The Peptide Encyclopedia

For education only

This guide cannot diagnose a condition or recommend a personal treatment plan. Discuss medical questions with a qualified professional.

Your comprehensive guide to therapeutic peptides. Explore mechanisms, clinical evidence, FDA status, and find clinics that offer them. 110 peptides covered and growing.

Showing 110 peptides

Weight Loss

Semaglutide

GLP-1 Receptor Agonist

FDA-approved GLP-1 agonist for weight loss and type 2 diabetes.

Tirzepatide

GIP/GLP-1 Receptor Agonist

Dual GIP/GLP-1 agonist for weight loss and type 2 diabetes.

Liraglutide

FDA-approved GLP-1 receptor agonist for weight management and type 2 diabetes.

Retatrutide

Triple Incretin Agonist

Retatrutide (LY3437943) is an investigational triple GLP-1/GIP/glucagon receptor agonist from Eli Lilly. In Phase 2 obesity trials it produced up to ~24% mean weight loss at 48 weeks — the highest reported for any obesity drug — but it is not FDA-approved and has no legal commercial source as of 2026.

Cagrilintide

Amylin Analogue

Cagrilintide is a long-acting amylin analogue in Phase 3 development, studied in combination with semaglutide (CagriSema). The CagriSema combination achieved approximately 22.7% body weight reduction at 68 weeks in the SCALE trial.

Survodutide

GLP-1/Glucagon Dual Agonist

Survodutide (BI 456906) is a dual GLP-1 and glucagon receptor agonist in Phase 3 trials for obesity and MASH (metabolic-associated steatohepatitis), demonstrating approximately 14.9% weight loss at 46 weeks in Phase 2b studies.

Mazdutide

Mazdutide (IBI362) is a weekly GLP-1 and glucagon receptor dual agonist developed by Innovent Biologics, currently in Phase 3 trials in China. Phase 3 GLORY-1 trial data showed 14.5% body weight reduction over 36 weeks.

L-Carnitine

Amino Acid Derivative

L-Carnitine is a conditionally essential amino acid derivative (β-hydroxy-γ-trimethylaminobutyric acid) that facilitates the transport of long-chain fatty acids across the inner mitochondrial membrane for β-oxidation, serving as a critical cofactor in energy metabolism.

Tesamorelin

Growth Hormone Releasing Hormone Analog

Tesamorelin is a synthetic research peptide and stabilized analog of growth hormone–releasing hormone (GHRH).

Cagrilintide + Semaglutide Blend

Peptide Blend

CagriSema, a compounded combination of the amylin analogue cagrilintide and the GLP-1 agonist semaglutide, studied in Phase 3 REDEFINE trials with approximately 22.7% body weight reduction at 68 weeks.

Tesamorelin, CJC-1295 (no DAC), Ipamorelin 12mg (Blend)

Growth Hormone Secretagogue

A research peptide blend formulated to investigate growth hormone axis modulation through combined GHRH and ghrelin receptor pathways.

AICAR

AICAR is a research compound that acts as an AMP analog activating AMP-activated protein kinase (AMPK).

O-304

O-304 is a synthetic small-molecule research compound developed to modulate cellular senescence-associated pathways.

Adipotide (FTPP)

Targeted proapoptotic compound

Adipotide, also known as FTPP, is a synthetic research peptide designed as a targeted proapoptotic compound.

AOD-9604

Growth Hormone Fragment

AOD-9604 is a research peptide consisting of amino acids 177–191 of the human growth hormone sequence.

AOD-9604 + CJC-1295 + Ipamorelin Blend

A triple-peptide compounded blend combining AOD-9604 (fat-mobilizing GH fragment) with CJC-1295 and ipamorelin for comprehensive GH-axis optimization with targeted lipolysis.

Ipamorelin + Tesamorelin Blend

A compounded blend combining ipamorelin (ghrelin receptor agonist) with tesamorelin (GHRH analogue) for synergistic GH secretion with tesamorelin's additional visceral fat-reducing properties.

Tesofensine

Triple Monoamine Reuptake Inhibitor

Tesofensine is a synthetic small-molecule research compound classified as a triple monoamine reuptake inhibitor.

MOTS-c

Mitochondrial-Derived Peptide

MOTS-c is a mitochondrial-derived peptide composed of 16 amino acids.

5-Amino-1MQ

5-amino-1MQ is a small-molecule research compound that functions as a selective nicotinamide N-methyltransferase (NNMT) inhibitor.

Anti-Aging & Longevity

Sermorelin

Growth Hormone Releasing Hormone

FDA-approved GHRH analog for growth hormone deficiency.

CJC-1295 / Ipamorelin

Combination growth hormone secretagogue therapy.

HGH 191AA

Growth Hormone

HGH 191AA refers to recombinant human growth hormone (somatropin) with the full 191 amino acid sequence. It is FDA-approved under multiple brand names for growth hormone deficiency, Turner syndrome, and other specific indications.

TB-500

Thymosin Peptide

Synthetic fragment of thymosin beta-4 used for tissue repair, recovery, and reducing inflammation.

NAD+

Coenzyme vital for cellular energy, DNA repair, and longevity.

Ipamorelin

Growth Hormone Releasing Peptide

A selective growth hormone-releasing peptide with minimal side effects.

CJC-1295

A growth hormone-releasing hormone analog that increases GH and IGF-1 levels.

Hexarelin

Potent GHRP that stimulates GH secretion for muscle recovery and anti-aging.

Glutathione

Antioxidant Tripeptide

Glutathione (GSH) is the body's master antioxidant, a tripeptide (γ-Glu-Cys-Gly) synthesized in every cell. IV glutathione bypasses poor oral bioavailability to rapidly replenish intracellular GSH, supporting detoxification, immune function, and skin brightening.

Epithalon

Telomerase Activator

Tetrapeptide that activates telomerase, studied for anti-aging and longevity.

GHRP-6

Growth hormone-releasing peptide that stimulates appetite and GH secretion.

Copper Peptides

Copper Peptide

Family of copper-binding peptides used for skin rejuvenation, wound healing, and hair growth.

SS-31

Mitochondria-Targeting Peptide

SS-31 (Elamipretide, MTP-131) is a tetrapeptide (D-Arg-Dmt-Lys-Phe-NH2) that selectively targets the inner mitochondrial membrane to stabilize cardiolipin, reduce electron leak, and restore mitochondrial cristae architecture in aged and failing mitochondria.

Adamax

Adamax is a branded compounded peptide blend typically combining CJC-1295 DAC, Ipamorelin, and BPC-157, formulated to simultaneously stimulate growth hormone secretion, promote tissue repair, and support recovery — often available as a single reconstitution vial.

Cerebrolysin

Neurotrophic Factor Mixture

Cerebrolysin is a standardized porcine brain-derived peptide mixture containing approximately 25% low-molecular-weight peptides and amino acids, including neurotrophic factors analogous to BDNF, NGF, CNTF, and GDNF. It is approved in multiple countries for stroke and dementia.

DSIP

Neuropeptide

Delta Sleep-Inducing Peptide (DSIP) is a naturally occurring nonapeptide (Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu) found in the hypothalamus and peripheral blood that promotes deep (delta-wave) sleep and modulates stress hormone release.

PNC-27

Anticancer Peptide

PNC-27 is a 27-amino acid peptide containing a p53 MDM-2 binding domain fused to a membrane-penetrating sequence, designed to selectively induce apoptosis in cancer cells that aberrantly express HDM-2 (MDM-2) on their plasma membrane.

Cardiogen

Russian Bioregulator Peptide

Cardiogen is a synthetic tetrapeptide bioregulator (Ala-Glu-Asp-Arg) developed at the St. Petersburg Institute of Bioregulation for cardiac tissue restoration, studied for cardiomyocyte protection and heart muscle recovery following ischemia.

Testagen

Testagen is a synthetic tetrapeptide bioregulator (Lys-Asp-Glu-Ala) developed for testicular tissue support and male reproductive system restoration, studied for effects on Leydig and Sertoli cell function in aging males.

Cortagen

Cortagen is a synthetic tetrapeptide bioregulator (Ala-Glu-Asp-Pro) developed for vascular and cardiac tissue support, particularly targeting the regulation of blood vessel tone and endothelial function in aging cardiovascular tissue.

Livagen

Livagen is a synthetic tetrapeptide bioregulator (Lys-Glu-Asp-Ala) developed for liver and immune system restoration, studied for hepatoprotective properties and immune cell normalization in animal models of aging and hepatotoxicity.

Crystagen

Crystagen is a synthetic tripeptide bioregulator (Lys-Glu-Asp) developed for prostate tissue support and urogenital health, studied for effects on prostate epithelial cell normalization and benign prostatic hyperplasia management.

Cartalax

Cartalax is a synthetic tripeptide bioregulator (Ala-Glu-Asp) developed for cartilage and joint tissue restoration, studied for chondroprotective effects and articular cartilage regeneration in animal models.

Chonluten

Chonluten is a synthetic tripeptide bioregulator (Glu-Asp-Leu) developed for bronchial and lung tissue support, studied for airway epithelial protection and pulmonary function restoration in aged and compromised tissue.

AHK-Cu

AHK-Cu is a research peptide complex studied for its role in extracellular matrix remodeling and fibroblast activation.

AHK (Tripeptide-3)

AHK (Tripeptide-3) is a research peptide composed of the tripeptide Ala-His-Lys, studied for its effects on dermal fibroblast function and extracellular matrix gene regulation.

Pal-AHK

Pal-AHK is a research peptide consisting of the tripeptide Ala-His-Lys conjugated with palmitic acid to enhance skin absorption and bioavailability.

Palmitoyl Dipeptide-6

Palmitoyl Dipeptide-6 is a research peptide composed of a short dipeptide conjugated to a palmitic acid chain to enhance lipophilicity and dermal penetration.

Rigin (Palmitoyl Tetrapeptide-7)

Rigin is a research peptide designed to modulate cytokine expression and dermal peptide signaling.

Syn-Coll (Palmitoyl Tripeptide-5)

Syn-Coll is a research peptide designed to enhance stability and skin permeability for in vitro studies.

Tripeptide-29

Collagen peptide

Tripeptide-29 is a research peptide composed of Gly-Pro-Hyp, studied for its role in extracellular matrix synthesis and fibroblast regulation.

Ovagen

Bioregulator

Ovagen is a peptide bioregulator derived from liver tissue extracts used in studies of detoxification and cellular regeneration.

GLOW Peptide Blend

Research Peptide Blend (BPC-157 + TB-500 + GHK-Cu)

The GLOW peptide blend combines BPC-157, TB-500, and GHK-Cu, three research peptides studied for tissue repair, angiogenesis, and skin and connective-tissue remodeling.

KLOW Peptide Blend

Research Peptide Blend (BPC-157 + TB-500 + KPV + GHK-Cu)

The KLOW peptide blend combines BPC-157, TB-500, KPV, and GHK-Cu, the GLOW blend plus KPV, studied for cellular repair, immune modulation, and extracellular matrix regulation.

Pal-GHK (Palmitoyl Tripeptide-1)

Pal-GHK is a research peptide formed by conjugating Gly-His-Lys to palmitic acid to enhance dermal delivery.

CJC-1295 (no DAC), Ipamorelin 10mg (Blend)

CJC-1295 (no DAC) and Ipamorelin is a research peptide blend combining two mechanistically distinct secretagogues that act synergistically on the growth hormone axis.

GHRP-2

GHRP-2 is a synthetic hexapeptide that functions as a potent growth hormone secretagogue.

Vesugen

Vesugen is a synthetic short peptide bioregulator derived from vascular tissue extracts.

CJC-1295 No DAC + Ipamorelin Blend

The most widely used compounded GH peptide combination, pairing modified GRF 1-29 (CJC-1295 without DAC) with ipamorelin for a clean, pulsatile GH release that mimics natural secretory patterns.

SLU-PP-332

SLU-PP-332 is a small-molecule research compound identified as a selective agonist of peroxisome proliferator-activated receptor delta (PPARδ).

FOX04-DRI

FOXO4-DRI is a synthetic D-retro-inverso research peptide designed to selectively disrupt the FOXO4–p53 interaction.

SNAP-8

SNAP-8 is a synthetic octapeptide derived from SNAP-25, designed to modulate vesicle exocytosis-associated protein interactions.

Acetyl Hexapeptide-3 (Argireline)

Acetyl Hexapeptide-3 (Argireline) is a hexapeptide analog of SNAP-25 developed to modulate vesicle docking and catecholamine release.

Matrixyl

Matrixyl is a palmitoylated pentapeptide investigated for its regulatory effects on extracellular matrix synthesis and dermal signaling.

Pentapeptide-18 (Leuphasyl)

Pentapeptide-18 (Leuphasyl) is a research peptide derived from the enkephalin sequence, designed to study neuromodulatory mechanisms.

Vialox (Pentapeptide-3V)

Synthetic Pentapeptide

Vialox (Pentapeptide-3V) is a research peptide designed as a synthetic pentapeptide analog modeled after snake venom proteins.

Pinealon

Pinealon is a synthetic tripeptide investigated for its potential to regulate neuronal differentiation and oxidative-stress responses.

Vilon

Vilon is a short research peptide derived from thymic extracts, known for its role in gene expression modulation studies.

Bronchogen

Bronchogen is a short tetrapeptide examined in laboratory research for its association with bronchial tissue and lung-related cellular systems.

Prostamax

Prostamax is a peptide bioregulator derived from prostate tissue extracts that modulates peptide-mediated regulation of cell differentiation and proliferation.

GHK-Cu

GHK-Cu is a research peptide composed of the tripeptide sequence Gly-His-Lys bound to copper(II) ions, studied for its role in extracellular matrix modulation and cellular signaling.

CJC-1295 + GHRP-2 Blend

A compounded blend of CJC-1295 (GHRH analogue) and GHRP-2 (ghrelin receptor agonist) for synergistic growth hormone stimulation through complementary receptor pathways.

B7-33

Relaxin-family peptide analog

B7-33 is a single-chain relaxin-family peptide analog designed to selectively activate the RXFP1 receptor.

Tissue Repair & Recovery

BPC-157

Synthetic Fragment

Research peptide studied for tissue repair and gut health.

Pentadecapeptide

Body Protection Compound

15-amino acid peptide related to BPC-157 used for tissue repair and recovery.

IGF-1 LR3

IGF-1 Analogue

IGF-1 LR3 (Long R3 Insulin-like Growth Factor-1) is a modified 83-amino acid analogue of IGF-1 with an N-terminal arginine extension and Glu3→Arg3 substitution, conferring a half-life of approximately 20–30 hours versus 12–15 minutes for native IGF-1.

MGF

IGF-1 Splice Variant

Mechano Growth Factor (MGF) is an alternatively spliced form of the IGF-1 gene expressed locally in muscle tissue following mechanical stretch or damage, promoting satellite cell activation and muscle repair.

KPV

Alpha-MSH Fragment

KPV (Lys-Pro-Val) is a C-terminal tripeptide of alpha-melanocyte stimulating hormone (α-MSH) that retains the anti-inflammatory and gut-healing properties of the parent peptide while being resistant to peptidase degradation. It has demonstrated efficacy in inflammatory bowel disease models.

Tri-Heal

Tri-Heal is a compounded triple-peptide repair blend combining TB-500 (Thymosin Beta-4 fragment), BPC-157, and KPV for comprehensive anti-inflammatory and tissue regeneration support across musculoskeletal and gut tissues.

Follistatin 315

Follistatin 315 is a research peptide isoform of the follistatin protein that binds and neutralizes activins and myostatin.

Follistatin

Follistatin is a multifunctional glycoprotein studied for its role in growth factor signaling networks.

Follistatin 344

Follistatin 344 is a research peptide variant known to bind myostatin and activin-A, modulating TGF-β signaling.

PEG MGF

IGF-1 splice variant

PEG-MGF is a PEGylated splice variant of IGF-1 designed to extend peptide stability and half-life for research applications.

KPV (Ac-KPV-NH2)

KPV is a synthetic tripeptide fragment derived from the C-terminal sequence of alpha-melanocyte-stimulating hormone (α-MSH).

ARA-290

ARA-290 is a synthetic research peptide engineered from the B-helix domain of erythropoietin.

LL-37

Host Defense Peptide

LL-37 is a cationic α-helical research peptide derived from the C-terminal region of human cathelicidin (hCAP18).

TB-500 Fragment (17-23)

TB-500 Fragment (17-23) is a research peptide derived from the actin-binding region of Thymosin Beta-4.

BPC-157, TB-500 (Blend)

The BPC-157 and TB-500 blend combines two well-characterized research peptides studied for their roles in cellular repair, angiogenesis, and tissue remodeling.

Hormone Optimization

HCG

Gonadotropin

Human chorionic gonadotropin (HCG) is an LH-analogous glycoprotein hormone produced during pregnancy. In men, it stimulates Leydig cell testosterone production, maintaining testicular size and function during exogenous testosterone therapy.

Kisspeptin-10

Neuropeptide involved in reproductive hormone regulation and sexual health.

HMG

Gonadotropin Mixture

Human menopausal gonadotropin (HMG) is a purified gonadotropin preparation derived from the urine of postmenopausal women, containing both FSH and LH activity. It is used primarily for fertility induction and restoration of spermatogenesis.

Oxytocin

Oxytocin is a 9-amino acid nonapeptide neuropeptide produced in the hypothalamic paraventricular and supraoptic nuclei, with wide-ranging effects on social bonding, anxiety, pain modulation, inflammation, and uterine/mammary function.

Gonadorelin

Gonadotropin-Releasing Hormone

Gonadorelin is a research peptide corresponding to the natural gonadotropin-releasing hormone (GnRH).

Pancragen

Pancragen is a peptide bioregulator derived from pancreatic tissue extracts studied for its role in modulating endocrine and exocrine gene expression.

GHRH

GHRH is a 44-amino acid hypothalamic research peptide that stimulates growth hormone release.

TRH Thyrotropin (Protirelin)

Hypothalamic regulatory peptide

Thyrotropin releasing hormone (TRH or Protirelin) is a research peptide that modulates pituitary secretion of thyrotropin (TSH) and prolactin.

Triptorelin (GnRH)

Gonadotropin-Releasing Hormone Analog

Triptorelin is a synthetic decapeptide analog of gonadotropin-releasing hormone (GnRH).

Cognitive Enhancement

Dihexa

Nootropic Peptide

Nootropic peptide studied for cognitive enhancement and neuroprotection.

Semax

Semax is a synthetic heptapeptide derived from the ACTH(4-10) fragment, used in research on neurotrophic and nootropic signaling.

PE-22-28

PE-22-28 is a research peptide derived from the C-terminal fragment of pituitary adenylyl cyclase-activating polypeptide (PACAP 1–38).

Fraternine

Venom-Derived Peptide

Fraternine is a peptide isolated from the venom of the social wasp Parachartergus fraternus, studied for its potential in neurodegeneration research.

Melanostatin DM

Melanostatin DM is a research peptide analog of the tripeptide Prolyl-Leucyl-Glycinamide (PLG), designed to study melanocyte-stimulating hormone (α-MSH) receptor modulation.

Selank

Selank is a synthetic research peptide derived from the natural tuftsin sequence.

Sexual Wellness

PT-141

Melanocortin Receptor Agonist

FDA-approved for hypoactive sexual desire disorder.

Melanotan II

Melanocortin Peptide

Synthetic melanocortin peptide studied for tanning, sexual dysfunction, and appetite suppression.

Melanotan 1 (MT1)

α-Melanocyte-Stimulating Hormone Analog

Melanotan I is a synthetic analog of α-melanocyte-stimulating hormone (α-MSH) used to study melanocortin receptor activation.

Immune Support

Thymosin Alpha-1

Thymosin Alpha-1 is a synthetic polypeptide consisting of 28 amino acids derived from the thymic hormone thymosin fraction 5.

Thymagen (Thymogen)

Thymic peptide

Thymogen is a synthetic dipeptide derived from thymic extracts with regulatory activity in preclinical research.

VIP 6mg

VIP (Vasoactive Intestinal Peptide) is a 28 amino acid neuropeptide that functions as a potent endogenous ligand for VPAC1 and VPAC2 receptors.

Other

Longevity, Performance & Obesity Research

A research peptide formulation developed to investigate metabolic regulation, mitochondrial function, and nutrient-sensing pathways.

Connected reading

Helpful context for this guide

Source-derived material selected through this article’s indexed topics.

Related questions

01A peptide identified in a fungus found in northern European pine forests possesses as much power as penicillin as well as vancomycin, according to an international team of researchers.

Reporting in the October 13 issue of Nature, a team from Denmark-based biotech company Novozymes, and researchers from Georgetown University Medical Center and the David Geffen School of Medicine at UCLA, say they have isolated "plectasin," the first defensin ever found in fungi. The research was performed at Novozymes laboratories in Denmark. Defensins are peptides, miniature protein molecules that are produced by a wide range of animals to protect themselves against infection. Humans have defensins in their white blood cells and in their skin, for example, but it is believed that this new fungal defensin, plectasin, is more potent and targets certain bacteria more specifically. Indeed, when plectasin was tested in the laboratory and in animals, it proved to be highly effective against the bacteria Streptococcus pneumoniae, and Streptococcus pyogenes, including strains that are now resistant to conventional antibiotics. These bacteria are responsible for such diseases as meningitis, community-acquired pneumonia, strep throat, life-threatening sepsis, and flesh destroying skin infections. The discovery of plectasin has implications for the development of defensins as a treatment against many common, and deadly, infections, and may initiate a new era of antibiotic discovery and development, said study co-author Michael Zasloff, M.D., Ph.D., Professor in the Departments of Surgery and Pediatrics at Georgetown University Medical Center. Zasloff says that the field of antibiotic development has not changed much since 1929 when Alexander Fleming realized that the fungal "bread mold" Penicillium, which had landed by chance in a Petri dish produced a substance that eliminated colonies of staphylococcal bacteria. "Most antibiotics used by humans are produced by fungi and certain soil bacteria," he said. "Using our existing tools of discovery, we have failed to uncover any new classes of antibiotics from these sources over the past decade. However, by utilizing a new genetic approach that allowed the team to discover plectasin, we now know that a whole class of antibiotics has been overlooked." "This finding (plectasin), and the existence of about 200,000 additional species of fungi, opens up a vast universe to explore for novel peptide antibiotics," said co-author Robert Lehrer, M.D., Distinguished Professor of Medicine at the David Geffen School of Medicine at UCLA. Plectasin, if proven safe and effective in humans, could be on the market by 2012, said Lehrer. Zasloff and Lehrer are known internationally as experts in antimicrobial peptides - the class of antibiotics that plectasin falls within - and in this study they collaborated with Novozymes, a Danish biotech company that led the research. Zasloff and Lehrer are the only two scientists from U.S. universities on the team of 20 researchers who co-authored the research paper. All life forms have to defend themselves against microbial invaders - bacteria, fungi, viruses - and to do this, they produce antimicrobial defensin peptides. In humans, defensins are made by specific white blood cells and immune cells that later engulf foreign invaders, and by the skin and mucous membranes, in order to kill microbes before they invade protective barriers. Researchers believe that fungi have a similar system of defense, especially since these plant-like organisms live off rotting matter, said Zasloff. "They must compete with other organisms, like bacteria and viruses, which also want to consume the same meal. In addition, they need to defend themselves from being eaten by the microbes which surround them." But he said no one had been able to find defensins in fungi using traditional research techniques, which involved growing fungi in liquid cultures and then testing the culture to see if it contained any antibiotic molecule. The research team instead used the latest genetic science to search for the defensins they thought fungi must have. Selecting the Pseudoplectania nigrella species of fungus may have been serendipitous, Lehrer said, but the Novozymes team used state-of-the-art biotechnology to intercept ,and interpret its genetic messages and exhibited tremendous skill in producing plectasin efficiently, economically, and in large amounts." "I started working on antimicrobial peptides over three decades ago, said Lehrer, and my laboratory first described human defensins in 1985. So, the discovery of plectasin makes me feel like a grandfather." Further examination revealed that this defensin, plectasin, resembles defensins found in spiders, scorpions, dragonflies and mussels - thus suggesting that the defensins found in insects, molluscs and fungi arose from a common ancestral gene, the researchers say. Based on this information, the scientists now believe that defensins appeared in living things more than a billion years ago. The investigators then turned to the National Center for Antimicrobials and Infection Control, the Danish equivalent of the U.S. Centers for Disease Control, to test plectasin in the laboratory for antimicrobial activity against a broad spectrum of bacteria. It showed potent activity against several species of Gram-positive bacteria, and was especially active against S. pneumoniae (the leading cause of pneumonia), including all known clinical strains and those that are now resistant to conventional antibiotics. "That is important because increasing bacterial resistance to conventional antibiotics threatens the future of many antibiotics in current use," Zasloff said. "In mouse studies, plectasin showed extremely low toxicity, and was as effective as vancomycin and penicillin in curing the animals of experimental peritonitis (inflammation of the lining of the abdominal cavity, which can be deadly) and pneumonia caused by S. pneumoniae, the researchers report. "Although the precise mechanism by which plectasin exerts its antimicrobial activity is still under investigation, it may work by a mechanism that is very different from traditional antibiotics, Zasloff said. "As a group, defensins exhibit activity against many types of bacteria, fungi, protozoa, and even viruses. It is entirely possible that fungal defensins will be discovered that could be developed against all of these human pathogens," Zasloff added.

Source: www.news-medical.net ↗

02What is the concept of the immune self, and how has it evolved over the decades?

Adaptive immunity is the ability of specific lymphocytes to differentiate between self and non-self (foreign) antigens and defend the body by selectively destroying non-self-peptides. This concept is possibly the most crucial factor in several immunological medical domains and is increasingly being explored across cancer immunotherapy, vaccine design, pathogen identification, and autoimmune disorders (including allergies). A growing body of literature elucidates the importance of peptides, short amino acid chains linked via peptide bonds, in providing the adaptive immune system with the information required to effectively distinguish between self and non-self particles. This has resulted in the proposal of the ‘immune self’ concept, which postulates that self-similarity is a fundamental determinant of immune recognition. First introduced by Frank MacFarlane Burnet in 1949, the immune self-concept and its sister, the self-nonself theory, have substantially evolved over the decades. Initially driven by observations from Medawar’s early transplantation experiments, Nils K. Jerne (1974; eigen-behavior theory), Polly Matzinger (1994; danger theory), and most recently, evidence from research conducted independently by Waldmann, Mitchison, and Janeway has refined the immune self-concept from ‘all body elements are self, and foreign elements are non-self’ to the most recent ‘infectious non-self (foreign and usually harmful) versus noninfectious self (safe) elements.’

Source: www.news-medical.net ↗

03What roles does the system play?

The endogenous opioids and their receptors are widely distributed throughout the central and peripheral nervous systems, particularly the parts of these systems that regulate pain, emotion, reward, stress responses, motivation, drug addiction, and autonomic control. The differential expression and location of the various receptor subtypes across different neurons account for the wide range of opioid-related behaviors. The activation of µ-opioid receptors is mainly known for playing a role in pain relief. Still, research has also indicated it may be involved in behaviors related to survival, such as appetite and reproduction. The activity of µ-opioid receptors is also known to play a critical role in responses to social stimuli by modulating responses to social rejection or social acceptance, for example. Activation of the δ-opioid receptors and κ-opioid receptors is also known to be involved in pain modulation. Also, studies have shown that NOP activation is involved in pain mechanisms and several behaviors related to psychological stress. Alterations in the endogenous opioid system are suspected to be involved in Parkinson's disease, seizures, neuroprotective mechanisms, and depression.

Source: www.news-medical.net ↗

04What are functional peptides?

Conventional pharmacological studies on spices have traditionally focused on secondary metabolites like polyphenols, alkaloids, and terpenes. More recently, food science research has also examined spice proteins and their enzymatic hydrolysates, using proteomic methods such as liquid chromatography–tandem mass spectrometry (LC-MS/MS) to identify short bioactive peptide sequences released from larger precursor proteins.6 Once released during food processing, fermentation, or gastrointestinal digestion, these functional peptides can act as metabolic regulators, antimicrobials, or antioxidants.1 Functional peptides refer to specific protein fragments that, once released from their parent proteins, exert biological activities.1,2 In the context of foods, these activities are most often demonstrated using in vitro biochemical or cell-based assays, and their physiological relevance depends on bioavailability and dose.2 Unlike intact proteins, which can have the potential to be allergenic or difficult to absorb due to their complex tertiary structures, functional peptides may exhibit improved bioaccessibility, and some small peptides can cross the intestinal epithelial barrier via peptide transport systems. However, absorption efficiency varies substantially by peptide sequence and digestive conditions.6 Nutriomics and mechanistic investigations have established that the bioactivity of a peptide is dictated by its physicochemical properties, particularly its amino acid composition, molecular weight, and net charge. For example, the presence of hydrophobic amino acids like proline, leucine, and valine often correlates with high antioxidant and enzyme-inhibitory activity.2,3 Smaller peptides, typically those less than three kilodaltons (kDa) in size, exhibit greater stability against proteolytic degradation in the gastrointestinal tract.3 Moreover, cationic peptides are particularly effective as antimicrobial agents through their electrostatic interactions with bacterial membranes.3

Source: www.news-medical.net ↗

05How do these peptides act?

These peptides, like the parent compound AC253, acted as antagonists at the AMY receptor. They were also resistant to protein breakdown, and crossed the blood-brain barrier easily when injected into the abdominal cavity, to localize in the hippocampus, which is crucial in memory. These peptides protected the brain against beta-amyloid injury, and normalized the AD-associated impairment of the memory-associated long-term potentiation of nerve impulses in the hippocampus. They improved memory testing results, and reduced the level of inflammation in the brain. These effects appear to be mediated via the blockade of AMY receptors. For instance, inhibition of microglial AMY receptors reduce the activation of the inflammasome NLRP3. This reduces the secretion of inflammatory chemicals in the surrounding brain tissue, which offers another mechanism for lower amyloid production. In addition, these peptides increase the rate of outflow of amyloid beta from the brain, which also contributes to a lower level of amyloid after treatment. These marked changes all occurred within a relatively short span of treatment. A very important additional finding was that treatment with these peptides brought about improvement in mice which were showing signs of well-established AD in the brain as well as in their behavior. This is unique in that most therapies fail to affect the progress of AD once it has begun to manifest clinically. Peptides also have fewer off-target effects. Small molecules are easy to administer, inexpensive to make and cross the blood-brain barrier more rapidly. For this reason, the team resorted to computational tools and artificial intelligence to come up with a new small molecular drug based on these peptides. This can be taken orally, and is similar in size and structure to the medications used for medical conditions like high blood pressure. An optimized version is being developed to enable human trials to be conducted. The work so far has taken about two decades, building step upon painstaking step to come up with the right solution. However, says Jhamandas, “Occasionally you come across a discovery that has the potential to change the game in a very fundamental way, like hitting a home run, and I'm very excited that we are really on to something here.” Short amylin receptor antagonist peptides improve memory deficits in Alzheimer’s disease mouse model. Rania Soudy, Ryoichi Kimura, Aarti Patel, Wen Fu, Kamaljit Kaur, David Westaway, Jing Yang & Jack Jhamandas. Scientific Reports, volume 9, Article number: 10942 (2019). https://doi.org/10.1038/s41598-019-47255-9. https://www.nature.com/articles/s41598-019-47255-9

Source: www.news-medical.net ↗

comparison

Comparisons

Side-by-side pages for commonly compared peptides and research compounds.

Source: peptideuniv.com

About the author

Peptide Therapy Guide Editorial Team

Editorial team for Peptide Therapy Guide.

View all articles →