Semax, Selank and the serum experiment

Human serum sounds like human evidence. Here it means material in a laboratory assay, with nobody’s pain or anxiety being tested.

The cell-free serum experiment

The 2001 serum experiment examined enzymes that break down enkephalins, substances involved in the body's natural pain-control signalling. Semax and Selank inhibited that breakdown in a cell-free assay using human serum.

The reported IC50 was about 10 micromolar for Semax and about 20 micromolar for Selank. IC50 is the concentration associated with halving the measured enzyme activity. Micromolar describes concentration in a solution; these values are laboratory measurements, with no human dosing instructions attached.

Within the serum assay, I can compare how readily the two peptides inhibited the enzymes. Semax reached that level of inhibition at the lower concentration. The experiment measured neither pain relief nor anxiety relief in a person, so a ranking of clinical benefits would need evidence from somewhere else.

Approximate half-inhibition concentrations for Semax and Selank in human serum — The same cell-free serum assay: approximate concentrations associated with half-maximal enzyme inhibition.

Shared activity, different research questions

That serum finding is a useful shared point between Semax and Selank. Their main experiments then move apart. Semax research includes locomotor recovery after spinal injury in female mice and BDNF protein in rat basal forebrain. Selank work includes anxiety-like behaviour in stressed rats and immune assays in patients with anxiety-asthenic disorders.

The serum result explains why it is reasonable to discuss a biochemical overlap. I resist using it to make the compounds interchangeable. The other studies tested different populations, tissues and outcomes, and cannot supply a head-to-head human comparison.

DSIP and the ACTH measurement

DSIP enters a different laboratory question. In the human hormone experiment, an antibody-based ACTH signal fell while cortisol followed its normal daily pattern. The small human sleep experiment measured sleep duration and interruptions. Those experiments answer separate questions even though both gave DSIP to people.

I trust a comparison more when it leaves the outcome names visible: enzyme activity, ACTH-like immunoreactivity, sleep duration. Combining them under a single brain-health score would erase most of the useful information.

For each compound's larger story, there are the Semax, Selank and DSIP pages. None has FDA approval, and none of these comparisons establishes a personal treatment choice. The safety questions cover the common regulatory and human-safety gaps.