Tachyplesin
A rigid, disulfide-stabilised antimicrobial peptide from horseshoe-crab blood — broad-spectrum, membrane-disrupting, and a notable anticancer lead. Research compounds, not drugs
Tachyplesin is one of the classic antimicrobial peptides, isolated in the late 1980s from the blood cells (hemocytes) of the Japanese horseshoe crab. It is small — about seventeen amino acids — but unusually rigid: two disulfide bonds lock it into a hairpin-shaped beta structure, and its end is amidated. That compact, highly cationic shape lets tachyplesin bind and disrupt microbial membranes, and it is broadly active against Gram-positive and Gram-negative bacteria, fungi and some viruses, as well as binding bacterial endotoxin (LPS). There are a few natural variants — tachyplesin I, II and III — and a close relative, polyphemusin, from the American horseshoe crab. Beyond killing microbes, tachyplesin has drawn major interest as an anticancer and anti-inflammatory peptide, and because the natural disulfide version is costly to make, much of the research uses engineered forms — linear analogs, backbone-cyclised versions and gene- or nanoparticle-delivered constructs. Tachyplesins 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
Tachyplesins are horseshoe-crab research peptides; none has been given to people as a treatment. The work is in bacteria, cultured cells and animals, often with engineered, cyclised or gene-delivered forms, at experimental amounts that do not carry over to people.
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What is it?
Horseshoe crabs are famous in biomedicine for the clotting test made from their blood, but their hemocytes also carry potent antimicrobial peptides, and tachyplesin is the best known. Isolated from Tachypleus tridentatus in 1988, it is a short peptide of about seventeen residues that folds into a rigid beta-hairpin, stapled by two disulfide bonds and capped by a C-terminal amide. This makes it stiffer and more structurally defined than the floppy, helix-forming peptides of frog skin, and that rigidity, together with a strong positive charge, is central to how it works.
Tachyplesin's core mechanism is membrane disruption: the cationic hairpin binds the negatively charged surface of microbial membranes and permeabilises them. It is broadly active — against Gram-positive and Gram-negative bacteria, fungi and some viruses — and it also binds bacterial lipopolysaccharide (LPS, endotoxin), which underlies some of its anti-inflammatory effects. Natural variants tachyplesin I, II and III differ by only a few residues, and the American horseshoe crab makes a close relative called polyphemusin. Remarkably, a peptide with over fifty percent similarity to tachyplesin was recently found in spider venom, extending the family beyond horseshoe crabs.
Because the disulfide-bonded natural peptide is expensive and fiddly to produce, much of the modern work re-engineers tachyplesin. Linear analogs that delete the cysteines (and sometimes arginines) keep antibacterial potency while simplifying synthesis, and one such analog also interfered with bacterial quorum sensing — the chemical signalling bacteria use to coordinate virulence. Tachyplesin II has been built into wound-dressing hydrogels that speed healing of infected wounds, and tachyplesin III calms airway inflammation driven by respiratory bacteria by acting on inflammatory signalling.
Tachyplesin's most striking second life is in cancer research. Like many membrane-active peptides it kills tumour cells, but its rigidity has made it a favourite scaffold for stable anticancer designs: a backbone-cyclised tachyplesin I killed drug-sensitive, drug-tolerant and drug-resistant melanoma cells by a fast membrane-permeabilising mechanism without the cells evolving resistance, and improved survival when combined with a targeted drug in mice, while gene- and nanoparticle-delivered tachyplesin constructs suppressed breast and other tumours and stimulated anti-tumour immunity in animal models. These are laboratory and animal studies, not treatments given to people.
Through all of this, tachyplesins remain research peptides. No published study has given a tachyplesin 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
Tachyplesin is a small, highly cationic horseshoe-crab antimicrobial peptide locked into a rigid beta-hairpin by two disulfide bonds. It binds and disrupts microbial membranes (broad-spectrum antibacterial, antifungal, antiviral) and binds endotoxin (LPS); it also kills cancer cells and damps inflammation, and its rigid scaffold is widely engineered.
Horseshoe-crab host defense
A ~17-residue cationic beta-hairpin stabilised by two disulfide bonds, from Tachypleus tridentatus hemocytes; variants I/II/III and the relative polyphemusin (PMIDs 41071843, 39560721).
Membrane disruption + LPS binding
Binds anionic microbial membranes and permeabilises them (bacteria, fungi, some viruses) and binds endotoxin — broad antimicrobial and anti-inflammatory activity (PMIDs 39770850, 39560721).
Anticancer scaffold
Kills tumour cells by fast membrane permeabilisation; cyclic and gene/nanoparticle-delivered tachyplesins suppress melanoma and breast cancer and stimulate anti-tumour immunity in animals (PMIDs 39032840, 38691208).
Published Research
These are studies of tachyplesins read from their PubMed records on November 7, 2026: a simplified linear tachyplesin analog with antibacterial and quorum-sensing-interfering activity; a tachyplesin II wound-healing hydrogel and a tachyplesin-family spider peptide with antifungal activity (both in animals); tachyplesin III calming airway inflammation in lung epithelial cells; and two anticancer studies (a cyclic tachyplesin I against drug-resistant melanoma, and gene-delivered tachyplesin against breast cancer, both with mouse work). The evidence is in bacteria, cells and animals; tachyplesins have not been given to people as a treatment.
A simplified linear tachyplesin analog with antibacterial and anti-virulence activity
Synthetic analogs of tachyplesin I with the cysteines (and, in one, arginines) deleted kept potent antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa while being simpler to make; the cysteine- and arginine-deleted analog disrupted membranes and also bound bacterial quorum-sensing regulators and down-regulated virulence genes — a dual bactericidal and anti-virulence profile (an in-vitro study).
Tachyplesin II wound-healing hydrogel for infected wounds (rats)
Tachyplesin II incorporated into a methacrylated-gelatine hydrogel gave the dressing antibacterial and antioxidant activity with good biocompatibility and self-healing properties, and in a rat infected-wound model it reduced inflammation, boosted collagen and accelerated healing — a preclinical wound-dressing result.
A tachyplesin-family spider peptide with antifungal activity (mice)
A peptide sharing over half its sequence with tachyplesins was found in the venom of a Chinese tarantula, extending the family to spiders; oxidatively folded, it was potently antifungal against Cryptococcus by disrupting the cell membrane, had low hemolysis and showed antifungal and anti-inflammatory activity in a mouse model — a preclinical study.
Tachyplesin III calms airway inflammation from a respiratory pathogen
In human lung epithelial cells stimulated with nontypeable Haemophilus influenzae (a driver of COPD exacerbations), tachyplesin III reduced pro-inflammatory mediators and inflammasome signalling without toxicity, pointing to an anti-inflammatory role alongside its antimicrobial activity (an in-vitro study).
Cyclic tachyplesin I kills drug-resistant melanoma (mice)
A backbone-cyclised tachyplesin I rapidly permeabilised and killed melanoma cells that were sensitive, tolerant or resistant to the targeted drug dabrafenib, without the cells evolving resistance or changing their membrane lipids; combined with dabrafenib in mice it reduced metastasis and improved survival — a preclinical anticancer result.
Gene-delivered tachyplesin against breast cancer (mice)
A plasmid encoding tachyplesin (pDNA-tachyplesin) suppressed the proliferation of breast-cancer cells and, in tumour-bearing mice, stimulated anti-tumour immune-cell populations and up-regulated apoptosis-related signalling without evident toxicity — an early gene-delivered anticancer study.
No Established Human Dose
Tachyplesins are horseshoe-crab research peptides; none has been given to people as a treatment. The work is in bacteria, cultured cells and animals, often with engineered, cyclised or gene-delivered forms, 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 41071843, PMID 39032840, PMID 38691208.
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 Tachyplesin 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 Tachyplesin 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 Tachyplesin, 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 Tachyplesin stays intact once mixed.
How it is taken
Unknown: with no established human dose, there is no established way of taking Tachyplesin. 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 disulfide-stabilised peptide is more protease-resistant than linear AMPs. After about five half-lives almost none is left.
When effects appear: unknown; no source on this page gives a time to effect for Tachyplesin. Results reported in the studies are under Published Research.
Source: half-life: PMID 39032840.
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 tachyplesin to people; As membrane-active peptides, hemolysis and cytotoxicity to host cells are the central safety concern; analog and spider-homolog design explicitly aims for low hemolysis (PMIDs 39770850, 41071843) — a design issue, not human data; Tachyplesin and its cyclic/engineered forms are cytotoxic to cancer cells by design (PMIDs 39032840, 38691208); selectivity for tumour over healthy cells is an open research question; Material sold online as a 'tachyplesin' 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 Tachyplesin. Treat a severe or unexpected reaction as a reason to stop and see a doctor.
Source: the Side Effects section below (“Tachyplesins 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 Tachyplesin (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 Tachyplesin 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 tachyplesin 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
Tachyplesins 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
Tachyplesins have no approved use and no label. These points reflect their research status.
Legal Status
Tachyplesins are horseshoe-crab antimicrobial peptides used as research compounds; they are not drugs and are not approved in any country.
Frequently Asked Questions
?What is tachyplesin?
An antimicrobial peptide from the blood cells of the horseshoe crab (Tachypleus tridentatus), first isolated in 1988. It is a small (~17 amino acid) cationic peptide held in a rigid beta-hairpin by two disulfide bonds; variants include tachyplesin I, II and III (PMID 41071843).
?How does it work?
It binds and disrupts microbial membranes and binds bacterial endotoxin (LPS), giving broad-spectrum antibacterial, antifungal and antiviral activity plus anti-inflammatory effects (PMIDs 39770850, 39560721).
?What is it studied for?
As a broad-spectrum antimicrobial, a wound-healing agent, an anti-inflammatory, and especially as an anticancer scaffold — cyclic and gene-delivered tachyplesins kill tumour cells and stimulate anti-tumour immunity in animals (PMIDs 39032840, 38691208).
?Is it approved or available to buy?
No. Tachyplesins are not medicines, have no FDA application or label, and are approved nowhere. Material sold online as a tachyplesin is an unregulated research chemical. Grey Peptides lists no sellers and recommends no source; this page records the published science.
References
- [mechanism] Santajit S, et al. "Antimicrobial and quorum sensing interference of a cysteine- and arginine-deleted linear Tachyplesin analog (CRDT) against Staphylococcus aureus and Pseudomonas aeruginosa." PLoS One, 2025;20(10):e0334547. PMID: 41071843.
- [animal] Wu J, et al. "Construction of a methacrylated gelatine composite hydrogel based on tachyplesin II and its application in the repair of infected wounds." Colloids Surf B Biointerfaces, 2025;250:114575. PMID: 39985891.
- [animal] Michira BB, et al. "A Tachyplesin Antimicrobial Peptide from Theraphosidae Spiders with Potent Antifungal Activity Against Cryptococcus neoformans." Microorganisms, 2024;12(12). PMID: 39770850.
- [mechanism] Jantaruk P, et al. "Potential role of the antimicrobial peptide Tachyplesin III in regulating nontypeable Haemophilus influenzae-induced inflammation in airway epithelial cells." Arch Microbiol, 2024;206(12):471. PMID: 39560721.
- [animal] Benfield AH, et al. "Cyclic tachyplesin I kills proliferative, non-proliferative and drug-resistant melanoma cells without inducing resistance." Pharmacol Res, 2024;207:107298. PMID: 39032840.
- [animal] Mahmoudi-Filabadi F, et al. "pDNA-tachyplesin treatment stimulates the immune system and increases the probability of apoptosis in MC4-L2 tumor cells." Amino Acids, 2024;56(1):34. PMID: 38691208.
- [other] Tachyplesin is an antimicrobial peptide from the hemocytes (blood cells) of the horseshoe crab Tachypleus tridentatus, first isolated and chemically characterised by Nakamura and colleagues (J Biol Chem, 1988). It is a rigid beta-hairpin held by two disulfide bonds; related peptides include tachyplesin I, II and III and the American-horseshoe-crab homolog polyphemusin. Its 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 tachyplesin peptides. They are horseshoe-crab research antimicrobial/anticancer 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. Tachyplesin's horseshoe-crab-hemocyte origin, its rigid two-disulfide beta-hairpin structure, its membrane-disrupting and LPS-binding mechanism, its variants (I/II/III) and relatives (polyphemusin, a spider homolog), and its anti-inflammatory and anticancer activity and engineered forms are from the studies carded here; the discovery is Nakamura et al. (J Biol Chem, 1988). 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.