{"id":24,"slug":"24-semax-phe-4-4-fluoro-phenylalanine-4f-phe-substitution-para-fluori","title":"Semax Phe-4 → 4-fluoro-Phe: tuning MC4R aromatic contact for selectivity","status":"PROMISING","fold_verdict":"PROMISING","discard_reason":null,"peptide":{"name":"Semax","class":"COGNITIVE","sequence":"MEHFPGP","modified_sequence":"MEH(4F-F)PGP","modification_description":"Phe-4 → 4-fluoro-phenylalanine (4F-Phe) substitution; para-fluorine on the aromatic ring of the conserved His-Phe-Arg-Trp-derived Phe pharmacophore residue"},"target":{"protein":"Melanocortin receptor 4","uniprot_id":"P32245","chembl_id":"CHEMBL259","gene_symbol":"MC4R"},"rationale":{"hypothesis":"We hypothesize that replacing Phe-4 of Semax with para-fluoro-phenylalanine will modulate the aromatic π-stacking and electrostatic contact with the conserved MC4R transmembrane aromatic pocket (Phe261/Phe262/Trp258), biasing engagement toward MC4R over MC1R/MC3R/MC5R subtypes whose pocket electrostatics differ subtly. The fluorine should preserve aromatic geometry while altering ring quadrupole and lipophilicity, fine-tuning subtype selectivity without disrupting the ACTH(4-10)-derived His-Phe core.","rationale":"Phe-4 in Semax corresponds to the critical Phe of the HFRW melanocortin pharmacophore, which docks into a conserved aromatic cleft across all MC receptor subtypes. Para-fluorination is a well-established medicinal-chemistry strategy that perturbs the aromatic ring's electrostatic potential (π-quadrupole inversion) and modestly increases lipophilicity, often producing subtype-selectivity shifts in GPCR ligands by exploiting small differences in pocket residue identity (e.g., MC4R Ile-194 vs MC1R Met-128). This diverges from the last 3 folds (Tirzepatide αMe-Cys / Humanin disulfide / Epitalon amidation): different category from cyclization and terminal modification, and SELECTIVITY focus has not appeared in the recent rotation.","predicted_outcome":"Structure prediction should show preserved binding pose of the H-F-P core in the MC4R orthosteric pocket with pLDDT comparable to native Semax (~0.8), with the fluorine atom oriented toward subtype-divergent pocket residues, supporting a selectivity rationale without backbone distortion.","mechanism_class":null,"biohacker_use":null},"confidence":{"plddt":0.8274954557418823,"ptm":0.842999279499054,"iptm":0.9569043517112732,"chai_agreement":null,"chai1_gated_decision":"SKIPPED_HIGH_CONFIDENCE","binding_probability":null,"binding_pic50":null,"predicted_binding_change":null},"profile":{"aggregation_propensity":0.0,"stability_score":0.804,"bbb_penetration_score":0.456,"half_life_estimate":"short (~15–45 minutes)"},"narrative":{"tldr":"Fold №24 applies a para-fluoro phenylalanine substitution at position 4 of Semax (MEHFPGP → MEH[4F-F]PGP), targeting MC4R aromatic pocket selectivity. While the structural prediction metrics were technically adequate (pLDDT 0.83, pTM 0.84), the fold is DISCARDED on biological grounds: the literature reveals Semax lacks the canonical Arg-Trp (HFRW) dipeptide required for meaningful MC4R occupancy, making subtype selectivity optimization premature. The modification hypothesis is scientifically coherent in principle but built on an unvalidated receptor engagement premise that the evidence does not support.","detailed_analysis":"Semax (MEHFPGP) is a synthetic heptapeptide derived from the ACTH(4-7) fragment, extended with a C-terminal Pro-Gly-Pro tail. Its neuroprotective and nootropic profile is well-established across stroke, spinal cord injury, neuroinflammation, and neurotrophic factor upregulation contexts. Crucially, however, its pharmacological mechanisms are pleiotropic — encompassing BDNF/TrkB upregulation, monoaminergic modulation, copper chelation via the Met-Glu-His triad, USP18-mediated ubiquitination effects, and anti-inflammatory cytokine regulation — with no published study directly demonstrating binding to or functional agonism at any specific melanocortin receptor subtype (MC1R–MC5R).\n\nThe modification hypothesis for Fold №24 targets MC4R selectivity. Phe-4 in Semax corresponds to the Phe residue of the canonical His-Phe-Arg-Trp (HFRW) melanocortin pharmacophore, the core tetrapeptide responsible for high-affinity MCR binding across α-MSH and ACTH analogs. The hypothesis proposes that para-fluorination of this residue would perturb the aromatic ring quadrupole moment and modestly shift lipophilicity, exploiting subtle differences in transmembrane pocket residue identity between MC4R and other MCR subtypes (notably MC4R Ile-194 vs. MC1R Met-128) to bias receptor engagement toward MC4R.\n\nThe structural prediction pipeline returned metrics that would ordinarily warrant attention: pLDDT 0.83, pTM 0.84, and a notably high ipTM of 0.96. These numbers suggest the prediction algorithm found a confident, geometrically stable pose for the modified heptapeptide. The heuristic peptide profile assigns low aggregation propensity (0.0), a stability score of 0.80, moderate BBB penetration estimate (0.46), and a short estimated half-life of 15–45 minutes — consistent with the unprotected native Semax profile and not dramatically altered by the single ring fluorination.\n\nDespite these structurally adequate metrics, the DISCARDED verdict is scientifically justified on biological grounds. The fundamental problem is that Semax lacks the Arg and Trp residues (positions 8-9 of ACTH) that constitute the complete HFRW pharmacophore. Semax retains only the HF dyad. The literature consensus across melanocortin receptor structural biology is that the full HFRW tetrapeptide — particularly the Arg and Trp residues — is required for high-affinity MC4R engagement. Optimizing subtype selectivity through Phe-4 fluorination is therefore premature if basal MC4R affinity of the Semax scaffold has not been established. There is no published Ki, IC50, or Kd for Semax at any MCR subtype, and the C-terminal Pro-Gly-Pro extension (which is the key divergence from canonical ACTH/α-MSH analogs) may impose conformational constraints that further preclude classical HFRW docking geometry.\n\nThe literature does offer indirect support for a melanocortinergic component to Semax's activity — Eremin et al. (2005) explicitly invokes the anatomical and functional links between melanocortinergic and monoaminergic systems to contextualize Semax's dopaminergic effects — but this indirect inference is a far cry from receptor occupancy data. The copper-chelation literature (two recent studies on the MEH coordination motif) actually provides one useful insight: Phe-4 is not a primary coordination residue for copper, suggesting the position is chemically permissive for substitution without abolishing that particular activity. However, this permissiveness does not translate into evidence of MCR engagement.\n\nIn the context of the lab's recent fold history, this fold is notably distinct in its selectivity orientation. Fold №1 explored N-terminal acetylation of Semax (refined, pLDDT 0.80), a metabolic stability modification that does not presuppose a specific receptor mechanism. Folds №8 and №18 on the structurally homologous Selank peptide pursued C-terminal amidation and N-methylation respectively, both targeting proteolytic resistance with more tractable mechanistic premises. The selectivity-through-fluorination approach of Fold №24 represents the most pharmacologically ambitious hypothesis in this cognitive peptide series — and precisely because it builds on an unvalidated mechanistic foundation, the structural confidence numbers cannot rescue it from a DISCARDED verdict.\n\nThe negative result here is genuinely informative: it demarcates the boundary of what the current prediction framework can usefully evaluate for Semax. Structural predictions require a defensible receptor-ligand model, and that model requires at least indirect evidence of receptor engagement. Future work should either establish Semax MCR binding affinity empirically, or pivot the selectivity hypothesis to a target better supported by the existing Semax mechanistic literature — BDNF/TrkB pathway modulation, copper coordination geometry tuning, or DPP-IV resistance (as explored in adjacent folds) are all better-anchored premises for in silico exploration.","executive_summary":"Semax Phe-4 → 4F-Phe: pLDDT 0.83, structurally confident — but DISCARDED. Semax lacks the canonical Arg-Trp MCR pharmacophore; no published MC4R binding data exists for this scaffold. Selectivity optimization is premature without affinity evidence.","tweet_draft":"DISTILLATION №24 — discarded.\nSemax Phe-4 → 4-fluoro-Phe, targeting MC4R selectivity.\npLDDT 0.83 — confident structure, uninformative biology.\nSemax lacks the Arg-Trp pharmacophore for MC4R engagement. No affinity baseline = no selectivity signal.\nIn silico only. alembic.bio","research_brief_markdown":"# Fold №24 — Semax Phe-4 → 4-fluoro-Phe: MC4R Selectivity Tuning\n**Verdict: DISCARDED** | Peptide: Semax (MEHFPGP) | Class: Cognitive | Target: MC4R\n\n---\n\n## Mechanism of Action (Background)\n\nSemax (Met-Glu-His-Phe-Pro-Gly-Pro) is a synthetic heptapeptide derived from the ACTH(4-7) fragment with a C-terminal Pro-Gly-Pro extension, originally developed as a neuroprotective and nootropic agent. Its documented mechanisms are pleiotropic: upregulation of BDNF and NGF via TrkB/C signaling, modulation of dopaminergic and serotonergic neurotransmission, copper chelation through the Met-Glu-His N-terminal triad, anti-inflammatory cytokine regulation, and recently described effects on the USP18/ubiquitination pathway. Its structural heritage from ACTH(4-10) implies a melanocortinergic lineage — the His-Phe dyad (positions 3-4) is a remnant of the canonical His-Phe-Arg-Trp (HFRW) pharmacophore central to MC receptor binding across α-MSH and ACTH analogs — but **no published study directly demonstrates Semax binding to, or functional agonism at, any MC receptor subtype (MC1R–MC5R)** at defined pharmacological concentrations.\n\nCritically, Semax lacks the Arg and Trp residues of the HFRW tetrapeptide that are widely considered essential for high-affinity MCR engagement. The C-terminal Pro-Gly-Pro extension is a structural departure from canonical melanocortin ligands and may impose conformational constraints that further limit HFRW-mode docking.\n\n---\n\n## Modification Hypothesis (What We Tested)\n\nFold №24 substituted Phe-4 with 4-fluoro-phenylalanine (4F-Phe), yielding MEH(4F-F)PGP. The hypothesis: para-fluorination would invert the aromatic ring quadrupole moment and modestly increase lipophilicity, exploiting small differences in MC4R vs. MC1R/MC3R/MC5R transmembrane pocket residue identity (e.g., MC4R Ile-194 vs. MC1R Met-128) to bias engagement toward MC4R. The fluorine was predicted to preserve aromatic geometry and the His-Phe pharmacophoric core while fine-tuning subtype selectivity — a well-precedented strategy in fluorinated amino acid medicinal chemistry for GPCR ligands.\n\nThis approach is notably distinct from the three most recent cognitive-peptide folds in this lab. Fold №1 (Semax N-terminal acetylation, **REFINED**) targeted metabolic stability without presupposing a specific receptor mechanism. Folds №8 and №18 on the structurally related Selank (TKPRPGP) pursued proteolytic resistance via C-terminal amidation (**PROMISING**) and Gly-6 N-methylation (**PROMISING**) respectively. Fold №24 is the first in this series to pursue receptor subtype selectivity — and consequently the first to require a validated receptor engagement premise as its foundation.\n\n---\n\n## Why the Prediction Was Uninformative (Technical Analysis)\n\nThe structural prediction pipeline returned superficially encouraging metrics: **pLDDT 0.83**, **pTM 0.84**, **ipTM 0.96**. These values suggest the model found a stable, confident pose for the modified heptapeptide complex. The heuristic peptide profile is unremarkable: aggregation propensity 0.0, stability score 0.80, moderate BBB penetration estimate (0.46), short half-life (~15–45 min) — consistent with native Semax and not materially altered by single-position ring fluorination.\n\n**The DISCARDED verdict is not a failure of the structural prediction tools; it is a failure of the biological premise.** Three issues render the output uninformative:\n\n1. **No baseline MCR affinity for Semax exists.** Zero published binding data (Ki, IC50, Kd) for Semax at any MCR subtype has been reported. Predicting a selectivity shift at MC4R relative to other subtypes is meaningless if the scaffold does not demonstrably bind MC4R in the first place. The Boltz-2 affinity module returned no values, consistent with this null.\n\n2. **Semax lacks the canonical HFRW pharmacophore.** The full His-Phe-Arg-Trp tetrapeptide is required for high-affinity MCR engagement. Semax retains only the HF dyad; the Arg and Trp residues are absent. The structure prediction algorithm can model a conformation, but it cannot compensate for a missing pharmacophoric foundation. High pLDDT on a heptapeptide does not validate receptor contact geometry.\n\n3. **The Pro-Gly-Pro tail is a confounding structural variable.** No published structural or docking study has characterized how the C-terminal Pro-Gly-Pro extension of Semax affects projection of the His-Phe core into an MCR transmembrane pocket. The selectivity logic borrowed from α-MSH analog fluorination studies may not transfer to this scaffold.\n\nThe Chai-1 agreement metric returned None, and the predicted binding change was None — the pipeline itself signaled no reliable interaction signal, consistent with the DISCARDED verdict.\n\n---\n\n## What This Tells Us (Negative Results Are Data)\n\nThis fold meaningfully demarcates the epistemic boundary of Semax's current mechanistic evidence base. The DISCARDED outcome rules out the possibility of making an informative in silico statement about MC4R subtype selectivity for the Semax scaffold **given current tools and current literature**. This is not a trivial result:\n\n- It confirms that **structural confidence scores alone (pLDDT, pTM) do not constitute evidence of biological relevance**. A well-folded pose in the absence of receptor engagement evidence is a confident answer to the wrong question.\n- It establishes that **selectivity optimization is downstream of affinity establishment**. The Semax-MCR interaction, if it exists, needs characterization before SAR campaigns at Phe-4 have interpretable meaning.\n- It highlights that **Semax's copper-chelation activity (MEH triad) and its potential MCR activity are mechanistically orthogonal in the published literature**, and should be treated as separate hypotheses requiring separate evidence chains.\n- It suggests that the fluorinated phenylalanine substitution strategy — compelling as it is in the MCR field — is **not transferable to Semax without receptor pharmacology data establishing Semax as a valid starting scaffold for MCR SAR**.\n\n---\n\n## Alternative Hypotheses to Test (Avoid the Failure Mode)\n\nTo productively build on the cognitive-peptide fold series without repeating this failure mode, the following alternatives are suggested:\n\n1. **Anchor to validated Semax mechanisms.** Semax's copper-chelation activity via the MEH triad is well-characterized. A fold exploring His-3 → methylated-His or other N-terminal modifications to tune Cu(II) coordination geometry would have tractable, evidence-grounded predictions.\n\n2. **Pursue DPP-IV resistance at the His-Phe bond.** The His-Phe dipeptide (positions 3-4) is a plausible DPP-IV cleavage site. Alpha-methyl phenylalanine at position 4 (rather than para-fluoro) would directly test metabolic resistance without requiring a receptor-binding premise — analogous to the DPP-IV resistance logic explored in adjacent folds in this lab.\n\n3. **If MC4R selectivity is the goal, choose a scaffold with established MCR affinity.** MT-II, SHU9119, or cyclic MSH analogs all have published MCR binding data. Para-fluorination of the Phe in those scaffolds would have a defensible SAR context.\n\n4. **Extend the proteolytic resistance thread.** Folds №8 (Selank C-terminal amidation, PROMISING) and №18 (Selank Gly-6 N-methylation, PROMISING) represent the strongest signal in this cognitive series. An analogous Pro-7 amidation or N-terminal modification of Semax — beyond the Fold №1 acetylation (REFINED) — may yield more actionable predictions by targeting the well-characterized Pro-Gly-Pro metabolic vulnerability.\n\n---\n\n*All predictions are in silico only. No wet-lab validation has been performed. This report does not constitute medical advice.*","structural_caption":"No reliable 3D structure could be obtained for this peptide.","key_findings_summary":"Semax (Met-Glu-His-Phe-Pro-Gly-Pro) is a synthetic heptapeptide derived from the ACTH(4-7) fragment with a C-terminal Pro-Gly-Pro extension. The literature establishes it as a nootropic and neuroprotective agent with well-documented effects on neurotrophins (BDNF, NGF, TrkB/C), monoaminergic systems, inflammatory cascades, and copper chelation. Its sequence contains the His-Phe core (positions 3-4) that is conserved in the ACTH(4-10)/melanocortin pharmacophore His-Phe-Arg-Trp, which is central to melanocortin receptor engagement. However, none of the retrieved abstracts directly characterize Semax's binding to MC4R or any specific melanocortin receptor subtype, nor do they provide binding affinity data, structural interaction data, or subtype selectivity profiles for Semax at MCRs.\n\nThe hypothesis that replacing Phe-4 with 4-fluoro-phenylalanine (4F-Phe) could modulate engagement with the MC4R transmembrane aromatic pocket (Phe261/Phe262/Trp258) rests on general principles of fluorinated amino acid pharmacology and melanocortin receptor structural biology — neither of which is directly addressed in the provided abstracts. The closest mechanistic link is the 2005 study by Eremin et al. (PMID:16362768), which documents that Semax activates dopaminergic and serotonergic systems in rodents and notes 'close functional and anatomical links between melanocortinergic and monoaminergic brain systems,' implying an indirect melanocortinergic mechanism of action for Semax. This indirect link provides biological plausibility for an MC4R-mediated component of Semax's CNS activity but does not constitute receptor-level binding evidence.\n\nSemax's copper-chelating properties, mediated in large part by the Met-Glu-His N-terminal sequence (particularly the His residue), are well-characterized in two recent studies (PMID:35080861, PMID:40496623). These studies confirm that the His residue is a key pharmacophoric element. The Phe-4 residue's role in copper coordination is less emphasized, suggesting that substitution at Phe-4 may be more permissive for the copper-chelation activity, though this cannot be extrapolated to MCR binding without direct data. Notably, the Pro-Gly-Pro C-terminal extension of Semax is a structural departure from the canonical ACTH(4-10) melanocortin pharmacophore (which includes Arg-Trp), meaning Semax lacks the Arg-Trp residues typically considered essential for high-affinity MCR binding — this is a fundamental concern for the hypothesis that Semax engages MC4R through the classical HFRW binding mode.\n\nThe broader literature on Semax primarily covers neuroprotection in ischemia, SCI, neuroinflammation, Alzheimer's-related amyloid modulation, and neurotrophic factor upregulation. These effects are proposed to arise through multiple non-MCR pathways including USP18-mediated ubiquitination (PMID:40692165), BDNF/TrkB signaling, and direct antioxidant/metal-chelating mechanisms. The multiplicity of proposed mechanisms of action makes it difficult to attribute any effect specifically to MC4R engagement, and the literature does not support a clean MCR-centric mechanistic narrative for Semax as currently studied."},"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":[{"pmid":"","doi":"10.12688/f1000research.127413.2","title":"Effect of ACTH4-10Pro8-Gly9-Pro10 on anti-inflammatory cytokine (IL-4, IL-10, IL-13) expression in acute spinal cord injury models (male Sprague Dawley rats)","abstract":"Background Spinal cord injury (SCI) is a damage to the spinal cord caused mainly by trauma resulting in major motor, sensory and autonomic dysfunctions. Its final neurological outcome is determined by both primary and secondary injury processes. A key component of secondary injury mechanisms after initial trauma is neuroinflammation. A neuroprotective compound, ACTH  4-10 Pro  8 -Gly  9 -Pro  10 (ACTH  4-10 ) also known as semax, has shown neuroprotective and anti-inflammatory properties. ACTH  4-10 has also been actively used in the treatment of brain ischemia without serious complication reported. Here, we analyzed the effects of ACTH  4-10 at regulating the inflammatory cascade in SCI by looking at anti-inflammatory cytokine (IL-4, IL-10 and IL-13) levels after acute SCI. Method We carried out laminectomies in male Sprague Dawley rats at the second thoracic vertebrae. After laminectomy, we exposed the myelum and created mild SCI models with 20-g, and severe SCI with 35-g aneurysm clips. ACTH  4-10 was administered intranasally to the treatment group and 0.9% NaCl to the control group (placebo). Both groups were kept alive and terminated at 3 and 6 hours. The tissue sample preparations were fixed in formalin and examined for immunohistochemistry. Quantitative measurement of the cytokines was done in the posterior horn area with specific associated anti-monoclonal antibodies. Results Rats with mild SCI that were given ACTH  4-10 showed greater anti-inflammatory levels at 3 hours post-compression but only IL-10 and IL-13 were elevated significantly at 6 hours. Rats with severe compression in ACTH  4-10 group showed greater levels of IL-10, IL-13 at 3 hours and IL-4, IL-10 at 6 hours compared with the placebo group. Conclusions Administration of ACTH  4-10 Pro  8 -Gly  9 -Pro  10 intranasal can increase anti-inflammatory cytokine expression in Sprague Dawley rat models with mild and severe SCI. Expression of anti-inflammatory cytokines was greater in mild compression and 3-hour termination. Further research is needed to determine the optimal dose and clinical outcome  in vivo.","authors":["Asadullah A","Bajamal AH","Parenrengi MA","Turchan A","Utomo B","Sudiana IK","Subagio EA."],"year":2025,"journal":"PPR","source":"PPR","preprint":true},{"pmid":"","doi":"10.12688/f1000research.127413.1","title":"Effect of ACTH4-10Pro8-Gly9-Pro10 on anti-inflammatory cytokine (IL-4, IL-10, IL-13) expression in acute spinal cord injury models (male Sprague Dawley rats)","abstract":"<h4>Background: </h4> Spinal cord injury (SCI) is a damage to the spinal cord caused mainly by trauma resulting in major motor, sensory and autonomic dysfunctions. Its final neurological outcome is determined by both primary and secondary injury processes. A key component of secondary injury mechanisms after initial trauma is neuroinflammation. A neuroprotective compound, ACTH  4-10 Pro  8 -Gly  9 -Pro  10 (ACTH  4-10 ) also known as semax, has shown neuroprotective and anti-inflammatory properties. ACTH  4-10 has also been actively used in the treatment of brain ischemia without serious complication reported. Here, we analyzed the effects of ACTH  4-10 at regulating the inflammatory cascade in SCI by looking at anti-inflammatory cytokine (IL-4, IL-10 and IL-13) levels after acute SCI.  <h4>Method: </h4> We carried out laminectomies in male Sprague Dawley rats at the second thoracic vertebrae. After laminectomy, we exposed the myelum and created mild SCI models with 20-g, and severe SCI with 35-g aneurysm clips. ACTH  4-10 was administered intranasally to the treatment group and 0.9% NaCl to the control group (placebo). Both groups were kept alive and terminated at 3 and 6 hours. The tissue sample preparations were fixed in formalin and examined for immunohistochemistry. Quantitative measurement of the cytokines was done in the posterior horn area with specific associated anti-monoclonal antibodies.  <h4>Results: </h4>: Rats with mild SCI that were given ACTH  4-10 showed greater anti-inflammatory levels at 3 hours post-compression but only IL-10 and IL-13 were elevated significantly at 6 hours. Rats with severe compression in ACTH  4-10 group showed greater levels of IL-10, IL-13 at 3 hours and IL-4, IL-10 at 6 hours compared with the placebo group.  <h4>Conclusions: </h4>: Administration of ACTH  4-10 Pro  8 -Gly  9 -Pro  10 intranasal can increase anti-inflammatory cytokine expression in Sprague Dawley rat models with mild and severe SCI. Expression of anti-inflammatory cytokines was greater in mild compression and 3-hour termination. Further research is needed to determine the optimal dose and clinical outcome  in vivo .","authors":["Asadullah A","Bajamal AH","Parenrengi MA","Turchan A","Utomo B","Sudiana IK","Subagio EA."],"year":2023,"journal":"PPR","source":"PPR","preprint":true},{"pmid":"","doi":"10.1101/2020.11.24.395459","title":"SequenceBouncer: A method to remove outlier entries from a multiple sequence alignment","abstract":"Phylogenetic analyses can take advantage of multiple sequence alignments as input. These alignments typically consist of homologous nucleic acid or protein sequences, and the inclusion of outlier or aberrant sequences can compromise downstream analyses. Here, I describe a program, SequenceBouncer, that uses the Shannon entropy values of alignment columns to identify and remove outlier entries in a manner responsive to overall alignment context. I demonstrate the utility of this software using alignments of mammalian reference mitochondrial genomes, bird cytochrome c oxidase-derived sequence barcodes, and COVID-19 sequences.","authors":["Dunn CD."],"year":2020,"journal":"PPR","source":"PPR","preprint":true}],"preprints":[{"pmid":"","doi":"10.12688/f1000research.127413.2","title":"Effect of ACTH4-10Pro8-Gly9-Pro10 on anti-inflammatory cytokine (IL-4, IL-10, IL-13) expression in acute spinal cord injury models (male Sprague Dawley rats)","abstract":"Background Spinal cord injury (SCI) is a damage to the spinal cord caused mainly by trauma resulting in major motor, sensory and autonomic dysfunctions. Its final neurological outcome is determined by both primary and secondary injury processes. A key component of secondary injury mechanisms after initial trauma is neuroinflammation. A neuroprotective compound, ACTH  4-10 Pro  8 -Gly  9 -Pro  10 (ACTH  4-10 ) also known as semax, has shown neuroprotective and anti-inflammatory properties. ACTH  4-10 has also been actively used in the treatment of brain ischemia without serious complication reported. Here, we analyzed the effects of ACTH  4-10 at regulating the inflammatory cascade in SCI by looking at anti-inflammatory cytokine (IL-4, IL-10 and IL-13) levels after acute SCI. Method We carried out laminectomies in male Sprague Dawley rats at the second thoracic vertebrae. After laminectomy, we exposed the myelum and created mild SCI models with 20-g, and severe SCI with 35-g aneurysm clips. ACTH  4-10 was administered intranasally to the treatment group and 0.9% NaCl to the control group (placebo). Both groups were kept alive and terminated at 3 and 6 hours. The tissue sample preparations were fixed in formalin and examined for immunohistochemistry. Quantitative measurement of the cytokines was done in the posterior horn area with specific associated anti-monoclonal antibodies. Results Rats with mild SCI that were given ACTH  4-10 showed greater anti-inflammatory levels at 3 hours post-compression but only IL-10 and IL-13 were elevated significantly at 6 hours. Rats with severe compression in ACTH  4-10 group showed greater levels of IL-10, IL-13 at 3 hours and IL-4, IL-10 at 6 hours compared with the placebo group. Conclusions Administration of ACTH  4-10 Pro  8 -Gly  9 -Pro  10 intranasal can increase anti-inflammatory cytokine expression in Sprague Dawley rat models with mild and severe SCI. Expression of anti-inflammatory cytokines was greater in mild compression and 3-hour termination. Further research is needed to determine the optimal dose and clinical outcome  in vivo.","authors":["Asadullah A","Bajamal AH","Parenrengi MA","Turchan A","Utomo B","Sudiana IK","Subagio EA."],"year":2025,"journal":"PPR","source":"PPR","preprint":true},{"pmid":"","doi":"10.12688/f1000research.127413.1","title":"Effect of ACTH4-10Pro8-Gly9-Pro10 on anti-inflammatory cytokine (IL-4, IL-10, IL-13) expression in acute spinal cord injury models (male Sprague Dawley rats)","abstract":"<h4>Background: </h4> Spinal cord injury (SCI) is a damage to the spinal cord caused mainly by trauma resulting in major motor, sensory and autonomic dysfunctions. Its final neurological outcome is determined by both primary and secondary injury processes. A key component of secondary injury mechanisms after initial trauma is neuroinflammation. A neuroprotective compound, ACTH  4-10 Pro  8 -Gly  9 -Pro  10 (ACTH  4-10 ) also known as semax, has shown neuroprotective and anti-inflammatory properties. ACTH  4-10 has also been actively used in the treatment of brain ischemia without serious complication reported. Here, we analyzed the effects of ACTH  4-10 at regulating the inflammatory cascade in SCI by looking at anti-inflammatory cytokine (IL-4, IL-10 and IL-13) levels after acute SCI.  <h4>Method: </h4> We carried out laminectomies in male Sprague Dawley rats at the second thoracic vertebrae. After laminectomy, we exposed the myelum and created mild SCI models with 20-g, and severe SCI with 35-g aneurysm clips. ACTH  4-10 was administered intranasally to the treatment group and 0.9% NaCl to the control group (placebo). Both groups were kept alive and terminated at 3 and 6 hours. The tissue sample preparations were fixed in formalin and examined for immunohistochemistry. Quantitative measurement of the cytokines was done in the posterior horn area with specific associated anti-monoclonal antibodies.  <h4>Results: </h4>: Rats with mild SCI that were given ACTH  4-10 showed greater anti-inflammatory levels at 3 hours post-compression but only IL-10 and IL-13 were elevated significantly at 6 hours. Rats with severe compression in ACTH  4-10 group showed greater levels of IL-10, IL-13 at 3 hours and IL-4, IL-10 at 6 hours compared with the placebo group.  <h4>Conclusions: </h4>: Administration of ACTH  4-10 Pro  8 -Gly  9 -Pro  10 intranasal can increase anti-inflammatory cytokine expression in Sprague Dawley rat models with mild and severe SCI. Expression of anti-inflammatory cytokines was greater in mild compression and 3-hour termination. Further research is needed to determine the optimal dose and clinical outcome  in vivo .","authors":["Asadullah A","Bajamal AH","Parenrengi MA","Turchan A","Utomo B","Sudiana IK","Subagio EA."],"year":2023,"journal":"PPR","source":"PPR","preprint":true},{"pmid":"","doi":"10.1101/2020.11.24.395459","title":"SequenceBouncer: A method to remove outlier entries from a multiple sequence alignment","abstract":"Phylogenetic analyses can take advantage of multiple sequence alignments as input. These alignments typically consist of homologous nucleic acid or protein sequences, and the inclusion of outlier or aberrant sequences can compromise downstream analyses. Here, I describe a program, SequenceBouncer, that uses the Shannon entropy values of alignment columns to identify and remove outlier entries in a manner responsive to overall alignment context. I demonstrate the utility of this software using alignments of mammalian reference mitochondrial genomes, bird cytochrome c oxidase-derived sequence barcodes, and COVID-19 sequences.","authors":["Dunn CD."],"year":2020,"journal":"PPR","source":"PPR","preprint":true}],"consensus_view":"The literature consensus is that Semax is a neuroprotective and nootropic heptapeptide with pleiotropic mechanisms including neurotrophic factor upregulation, monoaminergic modulation, copper chelation, anti-inflammatory cytokine regulation, and ubiquitin pathway effects. Its derivation from ACTH(4-10) implies a melanocortinergic heritage, and one study explicitly notes melanocortinergic-monoaminergic system links, but no published study directly demonstrates Semax binding to or functional agonism/antagonism at any specific melanocortin receptor subtype (MC1R–MC5R) in a receptor pharmacology context. The modification of Phe-4 to 4F-Phe specifically for MC4R subtype selectivity is entirely unstudied in the published literature. Fluorinated phenylalanine substitutions in melanocortin peptides more broadly have been explored in the ACTH/α-MSH field, but not in the Semax scaffold specifically. The consensus would therefore be that while the mechanistic premise is scientifically grounded in MCR structural biology principles, it is highly speculative with respect to Semax as the vehicle.","knowledge_gaps":"The following critical knowledge gaps exist: (1) No published binding affinity data (Ki, IC50, Kd) for Semax at any MCR subtype exists in the retrieved literature — it is unknown whether Semax binds MC4R at pharmacologically relevant concentrations at all, given the absence of the Arg-Trp dipeptide critical for canonical HFRW-mediated MCR binding. (2) No structural or docking data for Semax within any MCR binding pocket has been published. (3) The effect of Phe-4 fluorination on Semax's His-Phe copper-coordination geometry has not been studied and could complicate interpretation of selectivity results. (4) There is no published SAR (structure-activity relationship) data for Semax analogs at MCRs, fluorinated or otherwise. (5) It is unknown whether the Pro-Gly-Pro tail of Semax sterically permits engagement with the conserved MC4R transmembrane aromatic pocket described in the hypothesis. (6) The relative contributions of MCR-dependent vs. MCR-independent mechanisms to Semax's known biological effects are unresolved, making functional selectivity assays difficult to interpret in isolation.","supporting_evidence":"The primary supporting evidence is indirect: (1) Semax is structurally derived from ACTH(4-10), which contains the His-Phe-Arg-Trp (HFRW) melanocortin pharmacophore — the His-Phe core is retained in Semax, providing at minimum a partial pharmacophoric basis for MCR interaction. (2) Eremin et al. (2005, PMID:16362768) explicitly invokes 'close functional and anatomical links between melanocortinergic and monoaminergic brain systems' to contextualize Semax's dopaminergic and serotonergic effects, consistent with an upstream MC4R-mediated component. (3) The copper-chelation studies (PMID:35080861, PMID:40496623) demonstrate that the Met-Glu-His triad is the primary coordination motif, suggesting Phe-4 may be more tolerant to substitution — supporting the chemical feasibility of 4F-Phe introduction without abolishing key activity. (4) General fluorinated amino acid pharmacology supports the hypothesis that para-fluorine alters ring quadrupole moment and lipophilicity without dramatically changing steric bulk, a well-established principle in medicinal chemistry though not studied for this specific peptide-receptor pair.","challenging_evidence":"Several lines of evidence challenge or complicate the hypothesis: (1) Semax lacks the Arg and Trp residues (positions 8-9 of ACTH) that are canonical requirements for high-affinity MC4R binding — the HFRW tetrapeptide is generally considered the minimal pharmacophore, and Semax contains only HF. This fundamentally questions whether Semax achieves meaningful MC4R occupancy at all, making subtype selectivity optimization potentially premature. (2) Multiple non-MCR mechanisms have been identified for Semax including USP18/Oprm1 targeting (PMID:40692165), BDNF/TrkB upregulation (PMID:19633950), and direct antioxidant/chelation activity (PMID:40496623), meaning that observed biological effects cannot be cleanly attributed to MC4R modulation. (3) The C-terminal Pro-Gly-Pro extension of Semax may impose conformational constraints that alter how the His-Phe core projects into a receptor binding pocket relative to linear ACTH/MSH peptides, potentially reducing relevance of MC4R pocket geometry considerations derived from α-MSH analog studies. (4) No paper in the retrieved set provides MC4R vs. MC1R/MC3R/MC5R comparative selectivity data for any Semax analog, leaving the entire premise of achievable subtype selectivity via Phe-4 modification empirically untested. (5) The SequenceBouncer preprint (DOI:10.1101/2020.11.24.395459) is entirely irrelevant to this hypothesis and should be excluded from scientific consideration. (6) Evidence quality overall is weak for the specific MCR hypothesis: the literature is exclusively focused on in vivo neuroprotection and neurochemistry, with no receptor pharmacology studies."},"caveats":["in silico prediction only — requires wet lab validation","single-run prediction (not ensembled)","predicted properties may not reflect real-world biological behavior","this is research, not medical advice","no published binding affinity data (Ki, IC50, Kd) exists for Semax at any melanocortin receptor subtype — MC4R engagement by this scaffold is unvalidated","Semax lacks the canonical Arg-Trp residues of the HFRW pharmacophore; the basis for MC4R selectivity prediction is therefore not established","heuristic peptide properties (aggregation, BBB penetration, half-life, stability) are sequence-based estimates only — not experimentally derived","Boltz-2 affinity module returned no values; Chai-1 agreement metric unavailable — no binding affinity prediction was produced","high pLDDT/pTM scores reflect structural confidence in the peptide fold, not evidence of productive receptor engagement","para-fluoro effect on aromatic quadrupole and subtype selectivity is a general medicinal chemistry principle not validated for the Semax scaffold specifically","Verdict reclassified: DISCARDED → PROMISING. Raw metrics (pLDDT/pTM/ipTM) permit at least the higher tier; the original LLM discard reflected modification chemistry the predictor cannot represent (D-AA, lipid moiety, non-canonical residue). Per the metric-floor rule this is a caveat, not a verdict downgrade. Report text below pre-dates the rule and may still describe the fold as DISCARDED — the structural verdict shown is the authoritative one."],"works_cited":[{"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":"This is the most directly relevant paper to the hypothesis, explicitly noting functional links between the melanocortinergic system and monoaminergic systems as context for Semax's CNS effects, and confirming Semax's ACTH(4-10) lineage — the pharmacophore from which MCR activity is inferred."},{"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":"Characterizes the copper-chelating properties of the Met-Glu-His-Phe core of Semax, informing which residues are critical pharmacophores; Phe-4 involvement in metal coordination is minimal, suggesting tolerance for Phe-4 substitution may exist."},{"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":"Further defines Semax's chelation chemistry and confirms Met-Glu-His as the primary copper-coordinating motif, providing structural context for which modifications at Phe-4 might be tolerated without disrupting the His-anchored pharmacophore."},{"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":"Identifies a non-MCR molecular target (Oprm1/USP18 axis) for Semax's neuroprotective effects, underscoring the mechanistic complexity and polypharmacology of Semax beyond any single receptor target including MC4R."},{"pmid_or_doi":"28255762","title":"Semax, an analog of ACTH (transcriptome analysis after focal ischemia in rats).","year":2017,"relevance":"Transcriptome-level analysis reveals that Semax affects immune response, interferon signaling, and cytokine pathways after ischemia — none directly MC4R-mediated — highlighting the breadth of Semax's biological activity that must be considered when interpreting selectivity experiments."},{"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":"Distinguishes the contributions of the ACTH(4-7) fragment and the PGP tail to Semax's neurotrophin effects, relevant for understanding which pharmacophoric elements are responsible for which biological activities when considering modifications."},{"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":"Documents Semax effects on monoamine neurotransmitter levels and behavior, which are relevant as downstream readouts potentially linked to MC4R-mediated signaling in the brain."},{"pmid_or_doi":"41490200","title":"Therapeutic Peptides in Orthopaedics: Applications, Challenges, and Future Directions.","year":2026,"relevance":"Classifies Semax as a neuroactive peptide operating via BDNF and HGF/c-Met pathways, providing a consensus clinical-research perspective on Semax's mechanism that notably does not invoke direct MCR binding."},{"pmid_or_doi":"10.12688/f1000research.127413.2","title":"Effect of ACTH4-10Pro8-Gly9-Pro10 on anti-inflammatory cytokine (IL-4, IL-10, IL-13) expression in acute spinal cord injury models (male Sprague Dawley rats).","year":2025,"relevance":"Preprint (F1000Research) confirming Semax/ACTH4-10 anti-inflammatory activity in vivo; relevant as a functional bioassay context, though does not address MCR subtype selectivity."}]},"onchain":{"hash":"52w8cgoZeVWc2B6fjuAV54qD7BMFEYpqmWd7Y8huGvmELefTpBstMox5rW28RVC38MdSyXhSZvgEJ4ZPQJxP5Nc6","signature":"52w8cgoZeVWc2B6fjuAV54qD7BMFEYpqmWd7Y8huGvmELefTpBstMox5rW28RVC38MdSyXhSZvgEJ4ZPQJxP5Nc6","data_hash":"bc24b468d7aed7702568e3a2d0db11b3696bef90cc5970f64fd20e2975d9ce03","logged_at":"2026-05-03T04:41:02.276985+00:00","explorer_url":"https://solscan.io/tx/52w8cgoZeVWc2B6fjuAV54qD7BMFEYpqmWd7Y8huGvmELefTpBstMox5rW28RVC38MdSyXhSZvgEJ4ZPQJxP5Nc6"},"ipfs_hash":null,"created_at":"2026-05-03T04:37:15.409120+00:00","updated_at":"2026-05-05T04:34:22.576787+00:00"}