Experimental

Retatrutide (LY3437943) is a novel synthetic peptide that acts as a triple agonist at the glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1), and glucagon receptors. This 39-amino acid peptide represents a significant advancement in obesity pharmacotherapy, demonstrating superior weight loss efficacy compared to existing dual agonists like tirzepatide and single agonists like semaglutide. Phase 2 clinical trials have shown up to 24.2% body weight reduction at 48 weeks with the 12 mg dose, making it one of the most effective weight loss therapeutics in development. The triple agonist mechanism combines appetite suppression and enhanced insulin secretion (via GIP and GLP-1) with increased energy expenditure (via glucagon receptor activation), while also showing promising results for metabolic dysfunction-associated steatotic liver disease (MASLD) and glycemic control in type 2 diabetes.

Thymosin Alpha-1 is a 28-amino acid immunomodulatory peptide naturally occurring in the thymus gland that has been extensively studied for its ability to enhance and restore immune function. The peptide acts through Toll-like receptors in dendritic cells, promoting T-cell differentiation and maturation, activating natural killer cells, and modulating cytokine production. With over 4,400 subjects enrolled in clinical trials across the United States, Europe, and China, Thymosin Alpha-1 has demonstrated efficacy in treating chronic hepatitis B and C, cancer immunotherapy, sepsis, COVID-19, and as a vaccine adjuvant. The synthetic form, thymalfasin (Zadaxin), has received regulatory approval in over 30 countries for conditions including hepatitis B, hepatocellular carcinoma, and malignant melanoma. However, it is not FDA-approved in the United States, though it received orphan drug designation. Clinical experience involving over 11,000 subjects across more than 30 trials demonstrates a favorable safety profile with only minor, transient side effects, primarily mild injection site reactions. The peptide is typically administered subcutaneously at doses of 0.8-6.4 mg twice weekly.

LL-37 is the sole human member of the cathelicidin family of antimicrobial peptides, derived from the C-terminal fragment of the human cationic antimicrobial protein 18 (hCAP18). This 37-amino acid peptide was identified in the 1990s as a critical component of human innate immunity. LL-37 functions through multiple mechanisms including direct antimicrobial activity via membrane disruption, immunomodulation through regulation of inflammatory responses, chemotaxis of immune cells, lipopolysaccharide neutralization, and promotion of wound healing and angiogenesis. The peptide is expressed in epithelial tissues of the skin, gastrointestinal tract, respiratory tract, and in various leukocytes including neutrophils, monocytes, and lymphocytes. Its expression is regulated by vitamin D, bacterial components, cytokines, and tissue injury signals. Currently, LL-37 is not FDA-approved for therapeutic use and remains available only for research purposes, though phase 1 clinical trials have been completed for melanoma and exploratory studies conducted for COVID-19 and sepsis.

Humanin is a 24-amino acid mitochondrial-derived peptide (MDP) encoded by a small open reading frame within the mitochondrial 16S ribosomal RNA gene (MT-RNR2). First discovered in 2001 as a neuroprotective factor, humanin belongs to the novel class of mitochondria-derived peptides and represents the first peptide identified to be encoded by mitochondrial DNA. The peptide can be translated both in the mitochondrial matrix (producing a 21-amino acid variant) and the cytosol (producing the full 24-amino acid peptide), with both forms being biologically active. Humanin functions as a signaling molecule with cytoprotective and antiapoptotic properties, exerting beneficial effects across multiple organ systems including the brain, heart, skeletal muscle, and vascular tissues. Research has demonstrated humanin's role as a regulator of both lifespan and healthspan, with levels naturally declining with age and in various disease states including Alzheimer's disease, diabetes, and cardiovascular disorders. The peptide exerts its effects through multiple mechanisms including binding to cell surface receptors (FPRL1/2 and trimeric CNTFR-α/gp130/WSX-1 complex), intracellular protein interactions (BAX, IGFBP3), and modulation of key signaling pathways (STAT3, AMPK, ERK1/2). The highly potent S14G-humanin analog (HNG) shows 1000-fold greater biological activity than native humanin. While extensive preclinical evidence supports humanin's therapeutic potential for age-related diseases, neurodegenerative disorders, metabolic dysfunction, and cardiovascular conditions, the peptide remains investigational with no completed human clinical trials for therapeutic applications. Humanin is not approved by the FDA or other regulatory agencies for clinical use.

PT-141 (Bremelanotide) is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone (α-MSH) developed as a melanocortin receptor agonist. Originally derived from Melanotan II in the 1990s by Palatin Technologies, bremelanotide was specifically developed to address sexual dysfunction after the parent compound unexpectedly caused sexual arousal in clinical trials for tanning. The peptide primarily activates melanocortin receptors MC3R and MC4R in the central nervous system, particularly in the hypothalamic regions involved in sexual response. After extensive clinical development including two large Phase 3 RECONNECT trials involving over 1,200 premenopausal women, bremelanotide received FDA approval in June 2019 for the treatment of acquired, generalized hypoactive sexual desire disorder (HSDD) in premenopausal women. It is marketed as Vyleesi and administered as a 1.75 mg subcutaneous injection at least 45 minutes before anticipated sexual activity. The FDA considers it a first-in-class medication, representing a novel non-hormonal approach to treating sexual dysfunction through central melanocortin pathway activation.

Vasoactive Intestinal Peptide (VIP) is a 28-amino acid neuropeptide that functions as both a potent anti-inflammatory agent and neuroprotective factor throughout the body. VIP operates through three G-protein-coupled receptors (VPAC1, VPAC2, and PAC1) to regulate immune homeostasis, modulate inflammatory responses, and protect neural tissue from degeneration. Clinical research has demonstrated VIP's therapeutic potential in treating chronic inflammatory response syndrome (CIRS), neurodegenerative diseases, autoimmune conditions, and inflammatory bowel disorders through its ability to suppress pro-inflammatory cytokines, promote regulatory T cells, and induce neuroprotective proteins.

Kisspeptin-10 (Kp-10) is a bioactive 10-amino acid peptide derived from the KISS1 gene, corresponding to amino acids 45-54 of metastin. It acts as a critical regulator of reproductive function through activation of the GPR54 receptor, stimulating the release of gonadotropin-releasing hormone (GnRH) and subsequently luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Originally discovered for its anti-metastatic properties in cancer, kisspeptin-10 has emerged as a key player in the hypothalamic-pituitary-gonadal axis. The peptide shows therapeutic potential for fertility disorders including PCOS, hypothalamic amenorrhea, and male hypogonadism. It is currently experimental with no FDA approval and is classified as a substantial safety risk for compounding pharmacy use.

Epitalon (also known as Epithalon or Epithalone) is a synthetic tetrapeptide with the amino acid sequence Ala-Glu-Asp-Gly (AEDG), originally derived from epithalamin, a bovine pineal gland extract. Its primary mechanism of action involves activation of telomerase enzyme activity, leading to telomere elongation in human somatic cells, as well as regulation of melatonin production and circadian rhythms. Over 25 years of research has demonstrated geroprotective effects in multiple animal models, including increased lifespan (11-16% in fruit flies, 12-13% maximum lifespan extension in mice), improved biomarkers of aging, and inhibition of spontaneous tumor development. Limited human clinical trials have shown positive results in treating retinitis pigmentosa and reducing cardiovascular mortality in elderly patients with coronary disease. However, Epitalon remains an experimental research compound with no FDA or EMA approval for therapeutic use. Its regulatory status is that of an investigational peptide, not approved for clinical application in the United States or Europe, though it has been extensively studied in Russian research institutions for decades.

Pinealon (EDR) is a synthetic tripeptide bioregulator composed of glutamic acid, aspartic acid, and arginine (Glu-Asp-Arg) developed by Russian scientist Vladimir Khavinson. Originally isolated from the polypeptide neuroprotective drug Cortexin, it demonstrates potent neuroprotective properties through multiple mechanisms including ROS suppression, gene expression regulation, and epigenetic modulation. Pinealon has been extensively studied in Russian scientific literature for its effects on cognitive function, neuroplasticity, and cellular aging processes.

TB-500 (Thymosin Beta-4) is a naturally occurring 43-amino acid peptide that functions as the major G-actin-sequestering molecule in mammalian cells. It plays crucial roles in tissue repair, wound healing, and cellular regeneration by regulating cell migration, proliferation, and differentiation. The peptide has demonstrated significant therapeutic potential in multiple clinical applications including dermal wound healing, corneal injuries, dry eye disease, and cardiac tissue repair following myocardial infarction. Phase I and Phase II clinical trials have established its safety profile at various dosing regimens, though it remains unapproved by regulatory agencies. TB-500 is sold on the gray market as a research chemical and is prohibited in competitive sports by the World Anti-Doping Agency due to its performance-enhancing and tissue regeneration properties.

MOTS-c (Mitochondrial Open Reading Frame of the 12S rRNA Type-C) is a 16-amino-acid peptide encoded within the mitochondrial genome's 12S ribosomal RNA region, discovered in 2015 by researchers at the University of Southern California. This mitochondrial-derived peptide functions as a signaling molecule that translocates to the cell nucleus during metabolic stress, where it regulates nuclear gene expression through AMPK-dependent mechanisms. Primary research has focused on its roles in metabolic regulation, exercise performance, aging, insulin resistance, obesity, cardiovascular health, and bone metabolism. MOTS-c levels naturally decline with age in plasma, though skeletal muscle expression may increase compensatorily. The peptide is not approved by the FDA or other regulatory agencies for clinical use and remains an investigational compound available only in research settings. It is prohibited by the World Anti-Doping Agency (WADA) under metabolic modulators. Currently, MOTS-c is only available through research suppliers and is not approved for human therapeutic use outside of clinical trials.

BPC-157 (Body Protection Compound-157) is a synthetic pentadecapeptide consisting of 15 amino acids (sequence: GEPPPGKPADDAGLV) derived from a protective protein found in human gastric juice. The peptide demonstrates pleiotropic biological activity through multiple mechanisms, including stimulation of vascular endothelial growth factor (VEGF) expression and VEGFR2 receptor activation, enhancement of growth hormone receptor expression, activation of the FAK-paxillin pathway for cell migration, and modulation of the nitric oxide system via Src-Caveolin-1-eNOS signaling. Preclinical research in animal models has shown consistent healing effects across diverse tissue types including tendons, ligaments, muscles, bones, gastrointestinal mucosa, and neural tissue. While BPC-157 was tested in Phase I clinical trials for inflammatory bowel disease (PL14736) by Pliva, Croatia, human clinical data remains extremely limited with only one small retrospective study in musculoskeletal pain. The FDA classified BPC-157 as a Category 2 bulk drug substance in 2023, prohibiting compounding due to insufficient safety evidence in humans. The World Anti-Doping Agency (WADA) and major sports organizations ban its use. Despite lack of FDA approval, the peptide is available through gray market channels and increasingly used by clinicians and athletes, raising significant safety and regulatory concerns.

Delta Sleep-Inducing Peptide (DSIP) is a naturally occurring nonapeptide (Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu) with molecular weight 848.824 Da, first isolated from rabbit cerebral venous blood in 1974. It functions as a neuromodulatory peptide found in the hypothalamus, limbic system, pituitary, and peripheral organs, crossing the blood-brain barrier easily without enzymatic degradation. DSIP's primary mechanisms involve modulation of sleep architecture, neurotransmitter regulation (serotonin, dopamine, glutamate), stress response via the HPA axis, and potential interaction with NMDA receptors and adrenergic pathways. Clinical applications have focused on chronic insomnia, stress-related disorders, pain management, and substance withdrawal symptoms, though exact mechanisms remain incompletely characterized. Despite 50 years of research, DSIP is not FDA-approved or regulated by major health authorities worldwide, remaining available only as a research compound. It exists in an unregulated gray market, with most commercially available forms being research-grade material not intended for human use, and the FDA has flagged it for potential immunogenicity risks.

FOX-04-DRI (Proxofim) is a synthetic 46-amino acid cell-penetrating peptide composed of D-amino acids (D-retro-inverso configuration) designed to selectively eliminate senescent cells by disrupting the FOXO4-p53 protein interaction. By perturbing this critical survival mechanism, the peptide causes p53 nuclear exclusion and triggers selective apoptosis specifically in senescent cells while sparing healthy cells, demonstrating an 11.73-fold selectivity difference. Preclinical studies in aged and accelerated-aging mouse models have shown restoration of tissue homeostasis, improved renal and mitochondrial function, fur density restoration, enhanced physical fitness, and neutralization of chemotherapy-induced toxicity, positioning it as a promising senolytic agent for age-related diseases and healthspan extension.

N-Acetyl Selank is an enhanced synthetic heptapeptide derived from the endogenous immune peptide tuftsin, featuring acetylation for improved stability and bioavailability. It functions as a potent anxiolytic and nootropic compound with demonstrated effects on GABAergic, dopaminergic, and serotonergic neurotransmission. Originally developed by the Institute of Molecular Genetics of the Russian Academy of Sciences and approved for anxiety disorder treatment in Russia, it exhibits neuroprotective, immunomodulatory, and cognitive-enhancing properties without the side effects typical of benzodiazepines.

Cagrilintide is a long-acting, acylated amylin analogue that functions as a non-selective agonist of amylin receptors (AMY1R, AMY2R, AMY3R) and the calcitonin receptor (CTR). Developed by Novo Nordisk, it is designed for once-weekly subcutaneous administration with a half-life of approximately 8 days, addressing obesity and type 2 diabetes through appetite suppression, delayed gastric emptying, and glucagon inhibition. Clinical trials have demonstrated remarkable weight loss efficacy, particularly when combined with semaglutide (branded as CagriSema), with the REDEFINE 1 trial showing 60% of participants achieving at least 20% body weight reduction. Cagrilintide represents a significant advancement in obesity pharmacotherapy by leveraging the complementary mechanisms of amylin and GLP-1 receptor agonism.

KPV is a tripeptide consisting of lysine-proline-valine, derived from the C-terminal sequence of alpha-melanocyte stimulating hormone (α-MSH). This short peptide exhibits potent anti-inflammatory properties without the pigmentation effects associated with full-length α-MSH. [1][2] The peptide functions by modulating inflammatory pathways, particularly through inhibition of pro-inflammatory cytokines and regulation of NF-κB signaling. Research has demonstrated its ability to reduce inflammation in various tissue types, with particular interest in gastrointestinal applications for inflammatory bowel disease. [3][4] KPV can be administered orally, topically, or via injection, with each route showing different tissue targeting properties. The oral route appears particularly promising for gut-targeted anti-inflammatory effects, while topical application may benefit skin conditions. Research remains largely preclinical, with human clinical trials still limited. [5][6]