LL – 37 (5 MG)

(2 customer reviews)


Molecular Formula: C205H340N60O53
Molecular Weight: 4493.342 g/mol
vCAS Number: 154947-66-7
Synonyms: CAP-18, Cathelicidin, antibacterial peptide LL-37

LL-37 is the only known human cathelicidin, which is a large protein family with diverse function. These peptides, which are primarily found in macrophages and polymorphonuclear leukocytes (both types of white blood cell), are important for killing bacteria, but have been found to have other dramatic effects as well. The entire class is often referred to as antimicrobial peptides (AMPs). LL-37 has been found to play important roles in autoimmune disease, cancer, and wound healing.



Grasping LL-37: An Emerging Powerhouse Peptide 

Have you ever pondered the mystery behind our body’s prowess in combating infections and mending injuries? The secret lies in the concealed armory of our immune system: LL-37. This peptide, a brief sequence of amino acids, assumes a heroic role in the realm of biology, bestowing us with a shield against malignant microorganisms.  LL-37 is a captivating peptide with extensive implications on human wellness, from combating infections and facilitating wound restoration to potential roles in regulating chronic ailments, aging, and cancer.

The labyrinth of biosciences teems with extraordinary elements, each embodying an unfathomable depth of sophistication that leaves investigators marveling. Within this domain, peptides, these diminutive sequences of amino acids – the cornerstone of proteins – are capturing spotlight due to their indispensable roles and promising therapeutic prospects.

Amongst these variegated peptides, the one that surpasses the rest in its peculiar characteristics and expansive functionality is the LL-37 peptide. This singular 37-amino acid peptide, the only representative of the cathelicidin clan in humans, piques the curiosity of the scientific fraternity. Its amphipathic alpha-helical structure confers an extraordinary malleability in its interplay, from tweaking immune reactions to manifesting antimicrobial prowess.

The Genesis and Morphology of LL-37

LL-37, the lone human cathelicidin, is a peptide assembled from 37 amino acids. The moniker “LL-37” originates from the initial duo of amino acids (Leucine, Leucine) coupled with the total count of amino acids. It’s a diminutive element with colossal significance in our defensive reaction.

The Multifaceted Aspects of LL-37

The utility of the LL-37 peptide is manifold, its ramifications reaching into various facets of human wellness. It emanates direct antimicrobial impacts against a wide array of microorganisms, spanning bacteria, viruses, and fungi. The peptide also dabbles in tweaking immune reactions, fostering wound recovery, and angiogenesis, thereby affirming its eclectic role in our physiology.

LL-37: A Vital Cog in Human Wellbeing

The relevance of the LL-37 peptide in human wellness is progressively coming to the fore. There is growing recognition that perturbations in its levels are tied to several pathologies. For instance, a dip in LL-37 levels is associated with psoriasis and atopic dermatitis, while a surge is linked with certain cancers, implying a tangled web of interplay between LL-37 and disease states.

LL-37 Research: The Accelerating Pace of Discovery

In the realm of LL-37 research, scientific strides are rapidly unfurling. Cutting-edge experimental methodologies are unmasking new facets of LL-37’s functionalities, from its role in innate immunity to its promise as a therapeutic tool. Moreover, scientists are delving into its potential to tweak the microbiome and the ensuing implications for human wellness.

Therapeutic Prospects of LL-37

Given its eclectic functionalities and implications for human wellness, it’s hardly startling that the LL-37 peptide is emerging as a hopeful prospect for therapeutic applications. Its antimicrobial properties are igniting explorations into its utility as an antimicrobial tool, particularly in this era of burgeoning antibiotic resistance. Furthermore, its capacity to tweak immune reactions and influence wound recovery portends potential applications in immune disorders and regenerative medicine.

Decoding the Modus Operandi of LL-37 Peptide

The conundrum surrounding the precise mechanisms underpinning the actions of the LL-37 peptide continues to engross researchers. The peptide navigates through variegated pathways, marking it as an exceptionally versatile entity. It can directly sabotage the membrane integrity of pathogens, leading to their downfall. Additionally, it tweaks the immune response by influencing the operation of various immune cells and the production of cytokines, key combatants in the body’s immune system. Further, LL-37 dabbles in cell proliferation and differentiation, essential processes in wound recovery and tissue regeneration.

LL-37 Peptide and the Microbiome

The human microbiome, a variegated ensemble of microbes residing in and on our bodies, is pivotal to our health and wellbeing. Recent studies intimate that the LL-37 peptide may tweak the composition of the microbiome. By selectively thwarting deleterious microbes while fostering the growth of beneficial ones, LL-37 might hold a key role in maintaining the delicate equilibrium of our microbiome.

The Function of LL-37 in Immunity 

LL-37 is a fulcrum in our congenital immune system, the body’s premier line of resistance. It can be likened to a vigilant sentinel posted at the gateway of a grandiose edifice, vigilantly monitoring for any unwelcome interlopers.

Deciphering the Operation of LL-37 

The Method LL-37 Utilizes to Counter Infections One might inquire, how does LL-37 thwart these minuscule trespassers? The mechanism is intriguing indeed. LL-37 excels at neutralizing a broad spectrum of bacteria, viruses, and fungi, essentially manifesting a defensive barricade encompassing our body. Envision it as a petite knight adorned in gleaming armor, valiantly engaging the microbial adversaries.

The Role of LL-37 in Wound Restoration

Beyond its antimicrobial capabilities, LL-37 also enhances wound recovery. It’s akin to a seasoned field surgeon, swift to mobilize and initiate the healing cascade when our body endures an injury.

The Importance of LL-37 in Human Wellness 

LL-37 and Chronic Maladies Fresh research intimates that LL-37 may contribute to various enduring conditions, from pulmonary disorders to rheumatoid arthritis. Picture a versatile sleuth, engaged in diverse investigations but persistently striving for the same objective – reinstating health and equilibrium.

Present Investigations and Prospective Horizons LL-37 in Oncological Therapy The potential of LL-37 surpasses infections and wound recuperation. Some scholars posit that it could be utilized in cancer therapy, functioning as a sharpshooter targeting malignant cells.

The Potential of LL-37 in Managing Inflammatory Disorders

Emerging research posits that LL-37 could be beneficial in addressing inflammatory diseases. Visualize it as a firefighter, prepared to extinguish the blaze of inflammation and reinstate tranquility within the body.

Potential Adverse Reactions and Hazards Striking the Balance: Advantages and Disadvantages 

As with all things in existence, equilibrium is key. While LL-37 possesses numerous promising potentials, it’s critical to acknowledge that it can also exhibit undesirable reactions and risks. It’s somewhat like navigating a slackline – excess or deficiency can precipitate a tumble.

Forward Gaze

The LL-37 peptide symbolizes an extraordinary facet of biological complexity. Its wide range of functionalities and potential therapeutic applications underscore its importance in the field of biomedical research. As we continue to unravel the enigma of this peptide, we inch closer to harnessing its potential to enhance human wellness.

While the promise of LL-37 peptide is immense, it’s not devoid of research challenges. The convolutions of LL-37’s interactions with various cellular and molecular components present a formidable obstacle. Nonetheless, with the exponential advancement of technology, we are progressively able to delve deeper into the subtleties of this peptide. In the impending years, we can anticipate significant revelations that will further illuminate our understanding of LL-37 and its potential applications.

Questions and Answers.  Answers are not validated, only shown as a probability through research.

Q: What exactly is LL-37?

A: LL-37 is a peptide, a compact sequence of amino acids, that assumes a vital role in the human immune machinery.


Q: What part does the LL-37 peptide play in human physiology?

A: LL-37 peptide is a jack-of-all-trades in human physiology. It exhibits antimicrobial activity against a broad spectrum of pathogens, modulates immune reactions, facilitates wound recovery, and participates in angiogenesis.


Q: What are some possible therapeutic applications of LL-37?

A: LL-37 peptide holds promise as an antimicrobial tool, particularly in the face of rising antibiotic-resistant infections. Additionally, its role in immune modulation and wound recovery suggests potential applications in the treatment of immune disorders and regenerative medicine.


Q: How is the study of the LL-37 peptide progressing?

A: The study of the LL-37 peptide is advancing at a brisk pace, with innovative experimental methodologies shedding light on novel facets of its functionality. These include its role in innate immunity, modulation of the microbiome, and its potential as a therapeutic tool.


Q: How does the LL-37 peptide function?

A: The LL-37 peptide functions through diverse mechanisms. It can break up the membranes of pathogens, modulate immune response, and is involved in cell proliferation and differentiation.


Q: Is LL-37 the Ultimate Anti-Viral?

A: Preliminary research suggests that LL-37 peptide may thwart certain viral infections by interfering with viral entry into host cells or disrupting viral replication.


Q: What hurdles are encountered in the study of LL-37 peptide?

A: Research in the realm of LL-37 peptide is confronted with challenges due to the convoluted nature of its interactions with various cellular and molecular components. Notwithstanding these hurdles, technological advancements are facilitating a deeper understanding of this peptide.

The journey of LL-37 peptide, from an unassuming constituent of the cathelicidin family to a prospective powerhouse in therapeutic applications, is a captivating tale. Its wide array of functionalities and associations with various health conditions mark it as a crucial player in biomedical research. As we continue to decode the secrets of this peptide, the potential to wield its power for human wellness becomes an increasingly tangible reality.


Q: How does LL-37 counter infections? 

A:  LL-37 has the capacity to neutralize a diverse array of bacteria, viruses, and fungi, erecting a protective barrier for our body against microbial assailants.


Q: Can LL-37 assist in wound mending?

A: Indeed, LL-37 possesses attributes that facilitate wound recuperation, functioning as a first responder when our body sustains damage.


Q: What part does LL-37 play in chronic ailments and aging? 

A: Studies imply that LL-37 might have roles in moderating various chronic disorders and the aging process, although further investigations are required to thoroughly comprehend these effects.


Q: Can LL-37 be employed in cancer therapy?

A:  Initial research indicates that LL-37 may hold potential in oncological treatment, but more in-depth studies are required to validate these claims and delineate safe and effective therapeutic methodologies.

Below are some findings from a number of past researches been done by renowned peptides researchers on LL-37:

LL-37 and Inflammatory Diseases

LL-37, while primarily billed as an antimicrobial peptide, plays a role in several inflammatory diseases such as psoriasis, lupus, rheumatoid arthritis, and atherosclerosis. Depending on the local inflammatory environment and the cells involved, LL-37 has several different immune system modulating behaviors. It has been found to: decrease keratinocyte apoptosis, increase IFN-alpha production, alter chemotaxis of neutrophils and eosinophils, down-regulate signaling through toll-like receptor 4 (TLR4), increase IL-18 production, and decrease levels of atherosclerotic plaques[1].

Interestingly, LL-37 does not affect the immune system in the same way all the time. Research in cell culture has shown that the inflammatory environment affects how cells of the immune system respond to LL-37. T-cells, for instance, will increase their inflammatory actions in response to LL-37 when they are not activated but decrease inflammatory action when already activated[2].

It appears that LL-37 has potent homeostatic effects, helping to balance the immune response and prevent it from becoming overactive in the setting of infection. These findings would suggest that LL-37 could play a role in helping to regulate the unchecked inflammation of autoimmune diseases. This may explain why there has been a strong correlation between LL-37 levels and autoimmune disease. It was previously thought that LL-37 might be causing autoimmune inflammation, but more recent evidence suggests that high levels of LL-37 in autoimmune disease may be preventing more fulminant inflammation. Source: Karger

LL-37 Is a Potent Antimicrobial

LL-37 is part of the innate immune system and as such is one of the first pieces of the immune system to be activated during infection. Research in skin infections suggests that normal skin has very low levels of LL-37 but that the peptide accumulates rapidly in the presence of invading pathogens. The peptide has been shown to work in tandem with other proteins, like human beta-defensin 2 to combat infection[3].

LL-37 primarily works by binding to bacterial lipopolysaccharide (LPS), a major component of the outer membrane of gram-negative bacteria. LPS is a critical component of membrane integrity in these bacteria. The ability of LL-37 to bind to and interfere with LPS means it is exceptionally deadly to certain bacteria. There is interest in using the peptide exogenously to treat serious bacterial infections in people[4].

Even though LL-37 acts on the cell membrane components of gram-negative bacteria, it still has potent gram-positive effects as well. This could make it a beneficial treatment for staph infections and other serious bacteria. In vitro research indicates that LL-37 enhances the effects of lysozyme, an enzyme responsible for the destruction of gram positive bacteria like Staph aureus[5].

LL-37 and Lung Disease

LPS, as mentioned above, is not unique to bacterial cell walls. It is found in several different organisms and, in some cases, becomes airborne when an environment is contaminated by mold or other fungi. When LPS is inhaled, normal lung tissue responds by producing. Unfortunately, the response is often inadequate to prevent toxic dust syndrome and the pathogenesis of respiratory diseases like asthma, COPD, and more. Research into the use of LL-37 as an inhaled treatment for toxic dust syndrome is currently under way[6].

One of the interesting findings of research into the effects of LL-37 on lung disease is that the peptide promotes epithelial cell proliferation and wound closure. It appears that one of the primary properties of LL- 37, at least in the lungs, is to attract airway epithelial cells to the site of injury and promote both wound healing and the growth of blood vessels necessary for providing nutrients to the new tissue. It seems that LL-37 is an important homeostatic regulator in the airways just as it has been found to be a homeostatic regulator of immune function[7].

Understanding LL-37 in Arthritis

Research in rats indicates that LL-37 is found in high concentrations in joints affected by rheumatoid arthritis. In particular, the peptide appears to be associated with the pathological events of arthritis. It isn’t clear, however, if the peptide is causative or its up-regulation in these joints is a part of the body’s attempt to control the pathological process[8]. Several things, however, suggest that LL-37 is beneficial in inflammation and not causative.

First, there is no evidence that LL-37 or any other cathelicidin is involved in the pathogenesis of inflammatory disease. This does not rule the peptide out as being causative, but evidence weighs pretty heavily against that being the case. LL-37 deficiency does not affect outcomes in animal models of arthritis or lupus. In other words, animals without LL-37 experience the same pathological progression as animals who have the peptide. Based on these findings, scientists have suggested that reactivity against cathelicidins in arthritis is likely an epiphenomenon that results from extensive overexpression of the peptide in inflamed tissues[9]. In other words, it is incidental.

Research in mouse models of arthritis indicate that peptides derived from LL-37 confer protection against collagen damage that often occurs in inflammatory arthritis. Administration of these peptides directly to affected joints decreases the severity of disease as well as serum levels of antibody against type II collagens[10]. Based on this study, it is reasonable to speculate that LL-37 probably has protective activity in arthritis, which could explain its high concentrations in tissues with substantial inflammation. This speculation is supported by the fact that LL-37 and its derivatives have been shown to regulate inflammation caused by interleukin-32, a molecule that has been directly associated with severity of inflammatory arthritis[11].

Arthritis has also been associated with an up-regulation of toll-like receptor 3 in the fibroblasts of synovial fluid, a factor that likely aggravates arthritis by increasing inflammatory cytokine levels[12]. LL- 37 has been shown to bind to TLR4 and either promote proinflammatory or anti-inflammatory effects. Which it does in the setting of TLR3 up-regulation isn’t clear, but research is ongoing. The idea that it might reduce inflammation selectively is not unreasonable given that LL-37 has been found to selectively reduce pro-inflammatory macrophage responses in the past[13].

LL-37 and the Intestine

Research in cell cultures indicates that LL-37 has several effects in the intestine. First, the peptide increases migration of cells necessary for maintaining the epithelial barrier of the intestine. Second, LL-37 reduces apoptosis in the setting of intestinal inflammation, helping to slow the pathogenesis of a number of inflammatory conditions. Overall, the research indicates that LL-37 may be a useful adjuvant treatment in inflammatory bowel conditions, following intestinal surgery, or in the setting of acute intestinal infections. It may even prove useful as an adjuvant to antibiotic therapy, helping to prevent the GI side effects that often limit oral antibiotic use[14]. LL-37 does not work alone in the intestine, pairing once again with human beta defensin 2 to promote wound healing. Research in cell culture indicates that the peptides work in tandem to both repair and maintain intestinal epithelium while reducing TNF-related cell death[15].

Currently, TNF-alpha inhibitors are a mainstay of treatment for inflammatory bowel conditions. The development of LL-37-based treatments of inflammatory bowel disease could help to reduce reliance on TNF-alpha inhibitors and improve morbidity and mortality in this patient population.

LL-37 and Intestinal Cancer

Research regarding LL-37 and cancer has produced mixed results, but the peptide appears to be beneficial in the setting of intestinal and gastric cancers, including oral squamous cell carcinoma associated with smoking and tobacco use. Interestingly, these effects appear to be mediated by a vitamin-D dependent pathway, which may explain why taking the vitamin has been previously associated with a reduced risk for GI cancer. It appears that vitamin D induces the anti-cancer activity of tumor-associated macrophages via LL-37[16].

LL-37 and Blood Vessel Growth

LL-37 appears to trigger the synthesis of prostaglandin E2 (PGE2) in endothelial cells. PGE2 is associated with both inflammatory pain and with the growth of blood vessels, but these effects differ based on where the molecule is being expressed. In endothelial cells, PGE2 triggers the development of blood vessels in a process called angiogenesis[17]. This can be both good and bad, depending on the setting. The ability to regulate angiogenesis has been the focus of much research in the last several decades because it impacts cancer development, heart disease, stroke outcomes, wound healing, and more. LL-37 activity offers a useful means for probing the angiogenesis pathway as well as a model for potential future interventions to both promote blood vessel growth when needed (e.g. heart disease) and discourage it when it is detrimental (e.g. cancer).

Ongoing LL-37 Research

One of the interesting things about LL-37 is that it has a different structure in humans than in other mammals[18]. These alternative Bioregulator Peptides structures result in different functions for the same basic peptide and provide insight into how three-dimensional configuration can impact receptor binding. This feature makes LL-37 of intense interest because it allows scientists to study the impacts of simple amino acid sequence changes on structure and ultimately function. This could inform an entire branch of biochemistry and make it easier for scientists to manipulate protein production to achieve very specific results.

Article Author

The above literature was researched, edited and organized by Dr. Logan, M.D. Dr. Logan holds a doctorate degree from Case Western Reserve University School of Medicine and a B.S. in molecular biology.

Scientific Journal Author

Daniela Xhindoli, PhD. operates from the University of Trieste, UNITS · Department of Life Sciences. Her focus surrounds gram-negative bacteria, the biological activities of LL-37 on simultaneously modulating pro-inflammatory and anti-inflationary pathways, and the antibacterial and antimicrobial effects of LL-37.

Daniela Xhindoli, PhD. is being referenced as one of the leading scientists involved in the research and development of LL-37. In no way is this doctor/scientist endorsing or advocating the purchase, sale, or use of this product for any reason. There is no affiliation or relationship, implied or otherwise, between PeptidesforSale.com and this doctor. The purpose of citing the doctor is to acknowledge, recognize, and credit the exhaustive research and development efforts conducted by the scientists studying this peptide. Daniela Xhindoli, PhD. is listed in [18] under the referenced citations.

References and Citations

[1] J. M. Kahlenberg and M. J. Kaplan, “Little peptide, big effects: the role of LL-37 in inflammation and autoimmune disease,” J. Immunol. Baltim. Md 1950, vol. 191, no. 10, Nov. 2013.

[2] D. S. Alexandre-Ramos et al., “LL-37 treatment on human peripheral blood mononuclear cells modulates immune response and promotes regulatory T-cells generation,” Biomed. Pharmacother. Biomedecine Pharmacother., vol. 108, pp. 1584– 1590, Dec. 2018.

[3] P. Y. Ong et al., “Endogenous antimicrobial peptides and skin infections in atopic dermatitis,” N. Engl. J. Med., vol. 347, no. 15, pp. 1151–1160, Oct. 2002.

[4] C. D. Ciornei, T. Sigurdardóttir, A. Schmidtchen, and M. Bodelsson, “Antimicrobial and chemoattractant activity, lipopolysaccharide neutralization, cytotoxicity, and inhibition by serum of analogs of human cathelicidin LL-37,” Antimicrob. Agents Chemother., vol. 49, no. 7, pp. 2845–2850, Jul. 2005.

[5] X. Chen et al., “Synergistic effect of antibacterial agents human β-defensins, cathelicidin LL-37 and lysozyme against Staphylococcus aureus and Escherichia coli,” Dermatol. Sci., vol. 40, no. 2, pp. 123–132, Nov. 2005.

[6] M. Golec, “Cathelicidin LL-37: LPS-neutralizing, pleiotropic peptide,” Ann. Agric. Environ. Med. AAEM, vol. 14, no. 1, pp. 1–4, 2007.

[7] R. Shaykhiev et al., “Human endogenous antibiotic LL-37 stimulates airway epithelial cell proliferation and wound closure,” Am. J. Physiol. Lung Cell. Mol. Physiol., vol. 789, no. 5, pp. L842-848, Nov. 2005.

[8] M. H. Hoffmann et al., “The cathelicidins LL-37 and rCRAMP are associated with pathogenic events of arthritis in humans and rats,” Ann. Rheum. Dis., vol. 72, no. 7, 1239–1248, Jul. 2013.

[9] D. Kienhöfer et al., “No evidence of pathogenic involvement of cathelicidins in patient cohorts and mouse models of lupus and arthritis,” PloS One, vol. 9, no. 12, p. e115474, 2014.

[10] L. N. Y. Chow et al., “Human cathelicidin LL-37-derived peptide IG-19 confers protection in a murine model of collagen-induced arthritis,” Mol. Immunol., vol. 57, no. 2, pp. 86–92, Feb. 2014.

[11] K.-Y. G. Choi, S. Napper, and N. Mookherjee, “Human cathelicidin LL-37 and its derivative IG-19 regulate interleukin-32-induced inflammation,” Immunology, vol. 143, 1, pp. 68–80, Sep. 2014.

[12] W. Zhu et al., “Arthritis is associated with T-cell-induced upregulation of Toll-like receptor 3 on synovial fibroblasts,” Arthritis Res. Ther., vol. 13, no. 3, p. R103, Jun. 2011.

[13] K. L. Brown et al., “Host defense peptide LL-37 selectively reduces proinflammatory macrophage responses,” J. Immunol. Baltim. Md 1950, vol. 186, no. 9, pp. 5497–5505, May 2011.

[14] J.-M. Otte et al., “Effects of the cathelicidin LL-37 on intestinal epithelial barrier integrity,” Regul. Pept., vol. 156, no. 1–3, pp. 104–117, Aug. 2009.

[15] J.-M. Otte et al., “Human beta defensin 2 promotes intestinal wound healing in vitro,” J. Cell. Biochem., vol. 104, no. 6, pp. 2286–2297, Aug. 2008.

[16] X. Chen et al., “Roles and Mechanisms of Human Cathelicidin LL-37 in Cancer,” https://www.peptidesciences.com/…-18?queryID=b22531aeccb7b39d00020eee4317e8d9&objectID=124&indexName=m1_default_products[7/21/2022 11:16:14 AM] Cell. Physiol. Biochem. Int. J. Exp. Cell. Physiol. Biochem. Pharmacol., vol. 47, no. 3, 1060–1073, 2018.

[17] Salvado M. Dolores, Di Gennaro Antonio, Lindbom Lennart, Agerberth Birgitta, and Haeggström Jesper Z., “Cathelicidin LL-37 Induces Angiogenesis via PGE2–EP3 Signaling in Endothelial Cells, In Vivo Inhibition by Aspirin,” Arterioscler. Thromb. Vasc. Biol., vol. 33, no. 8, pp. 1965–1972, Aug. 2013.

[18] D. Xhindoli, S. Pacor, M. Benincasa, M. Scocchi, R. Gennaro, and A. Tossi, “The human cathelicidin LL-37 — A pore-forming antibacterial peptide and host-cell modulator,” Biochim. Biophys. Acta BBA – Biomembr., vol. 1858, no. 3, pp. 546–566,


2 reviews for LL – 37 (5 MG)

  1. Brian

    Very happy with their service. And found this peptide LL – 37 really great.

  2. Johnson

    LL-37 has demonstrated potential in improving immune system function in our research. We’re excited to further explore its benefits for overall health.

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