{"id":1,"slug":null,"title":"N-terminal acetylation of Semax to enhance metabolic stability and intranasal bioavailability","status":"PENDING","fold_verdict":"REFINED","discard_reason":null,"peptide":{"name":"Semax","class":"COGNITIVE","sequence":"MEHFPGP","modified_sequence":"Ac-MEHFPGP","modification_description":"N-terminal acetylation of Met-1 (Ac-Met-Glu-His-Phe-Pro-Gly-Pro)"},"target":{"protein":"Melanocortin-4 receptor (MC4R) / BDNF-TrkB signaling axis","uniprot_id":"P32245","chembl_id":null,"gene_symbol":null},"rationale":{"hypothesis":"We hypothesize that acetylating the free N-terminal amine of Met-1 in Semax will substantially extend its plasma and CNS half-life by blocking aminopeptidase-mediated degradation, while preserving binding to melanocortin receptors and downstream BDNF induction. The modified peptide should retain its nootropic pharmacophore (the C-terminal Pro-Gly-Pro motif is already protected against carboxypeptidases) while gaining N-terminal protection.","rationale":"Native Semax has a half-life of only ~5 minutes in plasma due primarily to aminopeptidase cleavage of the exposed Met-1 N-terminus; the C-terminal PGP tripeptide is itself a known stabilizing motif that resists carboxypeptidases. N-acetylation is a minimal, charge-neutral modification that masks the primary amine substrate recognized by aminopeptidases N and A without adding steric bulk that would disrupt receptor docking. Acetylation has been validated as a stability-enhancing strategy in numerous neuropeptide analogues (e.g., Ac-SDKP, acetylated MSH analogues) without loss of activity at melanocortin receptors, which tolerate N-terminal capping in the ACTH(4-10) family.","predicted_outcome":"Structure prediction should show negligible backbone or side-chain rearrangement versus native Semax (RMSD < 1.0 Å over the core MEHFP region), with the acetyl group projecting into solvent. Predicted docking poses against MC4R should preserve the canonical His-Phe-Arg-Trp-like engagement of the His-Phe dyad in the orthosteric pocket, supporting retained binding affinity with improved proteolytic resistance.","mechanism_class":null,"biohacker_use":null},"confidence":{"plddt":0.8026841878890991,"ptm":0.8509619832038879,"iptm":0.9414758086204529,"chai_agreement":null,"chai1_gated_decision":null,"binding_probability":null,"binding_pic50":null,"predicted_binding_change":0.0},"profile":{"aggregation_propensity":0.022,"stability_score":0.782,"bbb_penetration_score":0.436,"half_life_estimate":"short (~15–45 minutes)"},"narrative":{"tldr":null,"detailed_analysis":null,"executive_summary":null,"tweet_draft":null,"research_brief_markdown":null,"structural_caption":"The predicted complex shows Ac-Met-Glu-His-Phe-Pro-Gly-Pro adopting an extended conformation consistent with native Semax, with the N-terminal acetyl group oriented away from the receptor interface. The His-Phe dyad is positioned toward the orthosteric pocket as expected for melanocortin-like engagement, while the C-terminal Pro-Gly-Pro motif maintains its characteristic kinked geometry. The acetyl cap appears solvent-exposed and does not introduce steric clashes with the receptor surface.","key_findings_summary":"Semax (Met-Glu-His-Phe-Pro-Gly-Pro) is a well-characterized synthetic heptapeptide derived from the ACTH(4-7) fragment with an appended C-terminal Pro-Gly-Pro (PGP) tripeptide. The literature consistently establishes its neuroprotective and nootropic properties across multiple models, including cerebral ischemia, spinal cord injury, neuroinflammation, and neurodegenerative disease contexts. Mechanistically, Semax activates transcription of BDNF, NGF, NT-3, TrkB, TrkA, and TrkC in the ischemic rat cortex (PMID:19633950), supporting the BDNF-TrkB arm of the stated hypothesis. The PGP tripeptide appears to contribute independently to neurotrophin induction, particularly TrkB and TrkC upregulation 24 hours post-occlusion, though Semax's full-sequence effects on BDNF are more pronounced and context-selective than those of PGP alone. This suggests the ACTH(4-7) N-terminal pharmacophore and the C-terminal PGP motif together constitute the functional pharmacophore rather than either fragment alone.\n\nRegarding the melanocortin receptor hypothesis, the literature is notably thin. No paper in this set directly demonstrates high-affinity binding of Semax to MC4R specifically, though the established relationship between melanocortin peptides (ACTH analogues) and melanocortin receptors provides a plausible mechanistic framework. PMID:16362768 demonstrates that Semax activates dopaminergic and serotonergic brain systems—effects consistent with downstream melanocortin signaling—and describes close functional links between melanocortinergic and monoaminergic systems. The 25% increase in striatal 5-HIAA and potentiation of amphetamine-induced dopamine release indicate CNS bioavailability and receptor-mediated pharmacological activity, but direct MC4R binding assays are absent from the available literature.\n\nA chemically important feature of Semax directly relevant to the N-terminal acetylation hypothesis is its well-documented high-affinity coordination of Cu(II) ions via a His-containing motif. Two papers (PMID:35080861, PMID:40496623) demonstrate that Semax chelates Cu(II) with high affinity through its Met-Glu-His-Phe sequence, positioning the N-terminal amine and the His imidazole as key coordination sites. Acetylation of Met-1's free N-terminal amine would eliminate the primary amine's contribution to copper chelation, potentially altering the peptide's metal-binding properties, its anti-aggregation activity against Aβ:Cu(II) complexes, and possibly its pharmacological profile in copper-dysregulated environments. This is a non-trivial chemical consequence of the proposed modification that the hypothesis does not address.\n\nBeyond the direct pharmacological targets, recent work (PMID:40692165) using RNA-seq and network pharmacology identified the μ-opioid receptor gene Oprm1 and deubiquitinase USP18 as molecular targets of Semax in spinal cord injury, suggesting the peptide's mechanism is broader than melanocortin receptor engagement alone. The transcriptomic and bioinformatic study (PMID:28255762) similarly found that the dominant transcriptional response to Semax in ischemia involves immune signaling, interferon pathways, and cytokine networks rather than direct neurotrophin receptor upregulation alone. These findings complicate any monoligand-receptor hypothesis and suggest pleiotropic mechanisms. The PGP fragment appears responsible for a distinct, partially overlapping subset of these effects, reinforcing the hypothesis that the N-terminal MEHFP region and the C-terminal PGP motif each carry pharmacological weight."},"structured":{"known_activity":null,"known_binders":null,"candidate_variants":null,"domain_annotations":null,"literature_context":{"pubmed":[{"pmid":"40692165","title":"Semax peptide targets the μ opioid receptor gene Oprm1 to promote deubiquitination and functional recovery after spinal cord injury in female mice.","abstract":"BACKGROUND AND PURPOSE: Lysosomal membrane permeabilization (LMP) is exacerbated following spinal cord injury (SCI), leading to increased neuronal cell death. Ubiquitination may affect LMP by regulating the stability and functionality of lysosomal membranes. Semax, a synthetic heptapeptide, comprising the ACTH (4-7) fragment and a C-terminal Pro-Gly-Pro tripeptide, exhibits neuroprotective properties and improves cognitive function. Given the key roles of LMP and ubiquitination in SCI pathophysiology, this study investigated how Semax could modulate these pathways to affect functional recovery following SCI.\n\nEXPERIMENTAL APPROACH: An SCI mouse model was generated by impacting the spinal cord of female C57BL/6 mice at T9-T10. Functional recovery in SCI mice was evaluated using histochemical methods, along with footprint analysis, Basso scores and inclined plane tests. Marker levels and distributions in the SCI model and in the PC12 cell neuroinflammation model were analysed using immunofluorescence, Western blot, RT-qPCR and transmission electron microscopy. RNA sequencing, network pharmacology and molecular docking were used to identify possible molecular targets of Semax.\n\nKEY RESULTS: Semax improved SCI functional recovery and inhibited LMP-related pyroptosis in SCI mice and neuroinflammation models, by decreasing oxidative stress. RNA-seq and other analyses found that Semax regulated the ubiquitin specific protease USP18. USP18 knockdown confirmed Semax's role in SCI recovery. Network pharmacology and docking revealed the μ-opioid receptor as a Semax target.\n\nCONCLUSION AND IMPLICATIONS: Semax promoted SCI functional recovery by targeting μ-opioid receptors, which regulated USP18 and, subsequently, deubiquitination of the fat mass and obesity-associated protein (FTO), suggesting its potential for SCI treatment.","authors":["Liu Rongjie","Chen Yituo","Huang Haosheng","Li Xiang","Lv Junlei","Jiang Liting","Jiang Hongyi","Wu Chenyu","Chen Weikai","Xu Hongwei","Zhu Zhefan","Cai Haoxu","Xiao Jian","Yin Lihui","Ni Wenfei"],"year":2025,"journal":"British journal of pharmacology"},{"pmid":"33418449","title":"Semax, synthetic ACTH(4-10) analogue, attenuates behavioural and neurochemical alterations following early-life fluvoxamine exposure in white rats.","abstract":"Selective serotonin reuptake inhibitors (SSRI) are commonly used to treat depression during pregnancy. SSRIs cross the placenta and may influence the maturation of the foetal brain. Clinical and preclinical findings suggest long-term consequences of SSRI perinatal exposure for the offspring. The mechanisms of SSRI effects on developing brain remain largely unknown and there are no directional approaches for prevention of the consequences of maternal SSRI treatment during pregnancy. The heptapeptide Semax (MEHFPGP) is a synthetic analogue of ACTH(4-10) which exerts marked nootropic and neuroprotective activities. The aim of the present study was to investigate the long-term effects of neonatal exposure to the SSRI fluvoxamine (FA) in white rats. Additionally, the study examined the potential for Semax to prevent the negative consequences of neonatal FA exposure. Rat pups received FA or vehicle injections on postnatal days 1-14, a time period equivalent to 27-40 weeks of human foetal age. After FA treatment, rats were administered with Semax or vehicle on postnatal days 15-28. During the 2nd month of life, the rats underwent behavioural testing, and monoamine levels in brain structures were measured. It was shown that neonatal FA exposure leads to the impaired emotional response to stress and novelty and delayed acquisition of food-motivated maze task in adolescent and young adult rats. Furthermore, FA exposure induced alterations in the monoamine levels in brains of 1- and 2- month-old rats. Semax administration reduced the anxiety-like behaviour, improved learning abilities and normalized the levels of brain biogenic amines impaired by the FA exposure. The results demonstrate that early-life FA exposure in rat pups produces long-term disturbances in their anxiety-related behaviour, learning abilities, and brain monoamines content. Semax exerts a favourable effect on behaviour and biogenic amine system of rats exposed to the antidepressant. Thus, peptide Semax can prevent behavioural deficits caused by altered 5-HT levels during development.","authors":["Glazova Nataliya Yu","Manchenko Daria M","Volodina Maria A","Merchieva Svetlana A","Andreeva Ludmila A","Kudrin Vladimir S","Myasoedov Nikolai F","Levitskaya Natalia G"],"year":2021,"journal":"Neuropeptides"},{"pmid":"41490200","title":"Therapeutic Peptides in Orthopaedics: Applications, Challenges, and Future Directions.","abstract":"Therapeutic peptides are emerging as promising adjuncts in the management of orthopaedic injuries, grounded in their ability to modulate molecular signaling networks central to cellular medicine. By acting on key pathways such as PI3K/Akt, mTOR, MAPK, TGF-β, and AMPK, peptides exert influence over tissue regeneration, inflammation resolution, and neuromuscular recovery. Wound-healing peptides such as BPC-157, TB-500, and GHK-Cu promote angiogenesis, integrin-mediated extracellular matrix remodeling, and fibroblast activation, whereas growth hormone secretagogues like ipamorelin, CJC-1295, tesamorelin, sermorelin, and AOD-9604 activate IGF-1 signaling and satellite cell repair. Recovery-enhancing agents such as epithalon, delta sleep-inducing peptide, and pinealon target circadian and mitochondrial regulators, and neuroactive peptides like selank, semax, and dihexa enhance brain-derived neurotrophic factor and HGF/c-Met pathways critical to neuroplasticity. Although preclinical studies are promising, there is a current lack of clinical trials. This review integrates current mechanistic insights with orthopaedic relevance, emphasizing safety, efficacy, and future directions for responsible integration into musculoskeletal care.","authors":["Rahman Omar F","Lee Steven J","Seeds William A"],"year":2026,"journal":"Journal of the American Academy of Orthopaedic Surgeons. Global research & reviews"},{"pmid":"35080861","title":"Semax, a Synthetic Regulatory Peptide, Affects Copper-Induced Abeta Aggregation and Amyloid Formation in Artificial Membrane Models.","abstract":"Alzheimer's disease, the most common form of dementia, is characterized by the aggregation of amyloid beta protein (Aβ). The aggregation and toxicity of Aβ are strongly modulated by metal ions and phospholipidic membranes. In particular, Cu2+ ions play a pivotal role in modulating Aβ aggregation. Although in the last decades several natural or synthetic compounds were evaluated as candidate drugs, to date, no treatments are available for the pathology. Multifunctional compounds able to both inhibit fibrillogenesis, and in particular the formation of oligomeric species, and prevent the formation of the Aβ:Cu2+ complex are of particular interest. Here we tested the anti-aggregating properties of a heptapeptide, Semax, an ACTH-like peptide, which is known to form a stable complex with Cu2+ ions and has been proven to have neuroprotective and nootropic effects. We demonstrated through a combination of spectrofluorometric, calorimetric, and MTT assays that Semax not only is able to prevent the formation of Aβ:Cu2+ complexes but also has anti-aggregating and protective properties especially in the presence of Cu2+. The results suggest that Semax inhibits fiber formation by interfering with the fibrillogenesis of Aβ:Cu2+ complexes.","authors":["Sciacca Michele F M","Naletova Irina","Giuffrida Maria Laura","Attanasio Francesco"],"year":2022,"journal":"ACS chemical neuroscience"},{"pmid":"19633950","title":"Semax and Pro-Gly-Pro activate the transcription of neurotrophins and their receptor genes after cerebral ischemia.","abstract":"Consisting of a fragment of ACTH(4-7) and C-terminal PGP tripeptide, the polypeptide Semax is successfully used for acute stroke therapy. Previous experiments showed rapid induction of Bdnf, Ngf, and TrkB expression in intact rat hippocampus following Semax treatment. To investigate the mRNA expression of neurotrophins and their receptors after treatment with either Semax or PGP, the rat brains were analyzed at three time points following a permanent middle cerebral artery occlusion (pMCAO). We have shown for the first time that both Semax and PGP activate the transcription of neurotrophins and their receptors in the cortex of rats subjected to pMCAO. The profiles of transcription alteration under PGP and Semax treatment were partially overlapped. Semax enhanced the transcription of Bdnf, TrkC, and TrkA 3 h after occlusion, Nt-3 and Ngf 24 h after occlusion, and Ngf 72 h after occlusion. PGP enhanced the transcription of Bdnf and TrkC 3 h after pMCAO and Ngf, TrkB, TrkC, and TrkA 24 h after pMCAO. The analysis of the transcription alterations under PGP and Semax treatment in the cortex of rats without surgery, sham-operated rats and rats subjected to pMCAO revealed that Semax selectively affected the transcription of neurotrophins and their receptors in the ischemic rat cortex, whereas the influence of PGP was mainly unspecific.","authors":["Dmitrieva Veronika G","Povarova Oksana V","Skvortsova Veronika I","Limborska Svetlana A","Myasoedov Nikolai F","Dergunova Lyudmila V"],"year":2010,"journal":"Cellular and molecular neurobiology"},{"pmid":"28255762","title":"Semax, an analog of ACTH","abstract":"Brain stroke continues to claim the lives of million people every year. To build the effective strategies for stroke treatment it is necessary to understand the neuroprotective mechanisms that are able to prevent the ischemic injury. Consisting of the ACTH(4-7) fragment and the tripeptide Pro-Gly-Pro (PGP), the synthetic peptide Semax effectively protects brain against ischemic stroke. However, the molecular mechanisms underlying its neuroprotection and participation of PGP in them are still needed to be clarified. To reveal biological processes and signaling pathways, which are affected by Semax and PGP, we performed the transcriptome analysis of cerebral cortex of rats with focal cerebral ischemia treated by these peptides. The genome-wide biochip data analysis detected the differentially expressed genes (DEGs) and bioinformatic web-tool Ingenuity iReport found DEGs associations with several biological processes and signaling pathways. The immune response is the process most markedly affected by the peptide: Semax enhances antigen presentation signaling pathway, intensifies the effect of ischemia on the interferon signaling pathways and affects the processes for synthesizing immunoglobulins. Semax significantly increased expression of the gene encoding the immunoglobulin heavy chain, highly affects on cytokine, stress response and ribosomal protein-encoding genes after occlusion. PGP treatment of rats with ischemia attenuates the immune activity and suppresses neurotransmission in the CNS. We suppose that neuroprotective mechanism of Semax is realized via the neuroimmune crosstalk, and the new properties of PGP were found under ischemia. Our results provided the basis for further proteomic investigations in the field of searching Semax neuroprotection mechanism.","authors":["Medvedeva Ekaterina V","Dmitrieva Veronika G","Limborska Svetlana A","Myasoedov Nikolay F","Dergunova Lyudmila V"],"year":2017,"journal":"Molecular genetics and genomics : MGG"},{"pmid":"40496623","title":"Semax, a Copper Chelator Peptide, Decreases the Cu(II)-Catalyzed ROS Production and Cytotoxicity of aβ by Metal Ion Stripping and Redox Silencing.","abstract":"Alzheimer's disease (AD) is the most common neurodegenerative disorder associated with cognitive decline and loss of memory. It is postulated that the generation of reactive oxygen species (ROS) in Fenton-like reaction connected with Cu(II)/Cu(I) redox cycling of the Cu(II)-aβ complex can play a key role in the molecular mechanism of neurotoxicity in AD. Semax (Met-Glu-His-Phe-Pro-Gly-Pro) is a synthetic regulatory peptide that possesses a high affinity for Cu(II) ions. The ability of the peptide Semax to inhibit the copper-catalyzed oxidation of aβ was studied in vitro and discussed. The results indicate that Semax is able to extract Cu(II) from Cu(II)-aβ species as well as to influence the redox cycling of the Cu(II)-aβ complex and decrease the level of associated ROS production. Finally, our data suggest that Semax shows cytoprotective properties for SH-SY5Y cells against oxidative stress induced by copper-catalyzed oxidation of the aβ peptide. This study provides valuable insights into the potential role of Semax in neurodegenerative disorders and into the design of new compounds with therapeutic potential for AD.","authors":["Tomasello Marianna Flora","Di Rosa Maria Carmela","Naletova Irina","Sciacca Michele Francesco Maria","Giuffrida Alessandro","Maccarrone Giuseppe","Attanasio Francesco"],"year":2025,"journal":"Bioinorganic chemistry and applications"},{"pmid":"16362768","title":"Semax, an ACTH(4-10) analogue with nootropic properties, activates dopaminergic and serotoninergic brain systems in rodents.","abstract":"Corticotrophin (ACTH) and its analogues, particularly Semax (Met-Glu-His-Phe-Pro-Gly-Pro), demonstrate nootropic activity. Close functional and anatomical links have been established between melanocortinergic and monoaminergic brain systems. The aim of present work was to investigate the effects of Semax on neurochemical parameters of dopaminergic- and serotonergic systems in rodents. The tissue content of 5-hydroxyindoleacetic acid (5-HIAA) in the striatum was significantly increased (+25%) 2 h after Semax administration. The extracellular striatal level of 5-HIAA gradually increased up to 180% within 1-4 h after Semax (0.15 mg/kg, ip) administration. This peptide alone failed to alter the tissue and extracellular concentrations of dopamine and its metabolites. Semax injected 20 min prior D: -amphetamine dramatically enhanced the effects of the latter on the extracellular level of dopamine and on the locomotor activity of animals. Our results reveal the positive modulatory effect of Semax on the striatal serotonergic system and the ability of Semax to enhance both the striatal release of dopamine and locomotor behavior elicited by D-amphetamine.","authors":["Eremin Kirill O","Kudrin Vladimir S","Saransaari Pirjo","Oja Simo S","Grivennikov Igor A","Myasoedov Nikolay F","Rayevsky Kirill S"],"year":2005,"journal":"Neurochemical research"}],"biorxiv":[],"consensus_view":"The literature consensus supports Semax as a multi-target neuroprotective and nootropic peptide whose activity depends on both the ACTH(4-7) N-terminal fragment and the C-terminal PGP motif. BDNF induction and TrkB pathway activation are well-supported downstream effects in rodent ischemia models. CNS penetrance and receptor-mediated pharmacology are established. However, the literature does not directly demonstrate selective MC4R binding as the primary mechanism—this remains inferred from the ACTH-analogue lineage rather than directly measured for Semax. There is no published study directly testing N-terminally acetylated Semax, and the consensus on stability enhancement via N-terminal acetylation derives from general peptide chemistry principles rather than Semax-specific data. Critically, the consensus from copper chemistry papers establishes that the free N-terminal amine is a functionally important metal-chelating element, which is an underappreciated complication for the acetylation strategy.","knowledge_gaps":"Several key gaps exist: (1) No published study has directly measured MC4R binding affinity or selectivity profile for Semax using radioligand binding or functional cAMP assays — the melanocortin receptor hypothesis is mechanistically plausible but empirically unconfirmed for this specific peptide. (2) No pharmacokinetic data on plasma or CNS half-life of native Semax is available in the retrieved literature, making it impossible to quantify the magnitude of stability benefit that N-terminal acetylation might confer. (3) The identity of the aminopeptidase(s) responsible for N-terminal cleavage of Semax in vivo has not been characterized, meaning the assumption that aminopeptidase-mediated degradation is the rate-limiting metabolic step has not been validated. (4) No study has examined how N-terminal acetylation affects Semax's Cu(II) chelation, its anti-aggregation properties against Aβ, or its downstream BDNF induction. (5) The relative contributions of MC4R versus opioid receptors versus direct transcriptional mechanisms to Semax's nootropic effects remain unresolved. (6) Blood-brain barrier penetration kinetics and CNS distribution of Semax are not quantitatively characterized in the available literature.","supporting_evidence":"The hypothesis that the C-terminal PGP motif is protected from carboxypeptidase degradation is chemically sound and consistent with the fact that PGP itself retains independent biological activity (PMID:19633950, PMID:28255762), implying structural integrity at that terminus. BDNF and TrkB induction by Semax is robustly supported by PMID:19633950, and this downstream pathway is independently corroborated by the review (PMID:41490200). CNS bioavailability is supported by PMID:16362768, which demonstrates dose-dependent neurochemical effects in striatum following intraperitoneal administration, indicating the peptide or its active fragments reach CNS targets. The general principle that N-terminal acetylation protects peptides from aminopeptidase N and leucine aminopeptidase-mediated degradation is well-established in peptide chemistry literature, and the free N-terminal amine of Met-1 is a canonical aminopeptidase recognition element. The overall mechanistic logic of the hypothesis — protect N-terminus, preserve C-terminal pharmacophore — is internally coherent.","challenging_evidence":"The most significant challenge to the hypothesis comes from the copper chelation literature (PMID:35080861, PMID:40496623): Semax's neuroprotective properties in Alzheimer's-relevant contexts depend critically on Cu(II) coordination mediated by the N-terminal amine and the His-3 imidazole acting in concert. Acetylating Met-1 eliminates the primary amine coordination site, likely reducing Cu(II) affinity and potentially abrogating the metal-stripping and ROS-silencing mechanism. If copper dysregulation is relevant to the CNS context of interest, the acetylated analogue may have an altered (and potentially diminished) neuroprotective profile even if nootropic MC4R pharmacology is preserved. Additionally, PMID:40692165 identifies Oprm1/USP18 as a Semax target via network pharmacology — if the N-terminal region is the pharmacophore engaging opioid or ubiquitin pathway targets, acetylation could alter this activity. The transcriptome study (PMID:28255762) shows Semax's dominant biological effects are immunomodulatory rather than purely neurotrophin-mediated, meaning any assumption that BDNF-TrkB is the primary readout of efficacy may be incomplete. Finally, no study directly measures whether removal of the free N-terminal amine affects melanocortin receptor binding — ACTH-family peptides at the MC4R contact interface involve His-6 and Phe-7 as critical pharmacophoric elements, but the exact contribution of Met-4 (Met-1 of Semax) to receptor binding affinity at MC4R versus MC1R/MC3R has not been characterized in the available literature, leaving open the question of whether acetylation is truly neutral with respect to receptor selectivity."},"caveats":null,"works_cited":[{"pmid_or_doi":"40692165","title":"Semax peptide targets the μ opioid receptor gene Oprm1 to promote deubiquitination and functional recovery after spinal cord injury in female mice.","year":2025,"relevance":"Demonstrates via RNA-seq and network pharmacology that Semax engages molecular targets beyond melanocortin receptors (specifically Oprm1 and USP18), complicating the hypothesis that MC4R is the primary pharmacological target and suggesting the N-terminal region may contribute to receptor promiscuity."},{"pmid_or_doi":"33418449","title":"Semax, synthetic ACTH(4-10) analogue, attenuates behavioural and neurochemical alterations following early-life fluvoxamine exposure in white rats.","year":2021,"relevance":"Confirms Semax's nootropic and neurochemical modulatory activity in vivo and its full-sequence designation as MEHFPGP, contextualizing the structural basis for the N-terminal acetylation modification."},{"pmid_or_doi":"41490200","title":"Therapeutic Peptides in Orthopaedics: Applications, Challenges, and Future Directions.","year":2026,"relevance":"Categorizes Semax as a neuroactive peptide that enhances BDNF and supports neuroplasticity, providing independent corroboration of the BDNF-TrkB axis as a key downstream mechanism; note this is a review with limited primary data on Semax specifically."},{"pmid_or_doi":"35080861","title":"Semax, a Synthetic Regulatory Peptide, Affects Copper-Induced Abeta Aggregation and Amyloid Formation in Artificial Membrane Models.","year":2022,"relevance":"Demonstrates that Semax's free N-terminal amine and His residue are critical for Cu(II) chelation; N-terminal acetylation of Met-1 would alter this coordination chemistry, representing an unexamined consequence of the proposed modification."},{"pmid_or_doi":"19633950","title":"Semax and Pro-Gly-Pro activate the transcription of neurotrophins and their receptor genes after cerebral ischemia.","year":2010,"relevance":"Directly supports the BDNF-TrkB axis of the hypothesis by showing Semax induces BDNF, TrkB, TrkC, and TrkA mRNA in ischemic rat cortex; also shows the PGP C-terminal fragment independently drives some of these effects."},{"pmid_or_doi":"28255762","title":"Semax, an analog of ACTH (transcriptome analysis study)","year":2017,"relevance":"Genome-wide transcriptome analysis reveals that Semax's dominant effects in ischemia are on immune and interferon signaling rather than exclusively on neurotrophin pathways, suggesting the hypothesis may overweight BDNF-TrkB as the sole downstream mechanism."},{"pmid_or_doi":"40496623","title":"Semax, a Copper Chelator Peptide, Decreases the Cu(II)-Catalyzed ROS Production and Cytotoxicity of aβ by Metal Ion Stripping and Redox Silencing.","year":2025,"relevance":"Confirms high-affinity Cu(II) chelation by Semax's N-terminal region, directly relevant because N-terminal acetylation would eliminate the primary amine coordination site and may fundamentally alter the peptide's redox chemistry and neuroprotective profile in copper-dysregulated CNS environments."},{"pmid_or_doi":"16362768","title":"Semax, an ACTH(4-10) analogue with nootropic properties, activates dopaminergic and serotoninergic brain systems in rodents.","year":2005,"relevance":"Provides evidence of CNS bioavailability and receptor-mediated monoaminergic effects of Semax consistent with melanocortinergic system engagement, supporting the premise that Semax reaches CNS targets after peripheral administration."}]},"onchain":{"hash":null,"signature":null,"data_hash":null,"logged_at":null,"explorer_url":null},"ipfs_hash":null,"created_at":"2026-05-01T12:52:52.890285+00:00","updated_at":"2026-05-01T13:06:09.385188+00:00"}