hBD-1
The body's constant, low-level epithelial antibiotic, far more potent once its disulfide bonds are reduced
Human beta-defensin 1 is made all the time by epithelial surfaces, from the kidney to the gut. Long thought a weak antibiotic, it turned out to kill fungi and gut bacteria powerfully once its disulfide bonds are reduced, as in the oxygen-poor colon. Variants in its gene have been linked to infections and other diseases. It is not a drug.
What is it?
Defensins are small, cysteine-rich peptides that form part of the body's innate defence. hBD-1 was the first human beta-defensin found: in 1995 researchers isolated it from human blood filtrate and showed it was 36 amino acids long with six cysteines joined into three disulfide bonds. Unlike its relatives hBD-2 and hBD-3, which rise sharply during infection or inflammation, hBD-1 is produced constantly.
For years it looked like the weak member of the family, with only modest killing activity in standard tests. A 2011 study changed that: once its disulfide bridges were reduced, as happens in the low-oxygen, chemically reducing environment of the colon, hBD-1 became a potent killer of the fungus Candida albicans and of anaerobic gut bacteria such as bifidobacteria and lactobacilli. The same peptide behaves differently depending on where it is.
In people, the research mostly concerns the DEFB1 gene. Small case-control studies have linked particular variants to a higher risk of infection around joint replacements and to coronary artery disease, and in the joint study the variants tracked higher hBD-1 levels in joint fluid. These are associations in modest samples, which the authors themselves say should be interpreted cautiously.
hBD-1 has never been developed as a treatment and has no human dose. Products sold online under defensin names are research chemicals with no evidence of benefit in people. Our defensins family page sets hBD-1 beside its relatives.
At a Glance
Every value in this table is printed from the Grey Peptides dataset, the same record the compound explorer and comparison tool read, so the three can never disagree.
Published Research
These studies were read from their PubMed abstracts on October 5, 2026.
Discovery in human blood filtrate
A novel 36-residue peptide with three intramolecular disulfide bonds and a mass of 3,928.6 Da was isolated from human blood filtrate and its sequence confirmed by cDNA cloning; it shared the conserved residues of beta-defensins from other species.
Reduced, it becomes potent
After its disulfide bridges were reduced, hBD-1 became a potent antimicrobial against Candida albicans and against anaerobic Gram-positive commensals of the Bifidobacterium and Lactobacillus genera, conditions resembling the reducing environment of the colon.
Gene variants and joint-replacement infection
The GG genotype of rs1800972 was associated with periprosthetic joint infection (odds ratio 4.12), and carriers of certain genotypes had higher synovial hBD-1; the authors caution that the sample was modest.
A variant and coronary artery disease
In a case-control study, the AA genotype of DEFB1 rs11362 was associated with coronary artery disease under several genetic models (odds ratios about 1.4 to 1.9), while rs1800972 was not.
Side Effects & Contraindications
Reported Side Effects
Not applicable.
Contraindications & Cautions
Not a medicine, so there is no label and no formal contraindication.
Legal Status
An endogenous peptide, not a medicine.
Frequently Asked Questions
?What does hBD-1 do?
It is a constantly produced antimicrobial peptide on epithelial surfaces, which becomes far more potent when its disulfide bonds are reduced, as in the colon.
?Is hBD-1 a treatment?
No. It has never been developed or tested as a medicine, and there is no human dose.
?Do DEFB1 gene variants matter?
Small studies link some variants to joint-replacement infection and coronary artery disease; these are associations that need larger confirmation.
References
- [pubmed] Bensch KW, et al. "hBD-1: a novel beta-defensin from human plasma." FEBS Lett, 1995;368(2):331-5. PMID: 7628632.
- [pubmed] Schroeder BO, et al. "Reduction of disulphide bonds unmasks potent antimicrobial activity of human β-defensin 1." Nature, 2011;469(7330):419-23. PMID: 21248850.
- [pubmed] Zamudio-Cuevas Y, et al. "Functional DEFB1 gene polymorphisms and synovial hBD-1 expression are associated with susceptibility to periprosthetic joint infection." Mol Biol Rep, 2025;52(1):929. PMID: 40974393.
- [pubmed] Vargas-Alarcón G, et al. "The DEFB1 gene rs11362 A/G genetic variant is associated with risk of developing CAD: a case-control study." Acta Cardiol, 2024;79(6):730-736. PMID: 38973431.
- [pubmed] Ganz T. "Defensins: antimicrobial peptides of innate immunity." Nat Rev Immunol, 2003;3(9):710-20. PMID: 12949495.
Sources & Citations
Studies from their PubMed abstracts, read October 5, 2026.
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. Consult a licensed healthcare provider before making health decisions.