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KCF-18 is an 18-residue synthetic peptide designed in silico from the binding regions of three cytokine receptors (TNFR1, IL-1R, IL-6R). It works as a soluble decoy that grabs the proinflammatory cytokines TNF-alpha, IL-1beta and IL-6 before they can dock on their own receptors, dampening downstream inflammation. It is a preclinical anti-inflammatory research peptide, not a nootropic or a CNS compound.
- Binds and sequesters three major proinflammatory cytokines (TNF-alpha, IL-1beta, IL-6) simultaneously (preclinical, in vitro and in silico)
- Cuts monocyte binding and transmigration across endothelium in cell culture (preclinical)
- Reduces NF-kB p65 nuclear translocation and NF-kB reporter activity dose-dependently (preclinical, in vitro)
- Lowers cytokine-induced reactive oxygen species in human monocytes (preclinical)
- Decreased white blood cell infiltration in a mouse peritonitis model (preclinical, in vivo)
- Reduced liver TNF-alpha, IL-1beta, IL-6 and MCP-1 expression and tissue damage in an LPS endotoxemia model (preclinical, in vivo)
- No observed cytotoxicity up to 500 nM in endothelial and monocyte cell lines (preclinical)
- Modest binding affinity (tens to hundreds of micromolar) suggests high doses would be needed for a biological effect
- Broadly dampening TNF-alpha, IL-1beta and IL-6 could in principle blunt useful immune responses, though this was not studied
Overview
The evidence base for KCF-18 is real but narrow: three peer-reviewed papers from one Taiwanese group (Tzu Chi University with computational collaborators), covering rational design, surface plasmon resonance binding, cell-culture assays in endothelial and monocyte lines, and two mouse models (thioglycollate peritonitis and LPS endotoxemia). All of it is in-vitro or rodent work; there are no human trials, no pharmacokinetics, and no independent replication outside the originating lab.
The measured binding affinities are modest (tens to low-hundreds of micromolar), so it is better read as a proof-of-concept multitarget cytokine sponge than a finished drug. A note on identity: KCF-18 is sometimes mislabeled online as a CREB/CRTC (TORC) transcription-factor peptide; that is not what the published literature describes. Every primary source characterizes it strictly as a cytokine-binding anti-inflammatory decoy.
- The whole peptide is a molecular mimic: its 18 residues are lifted from the parts of three different cytokine receptors that actually touch their cytokines, so it acts like a receptor fragment floating free in solution.
- It is genuinely multitarget, sponging TNF-alpha, IL-1beta and IL-6 at once rather than blocking a single cytokine the way most biologic anti-inflammatories do.
- Despite being labeled online in a few places as a CREB or CRTC/TORC transcription peptide, none of the primary literature supports that; every published study describes it as a cytokine-binding decoy.
- Its cytokine binding is driven mainly by electrostatic attraction, which is why the peptide was engineered with a strongly positively charged face.
Mechanism
KCF-18 (sequence KCRKEMFKQKLPYSTVYF) is a composite stitched together from the receptor residues that normally contact TNF-alpha, IL-1beta and IL-6, so it presents a -facing surface without the rest of the receptor. It is amphiphilic, with a positively charged, hydrophilic face and a more hydrophobic face, and it binds its target cytokines mainly through electrostatic interactions confirmed by molecular dynamics and MM/PBSA free-energy calculations.
Surface plasmon resonance gave dissociation constants of roughly 61 micromolar for TNF-alpha and 112 micromolar for IL-6; IL-1beta binding was inferred from simulation and cell assays rather than SPR. By sequestering the cytokines in solution it lowers their engagement of TNFR1, IL-1R and IL-6R, which in turn cuts NF-kB p65 nuclear translocation, reduces -driven reactive oxygen species, and suppresses TNF-alpha, IL-1beta and IL-6 transcription. The net cellular readout is less monocyte adhesion and transmigration across endothelium.
The is an 18-residue chimera assembled from three receptor fragments: a strongly cationic six-residue stretch from the TNF receptor, a mixed hydrophobic and cationic six from the IL-1 receptor, and a neutral six from the IL-6 receptor. The result is amphipathic by construction, with five positive charges and six hydrophobic residues segregated to opposite ends. Alanine scanning shows the cationic face carries the binding.
⚠️ THE POTENCY GAP IS THE CENTRAL PROBLEM AND NO PAPER ADDRESSES IT. The measured affinities are 60.9 micromolar for TNF-alpha and 111.5 micromolar for IL-6 [1]. The cellular effects are reported at 5, 50 and 500 nanomolar, and one study describes bacteria secreting about 19.5 nanomolar of the producing anti-inflammatory effects exceeding those of one micromolar of purified peptide [5]. A with a 60 micromolar dissociation constant is essentially unoccupied at 20 nanomolar. Either the binding measurement understates affinity by three or four orders of magnitude, or the cellular effects are not produced by the stoichiometric mopping-up the mechanism describes. A cationic amphipathic is exactly the chemotype that produces non-specific membrane and polyanion effects, and the scrambled control used does not fully exclude them.
⚠️ Two further findings undercut the multi-target rationale. Blocking TNF-alpha alone with a single- achieved effects comparable to the triple-binding peptide on every measured endpoint in endotoxin lung injury [4], so it is not clear the tri-specific design is doing the work it is credited with. And in the bacterial-delivery study, supernatant from the unmodified bacteria was itself anti-inflammatory and suppressed the same signalling comparably, a confound the authors acknowledge but do not resolve [5].
⚠️ Binding to IL-1beta, the third of its three named targets, has never been measured; the authors state the was extremely difficult to immobilise. The tri-specificity claim therefore rests on computational docking plus cell assays, with no binding data for one of the three.
receptor fingerprint
TNF-alphabinding decoy / sequestration
IL-6binding decoy / sequestration
IL-1betabinding decoy / sequestration
NF-kB (p65)downstream inhibitor
-induced reactive oxygen speciesreducer
monocyte adhesion and transmigrationinhibitor
TNF-alpha (measured binding)Binder
IL-6 (measured binding)Binder
Evidencehow good the literature is
⚠️ The entire corpus is five papers and there are no registered trials. Four of the five come from one interlocking collaboration; the fifth is from an independent group that used the peptide as a laboratory reagent rather than as a drug candidate [5]. There is no pharmacokinetic data, no plasma stability, no immunogenicity work, no toxicology package, no human exposure, and no structural confirmation of a peptide-cytokine complex; every structural claim is a docking model.
Doses used in animals were 5 milligrams per kilogram intravenously in peritonitis and a descending intraperitoneal schedule starting at 0.6 milligrams per kilogram in endotoxin shock [1][3]. Cell tolerance was good, with no toxicity up to 100 micromolar in one macrophage line [5].
Dosingtypical ranges, not medical advice
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Safetyrisks and cautions, not medical advice
There is no human safety data for KCF-18 at all; the safety picture is limited to what the mouse and cell studies reported. In cultured human endothelial (HMEC-1) and monocytic (THP-1) cells it showed no cytotoxicity up to 500 nM over 24 to 48 hours, and treated mice in the peritonitis and endotoxemia models survived the observation windows without reported acute toxicity. Beyond that, the important gaps are the whole story: no toxicology, no immunogenicity testing (a real concern for a synthetic multi-epitope peptide), no dosing ceiling, no repeat-dose or chronic data, and no pharmacokinetics. Anyone treating this as anything other than a laboratory reagent is well ahead of the evidence, and it should not be assumed safe for human use.
History
KCF-18 was developed by a group centered at Tzu Chi University in Hualien, Taiwan, led by Shinn-Jong Jiang with computational collaborators, using structure-based in silico design to fuse cytokine-contacting residues from TNFR1, IL-1R and IL-6R into a single short peptide. The first full report appeared in Scientific Reports in 2019, establishing binding and anti-inflammatory activity in cells and a peritonitis model. A 2021 paper in the Journal of Personalized Medicine extended it to an LPS endotoxemia model in mice, and a 2022 Frontiers in Pharmacology paper added mechanism detail around NF-kB, ROS and liver inflammation. Development has stayed within this academic program; there is no company, clinical program, or regulatory filing associated with it.
Reputation
In the research literature KCF-18 is regarded as an interesting example of computational multitarget peptide design, cited mainly in that context rather than as a therapeutic anyone is racing to the clinic. It has almost no footprint in the mainstream research-chemical or nootropics community, and where it does surface online it is occasionally confused with unrelated transcription-factor peptides. The honest read is a legitimate but early-stage academic peptide with a clean, coherent mechanism story and modest binding numbers, valued more as a proof of concept for sponging several cytokines at once than as a validated drug.
Subjective profileweighing the evidence above
Elegant design, weak execution. Binding sits in the micromolar range, so useful doses would be impractically large, the peptide half-life is short, and every result comes from one lab with no independent replication and no human data. A paper worth reading, not a compound worth obtaining.
Resources
This entry is here for reference.
Research
- 2019first citedA potential peptide derived from cytokine receptors can bind proinflammatory cytokines as a the…
- 2025most recentDeveloping an in vitro model of endotoxemia to assess the immunomodulatory effects of anti-infl…
- 1.A potential peptide derived from cytokine receptors can bind proinflammatory cytokines as a therapeutic strategy for anti-inflammation
- 2.A Multitarget Therapeutic Peptide Derived From Cytokine Receptors Based on in Silico Analysis Alleviates Cytokine-Stimulated Inflammation
- 3.Simultaneous Inhibition of Three Major Cytokines and Its Therapeutic Effects: A Peptide-Based Novel Therapy against Endotoxemia in Mice
- 4.Tumor Necrosis Factor-α Mediates Lung Injury in the Early Phase of Endotoxemia.
- 5.Developing an in vitro model of endotoxemia to assess the immunomodulatory effects of anti-inflammatory peptide-secreting living therapeutics
5 listed here; entry last updated August 2026
Reviews
My notesprivate to this device
FAQ
Is KCF-18 a nootropic or brain peptide?
No. It is an anti-inflammatory research peptide designed to bind proinflammatory cytokines. There is no cognitive or CNS data on it, and it is not used or studied as a nootropic.
How does KCF-18 actually work?
It is a decoy built from the cytokine-binding residues of three receptors (TNFR1, IL-1R, IL-6R). It grabs TNF-alpha, IL-1beta and IL-6 in solution, mostly through electrostatic attraction, so those cytokines can't dock on their real receptors and trigger inflammation.
Has KCF-18 been tested in humans?
No. All published work is in cell cultures and mice from one lab. There are no clinical trials, no human dosing, and no pharmacokinetic data.
Is it related to CREB or CRTC/TORC?
No, despite a few online listings suggesting that. Every primary paper describes KCF-18 strictly as a cytokine-binding anti-inflammatory peptide, not a transcription-factor-targeting one.
How strong is its cytokine binding?
Modest. Surface plasmon resonance gave dissociation constants around 61 micromolar for TNF-alpha and 112 micromolar for IL-6, which is weak compared with antibody-grade binders. That is a real limitation for it as a drug candidate.
Is KCF-18 safe to use?
Its safety in humans is unknown. It showed no cytotoxicity in cell lines up to 500 nM and treated mice survived the short study windows, but there is no toxicology, immunogenicity, or repeat-dose data. It should be treated as a laboratory research peptide, not a supplement.
Why hasn't it moved to the clinic?
It has stayed an academic project with modest binding affinity and the usual peptide-drug hurdles of short half-life and low bioavailability. No company or clinical program has picked it up in the published record.
Limitations of the evidence
- Measured affinity is 60.9 and 111.5 micromolar while claimed cellular activity is at nanomolar concentrations, a gap of three to four orders of magnitude that no paper addresses
- Binding to IL-1beta, one of its three named targets, was never measured
- Blocking TNF-alpha alone matched the triple-binding peptide on every endpoint in one model, which undercuts the multi-target rationale
- Five papers exist in total, four from one collaboration, and no registered trial
- No pharmacokinetics, stability, immunogenicity or toxicology data of any kind
Adverse effects
- Modest binding affinity (tens to hundreds of micromolar) suggests high doses would be needed for a biological effect
- Broadly dampening TNF-alpha, IL-1beta and IL-6 could in principle blunt useful immune responses, though this was not studied
Notes and cautions
- Potential immunogenicity of a synthetic multi-epitope peptide has not been tested