The library

Afamelanotide is a lab-made, longer-lasting version of a natural hormone (α-MSH) that tells pigment cells in the skin to make more of the dark protective pigment eumelanin. It does this by switching on the melanocortin-1 receptor (MC1R). The extra pigment builds up in the skin even without sun exposure, acting like a built-in sunscreen that reduces how much light penetrates. It also appears to boost the skin's antioxidant and DNA-repair defenses and to calm inflammation. In people with erythropoietic protoporphyria (EPP), this lets them tolerate more light and spend more pain-free time in sunlight.

Photoprotection · Skin pigmentation · Dermatologic disease management · Rare disease (EPP) symptom management

Argireline is a small synthetic peptide designed to mimic part of a natural muscle-signaling protein (SNAP-25). By imitating this fragment, it is proposed to interfere with the machinery nerves use to release the chemical messenger (acetylcholine) that tells facial muscles to contract. The idea is that reducing these contractions softens the repeated creasing that forms expression lines, giving it a marketing reputation as a topical, needle-free alternative to Botox. Importantly, this mechanism is well supported in lab dishes but its relevance to topical cosmetic use is uncertain, because very little of the peptide actually penetrates the skin to reach facial muscles.

Skin anti-aging / anti-wrinkle · Cosmetic skin conditioning / hydration · Scar and photodamage remodeling

Bremelanotide is a lab-made version of a natural hormone (alpha-MSH) that acts in the brain rather than on blood vessels. It switches on melanocortin receptors (mainly MC4R, and also MC3R) in the hypothalamus, tuning brain circuits involved in sexual desire and arousal. By influencing dopamine-related pathways, it is thought to increase sexual motivation. This is different from erectile-dysfunction pills like sildenafil, which work on blood flow and nitric oxide in the penis.

sexual health

Cerebrolysin is not a single molecule but a liquid preparation made from pig brain tissue, broken down by enzymes into a mix of free amino acids (roughly 75%) and small peptides under about 10,000 daltons (roughly 25%). These small components are thought to be able to cross into the brain and behave like the body's own natural nerve-growth signals (such as BDNF, NGF, GDNF and CNTF), helping nerve cells survive, form new connections, and grow. Researchers propose it protects neurons by reducing cell death, calming inflammation, lowering oxidative stress (free radicals), and supporting blood vessels in the brain. Because peptides are destroyed in the gut, it is given by injection or infusion rather than by mouth. It is approved in many countries for stroke, traumatic brain injury and dementia, but has never been approved by the U.S. FDA, and rigorous reviews disagree on how much real benefit it provides.

Neuroprotection · Cognitive support · Stroke recovery / neurorehabilitation · Dementia (vascular and Alzheimer's type) · Traumatic brain injury recovery · Mood / neuropsychiatric

According to Phase 1 trial reports and multiple reviews, CJC-1295 is a long-acting synthetic version of growth-hormone-releasing hormone (GHRH). Sources describe it as being built from the first 29 amino acids of natural GHRH with four amino-acid substitutions that make it resist breakdown by enzymes. The DAC (Drug Affinity Complex) version carries a chemical group that latches onto albumin, a blood protein, which sources say extends its active life from minutes to roughly a week. Reviews describe it binding the GHRH receptor on pituitary somatotroph cells to prompt the body's own growth hormone (GH) release, which in turn raises IGF-1. Sources emphasize that, unlike injecting GH directly, it amplifies the body's existing pulsatile GH pattern rather than replacing it.

growth hormone / IGF-1 elevation · muscle mass and recovery · fat loss / body composition · sleep quality · skin rejuvenation / anti-aging · performance enhancement

Cortexin is not a single molecule but a mixture of small water-soluble polypeptides (roughly 1,000–10,000 Da) extracted from the cerebral cortex of young cattle and pigs, along with amino acids and trace elements. It is proposed to act as a broad, multi-target neuroprotectant. Laboratory studies suggest its peptides bind to receptors that handle the brain's main excitatory (glutamate) and inhibitory (GABA) signaling, which could dampen overexcitation (excitotoxicity). It is also reported to protect neurons from damaging factors like glutamate excess, calcium overload, and free radicals, to reduce a step in the cell-death (apoptosis) cascade, to support the brain's antioxidant and anti-inflammatory balance, and to encourage nerve-cell survival, growth, and connections in ways compared to natural growth factors. It is claimed to help balance neurotransmitters (including dopamine and serotonin). It is used clinically in Russia and CIS countries as an injectable for stroke, brain injury, cognitive problems, and pediatric developmental issues, though independent reviewers judge the human evidence weak.

Cognitive enhancement / nootropic · Neuroprotection · Recovery from stroke / brain injury · Pediatric neurodevelopment support

Davunetide (NAP) is a short 8-amino-acid piece of a natural brain protein called ADNP (activity-dependent neuroprotective protein). Its main proposed action is to help stabilize microtubules — the internal scaffolding of nerve cells — and to reduce abnormal phosphorylation of the tau protein that, when overloaded, forms toxic tangles seen in diseases like Alzheimer's. By binding to microtubule end-binding proteins and helping tau attach to microtubules, it is proposed to protect neurons from damage, prevent cell death, and support the growth of nerve fibers and synapses. Additional proposed effects include anti-inflammatory activity, antioxidant activity, and reducing protein aggregation.

Cognitive function · Neuroprotection · Neurodegenerative disease research · Tauopathy research

Elafin (also called Trappin-2 or SKALP) is described by DrugBank as a human protein made naturally in the skin, lung and breast that protects tissue from destruction by the immune system and blocks destructive enzymes involved in inflammation. A vendor profile and reviews describe it as an endogenous serine protease inhibitor produced by epithelial cells at mucosal surfaces that blocks neutrophil enzymes (elastase and proteinase 3) and also has direct antimicrobial activity against bacteria and fungi. Because the enzyme elastase is increased in pulmonary hypertension and inflammatory tissue damage, researchers have investigated giving extra elafin to dampen this damage. In its most rigorous human test — a randomised trial in heart-bypass surgery patients — elafin dramatically raised blood elafin levels and inhibited elastase but did not reduce heart-muscle injury over 48 hours.

Anti-inflammatory · Tissue protection / repair · Antimicrobial / antiviral · Cardiovascular / ischaemia-reperfusion protection

Hexarelin is a synthetic six-amino-acid peptide that acts as a growth hormone secretagogue. It mimics the natural hormone ghrelin by binding to the growth hormone secretagogue receptor (GHS-R1a) on the pituitary gland, prompting a strong, pulsatile release of growth hormone. It also acts at the hypothalamus to boost GHRH activity and reduce somatostatin's braking effect. Because release stays pulsatile and subject to normal feedback, it tends to avoid continuously supra-physiologic GH levels. Beyond growth hormone, hexarelin engages a separate cardiac receptor (CD36) that produces heart-related effects independent of growth hormone, and it mildly stimulates cortisol, ACTH, and prolactin.

gh stimulation · longevity · body composition

Investigators describe lactoferrin as a natural iron-binding defence protein found in milk, tears, saliva, other body fluids and neutrophils, with a broad range of reported functions: killing microbes, calming inflammation, acting as an antioxidant and helping regulate cell growth and the immune system (src-1, src-2, src-4, src-23). Researchers report it works partly by sequestering the iron that many pathogens need to grow while sparing beneficial commensals such as lactobacilli and bifidobacteria, and partly through short positively charged sequences at its N-terminus that bind and disrupt microbial cell surfaces (src-4, src-15, src-67). Reviewers note that ingested lactoferrin is also taken up by cells through a receptor-mediated pathway that can influence gene transcription and immune function (src-55). The peptide fragment hLF1-11 represents the first 11 amino acids of human lactoferrin, which investigators say carry much of its antimicrobial and anti-inflammatory activity (src-5, src-8).

Iron deficiency / anemia support · Immune support · Antimicrobial / anti-infective · Gut health · Anti-inflammatory / antioxidant · Reproductive and vaginal health

Linaclotide is a small 14-amino-acid peptide that mimics the body's natural guanylin hormones. Taken by mouth, it stays inside the gut and switches on a receptor called guanylate cyclase-C (GC-C) on the lining of the intestine. This raises a signaling molecule called cGMP, which prompts the gut to secrete chloride, bicarbonate, and fluid into the intestine. The extra fluid softens stool and speeds up movement through the bowel, relieving constipation. The rise in cGMP also appears to reduce gut pain signaling, which helps with the abdominal pain and bloating of IBS-C. Because it is barely absorbed into the bloodstream, its effects are almost entirely local to the intestine.

Digestive health / constipation relief · IBS symptom management

Melanotan II is a lab-made, ring-shaped copy of the natural hormone alpha-MSH that our bodies use to signal skin pigment cells. It switches on melanocortin receptors (MC1R, MC3R, MC4R and MC5R), which raises a cell-signaling molecule called cyclic AMP. In the skin this ramps up production of the dark pigment eumelanin, tanning the skin even without sunlight and offering some UV protection. Because it also hits receptors in the brain, it can trigger erections and sexual desire, suppress appetite, and affect glands — effects that cannot be separated from the tanning effect because the peptide is non-selective. It is far more potent than the natural hormone and its ring structure makes it last longer than natural alpha-MSH before being broken down.

Cosmetic tanning / skin pigmentation · Sexual function / erectile support · Weight management / appetite suppression

MK-677 (ibutamoren) is an orally active, non-peptide molecule that mimics the hunger hormone ghrelin. It switches on the ghrelin receptor (GHS-R1a) in the pituitary gland and hypothalamus, prompting the body to release more of its own growth hormone (GH), which in turn raises IGF-1. Unlike injected GH, it amplifies the body's natural pulsing pattern of GH release without shutting down the normal feedback system. Because it survives stomach digestion, it can be taken by mouth once daily and keeps GH and IGF-1 elevated for up to about 24 hours. Through the same ghrelin pathway it also increases appetite and can affect sleep, insulin sensitivity, and repair processes.

gh stimulation · body composition · fat loss · longevity · cognitive

Oxytocin is a small nine-amino-acid hormone made in the hypothalamus and released from the posterior pituitary gland, as described across multiple reviews and the FDA prescribing information. Its best-established action, per the Pitocin label, is stimulating rhythmic contractions of the uterine smooth muscle by raising intracellular calcium, an effect that becomes strong toward the end of pregnancy when uterine receptors are most abundant. Beyond the uterus, reviews describe oxytocin acting in the brain as a 'prosocial' signaling molecule linked to social recognition, bonding, trust, empathy, stress responses and anxiety, though human behavioral findings are mixed and often fail to confirm effects seen in animals.

Obstetric labor induction and augmentation · Postpartum hemorrhage control · Social/behavioral and psychiatric research (autism, anxiety, PTSD, OCD) · Investigational mood, feeding, and sexual-behavior research

Plecanatide is a synthetic 16-amino-acid peptide that mimics a natural human hormone called uroguanylin. It works locally inside the gut by switching on a receptor (guanylate cyclase-C, or GC-C) on the surface of intestinal lining cells. This triggers the cells to pump chloride and bicarbonate into the intestine, which draws in more fluid, softens stool, and speeds up movement through the bowel. It is designed to stay in the gut and is barely absorbed into the bloodstream. Animal studies also suggest it can quiet pain-sensing nerves in the intestine.

Digestive/gastrointestinal function · Chronic constipation relief · IBS-C symptom management

Semaglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist that mimics the natural gut hormone GLP-1. It tells the pancreas to release more insulin and less glucagon, but only when blood sugar is elevated, which lowers blood glucose with a low risk of hypoglycemia. It also acts on appetite regulation and slows the rate at which the stomach empties, leading to reduced food intake and weight loss.

fat loss · body composition

Sermorelin is a lab-made copy of the active part of the body's own growth hormone-releasing hormone (GHRH). Rather than supplying growth hormone directly, it signals the pituitary gland to make and release its own growth hormone in natural bursts. That released growth hormone then prompts the liver to produce IGF-1. Because it works within the body's normal feedback loops, growth hormone release stays pulsatile and is still held in check by the body's natural braking hormone, somatostatin.

gh stimulation · body composition · fat loss · longevity · healing

Teduglutide is a lab-made, longer-lasting copy of a natural gut hormone called GLP-2. Like the natural hormone, it tells the cells lining the intestine to grow, repair themselves and resist dying off. This makes the intestinal surface healthier and better able to absorb fluids and nutrients. It also slows how fast the stomach empties, reduces excess stomach acid, and boosts blood flow to the gut. In people with short bowel syndrome — who have lost a lot of functional intestine — these effects help the remaining bowel absorb more, so they need less nutrition delivered through an IV (parenteral support).

Short bowel syndrome / intestinal failure · Intestinal rehabilitation and adaptation · Reduction/weaning of parenteral nutrition

Tesamorelin is a synthetic, stabilized version of growth hormone-releasing hormone (GHRH), the natural brain signal that tells the pituitary gland to release growth hormone. Rather than injecting growth hormone directly, tesamorelin prompts the body to release its own growth hormone in a natural, pulsing pattern. The extra growth hormone then drives the liver to make IGF-1 and promotes the breakdown of fat (lipolysis), which is why it reduces excess visceral (deep abdominal) fat in HIV-infected patients with lipodystrophy.

fat loss · gh stimulation · body composition

Thymosin alpha-1 is a 28-amino-acid peptide the thymus gland naturally makes; reviews describe it as long recognized for modifying, enhancing and restoring immune function. Sources report it helps train and coordinate immune cells — encouraging T cells to mature and specialize, activating natural killer cells and dendritic cells, and tuning the mix of signaling molecules (cytokines) the immune system releases. One web source attributes to it a dual capacity to both boost an underactive immune response and calm an overactive, inflammatory one. Much of this mechanistic picture comes from expert opinion, in vitro work and animal studies rather than human trials.

Immune support and modulation · Antiviral / infectious disease support · Sepsis / critical care immunomodulation · Cancer immune adjunct · Vaccine adjuvant · Healthy aging / immunosenescence

According to a Tier 1 review, tirzepatide is a once-weekly injectable that activates two gut-hormone receptors at once — the GIP receptor and the GLP-1 receptor (a 'dual incretin' agonist). A review explains that GIP and GLP-1 are incretin hormones the intestine releases after eating; they prompt the pancreas to release insulin when blood glucose is high, and GLP-1 also reduces food intake and slows stomach emptying. A peptide protocol wiki describes how GLP-1 receptor activation by tirzepatide boosts glucose-dependent insulin secretion, lowers glucagon, slows gastric emptying and reduces appetite through the hypothalamus, while GIP receptor activation adds to insulin secretion, may improve lipid metabolism and fat distribution, and enhances central appetite control. A pharmacokinetic study reports the glucose-lowering effect may reflect GIP-receptor-mediated insulin action plus improved insulin sensitivity independent of weight change, while weight loss reflects combined GIP- and GLP-1-mediated effects on satiety and food intake.

Weight management / obesity · Glycemic control / type 2 diabetes · Metabolic health · Cardiovascular risk · Liver health (MASH)

Triptorelin is a lab-made, more potent copy of the natural hormone (GnRH/LHRH) that tells the pituitary gland to release the reproductive hormones LH and FSH. When given continuously as a long-acting depot, it first causes a brief surge in these hormones (and in testosterone or estrogen) for a few weeks, then shuts the system down. This sustained shutdown drops testosterone in men to levels seen after surgical castration, and lowers estrogen in women, which is useful when a cancer or condition is fueled by sex hormones or when puberty needs to be paused. The effect wears off after the drug is stopped.

Hormone-dependent cancer management (prostate, breast) · Androgen deprivation therapy · Central precocious puberty management · Endometriosis pain management · Ovarian function suppression / fertility-related applications · Gender-affirming hormone suppression (reported, weak evidence)

Alpha-MSH is a small, naturally occurring hormone (a 13-amino-acid peptide) that the body makes from a larger precursor protein called POMC. It is produced by skin cells after sun exposure and by the brain/pituitary. It works by switching on melanocortin receptors (MC1R, MC3R, MC4R, MC5R), which are found on many cell types. Through these receptors it drives skin tanning (melanin production), calms inflammation, dampens appetite (promotes feeling full), and influences glucose handling in muscle, immune activity, and sexual behavior. It binds MC1R most strongly, which is why pigment and anti-inflammatory effects are prominent.

Skin pigmentation / photoprotection · Anti-inflammatory · Metabolic / glucose regulation · Immune modulation · Sexual function

AOD-9604 is a small synthetic peptide copied from the tail end (C-terminal fragment) of human growth hormone—the portion thought to be responsible for growth hormone's fat-burning activity, separate from its growth-promoting and blood-sugar effects. It was designed to encourage the body to break down fat (lipolysis) and reduce the formation of new fat (lipogenesis) without raising blood glucose, suppressing the pituitary axis, or elevating IGF-1. Unlike full growth hormone, it does not meaningfully bind the classical growth hormone receptor or cause cell proliferation. Its fat effects appear linked to activity involving the beta-3 adrenergic receptor pathway in fat cells, though animal knockout studies suggest the effect is not directly mediated through that receptor.

fat loss · body composition · healing

Several reviews describe BPC-157 as a synthetic 15-amino-acid peptide originally isolated from human gastric juice (src-1, src-3, src-6). Animal and in vitro studies report it promotes the growth of new blood vessels, helps cells migrate to repair tissue, and protects tissues from damage. Studies attribute these effects to its interaction with nitric oxide production and growth-factor signaling, and reviews report it appears especially effective in poorly-vascularized tissues such as tendons and ligaments (src-3, src-4, src-6). Almost all of this evidence is preclinical; human data are minimal.

Injury recovery and tissue repair · Gastrointestinal protection · Tendon/ligament healing · Athletic recovery