Buforin
A toad-stomach antimicrobial peptide that kills microbes without bursting them — it slips inside and binds their DNA. A research peptide, not a drug
Buforin is an antimicrobial peptide family first found in the stomach of the Asian toad Bufo bufo gargarizans. Its parent, buforin I, is a 39-amino-acid peptide whose sequence is nearly identical to the front end of histone H2A — a DNA-packaging protein — which hints at how it works. A shorter, more potent 21-residue fragment, buforin II, became the star of the family because of a striking mechanism: unlike most antimicrobial peptides (such as magainin), which punch pores in the microbial membrane and burst the cell, buforin II slips across the membrane WITHOUT lysing it and kills the microbe from the inside by binding its DNA and RNA. That cell-penetrating, nucleic-acid-binding behaviour makes buforin interesting well beyond antibacterial use: a synthetic derivative, buforin IIb, kills cancer cells, and buforin peptides have been explored as cell-penetrating carriers and in antifungal, antiviral and materials applications. Buforin is a research peptide; it is not an approved medicine and has not been given to people as a treatment.
No established human dose Details ↓
Recommended Dosing
No established human dose
Buforin is a research antimicrobial peptide; it has never been given to people as a treatment. The work is in cells, microbes and materials, at experimental concentrations that do not carry over to people.
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What is it?
Buforin belongs to the large world of antimicrobial peptides, but it earned its reputation by breaking the usual rule. It was isolated from the stomach of the Asian toad Bufo bufo gargarizans: buforin I, a 39-residue peptide, turned out to be almost identical to the N-terminal region of histone H2A, one of the proteins that wrap DNA in the nucleus. A shorter 21-residue fragment of it, buforin II, is even more potent against a broad range of bacteria and fungi.
What made buforin II famous is how it kills. Most membrane-active antimicrobial peptides, like the frog peptide magainin, work by forming pores and rupturing the microbial membrane. Buforin II does not: in a direct comparison, it killed Escherichia coli without lysing the membrane, crossed into the cell, and accumulated inside, where it bound bacterial DNA and RNA far more strongly than magainin. The conclusion was that buforin II penetrates the membrane and then shuts down the cell's functions by binding its nucleic acids — a fundamentally different, non-lytic mechanism for a peptide that is structurally similar to the pore-formers (a linear amphipathic alpha-helix).
That cell-penetrating, DNA-binding behaviour opened other doors. A synthetic derivative, buforin IIb, acts as an anticancer peptide: in cervical-carcinoma (HeLa) cells it triggered apoptosis through endoplasmic-reticulum stress feeding into mitochondrial membrane permeabilization, with the cell-death pathway depending on stress kinases (JNK, p38). Because buforin peptides enter cells, they have also been studied as carriers: porphyrin-buforin conjugates delivered a photodynamic-therapy photosensitizer into bacteria and human cells, behaving like cell-penetrating peptides.
Buforin peptides are also a scaffold for anti-infective design. Chimeras joining the active motif of buforin II with that of bovine lactoferricin showed strong antifungal activity against drug-resistant Cryptococcus and Candida strains while sparing human fibroblasts, and were synergistic with fluconazole. And buforin I has been loaded into electrospun chitosan nanofibers as an antimicrobial food-packaging material that slowed spoilage of beef. A separate line of work even found buforin-1 can block neuronal SNARE-complex assembly, hinting at pharmacology beyond antimicrobial action.
Across all of this, buforin is a research peptide and a laboratory tool. No published study has given buforin to people as a treatment, it is approved nowhere, and material sold online under its name is an unregulated research chemical. Nothing here is a dose or a therapy; this page records what the published science says.
Mechanism of Action
Buforin is a histone-H2A-derived antimicrobial peptide. Its defining feature is a non-lytic mechanism: buforin II penetrates the microbial membrane without rupturing it and kills by binding DNA and RNA. This cell-penetrating behaviour also underlies its anticancer derivative (buforin IIb) and its use as a cargo-carrying peptide.
Histone-H2A origin
Buforin I matches the N-terminal region of histone H2A (a DNA-binding protein); buforin II is its more potent 21-residue fragment (PMID 9514864).
Cell penetration, not lysis
Enters cells without forming pores or lysing the membrane and binds DNA/RNA to kill — unlike pore-forming AMPs such as magainin (PMID 9514864).
Anticancer & delivery uses
Buforin IIb triggers ER-stress apoptosis in cancer cells, and buforin conjugates ferry cargo into cells as cell-penetrating peptides (PMIDs 25958204, 24456407).
Published Research
These are studies of buforin read from their PubMed records on November 7, 2026: the mechanism paper showing buforin II kills by penetrating the membrane and binding DNA/RNA; a study of the anticancer derivative buforin IIb; a study of buforin-1 and neuronal SNARE assembly; antifungal buforin-II chimeras; a cell-penetrating porphyrin-buforin photosensitizer; and a buforin-I antimicrobial food-packaging material. The evidence is in cells and materials; buforin has not been given to people as a treatment.
Buforin II kills by penetrating the membrane and binding DNA/RNA (not pore-forming)
Compared directly with the pore-forming peptide magainin 2, buforin II killed Escherichia coli WITHOUT lysing the membrane even well above its minimal inhibitory concentration; labeled buforin II penetrated the membrane and accumulated inside the cell, and it bound DNA and RNA far more strongly than magainin — indicating it kills by entering the cell and inhibiting nucleic-acid function, a non-lytic mechanism (the defining mechanistic study).
Buforin IIb (anticancer derivative) induces ER-stress apoptosis in cancer cells
The synthetic cell-penetrating anticancer peptide buforin IIb induced apoptosis in human cervical-carcinoma (HeLa) cells by up-regulating endoplasmic-reticulum stress proteins and driving mitochondrial membrane permeabilization through stress kinases (JNK, p38); ER-stress and calcium-chelation inhibitors rescued the cells — showing an ER-stress-mediated cell-death pathway (an in-vitro anticancer study).
Buforin-1 blocks neuronal SNARE-mediated membrane fusion
Buforin-1 inhibited assembly of the neuronal SNARE protein complex by directly binding the t-SNAREs syntaxin-1 and SNAP-25, thereby blocking SNARE-mediated membrane fusion in vitro and inhibiting SNARE-mediated exocytosis in PC-12 cells — a pharmacology distinct from its antimicrobial action, of possible interest for dysregulated neurotransmission (an in-vitro study).
Lactoferricin + buforin-II chimeras: antifungal against Cryptococcus
Chimeric peptides joining the minimal active motifs of bovine lactoferricin and buforin II showed strong antifungal activity against reference and clinical Cryptococcus strains, synergised with fluconazole, and left most human fibroblasts viable — identifying buforin-based chimeras as antifungal candidates (an in-vitro study).
Cell-penetrating porphyrin-buforin photosensitizer conjugates
Conjugating a photodynamic-therapy porphyrin photosensitizer to buforin (or magainin) let an otherwise inactive porphyrin efficiently photo-inactivate Gram-negative E. coli and also enter human fibroblasts — showing buforin can carry cargo into cells like a cell-penetrating peptide (an in-vitro study).
Buforin-I antimicrobial nanofibers for food packaging
Buforin I was encapsulated in electrospun chitosan/polyethylene-oxide nanofibers; the membranes showed antimicrobial inhibition exceeding a commercial antibiotic at high loading, and coating beef with them lowered microbial counts and slowed spoilage during cold storage — an applied antimicrobial-materials use (an in-vitro / materials study).
No Established Human Dose
Buforin is a research antimicrobial peptide; it has never been given to people as a treatment. The work is in cells, microbes and materials, at experimental concentrations 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 9514864, PMID 25958204, PMID 36551475.
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 Buforin 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 Buforin 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 Buforin, 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 Buforin stays intact once mixed.
How it is taken
Unknown: with no established human dose, there is no established way of taking Buforin. 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; a cationic peptide 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 Buforin. Results reported in the studies are under Published Research.
Source: half-life: PMID 9514864.
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 buforin to people; It is cell-penetrating and binds DNA/RNA, so effects on host cells (not only microbes) are an intrinsic consideration — chimeras are designed to spare human fibroblasts (PMID 36551475); A derivative (buforin IIb) is cytotoxic to cancer cells by design (PMID 25958204); selectivity for target over healthy cells is a key research question, not a settled safety profile; Material sold online as 'buforin' 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 Buforin. Treat a severe or unexpected reaction as a reason to stop and see a doctor.
Source: the Side Effects section below (“Buforin is a research peptide that has not been given to people as a drug, so there is no human safety profile; the points below reflect that research status and its biology”).
Interactions
Unknown: a PubMed search for human interaction studies of Buforin (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 Buforin 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 a drug: Drugs@FDA and the openFDA label endpoint hold no record, and FDA GSRS and ChEMBL hold no approved-drug record for buforin (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
Buforin is a research peptide that has not been given to people as a drug, so there is no human safety profile; the points below reflect that research status and its biology.
Contraindications & Cautions
Buforin has no approved use and no label. These points reflect its research status.
Legal Status
Buforin is a research antimicrobial peptide; it is not a drug and is not approved in any country.
Frequently Asked Questions
?What is buforin?
An antimicrobial peptide family from the stomach of the Asian toad Bufo bufo gargarizans. Buforin I is a 39-amino-acid histone-H2A-derived peptide; buforin II is a more potent 21-residue fragment (PMID 9514864).
?How is its mechanism unusual?
Unlike pore-forming antimicrobial peptides (e.g. magainin) that burst the cell membrane, buforin II penetrates the membrane without lysing it and kills by binding the microbe's DNA and RNA (PMID 9514864).
?Why is it studied for cancer and drug delivery?
Because it enters cells. A derivative, buforin IIb, kills cancer cells via ER-stress apoptosis (PMID 25958204), and buforin conjugates carry cargo into cells like cell-penetrating peptides (PMID 24456407).
?Is it approved or available to buy?
No. Buforin is not a medicine, has no FDA application or label, and is approved nowhere. Material sold online as buforin is an unregulated research chemical. Grey Peptides lists no sellers and recommends no source; this page records the published science.
References
- [mechanism] Park CB, et al. "Mechanism of action of the antimicrobial peptide buforin II: buforin II kills microorganisms by penetrating the cell membrane and inhibiting cellular functions." Biochem Biophys Res Commun, 1998;244(1):253-7. PMID: 9514864.
- [mechanism] Jang JH, et al. "Buforin IIb induces endoplasmic reticulum stress-mediated apoptosis in HeLa cells." Peptides, 2015;69:144-9. PMID: 25958204.
- [mechanism] Lee JG, et al. "Buforin-1 blocks neuronal SNARE-mediated membrane fusion by inhibiting SNARE complex assembly." Biochem Biophys Res Commun, 2019;514(1):105-111. PMID: 31027731.
- [mechanism] Carvajal SK, et al. "In Vitro Antifungal Activity of Chimeric Peptides Derived from Bovine Lactoferricin and Buforin II against Cryptococcus neoformans var. grubii." Antibiotics (Basel), 2022;11(12). PMID: 36551475.
- [mechanism] Dosselli R, et al. "Synthesis, spectroscopic, and photophysical characterization and photosensitizing activity toward prokaryotic and eukaryotic cells of porphyrin-magainin and -buforin conjugates." J Med Chem, 2014;57(4):1403-15. PMID: 24456407.
- [mechanism] Roshanak S, et al. "Fabrication and Characterization of Buforin I-Loaded Electrospun Chitosan/Polyethylene Oxide Nanofibrous Membranes with Antimicrobial Activity for Food Packing Applications." Polymers (Basel), 2025;17(4). PMID: 40006211.
- [other] Buforin was isolated from the stomach tissue of the Asian toad Bufo bufo gargarizans and named by Park, Kim and Kim (Biochem Biophys Res Commun, 1996): buforin I is a 39-residue peptide whose sequence matches 37 of the 39 N-terminal residues of histone H2A, and buforin II is a more potent 21-residue fragment derived from it. Its histone-H2A origin and family structure are described in the mechanism and other 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 buforin. It is a research antimicrobial/cell-penetrating peptide, not a drug; FDA GSRS and ChEMBL hold no approved-drug record for it.
Sources & Citations
The six studies carded above were read from their PubMed records on November 7, 2026. Buforin's histone-H2A origin from Bufo bufo gargarizans, its forms (buforin I/II/IIb), its non-lytic DNA/RNA-binding cell-penetrating mechanism versus pore-forming magainin, its anticancer derivative, its antifungal chimeras, its cell-penetrating delivery conjugates and antimicrobial materials are from the studies carded here; the discovery is Park, Kim & Kim (Biochem Biophys Res Commun, 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.