Research Library For Phiogen.is

BPC-157 is a synthetic pentadecapeptide with the sequence Gly-Glu-Pro-Pro-Pro-Gly-Lys-Pro-Ala-Asp-Asp-Ala-Gly-Leu-Val (GEPPPGKPADDAGLV), molecular formula C62H98N16O22 and a molecular weight of approximately 1419.5 g/mol (CAS 137525-51-0, PubChem CID 9941957). It also appears in the literature as PL 14736 and Bepecin. One point deserves care: BPC-157 is widely described as a fragment of a "body protection compound" found in human gastric juice, but that parent protein has never been isolated, sequenced, or deposited in any public protein database — a search of UniProt for the peptide sequence returns nothing, and the claim traces to a single 1993 review article. It is accurately described as a synthetic peptide, and this page does not assert a natural origin.

A related identity caution: BPC-157 is a common name rather than a United States Adopted Name, and more than one substance circulates under it. The free base (CAS 137525-51-0) and the acetate salt (CAS 216441-37-1) are distinct active ingredients, and the acetate has no fixed molecular weight because its stoichiometry varies. Material marketed as "BPC-157 arginate" or "Pentadeca Arginate" has no peer-reviewed literature at all — a PubMed search returns zero records — and the figures quoted for it originate in a patent application rather than a published study.

The size of the BPC-157 literature is often mistaken for its strength. There are roughly 222 PubMed-indexed records, but about 78 percent carry authorship from a single research group at the University of Zagreb, and the corpus is overwhelmingly rodent and cell-culture work. Independent laboratories — notably at Chang Gung University in Taiwan — have reproduced directional findings, including reports of tendon-fibroblast outgrowth and migration (Chang et al., Journal of Applied Physiology 2011, PMID 21030672) and effects on VEGFR2 signaling (Hsieh et al., Journal of Molecular Medicine 2017, PMID 27847966; Huang et al., Scientific Reports 2020, PMID 33051481). A 2025 systematic review in HSS Journal (PMID 40756949) examined 36 studies, of which 35 were preclinical, and graded the evidence at the two weakest levels; a companion review (PMID 40789979) concluded the compound should be considered investigational. Angiogenesis via VEGFR2 is the mechanism with the most independent support; the broader organ-protection framework comes largely from the originating laboratory and has not been independently replicated at scale. The molecular targets of the peptide have not been identified.

Formulation and stability data are also thin, which matters for reagent handling. The one formal absorption study in animals (PMID 36588717, in rats and dogs) reported a short elimination half-life, under about 30 minutes, and a 2026 review concluded that no pharmaceutical-grade formulation has been developed or validated and that permeability characterization is absent. No published study evaluates BPC-157 in combination with TB-500, so nothing in the literature supports treating the pair as characterized together. BPC-157 is not an approved drug and has no pharmacopeial monograph. This product is supplied strictly for in vitro and laboratory research and is not for human or veterinary use.

Bronchogen is a four-residue peptide, Ala-Glu-Asp-Leu (AEDL, ~C18H30N4O9), one of the short synthetic "peptide bioregulators" developed by V. Kh. Khavinson and colleagues. Some primary Khavinson-group papers write the sequence as Ala-Asp-Glu-Leu (ADEL); the two notations refer to the same named compound but disagree on the order of the internal glutamic- and aspartic-acid residues.

Published preclinical studies report a DNA-stabilizing effect (raising the melting temperature of isolated DNA) in a biophysical assay, modulation of proliferation- and differentiation-related genes and proteins in cultured human bronchial epithelial cells, and reduced airway-remodeling features in a rat model of obstructive lung pathology. The evidence is small and dominated by a single research group; there are no published human clinical trials, and it has no regulatory approval for human use.

Cardiogen is a linear tetrapeptide of four L-amino acids, Ala-Glu-Asp-Arg (AEDR; ~C18H31N7O9, ~489.5 g/mol), one of the short "bioregulator" peptides characterized in the work of V. Kh. Khavinson and colleagues.

In a peer-reviewed study, the AEDR tetrapeptide was reported to increase expression of cytoskeletal proteins (actin, tubulin, vimentin) and nuclear-matrix proteins (lamins A and C) in cultured mouse embryonic fibroblasts. Published research on this peptide is preclinical and originates primarily from a single research group using in vitro systems; independent replication is limited. Note that "Cardiogen" is also an unrelated nuclear-cardiology product name (the Cardiogen-82 rubidium-82 generator) — a different product, not this peptide.

Cartalax is the trivial name for the tripeptide Ala-Glu-Asp (AED), one of the short "peptide bioregulators" developed by V. Kh. Khavinson and colleagues at the St. Petersburg Institute of Bioregulation and Gerontology — a family of two-to-four-residue synthetic peptides studied for tissue-associated effects on gene and protein expression in cell-culture models.

The published primary research on AED is preclinical and largely in vitro. In cultured human skin fibroblasts undergoing replicative aging, AED has been reported to increase synthesis of sirtuin-1, sirtuin-6, and type I collagen, and — alongside the related peptides KE, KED and AEDG — to raise the proliferation marker Ki-67 and reduce MMP-9. These are observations of molecular changes in laboratory models, from a single research group; they are not evidence of any clinical or health effect, and AED has not been evaluated in human clinical trials.

Livagen is the tetrapeptide Lys-Glu-Asp-Ala (KEDA), one of the short synthetic peptides investigated by V. Kh. Khavinson and colleagues for effects on chromatin organization and gene activity in aged cells.

In peer-reviewed studies (Bulletin of Experimental Biology and Medicine, 2002 and 2004), Livagen applied to lymphocytes from elderly donors was reported to activate ribosomal genes and decondense pericentromeric heterochromatin, releasing genes repressed by age-related chromatin condensation. This reproducible primary evidence concerns chromatin and ribosomal-gene changes in cultured human lymphocytes; it is preclinical and from a single research group. Broader claims tied to the "liver" association implied by the name are not established by the primary literature and are not asserted here.

Melanotan I and afamelanotide are the same molecule: a synthetic analog of alpha-melanocyte-stimulating hormone (alpha-MSH) with the acetylated, C-terminally amidated sequence Ac-Ser-Tyr-Ser-Nle-Glu-His-D-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH2, molecular formula C78H111N21O19 and molecular weight approximately 1646.8 g/mol (CAS 75921-69-6, PubChem CID 16197727). It differs from native alpha-MSH at exactly two positions — methionine 4 replaced by norleucine, which blocks oxidation, and L-phenylalanine 7 replaced by its D-isomer, which resists proteolysis — which is why it appears in the literature as [Nle4, D-Phe7]-alpha-MSH (Sawyer et al., PNAS 1980, PMID 6777774).

A notation caution worth recording: the sequence cannot be written as a plain 13-letter string. Norleucine is non-proteinogenic and has no standard single-letter code, and the D-configuration at position 7 cannot be expressed in single-letter notation at all. Any listing showing a clean 13-letter sequence for this compound is inaccurate.

It is commonly described as MC1R-selective. That is not accurate. Afamelanotide is a full agonist at four melanocortin receptors — MC1, MC3, MC4 and MC5 — with roughly one to one and a half log units of preference for MC1 rather than exclusivity for it; it is not a recognised ligand at MC2, the ACTH receptor. Receptor affinities in the reference pharmacology databases are drawn from different assay types, so selectivity ratios computed across them are indicative rather than rigorous. Agonism at MC1, a Gs-coupled receptor, raises cyclic AMP and drives eumelanin synthesis in pigment-cell models independently of ultraviolet exposure. This product is supplied strictly for in vitro and laboratory research and is not for human or veterinary use.

Melanotan II is a cyclic seven-residue peptide, Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, closed by a side-chain lactam bridge between the aspartate at position 2 and the lysine at position 7, with an acetylated N-terminus and an amidated C-terminus. Its molecular formula is C50H69N15O9 and its molecular weight approximately 1024.2 g/mol (CAS 121062-08-6, PubChem CID 92432). It was designed from the alpha-MSH 4-10 core by residue substitution and cyclization, the constraint being intended to lock the pharmacophore into an active conformation (Al-Obeidi et al., Journal of Medicinal Chemistry 1989, PMID 2535874). Pharmacologically it is a non-selective full agonist at MC1, MC3, MC4 and MC5, and is not a recognised ligand at MC2.

Nomenclature is worth pinning down, because several distinct designations circulate. "MT-II" is the registered short form; "MT-2" is not a registered synonym, and both MT-1 and MT-2 additionally collide with the standard nomenclature for the melatonin receptors, which are unrelated. Melanotan II has no international nonproprietary name, no United States Adopted Name, and no ATC code. Two database artifacts are also routinely misread as approvals and are not: bulk-ingredient entries in the National Drug Code directory, which are registrations rather than approved products, and "approved" status in the FDA substance registry, which refers to the curation state of a database record rather than to any regulatory approval.

Analytical work on material circulating under this name is directly relevant to its use as a reagent, and it is not reassuring. Published analyses of samples obtained from circulation have found unidentified impurities and vials underfilled relative to their stated contents (PMID 24771717), a sample assayed at roughly 30 percent purity (PMID 39302005), and falsified peptide products containing the wrong compound, the wrong quantity, or none of the stated compound at all (PMID 26456392, PMID 30165334). Identity and purity should be verified analytically rather than assumed from a label. Melanotan II is not an approved drug, and this product is supplied strictly for in vitro and laboratory research and is not for human or veterinary use.

The compound sold under the name P21 is P021 (CAS 1246751-68-7; PubChem CID 56599151; FDA substance registry UNII VV8CZC8PAS), a synthetic peptidomimetic with the molecular formula C27H42N6O8 and an average molecular weight of about 578.7 g/mol. Structurally it is an adamantylated tetrapeptide: the four-residue sequence Asp-Gly-Gly-Leu (DGGL), corresponding to residues 148-151 of human ciliary neurotrophic factor, carrying an N-terminal acetyl group and a C-terminal amide bond to 3-amino-adamantane-1-carboxamide. The literature usually writes this shorthand as Ac-DGGLAG-NH2, which is a common source of confusion — the trailing "AG" denotes the adamantane cap, not alanine and glycine, so the molecule is a tetrapeptide rather than the six-residue peptide the shorthand appears to describe.

A separate and more important naming distinction: P21 in this catalog is not p21^Cip1/Waf1, the endogenous human cyclin-dependent kinase inhibitor encoded by the CDKN1A gene, nor is it p21^ras, the 21 kDa Ras protein. Those are naturally occurring proteins associated with cell-cycle arrest and with Ras signaling respectively, and the large literature on them describes entirely different molecules. Material published about cell-cycle arrest, p53, or tumor suppression under the name "p21" does not refer to this compound.

P021 originates from the laboratory of Khalid Iqbal at the New York State Institute for Basic Research in Developmental Disabilities, which derived it by epitope-mapping an earlier eleven-residue CNTF fragment ("Peptide 6") down to its active core and then acetylating and adamantylating that core; the design intent described in the associated patents (for example US 8,796,214 and US 9,327,011) was greater lipophilicity and resistance to peptidase breakdown. The mechanism proposed by that group involves competitive inhibition of leukemia inhibitory factor signaling and increased BDNF expression. That mechanism is the originating laboratory’s model, supported by their in vitro data rather than independently established.

The published evidence is entirely preclinical. Studies in mice and rats have reported effects on behavioural measures, hippocampal neurogenesis markers, and tau phosphorylation in transgenic and aged-rodent laboratory models (Kazim et al., Neurobiology of Disease 2014, PMID 25046994; Bolognin et al., Alzheimer’s Research & Therapy 2017, PMID 28655344; Kazim et al., Scientific Reports 2017, PMID 28368015; Bolognin et al., Neurobiology of Aging 2014, PMID 24702821). Two honest caveats belong alongside those results. First, every primary experimental study of P021 in the indexed literature includes the originating investigator as an author, so there is no fully independent replication; the one study led primarily by an outside laboratory in a new rodent model (Journal of Neurodevelopmental Disorders 2024, PMID 39592934) was largely negative on its in vivo endpoints. Second, although the adamantane modification was intended to aid brain penetration, how much P021 reaches the brain has not been directly measured, and sources conflict on whether penetration is established. P021 is not an approved drug, and this product is supplied strictly for in vitro and laboratory research and is not for human or veterinary use.

Pancragen is the four-residue peptide Lys-Glu-Asp-Trp (KEDW; sequence-derived formula C26H36N6O9), one of the short synthetic "bioregulator" peptides studied by V. Kh. Khavinson and colleagues and associated in that framework with pancreatic tissue.

In cell-culture research, the KEDW peptide has been reported to increase expression of pancreatic acinar and islet differentiation markers (such as Pdx1, Ptf1a, Pax6, Pax4, Foxa2 and Nkx2.2) in young and aged pancreatic cell cultures, and a review by the same group lists it among peptides reported to induce pancreatic-cell differentiation. A proposed mechanism of direct DNA interaction comes largely from one research group, part of it in a non-PubMed-indexed journal. These are preclinical findings only; no therapeutic efficacy in humans is established.

Mechano growth factor is not a separate gene product. It is a splice variant of the human IGF1 gene — IGF-1Ec (UniProt P05019-4) — and the peptide sold as MGF is the 24-residue C-terminal fragment of that variant’s E-domain propeptide, the portion cleaved away and discarded when IGF-1 matures. The reference human sequence is Tyr-Gln-Pro-Pro-Ser-Thr-Asn-Lys-Asn-Thr-Lys-Ser-Gln-Arg-Arg-Lys-Gly-Ser-Thr-Phe-Glu-Glu-Arg-Lys (YQPPSTNKNTKSQRRKGSTFEERK), as registered in UniProt, RefSeq NP_001104753.1, and the FDA substance registry under UNII Q86M4KXC2P. Worth knowing: material analyzed from circulation has repeatedly been found to differ from that reference. Analytical laboratories examining material obtained from circulation have characterized a C-terminally amidated analog (Esposito et al., Rapid Communications in Mass Spectrometry 2012, PMID 22328223) and an arginine-to-histidine substitution at position 23, designated MGF R23H (Cox et al., Drug Testing and Analysis 2017, PMID 28035768; see also Thevis et al., Growth Hormone & IGF Research 2014, PMID 25466910). "MGF" is therefore a name covering several distinct molecules rather than one defined substance.

On the PEGylation itself, the honest position is that almost nothing is published. A full-text search of the peer-reviewed literature returns no study characterizing PEG-MGF as a substance; public substance registries hold records for unmodified MGF and its C-terminal amide but none for a PEGylated form; and across three independent laboratories that analyzed real "MGF" products with high-resolution mass spectrometry, no PEGylated form was found or characterized. Consequently there is no published PEG chain length, no established attachment site, no confirmed mass, and no pharmacokinetic data of any kind. The general rationale for PEGylating a peptide — extending circulating half-life and slowing proteolysis and renal clearance — is well established for other molecules, but it has not been measured for this one, and a 2026 review notes explicitly that effects observed with native IGF-1Ec or isolated E-domain peptides cannot be assumed to carry over to PEG-conjugated constructs (PMID 42395176).

The research on unmodified MGF is in vitro and animal work. The E-domain variant was originally cloned from stretched rabbit muscle (Yang et al., Journal of Muscle Research and Cell Motility 1996, PMID 8884603), and a rat study reported that MGF messenger RNA rises rapidly after muscle damage and then falls as another isoform rises, a time course the authors interpreted as consistent with satellite-cell activation (Hill & Goldspink, Journal of Physiology 2003, PMID 12692175) — a temporal correlation rather than a causal demonstration. The synthetic 24-mer has been reported to increase myoblast proliferation while inhibiting terminal differentiation in cell culture (Yang & Goldspink, FEBS Letters 2002, PMID 12095637). Two caveats belong with all of this. The frequently repeated claim that the E-peptide acts independently of the IGF-1 receptor is contested rather than settled: it is supported by antibody-blockade and receptor-knockdown work (PMID 12095637; PMID 20844834) and directly rebutted by an independent laboratory whose paper is titled to that effect (Brisson & Barton, PLoS One 2012, PMID 23029120). And the endogenous free peptide has never actually been isolated from cells, tissue, or biological fluid — a point made in a 2010 review in Endocrinology (PMID 20130113) and conceded in a review co-authored by the originating group.

Neither MGF nor PEG-MGF is an approved drug. This product is supplied strictly for in vitro and laboratory research and is not for human or veterinary use.

Pinealon is the tripeptide Glu-Asp-Arg (EDR; PubChem CID 10273502, C15H26N6O8), one of the ultrashort peptide bioregulators described by V. Kh. Khavinson and colleagues and studied in relation to neuronal tissue.

In cell-culture studies, EDR has been reported to reduce accumulation of reactive oxygen species and support cell viability under oxidative-stress conditions; in rodent models it has been studied for effects on the developing and stressed brain, including models of prenatal hyperhomocysteinemia and Alzheimer’s-type pathology. A review by the originating group proposes DNA-binding and signaling mechanisms. The literature is genuine but concentrated in a single affiliated research group, and independent replication and randomized human trials are lacking; all findings are preclinical.

Prostamax is the four-residue peptide Lys-Glu-Asp-Pro (KEDP; PubChem CID 9848296, C20H33N5O9, ~487.5 g/mol), one of the short synthetic "peptide bioregulators" associated in the Khavinson framework with prostate tissue.

In the primary experimental report on this molecule, Prostamax was studied in rats with surgically induced chronic aseptic prostatitis; the authors reported reduced morphological signs of inflammation and, unlike the comparator agents tested, no promotion of atrophic change. This is a single-group, animal-model finding published in a non-PubMed-indexed journal and has not been independently replicated or evaluated in humans. Note that "Prostamax" is also used commercially for unrelated non-peptide products (herbal prostate supplements and other brands); this page refers only to the synthetic KEDP peptide.

SNAP-8 is the trade name for Acetyl Octapeptide-3 (also listed as Acetyl Glutamyl Heptapeptide-1), a synthetic eight-residue peptide with the acetylated, C-terminally amidated sequence Ac-Glu-Glu-Met-Gln-Arg-Arg-Ala-Asp-NH2 (Ac-EEMQRRAD-NH2). It is an elongated analog of the hexapeptide Argireline (Acetyl Hexapeptide-8, Ac-EEMQRR-NH2), extending that sequence by two residues (Ala-Asp); both are described as derived from the N-terminal region of the SNARE protein SNAP-25 and were developed as cosmetic ingredients (Lipotec, now part of Lubrizol Life Science).

The mechanism proposed for this peptide family is competition with SNAP-25 for a position in the SNARE complex, reducing calcium-dependent vesicle fusion. That mechanism was characterized experimentally for the parent hexapeptide Argireline rather than for SNAP-8 itself; for SNAP-8 it is inferred by structural analogy and is asserted mainly by the manufacturer. The independent peer-reviewed literature on SNAP-8 specifically is very thin — a PubMed search returns essentially an analytical-methods paper (an LC-MS/MS assay; Kim et al., 2020) and multi-ingredient formulation studies in which SNAP-8’s individual contribution cannot be isolated. SNAP-8 is not an approved drug and is supplied for laboratory research use only, not for human or veterinary use.

Tesamorelin (developmental code TH9507) is a stabilized synthetic analog of human growth-hormone-releasing hormone: it reproduces the full 44-amino-acid sequence of human GHRH (GHRH 1-44) and carries a hexenoyl group on its N-terminal tyrosine, a modification associated with greater resistance to enzymatic breakdown. Pharmacologically it is a GHRH-receptor (GRF-receptor) agonist — it stimulates pituitary somatotroph cells to synthesize and release endogenous growth hormone in a pulsatile manner, whose downstream effects are mediated largely by liver-derived IGF-1.

The molecule is distinguished from native GHRH by that N-terminal hexenoyl modification, which is the basis of its stability in laboratory preparations, and by being the full 44-residue sequence rather than a truncated fragment such as GHRH 1-29 (sermorelin). It is one of several structurally distinct compounds used as reagents in growth-hormone-axis research, alongside the ghrelin-receptor secretagogues. The material supplied here is a research chemical for in vitro and laboratory use. It is not an approved drug product and is not for human or veterinary use.

Testagen is the name assigned to the tetrapeptide Lys-Glu-Asp-Gly (KEDG), studied by V. Kh. Khavinson and colleagues among the short synthetic peptides of their bioregulator research program.

In cell-culture work, fluorescently labeled Testagen was reported to penetrate the cytoplasm and nucleus of HeLa cells and to bind preferentially to CAG-containing DNA oligonucleotides in a way sensitive to cytosine methylation; related work reported binding to the N-terminal regions of histones. The publicly indexed literature is limited to these in vitro molecular-interaction studies from a single research group. Its significance in living organisms has not been established, and there are no controlled clinical data or regulatory approvals for human use.

Thymosin Alpha-1 is a 28-residue, N-terminally acetylated peptide with the sequence Ac-Ser-Asp-Ala-Ala-Val-Asp-Thr-Ser-Ser-Glu-Ile-Thr-Thr-Lys-Asp-Leu-Lys-Glu-Lys-Lys-Glu-Val-Val-Glu-Glu-Ala-Glu-Asn (Ac-SDAAVDTSSEITTKDLKEKKEVVEEAEN), molecular formula C129H215N33O55 and molecular weight approximately 3108.3 g/mol (CAS 62304-98-7, PubChem CID 16130571). It corresponds to the N-terminal portion of prothymosin alpha, the product of the PTMA gene (UniProt P06454), and is generated from it by cleavage at the asparagine-glycine bond at position 28 — work that settled a long-running question about whether the peptide was merely an artifact of thymus extraction (Sarandeses et al., Journal of Biological Chemistry 2003, PMID 12554742). It was originally isolated from calf thymus and sequenced in 1977 (PMID 265536). The synthetic form carries the nonproprietary name thymalfasin and is identical in sequence to the natural peptide.

The mechanistic literature centers on innate immune signaling rather than the older "thymic hormone" framing. In cell culture and mouse models, Thymosin Alpha-1 has been reported to drive functional maturation and interleukin-12 production in dendritic cells through MyD88-dependent Toll-like receptor signaling (Romani et al., Blood 2004, PMID 14982877), and later work from the same group describes induction of indoleamine 2,3-dioxygenase, associated with immune tolerance as well as activation. A nuance usually lost in summary: in cultured monocyte-derived dendritic cells the effect is bidirectional rather than uniformly stimulatory, enhancing responses to viral TLR3 and TLR7/8 agonists while sharply lowering the same parameters after bacterial TLR2 and TLR4 stimulation (PMID 26096650). Characterising this molecule as something that simply "boosts immunity" misrepresents the primary data.

The older description of Thymosin Alpha-1 as a thymic hormone that matures T cells is not well supported. A review of the field concluded that none of the isolated thymosin peptides is really a thymic hormone (PMID 12852257) — the framing is inherited from 1960s and 1970s work on crude thymus extracts rather than from characterization of this peptide. Published findings are laboratory observations in cell and animal models and do not establish any effect in humans. Thymosin Alpha-1 is not an approved drug, and this product is supplied strictly for in vitro and laboratory research and is not for human or veterinary use.

Vesugen corresponds to the tripeptide Lys-Glu-Asp (KED; PubChem CID 87571363, C15H26N4O8, ~390.4 g/mol), one of the ultrashort "peptide bioregulators" developed by V. Kh. Khavinson and colleagues and categorized in that framework as a vascular-tissue peptide.

In cell- and tissue-culture research, KED has been reported to affect proliferation and apoptosis markers (for example, Ki-67 and p53) in organotypic cultures, and in vascular-endothelium models to offset an age-related decline in Ki-67; a molecular-docking study proposed an interaction with the MKI67 gene promoter. All of these findings are preclinical and originate largely from a single research group; they do not establish any effect in humans.

Vilon is the dipeptide L-lysyl-L-glutamic acid (Lys-Glu; PubChem lists the structure as lysylglutamic acid, CID 7010502, C11H21N3O5, ~275.3 g/mol). It is one of the shortest members of the "peptide bioregulator" family developed by V. Kh. Khavinson and colleagues at the St. Petersburg Institute of Bioregulation and Gerontology.

In preclinical work, a DNA-microarray study of mouse heart tissue reported that Vilon altered expression of a small number of gene clones, and an in vitro study of lymphocytes from elderly donors reported decondensation of heterochromatin and reactivation of ribosomal-gene regions. Several rodent studies have examined Vilon in tumor and lifespan models. This evidence base consists almost entirely of Russian preclinical (animal and cell-culture) studies; there are no registered Western randomized human trials, and Vilon is not an approved drug.

Vasoactive intestinal peptide is a 28-residue, C-terminally amidated neuropeptide with the sequence His-Ser-Asp-Ala-Val-Phe-Thr-Asp-Asn-Tyr-Thr-Arg-Leu-Arg-Lys-Gln-Met-Ala-Val-Lys-Lys-Tyr-Leu-Asn-Ser-Ile-Leu-Asn-NH2 (HSDAVFTDNYTRLRKQMAVKKYLNSILN-NH2), encoded by the VIP gene on chromosome 6q25.2 (UniProt P01282). The C-terminal amide is not incidental — it is required for binding at this receptor class. VIP belongs to the secretin/glucagon/PACAP superfamily and shares roughly 68 percent homology with PACAP (Miyata et al., 1989, PMID 2803320), but the two are distinct peptides from distinct genes: VIP from VIP on chromosome 6, PACAP from ADCYAP1 on chromosome 18. The synthetic peptide carries the nonproprietary name aviptadil and is the identical 28-mer rather than an analog.

One identity caution is worth recording because it affects the numbers most sources print. PubChem and ChEMBL publish a free-acid molecular formula and mass against the amidated sequence, so the formula and mass in those records do not describe the native peptide — converting the C-terminus to the amide loses an oxygen and gains a nitrogen and a hydrogen. The amidated values are the correct ones. A separate PubChem record carrying D-tyrosine and allo-residues describes a stereochemically different molecule and should not be used for this compound.

The receptor pharmacology is well characterized. VIP acts at two class B G-protein-coupled receptors, VPAC1 (gene VIPR1) and VPAC2 (gene VIPR2), coupling primarily through Gs to adenylyl cyclase and cyclic AMP; its affinity at the related PAC1 receptor is several hundred-fold lower, so it behaves effectively as a VPAC1/VPAC2 dual agonist (Harmar et al., British Journal of Pharmacology 2012, PMID 22289055). Its documented physiological roles in animal models include smooth-muscle relaxation and vasodilation, stimulation of epithelial water and electrolyte secretion, and circadian signaling in the suprachiasmatic nucleus — the last supported by the strongest genetic evidence in the field, since mice lacking the VPAC2 receptor fail to sustain circadian rhythms (Harmar et al., Cell 2002, PMID 12086606), a phenotype echoed in VIP-deficient mice (Nature Neuroscience 2005, PMID 15750589).

A frequent misreading is worth heading off: the "VIP interneurons" of cortical neuroscience are cells identified by the fact that they express the VIP gene, and their signaling is GABAergic. That literature describes those cells, not the actions of the peptide as a reagent. As a practical matter for laboratory work, VIP is also extremely short-lived — an initial plasma half-life on the order of one to two minutes in published animal and ex vivo work — and is cleaved by mast-cell tryptase and by neprilysin. It is not a substrate for DPP-4, contrary to a common assumption: VIP carries serine at position 2, and that enzyme requires proline or alanine there (PMID 8100523). VIP is not an approved drug, and this product is supplied strictly for in vitro and laboratory research and is not for human or veterinary use.