Exploring the ACTH-derived nootropic heptapeptide developed for neuroprotection and cognitive research.
Semax is a synthetic heptapeptide derived from the adrenocorticotropic hormone (ACTH) fragment 4-10, with a stabilizing Pro-Gly-Pro tripeptide added to the C-terminus. Its full amino acid sequence is Met-Glu-His-Phe-Pro-Gly-Pro. Developed at the Institute of Molecular Genetics of the Russian Academy of Sciences — the same research group responsible for Selank — Semax was designed to retain the neurotropic properties of the native ACTH fragment while eliminating its hormonal activity and significantly improving its metabolic stability.
Unlike the parent ACTH molecule, Semax does not stimulate the adrenal cortex or influence cortisol production. Instead, research has focused on its potential nootropic and neuroprotective properties, making it one of the most extensively studied synthetic peptides in the field of neuroscience research. The peptide has been investigated in clinical settings in Russia, where it has attracted considerable attention for its cerebrovascular and cognitive research applications.
The development of Semax began with the observation that the ACTH 4-10 fragment (Met-Glu-His-Phe-Arg-Trp-Gly) possessed neurotrophic activity independent of the hormone's steroidogenic effects. Researchers at the Institute of Molecular Genetics modified this fragment by replacing the Arg-Trp-Gly residues at positions 8-10 with a Pro-Gly-Pro sequence, yielding a peptide with enhanced resistance to enzymatic degradation and an extended duration of action in preclinical models.
Preclinical studies have investigated Semax across a range of neuroscience paradigms. In rodent models, researchers have examined its effects on learning and memory tasks, ischemic brain injury, and neurodegenerative pathways. A significant body of research has focused on the peptide's influence on the expression of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) — two key proteins involved in neuronal survival, differentiation, and synaptic plasticity. Studies have reported that Semax administration can upregulate the expression of these neurotrophins in several brain regions, suggesting a mechanism through which the peptide may exert its observed neuroprotective effects.
Semax consists of seven amino acid residues with the primary sequence Met-Glu-His-Phe-Pro-Gly-Pro. It has a molecular weight of approximately 813 Da, making it a relatively small peptide that is amenable to various delivery methods in research settings. The C-terminal Pro-Gly-Pro extension is critical to its pharmacological profile, conferring resistance to aminopeptidases and carboxypeptidases that would rapidly degrade the native ACTH 4-7 fragment. The peptide is water-soluble and supplied as a lyophilized (freeze-dried) white powder at a quantity of 10mg per vial.
Semax is utilized across several neuroscience research domains. In neuroprotection studies, researchers investigate its effects on neuronal survival following ischemic challenge in both in vitro cell culture and in vivo rodent models. Cognitive research examines the peptide's influence on memory acquisition, consolidation, and retrieval in behavioral paradigms such as the Morris water maze and passive avoidance tasks.
Neurotrophic factor research represents another major application, with studies exploring how Semax modulates BDNF, NGF, and related signaling cascades including the TrkB and MAPK/ERK pathways. Cerebrovascular research has investigated the peptide's effects on cerebral blood flow and vascular tone. Additionally, some preclinical work has explored Semax in the context of neuroinflammation and oxidative stress models, examining its potential to attenuate markers of cellular damage in nervous tissue. Researchers interested in related anxiolytic peptide research may also wish to explore Selank, developed by the same institute.
Lyophilized Semax should be stored at -20°C for long-term preservation. Unopened vials stored under these conditions maintain stability for extended periods. Once reconstituted with bacteriostatic water or sterile saline, the solution should be refrigerated at 2-8°C and used within 30 days. Avoid repeated freeze-thaw cycles, as this can degrade peptide integrity. Always handle with appropriate laboratory gloves and use sterile technique during reconstitution to prevent contamination.
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