# Highlander Peptide — Longevity & Cellular Health Research Peptides > Highlander Peptide is a reference desk for Longevity & Cellular Health research compounds — Epitalon and NAD+ — summarized from peer-reviewed literature. A digest, not a vendor or clinic. A rigorous reading desk for the published science on Epitalon and NAD+ — what each was actually studied for, in which species, and how strong the evidence really is. ## The short version Highlander Peptide is a reading desk, not a store. It collects what the published research literature actually says about two compounds that recur in conversations about **longevity and cellular health**: Epitalon and NAD+. A *research peptide* is a short chain of amino acids synthesized for study — the same building blocks as proteins, only far smaller. Epitalon is a four-amino-acid tetrapeptide proposed to act on the telomere-maintenance and pineal-melatonin systems. NAD+ is an endogenous coenzyme involved in virtually every energy-producing reaction in the cell and in signaling enzymes that govern DNA repair and gene regulation. This desk does one job: it tells you, in plain language and with citations, what each compound was tested on, in which species, and how far that evidence actually reaches. Much of it stops well short of controlled human trials. Neither compound is a prescription medicine for longevity in any major Western jurisdiction. We do not sell anything, we do not give medical advice, and we never list a human dose. ## What are research peptides? Proteins in your body — enzymes, structural scaffolding, signaling hormones — are long chains of amino acids folded into a shape. A *peptide* is a much shorter chain of the same building blocks, sometimes only three or four links long. Because they are small and specific, peptides can interact with particular receptor systems on or inside cells, potentially switching certain processes on or off. A *research peptide* is one that has been synthesized and studied in laboratory settings — in cell cultures, in animals, and occasionally in early human pilots — but has not been approved by a regulator as a medicine for a given indication. Sellers typically describe these compounds as being for laboratory research only, and that framing matters: it means dosing, long-term safety, and real-world effectiveness in people are usually unestablished. When this desk reports a number, it reports it the way the study did — for example, *studied at 0.1 ug/mL in human fibroblast culture* — never as a recommendation for human use. ## How these two fit into longevity research The two compounds on this desk approach the biology of aging from different angles, which is why they sit together. - [**Epitalon**](/epitalon) is the lead. It is a four-amino-acid tetrapeptide (Ala-Glu-Asp-Gly) synthesized from the composition of epithalamin, a bovine pineal extract. Most of its research was conducted by a single group at the St. Petersburg Institute of Bioregulation and Gerontology, and its two most-cited mechanisms are telomerase upregulation and stimulation of pineal melatonin synthesis [1][3]. A 2025 independent study provided the first external replication of the telomere-lengthening claim [2]. The human evidence is observational, not randomized or placebo-controlled [5]. - [**NAD+**](/nad) approaches the same question from a metabolic direction. It is not a peptide but a coenzyme — the central electron shuttle of cellular energy metabolism — and it also serves as the substrate for sirtuins, PARPs, and CD38, enzymes that regulate DNA repair and inflammation [11]. Tissue NAD+ declines with age. A substantial body of human RCT evidence now confirms that oral precursors (NMN, NR) reliably raise blood NAD+ [9][12]; whether that translates to clinical aging endpoints in humans is a more open question [8]. Together they sketch two sides of the aging picture: the telomere and circadian-neuroendocrine axis (Epitalon), and the metabolic-energetic axis (NAD+). Use the directory to read each one, or [compare these compounds](/compare) side by side. ## A note on how this desk reads the literature Highlander Peptide is a cross-referenced literature digest. Each compound page summarizes the peer-reviewed studies for that compound, cites them by number, and links to a single shared [references list](/references) that aggregates every source. Where the evidence is thin, single-lab, or preclinical, this desk says so plainly — that caution is part of the record, not a footnote to it. The goal is a quiet, accurate map of what is known: where the science is reproducible, where it depends on a single research lineage, and where it is still mostly promising animal data. --- A peer-reviewed literature digest for longevity and cellular health research — citations held to source, claims held to species.