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Antimicrobial peptide

Indolicidin

Indolicidin is a 13-residue cathelicidin antimicrobial peptide from bovine neutrophils, unusually rich in tryptophan and proline.

By The Peptides Codex Editorial TeamIndividual review date not recorded

Page data last changed: . Chemistry registry snapshot: . Registry refreshes and identity assessments are separate from scientific content review.

Length
13 aa
Class
Antimicrobial peptide
Function
Tryptophan-rich host-defense peptide (research)
Context
Antimicrobial-peptide research (not an approved drug)

One of the smallest natural AMPs — famously tryptophan-rich, active against bacteria, fungi and even HIV in vitro.

Part of the Foundational & therapeutic peptides cluster

Overview

Indolicidin is a 13-residue cathelicidin antimicrobial peptide from bovine neutrophils, unusually rich in tryptophan and proline. It is one of the shortest natural AMPs and is studied for membrane activity and DNA-binding effects against bacteria, fungi and viruses. It is a research peptide, not an approved drug.

Source & context

Biological / chemical source: Bovine neutrophils (cathelicidin family)

Primary research or clinical context: Antimicrobial-peptide research (not an approved drug)

A tryptophan-rich outlier

Indolicidin (ILPWKWPWWPWRR) packs five tryptophans and three prolines into just 13 residues, giving it an unusual conformation among antimicrobial peptides. Its high aromatic content makes it a favorite for studying how AMPs anchor into and cross membranes.

Research interest

Beyond membrane disruption, indolicidin has been reported to bind nucleic acids and act against fungi and enveloped viruses in laboratory studies. Such breadth keeps it prominent in AMP research; no clinical or therapeutic use is claimed here.

Sequence

One-letter sequence commonly cited for Indolicidin (educational; isoforms and modifications may differ):

ILPWKWPWWPWRR

ILPWKWPWWPWRR

Indolicidin13 aa · C100H132N26O13 · ≈ 1,906.3 DaPEPTIDESCODEX.COMN-terminus →→ C-terminusI1L2P3W4K+5W6P7W8W9P10W11R+12R+13nonpolarpolaracidicbasicGly / Pronon-canonical (X)Hydropathy (Kyte–Doolittle): ▮ hydrophobic (cyan) / ▮ hydrophilic (rose) · Side-chain charge at pH 7: + / −
Indolicidin — Structure cardDownload SVG
I1L2P3W4K5W6P7W8W9P10W11R12R13
Helical wheel projection

Residues plotted ~100° apart around an α-helix — clustering of one color reveals an amphipathic face.

Analyze sequences in the playground →

Structure & chemistry

Molecular identity & reference confidence

Source-supported reference

Reference values are taken from the cited molecular record or curated profile. A database match is not independent laboratory verification; modifications, counter-ions, and formulations can change the measured mass.

Molecular form
Indolicidin (source record; form not independently established)
Species
Not established by this molecular identity audit
Termini (N / C)
Not specified / Not specified

Average reference mass

Reference policy updated: 2026-10-05

Molecular formula
C100H132N26O13
Average reference mass
≈ 1,906.3
Identifiers

Chemistry values: PubChem · fetched 2026-10-01.

Concentration math

Indolicidin — reconstitution calculator

Enter how much peptide is in the vial and how much diluent (e.g. bacteriostatic water) is added. The tool returns the resulting solution concentration — and, for any amount you type, the volume it corresponds to. This is educational arithmetic, not a dosing recommendation.

Reference form: Indolicidin (source record; form not independently established)Average reference mass: 1,906.3 Da

Syringe graduation
Solution concentration
5 mg/mL5,000 mcg/mL
mcg

Enter an amount to see the volume it corresponds to.

Educational concentration mathematics only. This tool does not recommend a dose, amount, or protocol, and nothing here is medical advice. Many peptides are not authorized by Health Canada for human use — see our reconstitution and bacteriostatic-water guides for context.

Open the Indolicidin calculator on its own page →

FAQ about Indolicidin

What is Indolicidin?+

Indolicidin is a 13-residue cathelicidin antimicrobial peptide from bovine neutrophils, unusually rich in tryptophan and proline. It is one of the shortest natural AMPs and is studied for membrane activity and DNA-binding effects against bacteria, fungi and viruses. It is a research peptide, not an approved drug.

What Canadian product status is recorded for Indolicidin?+

Canadian product status for Indolicidin has not been verified in this profile. No verified record here does not mean no authorization exists. Status depends on the product, formulation and use; consult Health Canada's product records.

What is the typical length of Indolicidin?+

Indolicidin is commonly described as approximately 13 amino acids (Antimicrobial peptide).

Related peptides

Motilin
Gut hormone
Motilin is a 22-amino-acid gut hormone secreted by endocrine cells of the small intestine. It coordinates the migrating motor complex, the wave of contractions that clears the digestive tract between meals, earning it the nickname the housekeeper of the gut.
Obestatin
Gut hormone
Obestatin is a 23-amino-acid peptide cleaved from the same preproghrelin precursor that produces ghrelin. It was originally proposed to oppose ghrelin's appetite-stimulating effects, though its physiology and receptor remain actively debated in the research literature.
Albiglutide
Incretin mimetic (GLP-1 receptor agonist)
Albiglutide is a GLP-1 receptor agonist created by genetically fusing two modified GLP-1 sequences to human serum albumin, giving it a long half-life suited to once-weekly dosing. Approved as Tanzeum and Eperzan in 2014, it was later withdrawn from the market for commercial reasons and is now a historical case study.
Neurotensin
Neuropeptide
Neurotensin is a 13-amino-acid neuropeptide found in the brain and gut. Research examines its interactions with dopamine signaling and its roles as a neuromodulator and local hormone.

References & further reading

  1. 1.Martín Bedoya et al. (2026). Nanosystems for delivery of indolicidin peptide. Front Med Technol
  2. 2.Ladokhin et al. (1999). CD spectra of indolicidin antimicrobial peptides suggest turns, not polyproline helix. Biochemistry
  3. 3.Batista Araujo et al. (2022). Indolicidin revisited: biological activity, potential applications and perspectives of an antimicrobial peptide not yet fully explored. World J Microbiol Biotechnol
  4. 4.Waz et al. (2024). Pneumococcal surface protein A (PspA) prevents killing of Streptococcus pneumoniae by indolicidin. Sci Rep
  5. 5.Vergis et al. (2019). Antimicrobial Efficacy of Indolicidin Against Multi-Drug Resistant Enteroaggregative Escherichia coli in a Galleria mellonella Model. Front Microbiol
  6. 6.Rokitskaya et al. (2011). Indolicidin action on membrane permeability: carrier mechanism versus pore formation. Biochim Biophys Acta
  7. 7.Smirnova et al. (2020). Indolicidin analogs with broad-spectrum antimicrobial activity and low hemolytic activity. Peptides
  8. 8.Subbalakshmi et al. (1998). Mechanism of antimicrobial action of indolicidin. FEMS Microbiol Lett
  9. 9.PubChem — compound summary for Indolicidin (CID 90478486)
  10. 10.Wikipedia — Indolicidin
Disclaimer: Educational content only. Not medical advice. Not instructions for human use. Research peptides and unapproved products may be restricted or illegal to market for human consumption in your jurisdiction. Consult qualified professionals and applicable law.
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