Esculentin
A family of water-frog skin antimicrobial peptides — broad-spectrum (notably against Gram-negative bacteria), with wound-healing and metabolic members. Research compounds, not drugs
Esculentins are antimicrobial peptides from the skin of water and edible frogs. The family has two branches: esculentin-1, at about forty-six amino acids one of the longest and most potent frog antimicrobial peptides, and the shorter esculentin-2. Both are cationic, amphipathic alpha-helices that carry the disulfide-bridged C-terminal loop known as the 'Rana box', and both disrupt microbial membranes — esculentins are especially noted for hitting Gram-negative bacteria such as Pseudomonas, Klebsiella and E. coli, which are hard targets for many antibiotics. Much of the modern work focuses on short, engineered fragments: Esc(1-21), the first twenty-one residues of esculentin-1a, is a well-studied lead against Pseudomonas and a promoter of wound healing, and esculentin-2CHa has been engineered into long-acting forms studied for diabetes and fatty-liver disease. Esculentins are research antimicrobial peptides; they are not approved medicines and have not been given to people as a treatment.
No established human dose Details ↓
Recommended Dosing
No established human dose
Esculentins are frog-skin research peptides; none has been given to people as a treatment. The work is in bacteria, cultured cells and animals, often with engineered fragments or constructs, at experimental amounts that do not carry over to people.
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What is it?
Esculentins are among the most studied antimicrobial peptides from frog skin. They were first described from water and edible frogs (the genus Pelophylax, long known as Rana esculenta) in the early 1990s, in two branches: esculentin-1 and esculentin-2. Esculentin-1 peptides run to about forty-six residues, which makes them some of the longest and most potent frog antimicrobial peptides, while esculentin-2 peptides are shorter at around thirty-seven. Both carry the hallmark frog-skin 'Rana box' — a disulfide-bridged loop at the C-terminus — and fold into cationic, amphipathic alpha-helices.
The core mechanism is membrane disruption, and esculentins are particularly valued for reaching Gram-negative bacteria, which have an extra outer membrane that defeats many drugs. An esculentin-1 homolog cloned from a dark-spotted frog killed bacteria both by breaking the cell membrane and by hydrolysing bacterial DNA, and also acted on immune cells — amplifying the respiratory burst and pro-inflammatory gene expression in cultured macrophages — showing that esculentins combine direct killing with immunomodulation.
Because the full-length peptides are long, most translational work uses short engineered fragments and analogs. Esc(1-21), the first twenty-one residues of esculentin-1a, is a heavily studied lead: it and its D-amino-acid diastereomers permeabilise the outer membrane of carbapenemase-producing Klebsiella and can restore the activity of the antibiotic ceftazidime against otherwise-resistant strains, acting as a membrane-permeabilising adjuvant. Esc(1-21) and its derivatives also promote wound healing, accelerating the migration of keratinocytes and human dermal fibroblasts and switching on early wound-healing genes through EGFR and MAPK/ERK signalling.
The esculentin-2 branch has taken a different, metabolic direction. Esculentin-2CHa is an anti-diabetic peptide, and researchers have engineered long-acting versions — a genetically fused trimeric form with an albumin-binding domain, and gold-nanoparticle-coated forms — to overcome its very short lifetime in blood. In high-fat-diet mice these long-acting esculentin-2CHa constructs lowered blood glucose, improved glucose tolerance and reduced liver fat, pointing to a role against type-2-diabetes-associated fatty liver disease. These are animal and cell studies of engineered constructs, not treatments given to people.
Through all of this, esculentins remain research antimicrobial peptides. No published study has given an esculentin to people as a treatment, none is approved anywhere, and material sold online under these names is an unregulated research chemical. Nothing here is a dose or a therapy; this page records what the published science says.
Mechanism of Action
Esculentins are cationic, amphipathic alpha-helical frog-skin antimicrobial peptides with a C-terminal disulfide 'Rana box'. They disrupt microbial membranes broadly (notably Gram-negative bacteria) and can hydrolyse bacterial DNA; family members and engineered fragments also promote wound healing, modulate immune cells, and (the esculentin-2CHa branch) show anti-diabetic/anti-NAFLD activity.
Water-frog host defense
Cationic amphipathic helices with a C-terminal disulfide 'Rana box' from Pelophylax frog skin; esculentin-1 (~46 aa) and esculentin-2 (~37 aa) (PMID 38678277).
Broad-spectrum membrane disruption
Permeabilise bacterial membranes — notably the Gram-negative outer membrane — and can hydrolyse bacterial DNA; Esc(1-21) even restores a beta-lactam against resistant Klebsiella (PMIDs 42725961, 38678277).
Wound healing and metabolic effects
Esc(1-21) drives keratinocyte/fibroblast migration and angiogenesis via EGFR-MAPK/ERK and PI3K/AKT; esculentin-2CHa constructs lower glucose and liver fat in mice (PMIDs 36385013, 40125429).
Published Research
These are studies of esculentins read from their PubMed records on November 7, 2026: esculentin-1a-derived Esc(1-21) peptides restoring a beta-lactam antibiotic against resistant Klebsiella; esculentin-1a derivatives promoting human dermal fibroblast migration and wound-healing genes; an esculentin-1 homolog with antibacterial and immunoregulatory activity; and animal studies of wound healing and of long-acting esculentin-2CHa constructs for fatty-liver disease and diabetes in mice. The evidence is in bacteria, cells and animals; esculentins have not been given to people as a treatment.
Esc(1-21) peptides restore an antibiotic against resistant Klebsiella
The esculentin-1a fragment Esc(1-21) and D-amino-acid analogs permeabilised the outer membrane of carbapenemase-producing (KPC) Klebsiella pneumoniae and potentiated the cephalosporin ceftazidime, with the combination killing bacteria better than either agent alone — supporting esculentin-derived peptides as adjuvants that restore beta-lactam activity against multidrug-resistant Gram-negatives (an in-vitro mechanism study).
Esculentin-1a derivatives promote human dermal fibroblast wound healing
Esc(1-21) and its derivatives increased the migration of human primary dermal fibroblasts and closed a model wound by activating MAPK/ERK signalling (via EGFR for two of the peptides) and up-regulating early wound-healing genes such as collagen I and III, without changing cell proliferation — evidence for a tissue-regenerative role beyond antimicrobial activity (an in-vitro study).
Esculentin-2CHa nanoparticle construct against fatty-liver disease (mice)
A long-acting esculentin-2CHa(1-30) peptide coated onto gold nanoparticles had an extended blood lifetime and high liver accumulation, and in high-fat-diet obese mice lowered blood glucose, improved glucose tolerance and reduced liver fat — a preclinical anti-NAFLD and anti-diabetic result for an engineered esculentin construct.
Long-acting esculentin-2CHa(1-30) fusion protein for NAFLD (mice)
A genetically engineered fusion of trimeric esculentin-2CHa(1-30) with an albumin-binding domain extended the peptide's blood half-life several-hundred-fold, and twice-weekly dosing in mice improved blood-glucose control, reduced body weight and improved fatty-liver disease, apparently by inhibiting liver lipid uptake — a preclinical metabolic study.
An esculentin-1 homolog: antibacterial and immunoregulatory
An esculentin-1 peptide cloned from the dark-spotted frog killed bacteria both by disrupting the cell membrane and by hydrolysing bacterial DNA, and acted on cultured macrophages — amplifying the respiratory burst and pro-inflammatory gene expression — showing esculentins combine direct killing with immunomodulation (an in-vitro study).
Esculentin-1a(1-21) accelerates wound healing via angiogenesis (mice)
The esculentin-1a fragment Esc-1a(1-21) accelerated closure of full-thickness skin wounds in mice by increasing collagen deposition and new blood-vessel formation, and promoted endothelial cell migration and proliferation through the PI3K/AKT pathway in vitro — a preclinical wound-healing result.
No Established Human Dose
Esculentins are frog-skin research peptides; none has been given to people as a treatment. The work is in bacteria, cultured cells and animals, often with engineered fragments or constructs, at experimental amounts that do not carry over to people. No regulator has approved any dose, and no published human dose exists, so no amount is printed here.
What this rests on: PMID 42725961, PMID 38925336, PMID 36385013.
Educational information, not medical advice. The doses on this page come from approved labels, published studies and, where no study exists, amounts reported by users. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose. Full medical disclaimer.
What a Buyer Needs to Know
What is sold, how it is mixed, stored and taken, and what is known about its safety, quality and legal status. Each part names its source. Where we have none, it says unknown.
What is sold
Unknown: we hold no label and no published test that says what forms or vial sizes Esculentin is sold in. A vial's own label is a seller's claim, not a source.
Mixing a vial: a worked example
Unknown: no human dose of Esculentin has been established (see No Established Human Dose below), so there is no amount to work out. The reconstitution calculator does the arithmetic for any vial, water and dose.
Storage before and after mixing
Unknown: no label or published stability study on file says how to store Esculentin, before or after mixing. The mixing guide sets out the general rules, with their sources: keep a mixed vial in the fridge, and use it promptly, as the bacteriostatic water label says of any drug dissolved in it. The 28 days often quoted is the limit for an opened multiple-dose vial from a manufacturer, an outer limit set for sterility, not a time a mixed solution has been shown to keep. Nobody has published how long Esculentin stays intact once mixed.
How it is taken
Unknown: with no established human dose, there is no established way of taking Esculentin. What the human studies gave and how is set out under No Established Human Dose.
What to expect, and when
How long it stays in the body: a half-life of very short for the native peptides; engineered long-acting constructs extend it greatly. After about five half-lives almost none is left.
When effects appear: unknown; no source on this page gives a time to effect for Esculentin. Results reported in the studies are under Published Research.
Source: half-life: PMID 38925336.
Side effects, and when to stop or get help
From the Side Effects section: No human adverse-event data exist: no published study has administered an esculentin to people; As membrane-active peptides, hemolysis and cytotoxicity to host cells are the central safety concern; the short Esc(1-21) fragment and engineered constructs are chosen partly to lower toxicity (PMIDs 42725961, 38925336) — a design issue, not human data; Engineered esculentin-2CHa constructs are studied for metabolic disease in animals (PMID 40125429); their safety in people is unknown; Material sold online as an 'esculentin' is an unregulated research chemical of unverified content. Full list and cautions ↓
When to stop or get help: unknown; no label or trial on file sets rules for stopping Esculentin. Treat a severe or unexpected reaction as a reason to stop and see a doctor.
Source: the Side Effects section below (“Esculentins are research peptides that have not been given to people as drugs, so there is no human safety profile; the points below reflect that research status and their biology”).
Interactions
Unknown: a PubMed search for human interaction studies of Esculentin (reviewed 2026-11-07) found none. Unknown is not the same as safe to combine.
Every peptide's record, with its source: the interaction matrix.
Checking what you bought
Unknown: no published independent test of Esculentin products is in our lab-results database yet, so how products sold under this name measure up is not known.
To read a certificate of analysis, paste it into the COA decoder. Trust & Verification explains what independent testing can and cannot show.
Legal status
US: Research Chemical (Not drugs: Drugs@FDA and the openFDA label endpoint hold no record, and FDA GSRS and ChEMBL hold no approved-drug record for esculentin peptides (searched November 7, 2026)). Sport: Not on the 2026 List.
Country by country ↓ · Regulatory tracker
Source: this entry's approval status and the WADA Prohibited List, as in Legal Status below.
Side Effects & Contraindications
Reported Side Effects
Esculentins are research peptides that have not been given to people as drugs, so there is no human safety profile; the points below reflect that research status and their biology.
Contraindications & Cautions
Esculentins have no approved use and no label. These points reflect their research status.
Legal Status
Esculentins are frog-skin antimicrobial peptides used as research compounds; they are not drugs and are not approved in any country.
Frequently Asked Questions
?What are esculentins?
A family of antimicrobial peptides from the skin of water/edible frogs (Pelophylax). Esculentin-1 (~46 amino acids) is among the longest, most potent frog antimicrobial peptides; esculentin-2 (~37) is shorter. Both carry a C-terminal disulfide 'Rana box' (PMID 38678277).
?How do they work?
They are cationic, amphipathic helices that disrupt microbial membranes — notably the Gram-negative outer membrane — and can hydrolyse bacterial DNA (PMIDs 42725961, 38678277).
?What are they studied for?
As broad-spectrum antibacterial and antibiotic-potentiating leads, as wound-healing peptides (Esc(1-21)), and — the esculentin-2CHa branch — as anti-diabetic/anti-NAFLD peptides in animals (PMIDs 36385013, 40125429).
?Are they approved or available to buy?
No. Esculentins are not medicines, have no FDA application or label, and are approved nowhere. Material sold online as an esculentin is an unregulated research chemical. Grey Peptides lists no sellers and recommends no source; this page records the published science.
References
- [mechanism] Al Ismail D, et al. "Esculentin-1a Derived Peptides Potentiate Ceftazidime Activity against Multidrug-Resistant KPC-Producing Klebsiella pneumoniae." ACS Infect Dis, 2026;12(9):3169-3178. PMID: 42725961.
- [mechanism] Cappiello F, et al. "Bioactive derivatives of the antimicrobial peptide esculentin-1a promote human dermal fibroblast migration and activate genes involved in early wound healing." BBA Adv, 2026;9:100186. PMID: 42004462.
- [animal] Amatya R, et al. "Combined Esculentin-2CHa Fusion Protein-Coated Au Nanoparticles for Effective Against Non-Alcoholic Fatty Liver Disease in Mice Model." Int J Nanomedicine, 2025;20:3407-3421. PMID: 40125429.
- [animal] Lee J, et al. "Genetically engineered long-acting Esculentin-2CHa(1-30) fusion protein with potential applicability for the treatment of NAFLD." J Control Release, 2024;372:699-712. PMID: 38925336.
- [mechanism] Chen J, et al. "An esculentin-1 homolog from a dark-spotted frog (Pelophylax nigromaculatus) possesses antibacterial and immunoregulatory properties." BMC Vet Res, 2024;20(1):164. PMID: 38678277.
- [animal] Hu Q, et al. "The Antimicrobial Peptide Esculentin-1a(1-21)NH(2) Stimulates Wound Healing by Promoting Angiogenesis through the PI3K/AKT Pathway." Biol Pharm Bull, 2023;46(3):382-393. PMID: 36385013.
- [other] Esculentins are antimicrobial peptides from the skin of water/edible frogs (genus Pelophylax, formerly Rana esculenta and relatives), first described by Simmaco and colleagues in the early 1990s (J Biol Chem, 1994), who named esculentin-1 and esculentin-2. Esculentin-1 is among the longest frog antimicrobial peptides; both families carry a C-terminal disulfide 'Rana box'. Their structure and activities are described in the studies carded on this page (read November 7, 2026).
- [other] US FDA, Drugs@FDA and the openFDA label endpoint, searched November 7, 2026: no application and no label record for esculentin peptides. They are frog-skin research antimicrobial peptides, not drugs; FDA GSRS and ChEMBL hold no approved-drug record for them.
Sources & Citations
The six studies carded above were read from their PubMed records on November 7, 2026. The esculentin family's water-frog-skin origin, its division into esculentin-1 (~46 aa) and esculentin-2 (~37 aa), the C-terminal 'Rana box' disulfide loop, its broad-spectrum (notably Gram-negative) membrane-disrupting and DNA-hydrolysing mechanism, and its wound-healing and metabolic (esculentin-2CHa) members and engineered fragments are from the studies carded here; the discovery is Simmaco et al. (J Biol Chem, 1994). The absence of US approval or a drug record from Drugs@FDA, openFDA, FDA GSRS and ChEMBL was checked the same day. Grey Peptides sells nothing and links to no vendor.
Medical Disclaimer: This content is for educational and informational purposes only. It is not medical advice, and nothing here is an instruction to obtain or use any compound. Talk to a licensed clinician about your own situation.