Research peptides
Research peptides such as BPC-157, TB-500, GHK-Cu and epitalon: what the human and animal evidence shows, its limits, safety signals and legal status.
This section brings together investigational peptides such as BPC-157, medicines with licensed uses in specific conditions such as tesamorelin and oxytocin, and non-peptide compounds discussed alongside them. 5-Amino-1MQ and MK-677 are not peptides. Inclusion does not imply a shared licensing status or evidence level.
Each guide separates animal from human data, states participant numbers and whether there was a control group when human studies exist, and summarizes FDA categorization decisions and the legal position in Türkiye.
These guides provide no personal dosing, preparation, injection-technique or sourcing instructions. The aim is to show which evidence the claims circulating on social media actually rest on, and the known risks: purity, endotoxin, immune response and the absence of long-term data. Inclusion here does not mean a peptide is safe or effective; it means enough questions are asked about it that seeing the evidence in one place is useful.
5-Amino-1MQ
- NNMT enzyme: NNMT converts nicotinamide (a form of vitamin B3) to 1-methylnicotinamide by adding a methyl group; 5-amino-1MQ was developed as a selective inhibitor of this reaction.
- NAD+ and SAM: In fat cell culture, NNMT inhibitors increased intracellular NAD+ and S-adenosylmethionine (SAM) levels and reduced fat synthesis; this is a cell finding.
ARA-290 (Cibinetide)
- Innate repair receptor: EPO drives blood cell production through an EPO receptor pair and tissue protection through a separate complex of the EPO receptor and CD131 (β-common receptor); ARA-290 was designed to target this second pathway.
- Blood cell production: In animal and cell experiments, the 11-amino-acid peptide was reported not to stimulate blood cell production; this finding has not been confirmed with long-term use in humans.
Cerebrolysin
- Composition: Short-chain peptides obtained enzymatically from porcine brain protein; because they are similar or identical to those naturally present in the body, their blood levels cannot be measured directly.
- Animal models: Effects on synaptic plasticity and learning in dementia and brain injury models, and on infarct volume and edema in ischemia models, have been reported; these are not evidence of clinical benefit in humans.
CJC-1295
- GHRH receptor: Increases growth hormone release by stimulating the GHRH receptor in the pituitary; the pulse pattern is preserved while the trough level rises.
- Albumin binding: Binds covalently to albumin in the blood after injection; natural GHRH breaks down within minutes, whereas CJC-1295 stays in circulation for days.
Dihexa
- Synapse formation: It was reported to increase dendritic spine and synapse formation in rat brain cell cultures; a notice of concern was added to the paper in 2021.
- HGF/MET signaling: The paper proposing that the effect runs through hepatocyte growth factor (HGF) and its receptor MET was retracted in 2025; the mechanism is not considered proven today.
DSIP
- Brain waves (animal): When given into the brain ventricles of rabbits, it was reported to increase the delta and spindle waves characteristic of deep sleep; this finding could not be translated into a sleep-regulating role in humans.
- Opioid system: According to the animal data compiled by FDA, the effects arise partly through the opioid system in the brain; dependence potential has not been studied.
GHRP-2 / GHRP-6 / Hexarelin
- Ghrelin receptor: GHRP-2 is a synthetic agonist that binds the receptor of ghrelin, a hormone produced in the stomach; GHRP-6 and hexarelin belong to the same peptide family.
- Growth hormone release: They trigger a brief, strong release of growth hormone from the pituitary; given together with GHRH, the effect is greater than the sum of the parts.
- Not selective: The same peptides can also raise prolactin, ACTH and cortisol; GHRP-2 increases appetite.
Gonadorelin / hCG
- Gonadorelin → pituitary: Makes the pituitary release LH and FSH. Physiologically it is released in short pulses every 60–120 minutes; when given repeatedly, at high doses, or continuously, it reversibly suppresses gonadotropin secretion.
- hCG → testis and ovary: Its biological effect resembles LH but lasts longer: in men it stimulates Leydig cells in the testis to increase testosterone production, and in women it increases estradiol and progesterone production.
HGH Fragment 176-191
- Structure: A 16-amino-acid synthetic fragment consisting of amino acids 177-191 of human growth hormone with a tyrosine added at the N-terminus.
- Fat metabolism (animal data): Reported to reduce weight gain and increase markers of fat breakdown in obese rats and mice; the molecular target and mechanism of action are unknown.
- Growth hormone receptor: In cell experiments, it did not bind to the growth hormone receptor and did not stimulate cell proliferation through the receptor.
Humanin
- Mitochondrial peptide: It is produced from a small open reading frame in mitochondrial DNA; depending on whether it is translated inside the mitochondrion or in the cytoplasm, it can be 21 or 24 amino acids long.
- Cell protection: In cell culture, it prevented nerve cell death caused by amyloid beta and Alzheimer’s-associated gene mutations; this effect depended on the peptide’s amino acid sequence.
IGF-1 LR3 / DES
- IGF-1 receptor: IGF-1 and its analogs bind to the IGF-1 receptor and start signals for growth, protein synthesis and cell proliferation; mecasermin also has an insulin-like blood-sugar-lowering effect.
- Binding proteins: LR3 and DES(1-3) derivatives bind more weakly to IGF binding proteins in the blood; for this reason they show stronger effects than native IGF-1 in cell and animal experiments.
Ipamorelin
- Ghrelin receptor: Releases growth hormone from the pituitary by stimulating the receptor that the hunger hormone ghrelin binds to (GHS-R1a); the effect starts as a single wave and fades within hours.
- Selectivity claim: In pigs and rats it did not markedly raise ACTH, cortisol or prolactin, unlike the older secretagogue peptides; this finding has not been confirmed with the same measurements in humans.
Kisspeptin-10
- GnRH neurons: Kisspeptin neurons in the hypothalamus regulate the pulsatile release of GnRH; GnRH in turn starts LH and FSH release from the pituitary.
- LH and testosterone: In healthy men, kisspeptin-10 raised LH within minutes and testosterone within hours; these measurements are short-term hormone responses.
- Continuous exposure: With prolonged uninterrupted administration, loss of response (tachyphylaxis) due to desensitization of the kisspeptin receptor has been reported.
KPV
- The tip of α-MSH: Described as the C-terminal tripeptide of α-MSH that retains its anti-inflammatory effect but does not carry its skin-darkening effect.
- A route other than melanocortin receptors: In mouse studies, its effect is explained not through melanocortin receptors but through suppression of IL-1β function; it was reported to enter intestinal cells via the PepT1 transporter. According to the FDA, its molecular target is still unknown.
LL-37
- Natural defense: Cleaved from the end of the human cathelicidin protein (hCAP18); it increases resistance to microbes, recruits inflammatory cells, and supports wound closure and new blood vessel formation.
- Response to own DNA: In psoriasis, LL-37 binds the body's own DNA and triggers interferon production in immune cells that normally do not respond; this has been described as a pathway that feeds autoimmunity.
Melanotan-1 / Melanotan-2
- Skin pigment: Afamelanotide binds mainly to the melanocortin-1 receptor and increases production of the dark pigment eumelanin independently of sun or UV light.
- Non-selective action (Melanotan II): Melanotan II stimulates multiple melanocortin receptors; besides skin pigmentation, central nervous system effects such as spontaneous erection and sexual arousal have also been reported.
MK-677 (Ibutamoren)
- Ghrelin mimetic: An orally active, non-peptide growth hormone secretagogue; it stimulates the pituitary through the ghrelin receptor.
- GH and IGF-1: With daily use, it raises growth hormone and IGF-1 levels; in older adults, these levels rose to the young adult range.
- Metabolism: Reduces insulin sensitivity, increases appetite and can cause fluid retention.
MOTS-c
- Energy sensing: In cell experiments it activates the AMPK pathway, which senses energy status.
- Muscle metabolism: Its effects on muscle glucose use and response to insulin are examined in mice.
Oxytocin
- Uterus: By stimulating oxytocin receptors in the uterine muscle, it triggers calcium release inside the cell and causes contraction; the number of receptors increases toward the end of pregnancy.
- Breast: It contracts the myoepithelial cells of the mammary gland and facilitates milk letdown.
- Kidney: Even in pure form it has a weak, vasopressin-like antidiuretic (water-retaining) effect; this is the reason for water intoxication with long-term high-quantity use.
Cosmetic peptides
- Signal peptides: Peptides such as palmitoyl pentapeptide-4 are designed to stimulate collagen production; the abstract of the 93-woman study does not report skin collagen measurement.
- Neurotransmitter-inhibiting peptides: Acetyl hexapeptide-8 disrupts, in the laboratory, the SNARE complex needed for release at nerve endings; whether it reduces muscle contraction when applied to the skin is not fully understood.
PT-141 (Bremelanotide)
- Melanocortin receptors: Bremelanotide stimulates multiple melanocortin receptors without selectivity; at therapeutic doses, the most important are MC4 receptors in the central nervous system and MC1 receptors on pigment cells. The mechanism by which it improves HSDD is unknown.
- Blood pressure and heart rate: After each dose, it transiently raises blood pressure and lowers heart rate; values mostly return to baseline within 12 hours.
Sermorelin
- GHRH receptor: It increases growth hormone secretion by stimulating the GHRH receptor in the anterior pituitary; it is the shortest synthetic peptide carrying the full biological activity of GHRH.
- IGF-1: The IGF-1 rise following the growth hormone increase has been measured in older adults; this is a laboratory value and does not imply clinical benefit.
SS-31 (Elamipretide)
- Cardiolipin: It binds cardiolipin, a phospholipid specific to the inner mitochondrial membrane, through electrostatic and hydrophobic interactions; the FDA prescribing information classifies the drug as a "mitochondrial cardiolipin binder."
- Cytochrome c and energy production: According to animal and cell studies, it prevents cardiolipin from turning cytochrome c into a peroxidase and preserves its electron transport function; this mechanism has not been directly shown in humans.
Tesamorelin
- GHRH receptor: It stimulates growth hormone release from the pituitary; this is followed by an IGF-1 increase.
- Visceral fat: Through the role of growth hormone in the formation and breakdown of fat tissue, it is expected to reduce intra-abdominal (visceral) fat; subcutaneous fat does not change markedly.
Thymosin alpha-1
- Immune modulation: According to the FDA assessment, its immune-regulating effect depends, at least in part, on interaction with Toll-like receptor 9 (TLR9) in dendritic cells and lymphoid precursor cells.
- Animal models: In rodent studies it was reported to suppress tumor growth and viral infections and to reduce sepsis; most of these studies used equivalent doses markedly higher than those used in humans.
VIP
- Vessel widening: VIP is a potent vasodilator; it owes its name and its discovery to this effect. When given systemically by the intravenous route it can cause a drop in blood pressure.
- Intestinal secretion: VIP increases chloride and water secretion through VPAC1 receptors in the intestinal mucosa; tumors that secrete VIP (VIPoma) cause severe watery diarrhea and low potassium.
- Smooth muscle relaxation: Aviptadil relaxes smooth muscle in the penis; together with phentolamine it facilitates erection after stimulation.
BPC-157
- Tissue repair: In animal experiments, effects on the repair processes of injured tissues are examined.
- Blood vessel and cell signals: Blood vessel formation and cellular repair signals are investigated in experimental models; no established role in humans has been shown.
Epitalon
- Telomeres: In cell experiments, its effect on the enzyme telomerase, which acts on telomeres, the ends of chromosomes, is investigated.
- Aging processes: Changes associated with aging are examined in animal and cell models; no established role in humans has been shown.
GHK-Cu
- Copper binding: The small peptide called GHK binds a copper ion to form the GHK-Cu complex.
- Connective tissue: Its effects on the renewal of collagen and other connective tissue components are studied.
- Tissue repair: Its relation to cells' repair responses is examined; these mechanisms do not prove the benefit of injection.
PNC-27
- Binding to HDM-2: The p53 portion of PNC-27 is designed to bind HDM-2, a protein reported to be present in the membrane of cancer cells; it was found at low or undetectable levels in the membrane of normal cell lines.
- Pore formation in the membrane: In laboratory studies, the peptide forms pores together with HDM-2 in the cancer cell membrane and causes the cell to break apart and die (necrosis); this mechanism has not been shown in humans.
Selank
- Anxiety response: In Russian clinical studies, it was compared with benzodiazepines in anxiety disorders; there are no placebo-controlled data.
- GABA system: Animal and cell studies examine its effects on genes and receptors that regulate GABA signaling; there is no mechanism confirmed in humans.
- Immune signals: Because it is a tuftsin analog, its effects on blood cytokine balance are investigated.
Semax
- Brain ischemia: In animal models, its effects on the size of ischemic damage and on nerve growth factors are examined; in humans there are only small Russian studies.
- Nerve growth factors: It has been reported to increase BDNF and NGF gene expression in rat brain; the clinical counterpart of this has not been shown.
- Clotting and pain: Anticoagulant and pain-threshold-raising effects are examined in rodents; the mechanisms are not well understood.
TB-500
- Cell movement: Derived from thymosin beta-4, which binds the cytoskeleton protein actin; the effects of the two molecules cannot be assumed to be the same.
- Tissue repair: Its possible effects on cell and tissue repair are being investigated; it has no confirmed function in humans.
Tesofensine
- Triple reuptake blockade: Tesofensine blocks the reuptake of norepinephrine, dopamine and serotonin at nerve terminals; this increases the action of these three neurotransmitters.
- Heart rate: The same neurotransmitters also affect heart rate; a dose-dependent heart rate increase was seen with tesofensine in trials.
