Temporin
A family of tiny frog-skin antimicrobial peptides — membrane-disrupting, and templates for new antibacterial and anticancer designs. Research compounds, not drugs
Temporins are one of the largest and smallest families of antimicrobial peptides at once: smallest because each one is only about ten to fourteen amino acids — among the shortest natural antimicrobial peptides known — and largest because frogs make dozens of variants. They were first found in the skin of the European red frog, Rana temporaria, and have since turned up across many frog species (temporin A, B, L, SHa, GHa and more). Like other membrane-active peptides they are hydrophobic, amphipathic helices that disrupt microbial membranes, but temporins are unusual in carrying little or no net positive charge, and most are classically active against Gram-positive bacteria (temporin L is broader). Because they are so short and modular, temporins are a favourite scaffold for peptide engineering: researchers tune them into broader-spectrum antibacterials, antifungals, antibiofilm agents, anticancer peptides and immune-modulators. Temporins 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
Temporins are frog-skin research peptides; none has been given to people as a treatment. The work is in cells and animals, often with engineered analogs, at experimental amounts that do not carry over to people.
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What is it?
Frog skin is a rich source of antimicrobial peptides, and temporins are one of its best-known families. First described from the European red frog (Rana temporaria), temporins are very short peptides — typically ten to fourteen residues — that fold into hydrophobic, amphipathic alpha-helices. They are unusual among antimicrobial peptides for carrying little net positive charge, and the natural members are usually amidated at the C-terminus, a feature that matters for their activity. Dozens of temporins are now known across frog species, named by species and letter (temporin A, B, L, SHa, GHa, 1CEa, and many others).
Their core mechanism is membrane disruption: the amphipathic helix inserts into and permeabilises the microbial membrane. Most temporins are classically active against Gram-positive bacteria, with some (notably temporin L) reaching Gram-negatives and fungi. Newly discovered temporins keep expanding the family — temporin-PMb, isolated from the skin secretion of an Atlantic-Forest frog, was active against a panel including methicillin-resistant Staphylococcus aureus and Acinetobacter baumannii, and the C-terminal amide was essential for its activity — illustrating both the family's natural diversity and the structure-activity rules that govern it.
Because they are short and modular, temporins are heavily used as engineering scaffolds. Analogs of temporin A modified at single positions were tuned for antibacterial and antiproliferative activity and improved stability; retro-analogs of a temporin-SHa-derived peptide, with lysine additions and antibiotic conjugation, were optimised to balance antibacterial, antifungal and anticancer potency against hemolytic toxicity; and temporin-1CEa, a frog anticancer peptide, was built into reduction-responsive peptide-drug conjugates that killed cancer cells by combining membrane damage with apoptosis. These studies show both the promise and the central design challenge of temporins — getting selective potency without harming host cells (hemolysis and cytotoxicity).
Temporins also have effects beyond direct killing. A temporin-GHa-derived peptide suppressed Cutibacterium acnes, broke up its biofilm and calmed inflammation in a rat acne model by acting on the TLR2/NF-kB/MAPK pathway, and temporin-1LS from the dark-spotted frog combined direct antibacterial action with immunomodulation — boosting macrophage chemotaxis, phagocytosis and respiratory burst and improving survival in a frog infection model. These point to temporins as 'dual-defense' molecules of interest as anti-infective and immune-modulating leads.
Across all of this, temporins are research antimicrobial peptides. No published study has given a temporin 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
Temporins are short, amidated, amphipathic alpha-helical frog-skin antimicrobial peptides that work mainly by disrupting microbial membranes (classically Gram-positive; temporin L broader). Beyond direct killing, members show antibiofilm, anticancer and immunomodulatory activity, and the short scaffold is widely engineered.
Frog-skin host defense
Short (~10-14 aa) amidated amphipathic helices secreted by frog skin; a large, diverse family first found in Rana temporaria (PMIDs 39427973, 42039190).
Membrane disruption
Insert into and permeabilise microbial membranes, mostly Gram-positive bacteria, with temporin L and engineered analogs reaching more targets (PMID 40318277).
Antibiofilm / anticancer / immunomodulation
Members break up biofilms, kill cancer cells, and modulate macrophage function — a 'dual-defense' profile exploited in analog design (PMIDs 39753038, 42039190).
Published Research
These are studies of temporins read from their PubMed records on November 7, 2026: structure-activity work on temporin A analogues; a temporin-1CEa anticancer peptide-drug conjugate; temporin-SHa retro-analog design; a newly discovered frog temporin (temporin-PMb); and animal studies of a temporin-GHa-derived anti-acne peptide and the dual antimicrobial/immunomodulatory temporin-1LS. The evidence is in cells and animals; temporins have not been given to people as a treatment.
Temporin A analogues: structure-activity for antibacterial and antiproliferative effect
Temporin A analogues modified at positions 1 and 10 (e.g. substituting the N-terminal phenylalanine or the position-10 serine) were synthesised and tested; a serine-to-tyrosine change improved the antiproliferative effect while keeping antibacterial activity, and a fluorinated-phenylalanine analog was the most effective antibacterial — mapping how small changes tune temporin potency, toxicity and stability (an in-vitro SAR study).
Temporin-1CEa anticancer peptide-drug conjugates
The frog anticancer peptide temporin-1CEa (from Rana chensinensis) was truncated and cysteine-scanned to yield more active derivatives, and the best was conjugated via a reduction-responsive linker to the chemotherapeutic podophyllotoxin; the conjugate killed cancer cells through both membrane damage and apoptosis, with lower toxicity to normal endothelial cells than free drug (an in-vitro anticancer-design study).
Temporin-SHa retro-analogs: balancing potency and toxicity
Retro-analogs of a temporin-SHa-derived peptide, with lysine addition/substitution and levofloxacin conjugation, were designed to enhance antibacterial, antifungal and anticancer activity; lysine changes reduced hemolysis (safer peptides) while N-terminal antibiotic conjugation raised potency at some cost to selectivity — a structure-activity map for temporin engineering (an in-vitro study).
A new frog-skin temporin (temporin-PMb) with antibacterial and anticancer activity
A novel temporin, temporin-PMb, was isolated from the skin secretion of the frog Lithobates palmipes; it was active against Gram-negative and Gram-positive bacteria including MRSA and Acinetobacter baumannii and cytotoxic to cancer cells, and the C-terminal amide was essential — demonstrating both the family's natural diversity and its structure-activity rules (an in-vitro study).
Temporin-GHa-derived peptide treats acne and inflammation (rats)
A temporin-GHa-derived peptide killed Cutibacterium acnes by disrupting its membrane, inhibited and eliminated its biofilm, and in a rat ear model reduced bacterial colonisation and skin inflammation by down-regulating the TLR2/NF-kB/MAPK pathway and inflammatory cytokines — a preclinical anti-acne result.
Temporin-1LS: dual antimicrobial and immunomodulatory peptide (frog model)
Temporin-1LS from the dark-spotted frog combined direct antibacterial activity with immunomodulation — stimulating macrophage chemotaxis, phagocytosis and respiratory burst in a dose-dependent way — and, though weakly active in vitro against one pathogen, improved survival in a frog infection model, pointing to a 'dual-defense' anti-infective scaffold (a preclinical study).
No Established Human Dose
Temporins are frog-skin research peptides; none has been given to people as a treatment. The work is in cells and animals, often with engineered analogs, 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 40284394, PMID 40318277, PMID 42039190.
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 Temporin 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 Temporin 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 Temporin, 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 Temporin stays intact once mixed.
How it is taken
Unknown: with no established human dose, there is no established way of taking Temporin. 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 not established for humans; short cationic/hydrophobic peptides subject to proteolysis. After about five half-lives almost none is left.
When effects appear: unknown; no source on this page gives a time to effect for Temporin. Results reported in the studies are under Published Research.
Source: half-life: PMID 40284394.
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 a temporin to people; As membrane-active peptides, hemolysis and cytotoxicity to host cells are the central safety concern; analog design explicitly aims to reduce them (PMIDs 39766603, 39753038) — a design issue, not human data; Some temporins and derivatives are cytotoxic to cancer cells by design (PMID 39753038); selectivity for target over healthy cells is an open research question; Material sold online as a 'temporin' 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 Temporin. Treat a severe or unexpected reaction as a reason to stop and see a doctor.
Source: the Side Effects section below (“Temporins 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 Temporin (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 Temporin 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 temporin 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
Temporins 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
Temporins have no approved use and no label. These points reflect their research status.
Legal Status
Temporins 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 temporins?
A family of very short (~10-14 amino acid) antimicrobial peptides from frog skin, first found in the European red frog Rana temporaria. They are among the shortest natural antimicrobial peptides (PMID 39427973).
?How do they work?
They are amphipathic helices that disrupt microbial membranes, classically killing Gram-positive bacteria; temporin L and engineered analogs reach more targets (PMID 40318277).
?What are they studied for?
As antibacterial, antifungal, antibiofilm, anticancer and immunomodulatory leads, and as short scaffolds for peptide engineering (PMIDs 39766603, 39753038, 42039190).
?Are they approved or available to buy?
No. Temporins are not medicines, have no FDA application or label, and are approved nowhere. Material sold online as a temporin is an unregulated research chemical. Grey Peptides lists no sellers and recommends no source; this page records the published science.
References
- [mechanism] Dimitrova D, et al. "New Temporin A Analogues Modified in Positions 1 and 10-Synthesis and Biological Studies." Pharmaceutics, 2025;17(4). PMID: 40284394.
- [mechanism] Han Z, et al. "Design, synthesis and activity evaluation of reduction-responsive anticancer peptide temporin-1CEa drug conjugates." Bioorg Chem, 2025;154:108103. PMID: 39753038.
- [mechanism] Nazir S, et al. "Synthesis of Temporin-SHa Retro Analogs with Lysine Addition/Substitution and Antibiotic Conjugation to Enhance Antibacterial, Antifungal, and Anticancer Activities." Antibiotics (Basel), 2024;13(12). PMID: 39766603.
- [mechanism] Barbosa GG, et al. "A new temporin with antibacterial activity and cytotoxicity from the skin secretion of Lithobates palmipes (Spix, 1824) (Amphibia: Ranidae) from Brazilian Atlantic Forest." Comp Biochem Physiol B Biochem Mol Biol, 2025;275:111041. PMID: 39427973.
- [animal] Zhao T, et al. "Temporin-GHa derived peptide shows inhibitory efficacy against Cutibacterium acnes and alleviates inflammatory reactions in acne vulgaris." Int Immunopharmacol, 2025;157:114756. PMID: 40318277.
- [animal] Ma L, et al. "Dual-defense functionality of temporin-1LS from dark-spotted frogs (Pelophylax nigromaculatus): antimicrobial activity and immunomodulatory effects via macrophage activation." Front Immunol, 2026;17:1829966. PMID: 42039190.
- [other] Temporins are a family of short antimicrobial peptides from the skin of frogs (Ranidae), first described from the European red frog Rana temporaria by Simmaco and colleagues (Eur J Biochem, 1996); dozens of members have since been found across frog species (temporin A, B, L, SHa, GHa, 1CEa and others). Their frog-skin origin and family structure 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 temporin 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 temporin family's frog-skin origin, short amidated amphipathic structure, membrane-disrupting (mostly Gram-positive) activity, and its antibiofilm, anticancer and immunomodulatory members and engineered analogs are from the studies carded here; the discovery is Simmaco et al. (Eur J Biochem, 1996). 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.