Clavanin
A histidine-rich antimicrobial peptide from a sea squirt — more active in acid and when it binds zinc, and a scaffold for anti-infective coatings. Research compounds, not drugs
Clavanin is an antimicrobial peptide from the blood cells of a sea squirt, the marine tunicate Styela clava. It is a short, cationic, amphipathic alpha-helix, and its defining feature is that it is rich in the amino acid histidine. That histidine content gives clavanin two unusual properties. First, its activity is pH-dependent: because histidine picks up positive charge as the surroundings turn acidic, clavanin becomes more potent in acidic conditions like those at a site of infection. Second, the histidines let clavanin bind metal ions such as zinc and copper, and zinc binding can sharply increase its antibacterial activity. Like other membrane-active peptides clavanin binds and disrupts microbial membranes, and it is broadly active against bacteria and fungi. Beyond direct killing, engineered versions such as clavanin-MO add immune-modulating and wound-healing activity, and clavanin A has been built into antimicrobial coatings for medical devices such as catheters and surgical membranes. Clavanins are research 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
Clavanins are sea-squirt research peptides; none has been given to people as a treatment. The work is in model membranes, bacteria, fungi, human cells and biomaterials, often with engineered analogs, at experimental amounts that do not carry over to people.
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What is it?
Sea squirts — marine tunicates — defend themselves with antimicrobial peptides in their blood cells, and the clavanins, first described in 1997 from Styela clava, are the best known. Each is a short peptide of twenty-three residues that folds into a cationic, amphipathic alpha-helix, and the family (clavanin A, B, C and D) is unusually rich in histidine. That histidine content is the key to what makes clavanin distinctive, because histidine is the one common amino acid whose charge changes over the physiological pH range.
The first consequence is pH-sensitivity: as conditions turn acidic — as they often do at sites of infection or inside immune cells — clavanin's histidines gain positive charge and the peptide becomes more strongly cationic and more active. The second consequence is metal binding. The histidines, together with an N-terminal copper/nickel-binding (ATCUN) motif, let clavanin chelate zinc and copper ions, and this is not just incidental: zinc binding has been shown to increase clavanin A's antibacterial activity many-fold. Molecular-dynamics and bioinorganic studies have worked out the details — zinc stabilises clavanin's helix and strengthens its interaction with Gram-negative bacterial membranes, and even small differences in the non-metal-binding part of the sequence drastically change the metal coordination and antimicrobial efficiency, a 'butterfly effect' in the peptide's chemistry.
This metal-binding, pH-tunable chemistry makes clavanin a favourite scaffold for designed 'metallo-antimicrobial-peptides'. Recent work redesigned clavanin C into proteolytically stable mirror-image (all-D) and retro-inverso peptidomimetics that keep both their copper/zinc binding and their antimicrobial activity, with strong potency against MRSA and no mammalian-cell toxicity — a general strategy for turning fragile peptides into durable drug candidates.
Clavanin's core mechanism is membrane disruption, and this has been exploited in biomaterials as much as in free-peptide studies. Clavanin A immobilised on iron-oxide nanoparticles reduced bacterial attachment to central-venous-catheter tubing and, combined with mild heating, cleared established biofilm, and clavanin-A-coated amniotic membranes resisted biofilm formation by eye-surface fungal pathogens while staying biocompatible. Engineered derivatives broaden the repertoire further: clavanin-MO adds immunomodulatory activity, and in human skin-cell and ex-vivo skin models clavanin A promoted fibroblast proliferation, migration and wound closure. These are laboratory and tissue-model studies, not treatments given to people.
Through all of this, clavanins remain research peptides. No published study has given a clavanin 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
Clavanin is a 23-residue histidine-rich, cationic, amphipathic alpha-helical sea-squirt antimicrobial peptide that binds and disrupts microbial membranes (broad-spectrum antibacterial, antifungal). Its histidines make it more active at acidic pH and let it bind zinc and copper, with zinc markedly boosting activity; derivatives add immunomodulation and it is used in device coatings.
Sea-squirt host defense
A 23-residue histidine-rich cationic amphipathic helix from the hemocytes of the tunicate Styela clava; family members clavanin A, B, C and D (PMIDs 34382773, 30908921).
pH-dependence and metal binding
Histidines give pH-tunable activity (stronger in acid) and bind zinc/copper via a histidine cluster and N-terminal ATCUN motif; zinc markedly increases activity (PMIDs 42350299, 30908921).
Membrane disruption, coatings, regeneration
Permeabilises microbial membranes; used in antimicrobial device/membrane coatings, and derivatives (clavanin-MO) add immunomodulation and wound healing (PMIDs 29751343, 38999961).
Published Research
These are studies of clavanins read from their PubMed records on November 7, 2026: redesign of clavanin C into stable metal-binding peptidomimetics; the skin-regenerative potential of clavanin A and clavanin-MO; the coordination chemistry of clavanin zinc/copper complexes; molecular-dynamics study of how zinc changes clavanin A's structure and membrane interaction; and two biomaterial studies using clavanin A coatings against bacterial and fungal biofilms. The evidence is in model membranes, bacteria, human cells and biomaterials; clavanins have not been given to people as a treatment.
Stable metal-binding clavanin C peptidomimetics
Redesigning clavanin C by chirality inversion (an all-D peptide and a retro-inverso variant) gave proteolytically stable mimetics that kept their copper and zinc binding (via the N-terminal ATCUN motif and a histidine cluster) and their antimicrobial activity, with strong potency against MRSA and no mammalian-cell toxicity — a general route to durable metallo-antimicrobial peptides (an in-vitro study).
Clavanin A and clavanin-MO promote skin regeneration
Clavanin A and the engineered clavanin-MO (alongside mastoparan-MO) were non-toxic to human dermal fibroblasts at their working doses and promoted fibroblast proliferation and migration while switching on skin-regeneration genes; clavanin A accelerated wound closure in an ex-vivo human-skin model — evidence of a pro-regenerative role beyond antimicrobial activity (an in-vitro/ex-vivo study).
Coordination chemistry of clavanin zinc/copper complexes
A bioinorganic study of clavanins from tunicate hemocytes showed that a minor difference in the non-metal-binding part of the sequence drastically changes the zinc and copper coordination environment and the antimicrobial efficiency — a 'butterfly effect' linking small sequence changes to large activity differences in these histidine-rich peptides (an in-vitro study).
How zinc enhances clavanin A's membrane activity (simulation)
All-atom molecular-dynamics simulations showed that zinc binding stabilises clavanin A's helix in its binding region and makes its C-terminus interact more strongly and favourably with a model Gram-negative bacterial membrane, promoting insertion — a structural explanation for why zinc greatly increases clavanin A's antibacterial activity (a computational study).
Clavanin A nanoparticle coating clears catheter biofilm
Clavanin A immobilised on iron-oxide/silane core-shell nanoparticles and attached to central-venous-catheter tubing cut Gram-negative bacterial attachment by up to ninety percent by disrupting bacterial membranes, and a brief heat treatment of already-formed biofilm reduced attached-bacteria viability substantially — an antimicrobial-device study.
Clavanin A-coated amniotic membrane resists fungal biofilm
Coating an amniotic-membrane surgical scaffold with clavanin A gave antifungal activity against eye-surface pathogens (Candida, Aspergillus, Fusarium, Alternaria) and significantly reduced biofilm formation versus uncoated membrane, while remaining biocompatible and supporting cell attachment — a biomaterial study for eye infection control.
No Established Human Dose
Clavanins are sea-squirt research peptides; none has been given to people as a treatment. The work is in model membranes, bacteria, fungi, human cells and biomaterials, 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 42350299, PMID 38999961, PMID 29751343.
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 Clavanin 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 Clavanin 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 Clavanin, 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 Clavanin stays intact once mixed.
How it is taken
Unknown: with no established human dose, there is no established way of taking Clavanin. 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 peptide, chirality-inverted mimetics engineered for protease stability. After about five half-lives almost none is left.
When effects appear: unknown; no source on this page gives a time to effect for Clavanin. Results reported in the studies are under Published Research.
Source: half-life: PMID 42350299.
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 clavanin to people; As membrane-active peptides, cytotoxicity and hemolysis to host cells are the usual concern; clavanin A and stabilised clavanin C mimetics are reported non-toxic to mammalian cells in the lab (PMIDs 42350299, 38999961) — research findings, not human data; Clavanin binds zinc and copper, which changes its activity; metal interactions would need study in any therapeutic development (PMID 34382773); Material sold online as a 'clavanin' 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 Clavanin. Treat a severe or unexpected reaction as a reason to stop and see a doctor.
Source: the Side Effects section below (“Clavanins 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 Clavanin (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 Clavanin 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 clavanin 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
Clavanins 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
Clavanins have no approved use and no label. These points reflect their research status.
Legal Status
Clavanins are tunicate antimicrobial peptides used as research compounds; they are not drugs and are not approved in any country.
Frequently Asked Questions
?What is clavanin?
An antimicrobial peptide from the blood cells of a sea squirt (the tunicate Styela clava). It is a 23-amino-acid, histidine-rich, cationic amphipathic helix, first described in 1997; the family includes clavanin A, B, C and D (PMID 34382773).
?Why does histidine matter?
Histidine makes clavanin pH-dependent — more active in acidic conditions like infection sites — and lets it bind zinc and copper; zinc binding can increase its antibacterial activity many-fold (PMIDs 42350299, 30908921).
?What is it studied for?
As a broad-spectrum antibacterial and antifungal, a scaffold for stable metal-binding antimicrobial peptides, device and membrane coatings, and — as clavanin-MO — immunomodulation and wound healing (PMIDs 29751343, 38999961).
?Is it approved or available to buy?
No. Clavanins are not medicines, have no FDA application or label, and are approved nowhere. Material sold online as a clavanin is an unregulated research chemical. Grey Peptides lists no sellers and recommends no source; this page records the published science.
References
- [mechanism] Gawłowski J, et al. "Stereochemical Control of Cu(II) and Zn(II) Binding in Clavanin C Peptidomimetics." Inorg Chem, 2026;65(27):15845-15854. PMID: 42350299.
- [mechanism] Alencar-Silva T, et al. "Screening of the Skin-Regenerative Potential of Antimicrobial Peptides: Clavanin A, Clavanin-MO, and Mastoparan-MO." Int J Mol Sci, 2024;25(13). PMID: 38999961.
- [mechanism] Miller A, et al. "Chemical "Butterfly Effect" Explaining the Coordination Chemistry and Antimicrobial Properties of Clavanin Complexes." Inorg Chem, 2021;60(17):12730-12734. PMID: 34382773.
- [mechanism] Duay SS, et al. "Molecular Dynamics Investigation into the Effect of Zinc(II) on the Structure and Membrane Interactions of the Antimicrobial Peptide Clavanin A." J Phys Chem B, 2019;123(15):3163-3176. PMID: 30908921.
- [mechanism] Ribeiro KL, et al. "Clavanin A-bioconjugated Fe(3)O(4)/Silane core-shell nanoparticles for thermal ablation of bacterial biofilms." Colloids Surf B Biointerfaces, 2018;169:72-81. PMID: 29751343.
- [mechanism] Mandal SM, et al. "A self-assembled clavanin A-coated amniotic membrane scaffold for the prevention of biofilm formation by ocular surface fungal pathogens." Biofouling, 2017;33(10):881-891. PMID: 29047302.
- [other] Clavanins are histidine-rich antimicrobial peptides from the hemocytes (blood cells) of the marine tunicate (sea squirt) Styela clava, first described by Lee, Lehrer and colleagues (FEBS Lett, 1997). The family includes clavanin A, B, C and D; their structure, metal binding 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 clavanin peptides. They are tunicate 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. Clavanin's sea-squirt (Styela clava) origin, its 23-residue histidine-rich amphipathic helical structure, its pH-dependent activity and zinc/copper binding (via a histidine cluster and N-terminal ATCUN motif), its membrane-disrupting mechanism, and its engineered analogs (clavanin-MO), biomaterial coatings and wound-healing activity are from the studies carded here; the discovery is Lee, Lehrer et al. (FEBS Lett, 1997). 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.