What's on the label is the measured result — net peptide mass, not gross powder weight, plus RP-HPLC purity, on a lot-numbered COA for every batch.
Net peptide mass and RP-HPLC purity — a lot-numbered COA for every batch.
Net peptide mass + HPLC purity, per lot.
PCAC will review 7 peptides for the 503A bulks list, BPC-157, KPV, TB-500, MOTS-c, Emideltide, Semax, Epitalon. Read our briefing →
PCAC will review 7 peptides for the 503A bulks list. Read →
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D-retro-inverso FOXO4 / p53 interaction blocker · senolytic peptide
PeptideXpo buyer fit
This PeptideXpo page is intentionally positioned for distributors, OEM buyers, and procurement teams comparing FOXO4-DRI (FOX-04) inside a wider peptide catalog. It is not trying to be the deepest single-molecule monograph; the differentiated intent is assortment planning, export-ready documentation, fill-size comparison, and whether this SKU belongs in a broader buyer program.
Overview
FOXO4-DRI (also called FOXO4-D-Retro-Inverso, FOX04, or FOX04-DRI) is a 46-amino-acid D-retro-inverso peptide (a 34-residue FOXO4 p53-binding segment fused to a 12-residue cell-penetrating shuttle) designed to disrupt the FOXO4-p53 protein-protein interaction inside senescent cells. The D-retro-inverso architecture (using D-amino-acids in reversed sequence order) creates a peptide that is highly resistant to protease degradation while retaining the binding-interface topology of the natural L-peptide, a design strategy that dramatically extends the molecule's intracellular half-life. Originally described by Peter de Keizer's group at the University of Groningen in 2017, FOXO4-DRI became one of the most prominent published senolytic peptides, demonstrating selective induction of apoptosis in senescent cells in multiple aging and disease models. PeptideXpo supplies FOXO4-DRI as a lyophilized powder at ≥99.0% HPLC purity. The D-amino-acid synthesis is more demanding than typical L-peptide SPPS, D-Fmoc amino-acid building blocks cost substantially more than the L-amino-acid equivalents, which is the primary driver of FOXO4-DRI's higher per-mg pricing relative to similarly-sized L-peptides. The analytical packet covers peak-integration HPLC, mass spec confirming molecular weight, and on-request sequence verification by LC-MS/MS. Standard 2 mg and 10 mg fill sizes match typical senescence-research aliquot scales.
Who buys this, and why
Buyers for longevity-class peptides span research labs working on telomere, collagen, and circadian-rhythm models, plus cosmetic-formulation OEMs incorporating peptides like GHK-Cu into anti-aging finished products. Copper peptides in particular require attention to chelator-free water and EDTA-free buffers in downstream formulation work, incompatibility there is the most common cause of "the peptide didn't work" support tickets in this class.
Primary buyer fit: academic and contract research laboratories.
Specifications
Documentation available on request
Regulatory note
Sold for research and for use as a cosmetic ingredient where the receiving formulator's regulatory framework permits (e.g. EU cosmetic regulation 1223/2009, FDA cosmetic-monograph framework, equivalent regimes). Not a finished dosage form. Cosmetic-finished-product safety responsibility remains with the brand owner.
Frequently asked questions
A D-retro-inverso (DRI) peptide reverses two things relative to the natural L-peptide: the chirality of every amino acid (D instead of L), and the sequence order (C-to-N instead of N-to-C). The combined transformation preserves the overall side-chain topology and binding-interface geometry while making the molecule unrecognizable to natural proteases, which cleave specifically at L-peptide bonds in N-to-C-reading order. The practical consequence for FOXO4-DRI is dramatically extended intracellular half-life (hours to days versus minutes for the natural L-peptide), which is essential for a research tool that needs sustained intracellular concentration to interfere with a protein-protein interaction.
FOXO4-DRI is used as a research tool for selective induction of apoptosis in senescent cells (senolytic activity). The mechanism centers on disrupting the FOXO4-p53 nuclear interaction that senescent cells use to escape p53-mediated apoptosis; when the interaction is blocked, p53 redirects to mitochondria and triggers cell death selectively in senescent (but not proliferating) cells. The peptide has been studied in aging models, fibrosis models, cardiovascular disease, and as a hair-loss intervention in published research. It is a research tool only, not approved for any clinical indication.
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