

All compounds in this catalog are intended for in vitro and preclinical research use only. None are approved by the FDA or any other regulatory authority for therapeutic use in humans. The aging biology framework discussed on this page is provided as scientific context for the research field, not as claims for the compounds offered here. Compounds affecting cellular senescence, telomere biology, or related pathways have unresolved long-term safety questions that remain active areas of research.