The library

DSIP (delta sleep-inducing peptide) is a small 9-amino-acid peptide first isolated from the blood of sleeping rabbits in the 1970s. It was named for its ability to increase deep, slow-wave (delta) sleep in animals. Despite decades of study, no specific DSIP receptor, gene, or precursor protein has ever been identified, so how it works remains unresolved. Rather than sedating like a sleeping pill, it appears to support natural sleep — increasing sleep depth and efficiency and creating a subjective feeling of sleep pressure without suppressing REM sleep or causing next-day grogginess. It seems to influence sleep indirectly through several brain systems (GABA, glutamate/NMDA, and opioid/enkephalin pathways), circadian rhythms, melatonin, and stress hormones, and it turns up in many tissues and body fluids. Its human sleep effects are strongest in people with disrupted sleep and modest in healthy sleepers.

healing · cognitive · longevity

Follistatin is a natural glycoprotein that acts as a 'blocker' of muscle-limiting signals. It grabs onto and neutralizes myostatin (GDF-8) and activin A — proteins that normally put the brakes on muscle growth and promote muscle wasting. By mopping these up before they can dock onto their receptors on muscle cells, follistatin removes that brake, which in animal and gene-therapy studies allows muscles to grow larger and stronger. It also originally came to light for its ability to reduce release of follicle-stimulating hormone (FSH) from the pituitary. Importantly, the dramatic muscle-growth results reported in the research come mostly from genetic overexpression or gene therapy that keeps follistatin present continuously — not from injecting the short-lived peptide.

Muscle growth / hypertrophy · Strength and athletic performance · Muscle-wasting/dystrophy research (Becker MD, sIBM, cachexia, sarcopenia) · Tissue repair and recovery (theorized) · Anti-fibrotic / anti-inflammatory research

Multiple sources describe GHK-Cu as the copper complex of a naturally occurring three-amino-acid peptide (glycine-histidine-lysine) bound to a copper(II) ion. Several sources report it was first isolated from human plasma in 1973 by Loren Pickart, who described it as a serum factor that made old cultured liver cells behave like younger ones. Sources note it occurs naturally in human plasma, saliva, and urine and is released when tissue is injured, and that endogenous levels are reported to decline with age (a 2022 review and other sources cite roughly 200 ng/mL at age 20 falling to about 80 ng/mL by age 60). The overall picture drawn by sources is that GHK-Cu delivers copper to cells, boosts collagen and other skin-matrix components, dampens inflammation, and switches many genes involved in repair, antioxidant defense, and tissue remodeling on or off — though one source cautions the headline '4,000+ genes' figure rests on a single unreplicated reanalysis.

Skin health & anti-aging · Wound healing & tissue repair · Anti-inflammatory · Hair growth · Cognitive / neuroprotection (preclinical) · Musculoskeletal recovery (preclinical)

Gonadorelin is a lab-made copy of the body's own gonadotropin-releasing hormone (GnRH), the master hormone from the hypothalamus that tells the pituitary gland to release luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These in turn drive the testes and ovaries to make sex hormones and support sperm and egg development. A crucial feature is timing: the natural hormone is released in pulses every 90-120 minutes, and delivering gonadorelin in matching pulses keeps the pituitary responsive. If instead it is given continuously, the pituitary receptors shut down and hormone output paradoxically falls. Because of this, it is used both as a single-dose diagnostic test of pituitary function and, via a programmable pump giving pulses, to induce ovulation or restore fertility in people whose own hypothalamus is not producing GnRH.

Fertility and reproductive function · Diagnostic pituitary/HPG axis evaluation · Hormone optimization (off-label TRT adjunct) · Libido (anecdotal)

HCG is a hormone normally made by the placenta during pregnancy. It is built from two pieces (an alpha subunit shared with the pituitary hormones LH, FSH and TSH, and a unique beta subunit). HCG acts almost like the body's own luteinizing hormone (LH): it plugs into the LH receptor on the testes and ovaries and tells them to make sex hormones — androgens (testosterone) in men and progesterone in women. Because it mimics LH so closely, it is used to trigger ovulation, to stimulate testosterone and sperm production, and to help undescended testicles drop in boys. In pregnancy it keeps the corpus luteum producing progesterone so the pregnancy is maintained, and it is the molecule detected by pregnancy tests. Regulatory labels are explicit that HCG has no known effect on fat, appetite or body-fat distribution and has not been shown to help weight loss.

Fertility and reproductive health · Ovulation induction / assisted reproduction · Male hypogonadism and endogenous testosterone support · Cryptorchidism treatment · Pregnancy maintenance / diagnostic and tumor marker

Vendor and review sources describe humanin as a small peptide encoded within the mitochondrial genome that acts as a 'mitokine' — a signal that mitochondria send to the rest of the body when under stress. Sources report it works by latching onto cell-surface receptors and by blocking proteins inside the cell that would otherwise trigger cell death, and that its levels naturally decline with age. In cell and animal studies it is reported to protect neurons, heart and other cells from damage and to improve how the body handles insulin and glucose. A widely studied engineered version called HNG (the S14G analog) is reported to be about 1,000-fold more potent than the natural peptide in cell culture. Importantly, no human trials of giving humanin as a drug have been published.

Longevity / healthspan · Neuroprotection / cognitive health · Metabolic health / insulin sensitivity · Cardiovascular protection · Anti-inflammatory

Imunofan is a small synthetic peptide modeled on a fragment of thymopoietin, a natural thymic hormone that guides the development and activity of immune T-cells. Rather than simply revving up the immune system, it is described as an immunomodulator that nudges abnormal immune parameters back toward balance — boosting defenses when they are weak and calming them when they are overactive. It is reported to act in three overlapping stages: within a few hours it activates the body's antioxidant defenses (scavenging reactive oxygen species and raising glutathione); over the following days to weeks it enhances the activity of immune cells such as neutrophils, macrophages, NK cells and B-cells; and over months it helps normalize the ratio of T-cell subtypes and consolidate immune memory. It is also credited with antioxidant and liver-protective actions and with stimulating tissue repair.

Immune support and immunomodulation · Antioxidant / oxidative-stress reduction · Anti-infective adjunctive support (chronic viral/bacterial infections) · Vaccine adjuvant · Tissue repair and wound healing · Hepatoprotection · Oncology supportive care (adjunct to chemoradiotherapy)

Vendor and educational profiles describe ipamorelin (NNC 26-0161) as a synthetic five-amino-acid peptide that mimics the natural hunger hormone ghrelin by switching on the ghrelin receptor (GHSR-1a) in the pituitary gland and hypothalamus. According to these sources, this prompts the pituitary to release a pulse of growth hormone (GH), which in turn raises IGF-1 and is said to drive protein synthesis, fat breakdown and tissue repair. What multiple profiles emphasize is its selectivity: animal studies reported that ipamorelin releases GH without raising cortisol, prolactin, ACTH or other pituitary hormones, and expert commentary notes it does so while preserving the body's natural pulsatile GH rhythm rather than flooding the system with a constant elevation.

Growth hormone / IGF-1 stimulation · Body composition · Recovery / tissue repair · Sleep (claimed) · Gastrointestinal motility (investigational)

Kisspeptin-10 is a short 10-amino-acid fragment of the natural kisspeptin hormone that acts as a full activator (agonist) of the KISS1R receptor (also called GPR54) found on the GnRH neurons of the hypothalamus. By switching on these neurons, it triggers release of GnRH, which in turn prompts the pituitary to secrete the reproductive hormones LH and FSH. LH then stimulates testosterone production in men and progesterone/estradiol in women, while FSH supports sperm and egg development. In short, kisspeptin-10 sits at the top of the reproductive hormone cascade and 'kick-starts' it. Its effect depends heavily on how it is given: brief pulses stimulate the system, whereas continuous over-stimulation can, according to some sources, desensitize the receptor and instead suppress hormone output. Its effects also differ between the sexes and across the menstrual cycle.

Fertility and reproductive function · Hormone optimization (LH/FSH/testosterone) · Diagnostic evaluation of the reproductive axis · IVF / ovulation triggering

Klotho is a protein the body makes naturally, mostly in the kidney but also in the brain and pancreas, and reviews describe its levels as declining with age. It exists as a membrane-bound form and as a soluble form that circulates like a hormone. Reviews report that the membrane form works together with FGF23 to help the kidney manage phosphate and vitamin D, while the soluble form is described as having anti-inflammatory, anti-oxidative, and anti-scarring (antifibrotic) actions. Observational human studies associate higher Klotho with better cognition, lower dementia rates, and protection against kidney and cardiovascular disease, and animal studies report that adding Klotho can boost cognition and extend lifespan. Importantly, one primate study found a low dose helped memory while a high dose did not, and multiple sources caution that too much Klotho could disturb calcium and phosphate balance.

Longevity / anti-aging · Cognitive function · Kidney health · Metabolic health · Cardiovascular health

LL-37 is described by sources as the only human cathelicidin — a 37-amino-acid, positively charged peptide cut from a precursor protein called hCAP-18. Because it carries a positive charge, it is drawn to the negatively charged surfaces of bacteria, where a Tier-1 review reports it punches holes in and permeabilizes microbial membranes, killing many bacteria (gram-positive and gram-negative), some fungi, and some viruses. Beyond killing microbes directly, sources describe it as an immune-signaling molecule: it binds and neutralizes bacterial endotoxin, recruits immune cells, and can dissolve bacterial biofilms and drive neutrophils to release DNA nets. Reviews stress that it has both anti- and pro-inflammatory effects and can be both protective and harmful depending on context — it is also cytotoxic to human cells at higher concentrations and has been implicated in diseases such as psoriasis and lupus. In wound healing, sources report it promotes new blood-vessel growth and skin-cell migration.

Antimicrobial / anti-infective · Wound healing / tissue repair · Immune modulation · Anti-inflammatory · Antibiofilm

Matrixyl is the trade name for palmitoyl pentapeptide-4 (Pal-KTTKS), a lab-made peptide made by attaching a fatty acid (palmitic acid) to a five-amino-acid chain (KTTKS) originally found as a fragment of type I collagen. It acts as a 'matrikine' — a messenger peptide that signals skin cells called fibroblasts to behave as if collagen has been damaged and needs rebuilding. In response, fibroblasts increase production of collagen, fibronectin, and other components of the skin's supportive matrix. The attached fatty acid makes the otherwise water-loving peptide able to slip through the skin's oily outer barrier to reach the dermis. In human trials this translates into modest, measurable reductions in wrinkles and improvements in skin texture and firmness, with very good tolerability.

Anti-aging / skin rejuvenation · Wrinkle and fine line reduction · Skin firmness and elasticity · Wound healing (preclinical)

MOTS-c is a small 16-amino-acid peptide that, according to vendor and review sources, is encoded inside mitochondrial DNA and was discovered in 2015. Several sources describe it as a 'mitokine' — a signal that reports on mitochondrial health. Its most studied action, per multiple sources, is switching on AMPK, a cellular energy sensor that tells cells to burn fuel more efficiently, become more sensitive to insulin, and resist storing energy as fat. Under stress (low glucose, oxidative stress) sources report the peptide moves into the cell nucleus and turns on antioxidant and adaptive stress-response genes. Because exercise naturally raises MOTS-c and the peptide reproduces several exercise-like effects in animals, sources frequently describe it as an 'exercise-mimetic.'

Metabolic health / insulin sensitivity · Weight / fat loss · Exercise performance and recovery · Longevity / healthy aging

According to Examine and an information site, Noopept is a synthetic dipeptide built as an analog of piracetam and based on the natural brain peptide cycloprolylglycine. Sources report that Noopept itself is broken down very quickly and is barely detectable in the body, and that it works largely as a prodrug — it is converted into cycloprolylglycine, which is thought to be responsible for its longer-lasting nootropic effects. Animal and cell studies attribute its cognitive and neuroprotective actions to raising the neurotrophic factors BDNF and NGF, boosting acetylcholine signaling, reducing oxidative stress and glutamate excitotoxicity, and increasing HIF-1 activity. Human observational and open-label Russian studies report improvements in memory, attention, and mood along with an anxiolytic effect in people with mild cognitive impairment, though sources stress the human evidence is thin.

Cognitive enhancement / nootropic · Memory support · Anxiety / mood · Neuroprotection

According to peptide information sources, Palmitoyl Tripeptide-1 (Pal-GHK) is the small collagen-fragment peptide GHK (glycine-histidine-lysine) with a fatty (palmitic acid) tail attached to its N-terminus. Sources explain that GHK is naturally released when type I collagen breaks down and acts as a 'matrikine' — a signal that tells skin fibroblast cells to make new collagen and other matrix components. The fatty tail is described as a delivery vehicle that helps the otherwise water-loving peptide cross the oily outer skin barrier. Reference and reference-cited studies report that, in lab-grown skin cells, the peptide stimulates collagen and elastin production, appears to work through the TGF-β signaling pathway, and may reduce inflammation. Several sources stress that Pal-GHK is a copper-free analog and, unlike GHK-Cu, does not deliver copper ions.

Skin anti-aging / dermal remodeling · Wrinkle reduction · Skin firmness and elasticity · Wound healing / tissue repair (reported)

Reviews describe pidotimod as a synthetic dipeptide that acts as an immune-system modulator, working on both innate and adaptive immunity. According to these reviews and human observational sources, it stimulates dendritic cells, boosts toll-like receptor (TLR) expression, and promotes production of signaling molecules such as IL-2 and IFN-gamma, thereby supporting both cell-based and antibody-based immune defenses. In vitro studies report it pushes T lymphocytes toward a Th1 phenotype, raises natural killer cell activity, and increases antibody levels including salivary IgA.

Immune support · Respiratory infection prevention · Recurrent infection reduction

Selank is a lab-made seven-amino-acid peptide built from tuftsin, a natural immune-signaling fragment of human antibody (IgG), with a short tail added to make it last longer in the body. Sources describe it as producing calming (anxiolytic), memory-supporting (nootropic) and immune-modulating effects. Rather than binding the same site as Valium-type drugs, animal studies report it fine-tunes the brain's main calming system (GABA) indirectly, nudges serotonin and dopamine activity, boosts growth factors like BDNF, and slows the breakdown of the body's own pain- and mood-regulating enkephalins. Reviews note its overall profile resembles low-dose tranquilizers but is reported without the amnesia, withdrawal or dependence that accompany benzodiazepines.

Anxiety and mood · Cognitive enhancement · Stress resilience · Immune modulation

Semax is a lab-made short peptide (seven amino acids) based on a fragment of the natural hormone ACTH, with an added 'Pro-Gly-Pro' tail. It was designed to keep ACTH's brain-supporting and memory-enhancing effects while dropping its hormonal action, so unlike ACTH it does not push the adrenal glands to release cortisol. In animals it raises levels of brain growth factors (especially BDNF and NGF) and their TrkB receptor, and it nudges serotonin and dopamine signaling. After brain injury such as stroke, it appears to dial down inflammation and oxidative stress while turning on genes tied to nerve repair, new blood vessels, and neuron survival. In people it has mainly been studied for stroke recovery and for improving short-term memory and attention.

cognitive · longevity · immune support

SS-31 (elamipretide) is a small synthetic peptide that homes in on the powerhouses of the cell — the mitochondria. It carries a positive charge and rapidly penetrates cells, accumulating hundreds to thousands of times over inside the inner mitochondrial membrane. There it binds tightly to cardiolipin, a special fat found only in mitochondria that is essential for keeping the energy-producing machinery organized and working. By protecting cardiolipin, SS-31 helps preserve mitochondrial structure, keeps the electron transport chain assembled, boosts ATP (energy) production, and reduces harmful reactive oxygen species at their source rather than mopping them up after the fact. It has been studied in Barth syndrome, mitochondrial myopathy, heart failure, kidney injury, and age-related macular degeneration, and in September 2025 received FDA accelerated approval (as Forzinity) to improve muscle strength in Barth syndrome patients weighing at least 30 kg.

longevity · cognitive · body composition · healing

According to the source set, TB-500 is described as a lab-made version of thymosin beta-4, a small peptide that occurs naturally in nearly every human cell. Sources report its core action is grabbing hold of the cell's building-block protein actin, which lets cells move, migrate to injury sites and reorganize — processes tied to wound healing. Across animal and lab studies, sources describe it promoting new blood-vessel growth, calming inflammation and helping tissue repair. Two big cautions run through the sources: sources disagree on whether TB-500 is a short 7-amino-acid fragment or the full 43-amino-acid protein, and almost all human trial data actually used the full-length pharmaceutical protein rather than the fragment vendors sell — so whether the injected fragment itself works is genuinely disputed.

Injury recovery / tissue repair · Wound healing · Anti-inflammatory support · Cardiovascular repair (research) · Joint / musculoskeletal recovery

Dihexa is a synthetic, metabolically stabilized peptide derived from angiotensin IV. Rather than acting on classic receptors directly, it is reported to bind hepatocyte growth factor (HGF) and boost HGF's activity at its receptor, c-Met. Turning on this HGF/c-Met pathway is thought to trigger the growth of new connections between brain cells — promoting dendritic spines and functional synapses — which researchers link to improved learning and memory in animals. It is described as extraordinarily potent at building synapses in cultured neurons and is orally active and able to cross the blood-brain barrier in rodents. Importantly, all of this comes from animal and cell studies, and some of the original foundational papers have been retracted for data problems.

Cognitive enhancement / nootropic · Neuroprotection · Neurorepair / recovery · Anti-neuroinflammation

Epithalon is a small synthetic four-amino-acid peptide (Ala-Glu-Asp-Gly) modeled on epithalamin, a natural extract from the pineal gland. Researchers report that it can switch on telomerase — the enzyme that maintains the protective caps (telomeres) on chromosomes — by increasing production of the hTERT component, and that in lab-grown human cells this lengthened telomeres and let cells divide past their usual limit. It is also studied as a regulator of the body clock, appearing to help restore normal nighttime melatonin production and circadian rhythms, and it acts as an antioxidant. At a deeper level it is proposed to enter the cell nucleus and interact directly with DNA and histone proteins to influence which genes are turned on or off.

longevity · cognitive · immune support

Vendor and educational guides describe FOXO4-DRI as a synthetic peptide designed to selectively kill senescent ('zombie') cells — cells that have stopped dividing but remain metabolically active and secrete inflammatory signals. According to these sources, senescent cells survive by using a protein called FOXO4 to hold the tumor-suppressor protein p53 captive in the nucleus, blocking p53's ability to trigger cell death. A vendor guide explains that FOXO4-DRI mimics the part of FOXO4 that binds p53, competitively displacing the real FOXO4 so that p53 is released and can move to the mitochondria to switch on the cell's self-destruct (apoptosis) program, specifically in senescent cells. The peptide is built from D-amino acids in a retro-inverso arrangement, which sources say roughly preserves its shape while making it resistant to the enzymes that would normally break peptides down.

Longevity / anti-aging · Senolytic / senescent-cell clearance · Tissue repair / regeneration · Anti-fibrotic · Cognitive (reported in review only)

According to vendor and reference sources, KPV is a three-amino-acid fragment (Lys-Pro-Val) taken from the tail end of the natural hormone alpha-MSH, and most sources describe it as calming inflammation. A Tier 1 study using human airway cells reported that KPV dose-dependently dampened NF-κB — a master switch for inflammation — and reduced inflammatory molecules. Many sources say it enters cells (especially inflamed gut cells) via a transporter called PepT1 and quiets pro-inflammatory signals like TNF-alpha, IL-1beta and IL-6. Sources disagree on whether KPV works by activating melanocortin receptors or independently of them; several state it does NOT bind those receptors and therefore, they report, does not cause tanning or sexual side effects.

Inflammation & immune modulation · Gut health · Skin health · Wound healing & tissue repair

According to the sources, Leuphasyl (Pentapeptide-18) is a synthetic five-amino-acid peptide modeled on the body's own enkephalin opioid peptides. Reviews and vendor materials describe it as working like a topical, botox-like relaxant: it is reported to bind enkephalin/opioid receptors on the nerve side of the neuromuscular junction and dampen the release of acetylcholine, the signal that makes facial muscles contract. With less contraction of the muscles that create expression lines (such as around the eyebrows and eyes), sources report a reduction in the depth of expression wrinkles. Unlike botulinum toxin, several profiles note it acts at the receptor level upstream and is said to preserve partial muscle movement rather than freezing it. Sources describe it as applied topically in creams, gels, or serums, often combined with Argireline for a stronger effect.

Anti-aging / cosmetic skin health · Wrinkle reduction · Skin brightening (analog, in vitro)