NAD+ vs Selank: What's the Difference?

NAD+ and Selank show up in the same research forums, but structurally and mechanistically they have nothing in common. NAD+ is a coenzyme that every human cell already manufactures and runs through energy metabolism and DNA repair. Selank is a synthetic seven-amino-acid peptide, derived from tuftsin, that does not occur in nature and is studied for its activity on the central nervous system and the immune system. One is a molecule the body produces continuously; the other is a compound engineered in a lab.

What NAD+ is

NAD+ (nicotinamide adenine dinucleotide) is a coenzyme, not a peptide. It participates in hundreds of redox reactions inside the cell: it's the electron carrier in the mitochondrial respiratory chain, which ties it directly to ATP production. It's also the substrate used by sirtuins and PARPs, two enzyme families the literature links to DNA repair and to the epigenetic regulation of cellular aging.

As a cell ages, available NAD+ levels decline. That's the observation behind why NAD+ turns up so often in aging biology literature — not because it "reverses aging," but because it's the fuel for processes that become less efficient when it runs short. The PubMed index on NAD+ metabolism and aging is the place to read the primary studies, not a secondhand summary.

In the catalog, NAD+ is supplied as lyophilized reference material, the same format as the rest of the compounds PeptoClinic distributes.

What Selank is

Selank is a synthetic heptapeptide developed from tuftsin, an endogenous peptide with immunomodulatory activity. The Russian laboratories that originally described it added a stabilizing fragment to the tuftsin sequence to extend its biological activity, because natural tuftsin degrades very quickly in plasma.

Published research on Selank concentrates on two lines: its interaction with the GABAergic and serotonergic axes in animal models — the basis for interest in its anxiolytic profile in preclinical studies — and its effect on cytokine expression, the immunomodulatory part it inherits from tuftsin. It's structurally related to Semax, another compound from the same line of Russian peptide research into fragments of endogenous hormones, though Semax derives from an ACTH fragment rather than from tuftsin.

Selank also ships as lyophilized powder in a sealed vial.

The differences that matter

• Chemical nature: NAD+ is a dinucleotide, a small molecule that is part of the baseline metabolism of any cell. Selank is a short-chain peptide, seven amino acids, synthesized specifically for research.
• Mechanism: NAD+ acts as an enzymatic cofactor in oxidation-reduction reactions and as a substrate for sirtuins and PARPs. Selank acts as a ligand that modulates receptors and signaling pathways in the central nervous system and the immune system.
• Research area: NAD+ is studied in the context of energy metabolism, mitochondrial function, and cellular aging biology. Selank is studied in the context of anxiety in animal models, cognition, and immune modulation.
• Origin: NAD+ is a universal endogenous molecule, present in every cell with oxidative metabolism. Selank is a synthetic peptide with no exact natural equivalent; it's derived from tuftsin but it isn't tuftsin.
• Molecular role: in terms of molecular weight the two are roughly comparable, but the relevant difference isn't size — it's that one is a metabolic cofactor and the other is a peptide with signaling activity.

Choosing between the two doesn't make sense if the research question is different: they aren't substitutes, they're tools for separate lines of study. A protocol investigating mitochondrial metabolism works with NAD+; one investigating modulation of the GABAergic axis or immune response works with Selank or with peptides from that family.

What documentation ships with the material

PeptoClinic works to a purity standard of ≥99% HPLC on the research peptides in its catalog. The lowest published report to date, analyzed by Janoshik Analytical, came in at 99.669% purity — that's the floor figure worth citing, not the best one ever seen. Full analysis reports, with the method used and the corresponding batch, are explained on the quality page, which shows how to read a certificate of analysis instead of trusting an unsupported seal.

The full catalog, with specifications for each compound, is at catalog.

Shipping to Argentina

Material is quoted for destinations in Argentina, with customs documentation prepared to bring it in as laboratory reference material. The process starts with a technical inquiry: describe the compound, the quantity, and the intended use in the research program, and the technical team responds with a written quote. Shipping details for the region are at Argentina.

Research use only

Both NAD+ and Selank are supplied strictly for research use (Research Use Only). They are not medicines, supplements, or foods, and they are not approved for human or veterinary consumption, diagnosis, or treatment. None of the claims in this article have been evaluated by ANMAT, the FDA, or any equivalent authority, and nothing published here should be read as a usage recommendation for people. The material is supplied for studies in laboratory models, in vitro work, or research programs operating under their own regulatory framework.