For research purposes only. Not for human use. Nothing here is medical advice or an administration protocol.
What Pentadecarginine Is
Pentadecarginine is the name used in the research-chemical market for a synthetic homopolymer of fifteen L-arginine residues (R15, or Arg₁₅). It belongs to the oligoarginine family of cell-penetrating peptides (CPPs), the same family as the octa-arginine (R8) and nona-arginine (R9) carriers used in drug-delivery research and the arginine-rich HIV-1 TAT peptide.
The name "pentadecarginine" returns no results in PubMed. There are no peer-reviewed studies of a compound by that name, and none of the specific claims attached to it commercially (wound healing, nitric-oxide delivery, "tissue regeneration") have been tested on R15 as such. What exists is a substantial literature on arginine homopolymers of various lengths (R8 to R30 and polymeric poly-L-arginine), on arginine-rich CPPs generally, and on free L-arginine as a nitric-oxide precursor. This article summarises that literature and is explicit about where R15 sits inside it, which is mostly by extrapolation from chain-length trends.
How Arginine-Rich Peptides Enter Cells
The defining property of oligoarginines is that they cross plasma membranes, carrying attached cargo with them. The guanidinium side chain of arginine forms bidentate hydrogen bonds with phosphate and sulfate groups on the cell surface, and a run of arginines binds strongly enough to negatively charged lipids and proteoglycans to drive internalisation. In the membrane-curvature model of Schmidt and colleagues, every proposed entry route requires negative Gaussian membrane curvature, and the capacity to generate that curvature scales with arginine content specifically rather than with net charge alone (Schmidt et al., 2010).
Two entry routes operate in parallel and their balance depends on concentration, cell type and cargo. Direct translocation across the bilayer occurs at higher peptide concentrations and is associated with induction of negative Gaussian membrane curvature, which the arginine guanidinium groups generate (Schmidt et al., 2010). Endocytic uptake dominates at lower concentrations; for octa-arginine, syndecan-4 was identified as a primary cell-surface receptor initiating clathrin-mediated endocytosis, and the same pathway delivered bioactive protein cargo (Kawaguchi et al., 2016). Binding to membrane-associated proteoglycans is also what triggers the actin reorganisation and macropinocytosis seen with arginine-rich peptides (Nakase et al., 2007). A 2017 review in Accounts of Chemical Research and a 2022 review in the International Journal of Molecular Sciences cover the multiplex-entry model and current design strategies in detail (Futaki and Nakase, 2017; Int J Mol Sci, 2022).
Chain length matters. Uptake efficiency rises from about six arginines, is generally highest around eight to twelve, and cytotoxicity increases with length and concentration. R15 sits above the optimum for delivery efficiency in most cell-uptake studies, which is one reason it has not been a standard CPP carrier; it is, however, within the range studied for neuroprotection and antimicrobial activity described below.
Neuroprotection in Stroke Models
The clearest length-dependent activity of arginine homopolymers is neuroprotection in excitotoxicity and oxygen-glucose deprivation models. Meloni and colleagues showed in cortical neuronal cultures that poly-arginine and arginine-rich CPPs are neuroprotective with efficacy increasing with arginine content, reduce glutamate-induced calcium influx, and require heparan-sulfate-proteoglycan-mediated endocytosis to act. Neuroprotection was also achieved with R9 given intravenously after stroke onset in a rat model. The authors proposed peptide-induced endocytic internalisation of ion channels as the mechanism, and noted that the finding raises questions about neuroprotective peptides fused to arginine-rich carriers, since the carrier itself may be the active component (Meloni et al., 2015). A related review in Pharmacology & Therapeutics develops the same argument (Pharmacol Ther, 2015).
This body of work is the strongest evidence that longer arginine homopolymers have intrinsic biological activity rather than being inert carriers. It has been carried out with R9 through R18 and related sequences; R15 falls inside the range where the "more arginine, more protection" trend was observed, but has not been individually reported.
Antimicrobial Activity
Cationic homopeptides inhibit bacterial growth through charge-driven membrane interaction. In a study of synthetic L-lysine and L-arginine homopeptides of 7 to 14 residues against Gram-positive bacteria, inhibitory activity depended on both residue type and chain length, with arginine homopeptides showing higher selectivity than lysine (J Pept Sci, 2013). Polyarginine with a degree of polymerisation of 30 (PAR30) provides prolonged antibacterial activity in hyaluronic-acid hydrogels and reduces the inflammatory response of LPS-stimulated macrophages, a combination the authors proposed for infected-wound and implant applications (Macromol Biosci, 2022). Polyarginine-decorated polydopamine nanoparticles have been used to give hydrogels antimicrobial surfaces (Front Bioeng Biotechnol, 2020).
The most developed polyarginine antimicrobial is NP339, a 2 kDa polyarginine peptide designed from endogenous cationic defence peptides that shows broad activity against Candida, Aspergillus and Cryptococcus through charge-initiated membrane interaction (Antimicrob Agents Chemother, 2021). At roughly 2 kDa, NP339 is close in size to R15 (about 2.4 kDa), making it the nearest published analogue to pentadecarginine with an antimicrobial data set.
Wound Healing: What Is and Is Not Established
The commercial framing of pentadecarginine as a wound-healing peptide draws on two separate literatures, neither of which studied R15.
The first is free L-arginine. Arginine is the sole substrate for nitric-oxide synthase and is a precursor of ornithine and polyamines; supplementation enhances wound strength and collagen deposition in incisional wounds in rodents and humans, though its effect on chronic human wounds remained undetermined in a 2005 review (Stechmiller et al., 2005). In streptozotocin-diabetic rats, oral L-arginine restored impaired wound healing by normalising the nitric-oxide pathway (Witte et al., 2002). None of this involves a peptide; the arginine is free amino acid, and there is no published evidence that an intact R15 peptide is hydrolysed in a wound to release arginine for NOS at a useful rate.
The second is topical poly-L-arginine. In a randomised, blinded mouse frostbite model, topical poly-L-arginine lotion reduced tissue loss when applied around the freeze injury (Wilderness Environ Med, 2014). This used polymeric poly-L-arginine rather than a defined 15-mer, and the authors called for further study rather than claiming a mechanism.
Materials-science work uses polyarginine as a component of adhesives and coatings: a 2024 study co-released nitric oxide and L-arginine from a poly(β-amino ester) adhesive to shift macrophages toward a pro-healing phenotype (Biomater Adv, 2024), and methacrylated poly-L-arginine has been used in antibacterial, pH-sensitive soft-tissue scaffolds (J Mater Sci Mater Med, 2023). These are biomaterial applications of the polymer, not studies of a soluble R15 peptide.
Platform Market Data
There are no pentadecarginine listings in the Peptides.SO database. Across 119 suppliers and 10,922 priced listings (checked 24–25 September 2026), no product row matches "pentadecarginine," "R15" or "polyarginine." The compound is available from custom peptide synthesis houses rather than from research-peptide retailers, which is consistent with its status as a reagent rather than a marketed research compound.
For comparison, the wound-healing peptides that the research market does stock are listed by many suppliers: BPC-157 by 97 suppliers at a median list price of $65, and the BPC-157/TB-500 blend by 65 suppliers at $107. Researchers interested in arginine-rich sequences with a delivery literature behind them will find the cell-penetrating peptides overview more useful than the pentadecarginine label.
If ordering R15 from a synthesis house, the certificate should show HPLC purity, mass spectrometry confirming the expected mass of the 15-mer (not a distribution of chain lengths, which indicates polymeric poly-L-arginine rather than a defined peptide), the counter-ion (TFA or acetate), and net peptide content, since highly cationic peptides bind a large mass fraction of counter-ion. The supplier checklist covers these points.
Handling Notes for Laboratory Use
Arginine homopolymers are highly water-soluble and hygroscopic. In cell culture, oligoarginines above about ten residues show concentration-dependent membrane toxicity, so dose-ranging with a viability readout is a normal first experiment; serum proteins and heparan sulfate in the medium reduce both uptake and toxicity. TFA counter-ion from synthesis can itself affect cells and is usually exchanged for acetate or chloride before biological work. Store lyophilised peptide frozen and desiccated; reconstituted solutions in sterile water or buffer should be aliquoted to avoid freeze-thaw cycles. The peptide calculator converts vial mass to molarity given the net peptide content. These are handling notes for in vitro reagents only.
Frequently Asked Questions
Has pentadecarginine itself been studied?
No peer-reviewed study of a compound named pentadecarginine, or of R15 specifically as a wound-healing agent, exists in PubMed. Published data cover other arginine homopolymer lengths and polymeric poly-L-arginine.
Is it a cell-penetrating peptide?
Yes, by class. Oligoarginines from about R6 upward cross membranes; R15 is longer than the length most CPP studies find optimal for delivery.
Does it release arginine for nitric-oxide production?
That is a commercial hypothesis, not a published finding. The wound-healing data on arginine and nitric oxide come from free L-arginine given orally or in feed.
What is the best-supported activity of longer arginine homopolymers?
Neuroprotection in excitotoxicity and stroke models, where efficacy rose with arginine content and depended on proteoglycan-mediated endocytosis.
Why is it not sold by research-peptide retailers?
Our database of 119 suppliers has no listing for it. It is a custom-synthesis reagent, and defined-length oligoarginines are usually bought as R8 or R9 for delivery work.
What would a good certificate of analysis show?
A single mass peak for the 15-mer, HPLC purity, the counter-ion identity and net peptide content. A broad mass distribution means polymeric poly-L-arginine, which is a different material.
References
1. Schmidt N, et al. Arginine-rich cell-penetrating peptides. FEBS Lett. 2010. PMID 19925791
2. Kawaguchi Y, et al. Syndecan-4 Is a Receptor for Clathrin-Mediated Endocytosis of Arginine-Rich Cell-Penetrating Peptides. Bioconjug Chem. 2016. PMID 27019270
3. Nakase I, et al. Interaction of arginine-rich peptides with membrane-associated proteoglycans is crucial for induction of actin organization and macropinocytosis. Biochemistry. 2007. PMID 17209559
4. Futaki S, Nakase I. Cell-Surface Interactions on Arginine-Rich Cell-Penetrating Peptides Allow for Multiplex Modes of Internalization. Acc Chem Res. 2017. PMID 28910080
5. Hao M, et al. Membrane Internalization Mechanisms and Design Strategies of Arginine-Rich Cell-Penetrating Peptides. Int J Mol Sci. 2022. PMID 36012300
6. Meloni BP, et al. Poly-arginine and arginine-rich peptides are neuroprotective in stroke models. J Cereb Blood Flow Metab. 2015. PMID 25669902
7. Meloni BP, et al. Neuroprotective peptides fused to arginine-rich cell penetrating peptides: Neuroprotective mechanism likely mediated by peptide endocytic properties. Pharmacol Ther. 2015. PMID 26048328
8. Guzmán F, et al. Inhibitory effect of short cationic homopeptides against gram-positive bacteria. J Pept Sci. 2013. PMID 24243601
9. Gribova V, et al. Polyarginine as a Simultaneous Antimicrobial, Immunomodulatory, and miRNA Delivery Agent within Polyanionic Hydrogels. Macromol Biosci. 2022. PMID 35332672
10. Muller C, et al. Polyarginine Decorated Polydopamine Nanoparticles With Antimicrobial Properties for Functionalization of Hydrogels. Front Bioeng Biotechnol. 2020. PMID 32974312
11. Duncan V, et al. Preliminary Characterization of NP339, a Novel Polyarginine Peptide with Broad Antifungal Activity. Antimicrob Agents Chemother. 2021. PMID 34031048
12. Stechmiller JK, Childress B, Cowan L. Arginine supplementation and wound healing. Nutr Clin Pract. 2005. PMID 16207646
13. Witte MB, et al. L-Arginine supplementation enhances diabetic wound healing: involvement of the nitric oxide synthase and arginase pathways. Metabolism. 2002. PMID 12370845
14. Auerbach LJ, et al. Poly-L-arginine topical lotion tested in a mouse model for frostbite injury. Wilderness Environ Med. 2014. PMID 24631228
15. Heydari P, et al. Co-release of nitric oxide and L-arginine from poly(β-amino ester)-based adhesive reprogram macrophages for accelerated wound healing. Biomater Adv. 2024. PMID 38227989
16. Heydari P, et al. Antibacterial and pH-sensitive methacrylate poly-L-Arginine/poly(β-amino ester) polymer for soft tissue engineering. J Mater Sci Mater Med. 2023. PMID 37036618
Research Disclaimer
Pentadecarginine (R15) is a synthetic research reagent with no approved use and no published safety data in any species. This article summarises the arginine-homopolymer literature for laboratory researchers and does not recommend or describe administration to people or animals.