Semax

What is Semax?

ACTH is a 39-amino-acid pituitary hormone. Its 4-10 fragment (Met-Glu-His-Phe-Arg-Trp-Gly) was known to have central-nervous-system activity without the hormonal effect of the full molecule; Semax is a modified version of that fragment that swaps the last residues for Pro-Gly-Pro to slow enzymatic breakdown. It is one of two Russian-origin neuropeptides in the APX Labs catalog, the other being Selank.

What is Semax studied for in research?

• Neurotrophin expression. A 2007 *Neuroscience Letters* study reported changes in BDNF and related gene expression in rat brain [1]; a 2009 study compared nootropic agents' effects on hippocampal and cortical BDNF in mice [2].
• Stress and behavioural models. Semax has been studied for antidepressant-like and antistress effects alongside other ACTH(4-10) analogs [3], and for attenuating behavioural and neurochemical alterations in a stress model [4].
• Cellular mechanisms. A 2025 paper examined its effect on intracellular calcium dynamics in rat brain cells [5].

Rodent and cell findings only — not claims of human effect.

Semax vs Selank

Both are Russian-origin heptapeptides, both studied in neuro-behavioural models, but they derive from different parent molecules (ACTH vs the immunopeptide tuftsin) and are studied for different endpoints. Full comparison: Semax vs Selank.

Specifications, purity and documentation

Identity by mass spectrometry (expected 813.9 g/mol), purity by HPLC, batch-specific COA in every order. How to read the COA →

Semax — frequently asked

Further reading

• How to Reconstitute Lyophilized Peptides for Laboratory Use — Lyophilized peptides arrive as a dry cake in a sealed vial. Turning that into a solution of known concentration is simple, but the details protect the material.
• Semax vs Selank: Two Russian Heptapeptides, Two Different Research Questions — They share a country of origin, a length and a stabilising tail — and almost nothing else. Here is how the research literature separates them.