Peptide Research Encyclopedia: Structures, Biological Pathways & Experimental Use
Research Peptide Overview
Research Peptides: Structure, Applications, Targets & Protocols
Peptides are short chains of amino acids that act as messengers and building blocks throughout biology. In controlled research environments, specific synthetic and naturally derived peptides are being studied for their potential impact on metabolic regulation, body composition, tissue repair, immune balance, and cognitive performance.
The overview below highlights key characteristics of widely referenced research peptides: molecular structure features, primary application focus, the biological targets or pathways of interest, and how dosing is typically approached in research settings.
Peptides listed in alphabetical order
Metabolic, healing, immune & nootropic focus
High-level, research-only information
Side-by-Side Research Peptide Comparison
This table is designed like a “graph” view: peptides are listed vertically on the left, with core research categories running horizontally across the top. All descriptions are generalized and not exhaustive.
Metabolic & Body Composition
Growth Hormone & Anabolic Axis
Healing, Immune & Mitochondrial Support
Nootropic & Neuroprotective Focus
| Peptide | Structure | Application | Pathways | Approach |
|---|---|---|---|---|
| 5 Amino Small molecule / peptide-like analog Metabolic | Low molecular weight compound often described as a modified amide structure designed to influence cellular energy balance and adipocyte signaling. | Studied for potential effects on adipocyte lipolysis, fat mass, and metabolic rate in cell and animal models. | Cellular energy sensors, adipocyte signaling cascades, and pathways related to lipid storage and mobilization. | Preclinical models use varied dose ranges and schedules; investigators typically adjust exposure based on species, body mass, and study duration. |
| 9 ME BC 9-Methyl-β-carboline analog Nootropic | Heterocyclic β-carboline derivative rather than a classic peptide; lipophilic ring structure with a methyl substitution at the 9-position. | Investigated for potential support of dopaminergic neurons, cognitive performance, and neuroprotection in experimental models. | Dopaminergic signaling, mitochondrial function, and neurotrophic factors in the central nervous system. | Research typically employs low oral or parenteral doses with gradual titration; protocols vary widely between laboratories and are not standardized. |
| Adipotide Targeted pro-apoptotic peptidomimetic Metabolic | Chimeric peptidomimetic combining an adipose-vasculature–targeting sequence with a pro-apoptotic domain designed to localize to fat cell blood vessels. | Studied for selective effects on white adipose tissue vasculature and fat mass reduction in preclinical models. | Prohibitin/ANXA2-associated receptors on adipose vasculature, apoptotic signaling cascades, and adipocyte survival. | Animal studies employ tightly controlled dosing windows and course length due to potency; there is no standardized or generalized regimen. |
| AOD 9604 Fragment of HGH (176-191) Metabolic | Short peptide fragment derived from the C-terminal region of human growth hormone, retaining sequences linked to lipolytic signaling. | Studied for potential impact on fat metabolism and body-composition-related outcomes in research settings. | Adipocyte receptors, lipolysis pathways, and secondary messengers linked to fat mobilization. | Subcutaneous administration is common in models; researchers adjust frequency and dose based on species, experimental goals, and combination with other agents. |
| BAM 15 Mitochondrial uncoupler Mitochondrial | Small molecule mitochondrial protonophore; not a classical peptide but often grouped with advanced research compounds. | Explored for effects on mitochondrial uncoupling, energy expenditure, and metabolic regulation in preclinical studies. | Mitochondrial inner membrane, proton gradient, and oxidative phosphorylation efficiency. | Animal models use carefully titrated doses due to potency; dosing windows are tightly controlled and highly protocol-specific. |
| BPC 157 15-amino-acid gastric peptide fragment Healing | Linear pentadecapeptide derived from a protective protein in gastric juice, composed entirely of L-amino acids. | Studied for potential support of tendon, ligament, gut, and tissue repair processes in various animal models. | Angiogenic signaling, nitric oxide pathways, and local tissue repair cascades involving fibroblasts and endothelial cells. | Research may use oral, intraperitoneal, or subcutaneous administration; concentrations and duration differ widely by model and tissue of interest. |
| Cagrilinitide Amylin analog Metabolic | Synthetic long-acting amylin analog with amino acid modifications and lipidation to extend half-life and bioavailability. | Investigated for appetite modulation, satiety signaling, and weight-related metabolic research. | Amylin receptors in the CNS and periphery; interacts with pathways coordinating satiety, gastric emptying, and energy balance. | Typically administered via subcutaneous injection in long-acting formats within preclinical and clinical protocols, with study-specific titration. |
| Cerebrolyson Peptide & amino acid mixture Neuro | Complex mixture of low molecular weight neuropeptides and amino acids derived from porcine brain tissue. | Studied for neuroprotective and neurotrophic effects, including cognitive performance and recovery after neural injury. | Neurotrophic pathways, synaptic plasticity, and neuronal survival signaling. | Research commonly uses parenteral administration courses over defined cycles; dose and duration are determined by investigators and study endpoints. |
| CMS 121 Small molecule, neuroprotective candidate Neuro | Non-peptidic small molecule structurally based on flavonoid derivatives with enhanced brain-penetrant properties. | Investigated for mitigating neurodegenerative processes, oxidative stress, and cognitive decline in preclinical models. | Oxidative stress pathways, mitochondrial function, and inflammatory cascades in neural tissue. | Dosing in research is tailored to animal species and model type, often via oral or injection routes, with careful monitoring for neurobehavioral outcomes. |
| Dihexa Angiotensin IV-derived hexapeptide Nootropic | Modified hexapeptide derived from angiotensin IV with lipophilic modifications to enhance blood–brain barrier penetration. | Studied for potential promotion of synaptogenesis, cognitive function, and memory enhancement in experimental models. | HGF/c-Met signaling, synaptic plasticity, and pathways involved in learning and memory. | Research protocols vary, frequently using very low doses due to potency; route and schedule are chosen by the study team. |
| DSIP Delta Sleep-Inducing Peptide Sleep | Natural nonapeptide originally isolated from brain tissue, composed of nine amino acids in a specific sequence. | Investigated for modulatory effects on sleep architecture, stress response, and endocrine balance. | GABAergic and other neuroendocrine pathways associated with sleep regulation and stress adaptation. | Experimental designs have used parenteral administration around rest periods; exact amounts and timing are model-dependent. |
| Epithalon Tetrapeptide (Ala-Glu-Asp-Gly) Longevity | Synthetic tetrapeptide corresponding to a segment of the pineal gland peptide epithalamin. | Studied for potential effects on telomerase activity, oxidative stress, and age-related physiological markers. | Telomere maintenance pathways, antioxidant defenses, and circadian-related endocrine signaling. | Research protocols have used cyclical courses with defined durations; dosing strategy varies significantly by study and organism. |
| FOX04 DRI Peptide FOXO4-p53 interaction inhibitor Senolytic | Synthetic peptide that mimics a region of FOXO4, designed to disrupt binding with p53 in senescent cells. | Explored as a senolytic candidate for selectively influencing senescent cell survival in experimental models. | FOXO4-p53 axis, cellular senescence pathways, and apoptosis regulators. | Preclinical studies carefully control dose and exposure due to targeted cell-selective effects; no standardized regimen exists. |
| GHK-CU Tripeptide-copper complex Skin / Healing | Gly-His-Lys tripeptide that binds copper ions, forming a physiologic peptide-metal complex. | Studied for support of skin remodeling, wound repair, hair health, and extracellular matrix integrity. | Collagen synthesis, metalloproteinase modulation, and local inflammatory signaling in skin and connective tissues. | Topical, injectable, and in vitro protocols vary in concentration and contact time; investigators tailor conditions to tissue type and endpoints. |
| GHRP 2 Growth Hormone Releasing Peptide-2 GH Axis | Synthetic hexapeptide ghrelin receptor agonist that stimulates growth hormone release from the pituitary. | Studied for GH secretion, body composition changes, and potential anabolic effects in experimental models. | Ghrelin (GHS-R1a) receptors, pituitary somatotrophs, and downstream IGF-1 signaling pathways. | Intermittent dosing schedules are common in research; frequency and amount are customized to species and combination with GHRH analogs. |
| GHRP 6 Growth Hormone Releasing Peptide-6 GH Axis | Hexapeptide GH secretagogue structurally related to GHRP-2 with slightly different receptor binding profile and side-chain composition. | Investigated for GH release, appetite modulation, and anabolic-leaning effects in animal and in vitro models. | Ghrelin receptors, pituitary GH release, and peripheral appetite regulation centers. | Research use typically features multiple daily or cyclical exposures; protocols vary across models and should not be generalized. |
| GLOW Brand-specific peptide blend Skin | Typically a formulated blend of cosmetic / regenerative peptides aimed at skin texture, tone, and hydration research. | Investigated for cosmetic and dermal support, including fine lines, texture, and brightness outcomes in topical studies. | Dermal fibroblasts, collagen and elastin regulation, and superficial inflammatory pathways. | Applied topically or in localized research models at defined concentrations; regimen design is determined by formulation and study goals. |
| IGF LR3 Long R3 Insulin-Like Growth Factor-1 Anabolic | Modified IGF-1 analog with a 13-amino-acid extension and substitutions that reduce binding to IGF binding proteins and prolong activity. | Studied for muscle growth, cell proliferation, and metabolic effects in preclinical models. | IGF-1 receptors, PI3K/Akt/mTOR pathways, and anabolic signaling cascades. | Dosing in research is carefully titrated due to potent proliferative signaling; exposure time and amount are tightly controlled. |
| Ipamorelin Selective GHS-R agonist GH Axis | Pentapeptide growth hormone secretagogue with high selectivity for ghrelin receptors and minimal effect on other pituitary hormones. | Investigated for GH release, body composition, and potential synergy with GHRH analogs in research models. | Ghrelin receptor activation, pituitary GH secretion, and downstream IGF-1 pathways. | Often used in combination protocols in research; timing and amount are defined per study design and co-administration strategy. |
| Kisspeptin Neuropeptide family (Kiss1) Reproductive | Peptide family (most commonly Kisspeptin-10 or -54) derived from the Kiss1 gene, acting on GPR54 receptors. | Studied for regulation of GnRH, LH/FSH secretion, and reproductive endocrine function. | Hypothalamic GnRH neurons, GPR54 (Kiss1R) receptors, and HPG axis signaling. | Research dosing varies with species and reproductive endpoints; short courses or acute challenges are common in experimental setups. |
| KPV Lys-Pro-Val tripeptide Anti-Inflammatory | Tripeptide fragment derived from the C-terminus of alpha-MSH. | Investigated for local anti-inflammatory and barrier-support effects in gut and skin models. | Melanocortin-related pathways, NF-κB signaling, and epithelial barrier integrity. | Used orally, topically, or parenterally in research; concentration and exposure time are tailored to tissue and model. |
| LL37 Human cathelicidin antimicrobial peptide Immune | 37-amino-acid cationic peptide derived from the human cathelicidin hCAP-18. | Studied for antimicrobial, immunomodulatory, and wound-healing properties in vitro and in vivo. | Innate immune pathways, microbial membranes, and chemotactic signaling for immune cells. | Experimental use often employs localized or systemic exposure at carefully controlled concentrations due to potent biological activity. |
| MK 677 Ibutamoren, non-peptidic GHS-R agonist GH Axis | Small molecule ghrelin receptor agonist structurally distinct from peptides but functionally similar to GH secretagogues. | Studied for GH and IGF-1 elevation, body composition, and potential anabolic effects. | Ghrelin receptors in the pituitary and hypothalamus, GH/IGF-1 axis. | Research commonly uses oral administration over extended periods; dose levels and timing depend on species and co-variables. |
| Melanotan 2 α-MSH analog Pigmentation | Cyclic heptapeptide analog of alpha-melanocyte-stimulating hormone with enhanced stability. | Studied for effects on skin pigmentation, sexual function, and appetite in research settings. | Melanocortin receptors (MC1R, MC3R, MC4R, MC5R) in skin and CNS. | Research use often involves intermittent subcutaneous administration; exposure is carefully monitored due to multi-system effects. |
| MOTSC MOTS-c mitochondrial-derived peptide Metabolic | 16-amino-acid peptide encoded by mitochondrial DNA, endogenous to mammalian cells. | Investigated for effects on insulin sensitivity, exercise capacity, and metabolic homeostasis. | AMPK activation, metabolic stress responses, and mitochondrial signaling. | Animal studies use parenteral routes and controlled course lengths; dose selection is model-specific. |
| NAD Nicotinamide adenine dinucleotide Cellular Energy | Redox cofactor composed of adenine, nicotinamide, ribose, and phosphate groups; not a peptide but frequently paired with peptide research. | Studied for roles in cellular energy metabolism, sirtuin activity, DNA repair, and healthy aging. | NAD+/NADH redox cycling, sirtuins, PARPs, and mitochondrial function. | Research uses oral precursors, IV, or cell-culture supplementation; dosing and frequency depend on the experimental platform. |
| Oxytocin Nonapeptide hormone Neuro / Social | Nine-amino-acid cyclic peptide hormone produced in the hypothalamus and released from the posterior pituitary. | Studied for roles in social bonding, stress modulation, and various neuroendocrine functions. | Oxytocin receptors in CNS and peripheral tissues; interacts with limbic and autonomic systems. | Research employs intranasal, IV, or other routes at tightly controlled doses tailored to behavioral and physiological endpoints. |
| P21 Nootropic peptide analog Nootropic | Short peptide sequence sometimes modified with lipophilic groups to improve brain penetration. | Investigated for potential benefits to learning, memory, and neuroplasticity in early-stage research. | Neurotrophic signaling, synaptic plasticity, and neuronal survival pathways. | Experimental protocols are exploratory; dosing and duration vary and are not standardized across labs. |
| PE 22-28 Peptide fragment 22-28 Nootropic | Short peptide fragment derived from a larger parent protein, often researched alongside P-series peptides. | Studied for neuroprotective and cognitive-supportive properties in preclinical research. | CNS receptors and signaling networks associated with learning and memory. | Dosing in research is usually low and titrated; regimen depends heavily on model and co-administered agents. |
| Pinealon Tripeptide (Glu-Asp-Arg) Neuro / Longevity | Synthetic tripeptide associated with pineal gland regulatory peptides. | Investigated for neuroprotective effects, cognitive support, and age-related functional markers. | CNS antioxidant defenses, mitochondrial stability, and epigenetic regulation in neural tissue. | Research exposures are usually cyclical with defined courses; dose is determined by investigators and study design. |
| PNC 27 p53-derived peptide Oncologic Research | Peptide derived from the HDM-2 binding domain of p53, designed to interact with abnormal cell membranes. | Studied for selective cytotoxicity toward certain cancer cell lines in vitro and animal models. | p53-related signaling, aberrant membrane composition, and apoptotic pathways. | Dosing and exposure in research are highly controlled due to targeted cytotoxic effects; no generalized protocol. |
| PT-141 Bremelanotide, melanocortin agonist Sexual Health | Cyclic heptapeptide melanocortin receptor agonist derived from Melanotan-2 structure. | Studied for sexual function and arousal pathways, independent of nitric oxide. | Melanocortin receptors in CNS regions governing arousal and reward. | Research uses intermittent dosing with careful monitoring of cardiovascular and systemic responses; specifics vary by protocol. |
| Retatrutide Triple agonist (GIP/GLP-1/Glucagon) Metabolic | Multi-agonist peptide engineered to engage GIP, GLP-1, and glucagon receptors with extended half-life. | Studied for combined effects on weight-related outcomes, glycemic control, and energy expenditure. | GIP, GLP-1, and glucagon receptors in pancreatic and central metabolic circuits. | Once-weekly-style regimens are common in research, but dose and titration schemes are study-specific and investigator-defined. |
| Selank Heptapeptide Tuftsin analog Anxiolytic / Nootropic | Synthetic heptapeptide derived from the immunomodulatory peptide tuftsin, modified for stability. | Studied for anxiolytic, nootropic, and neuroprotective properties. | GABAergic modulation, BDNF expression, and immune-neuro interface signaling. | Intranasal and parenteral routes are used in research; concentration and duration differ by model and endpoint. |
| Semaglutide GLP-1 receptor agonist analog Metabolic | 31-amino-acid GLP-1 analog with a fatty acid side chain to increase albumin binding and extend half-life. | Studied for glucose control, appetite regulation, and weight-related metabolic research. | GLP-1 receptors in pancreas, gut, and CNS, influencing insulin secretion, gastric emptying, and satiety. | Research generally uses long-acting, once-weekly-type exposure with gradual titration; specific dose levels are protocol-dependent. |
| Semax ACTH(4-7) Pro-Gly-Pro analog Nootropic | Heptapeptide derivative of adrenocorticotropic hormone fragment (4-7) with Pro-Gly-Pro extension. | Studied for cognitive support, neuroprotection, and modulation of stress responses. | BDNF expression, antioxidant defense pathways, and neuroplasticity networks. | Often delivered intranasally in research; frequency and course length depend on experimental objectives. |
| Sermorelin GHRH (1-29) analog GH Axis | 29-amino-acid fragment of growth hormone–releasing hormone with activity at GHRH receptors. | Studied for stimulation of endogenous GH release and related metabolic and body composition effects. | GHRH receptors in the anterior pituitary, GH/IGF-1 axis signaling. | Research uses intermittent subcutaneous dosing, sometimes combined with GHS peptides; regimens vary widely. |
| SLU PP 331 Metabolic small molecule candidate Metabolic | Non-peptidic research compound targeting metabolic pathways, often investigated as a lipolysis or energy-modulating agent. | Evaluated for obesity, lipid metabolism, and energy expenditure in animal models. | Pathways related to β-adrenergic or thermogenic signaling (model-dependent). | Dose-finding studies are common; no uniform or standardized dosing scheme exists in the literature. |
| ss31 Mitochondria-targeted tetrapeptide Mitochondrial | Aromatic-cationic tetrapeptide (D-Arg-Dmt-Lys-Phe-NH2) designed to concentrate in the inner mitochondrial membrane. | Studied for protection against mitochondrial oxidative damage and improvement of cellular energetics. | Electron transport chain stability, cardiolipin interaction, and ROS reduction. | Research employs IV or other systemic administration with controlled infusion or bolus; dosing is tailored to organ system and model. |
| TB 500 Thymosin β4 fragment analog Healing | Synthetic peptide modeled on a portion of thymosin β4, a 43-amino-acid actin-binding protein. | Studied for support of tissue repair, angiogenesis, and recovery from musculoskeletal injury. | Actin cytoskeleton dynamics, cell migration, and angiogenic signaling. | Research regimens often start with a loading phase followed by maintenance exposure; specific patterns are experiment-specific. |
| Tesamorelin GHRH (1-44) analog GH Axis | Synthetic 44-amino-acid peptide analog of GHRH with substitutions for improved stability and activity. | Studied for GH secretion, visceral adiposity changes, and lipid profile modulation. | GHRH receptor activation, GH/IGF-1 axis, and downstream metabolic pathways. | Typically used as a once-daily subcutaneous exposure in research; actual dose levels and duration are protocol-defined. |
| Tesofensine Triple monoamine reuptake inhibitor Metabolic / CNS | Non-peptidic small molecule that inhibits reuptake of serotonin, norepinephrine, and dopamine. | Investigated for appetite suppression, weight-related outcomes, and CNS effects. | Monoamine transporters (SERT, NET, DAT) in the CNS. | Oral dosing in research is model-specific; titration is typically cautious due to CNS activity. |
| Thymosin Alpha 1 28-amino-acid thymic peptide Immune | Synthetic copy of a natural thymic peptide consisting of 28 amino acids. | Studied for immune modulation, T-cell function, and antiviral/anticancer adjunctive research. | T-cell maturation, cytokine regulation, and innate/adaptive immune crosstalk. | Research uses subcutaneous or parenteral administration in courses; protocols depend on the immune-related model. |
| Thymulin Nonapeptide thymic factor Immune | Nine-amino-acid peptide that forms a complex with zinc, produced by thymic epithelial cells. | Studied for T-cell differentiation, immune balance, and potential anti-inflammatory effects. | Thymic hormone signaling, T-cell receptor maturation, and cytokine networks. | Dosing regimens in research vary; typically used in cyclical courses with specific immune readouts. |
| Tirzepatide Dual GIP / GLP-1 receptor agonist Metabolic | 39-amino-acid peptide with a fatty-acid side chain, engineered to agonize both GIP and GLP-1 receptors. | Studied for synergistic effects on glycemic control and weight-related metabolic outcomes. | GIP and GLP-1 receptors in pancreas and CNS, influencing insulin, glucagon, and satiety pathways. | Long-acting subcutaneous regimens with gradual escalation are typical in research; exact parameters depend on the trial design. |
*All dosing information above is intentionally high-level and non-specific. It reflects how protocols are generally structured in the literature (route, frequency concepts, and titration approach), not numeric instructions. These compounds are for controlled laboratory research only, not for human or veterinary use, diagnosis, treatment, or cure.
Frequently Asked Questions About Research Peptides
What are research peptides?
Research peptides are purified amino acid sequences and related compounds that are supplied strictly for controlled laboratory use. They are used in cell, tissue, and animal models to explore how specific signaling pathways, hormones, and receptors behave under different conditions.
Are these peptides medications or supplements?
No. The peptides listed here are not approved drugs, supplements, or therapies. They are sold and labeled for research use only. They are not intended for human or veterinary administration, and nothing on this page should be interpreted as medical advice or usage guidance.
Why do different studies use different dosing protocols?
Each research group designs its own protocol based on the model (cell, animal), the endpoint being studied, and safety considerations. As a result, there is no single “correct” protocol for a given compound, and numeric dosing ranges are highly context-dependent.
How should I choose peptides for my research?
Many investigators start by defining their primary outcome—such as metabolic, neurocognitive, immune, or tissue-repair endpoints—then select peptides that target those pathways. Reviewing peer-reviewed literature and ensuring compliance with all local regulations and institutional guidelines is essential before designing any experiment.