Longevity & Cellular — 7 Compounds Compared

What this category covers

The longevity and cellular category collects compounds and cofactors studied in aging biology: mitochondrial function, NAD-dependent metabolism, pineal and telomere research, senescent-cell research, and thymic or immune restoration.

This is the category where the specification gaps are most conspicuous, and they are informative. Several entries have no reported half-life and some have no single molecular weight — a preparation defined as a fraction rather than a molecule cannot have one. The coverage note under the table gives the exact counts for this category rather than leaving the impression that the record is complete.

Evidence level varies more here than anywhere else in the library. Some entries rest on a broad published literature; others trace to a single research lineage. Each entry's own page states which, and that distinction matters more than any similarity in research area.

Every entry in this category, side by side

All 7 compounds PeptiDex documents under Longevity & Cellular, on the specifications that actually separate one entry from another. Values are reproduced from each entry's own record; follow any name for the full research overview.

Every Longevity & Cellular entry in the PeptiDex library, compared on compound class, residue count, molecular weight and reported half-life.
Entry	Compound class	Length (aa)	Molecular weight	Reported half-life
NAD+	Cellular coenzyme (dinucleotide)	Not listed	663.43 g/mol (free acid)	Not listed
Epitalon	Synthetic tetrapeptide (pineal bioregulator)	4	390.35 g/mol	Not listed
Thymalin	Thymic peptide fraction	Not listed	Not listed	Not listed
Thymosin Alpha-1	Immunomodulatory peptide (thymic)	28	3108 g/mol (approx.)	~2 hours (circulating)
FOXO4-DRI	Senolytic peptide	Not listed	Not listed	Not listed
SS-31 (Elamipretide)	Mitochondria-targeted tetrapeptide	4	639.8 g/mol (approx.)	Not listed
Humanin	Mitochondrial-derived peptide	24	2687 g/mol (approx., 24-aa form)	Not listed

Of the 7 compounds above, 5 carry a published molecular weight, 1 has a reported half-life, 4 have a documented residue count and 4 have a published amino-acid sequence. No half-life is recorded for NAD+, Epitalon, Thymalin, FOXO4-DRI and 2 others.

A cell reading "Not listed" is a gap in the published record, not an omission on this page. PeptiDex records a specification only where a source documents it. Some entries here are blends or multi-component preparations, which have no single molecular weight to report at all. Where a value has never been established in the published literature the cell says so, rather than carrying an estimate — a plausible-looking number would make the table read as complete while making it wrong.

Mechanisms represented in this category

Every one of the 7 compounds here carries a distinct compound class — this category is grouped by research context, not by a shared mechanism. That is worth knowing before comparing findings across two entries.

Cellular coenzyme

NAD+ — NAD+ functions as a central redox cofactor, cycling between its oxidized (NAD+) and reduced (NADH) forms to shuttle electrons in glycolysis, the citric acid cycle, and oxidative phosphorylation.

Immunomodulatory peptide

Thymosin Alpha-1 — Thymosin alpha-1 acts as an immunomodulator, reported to enhance T-cell maturation and function, influence dendritic cell activity, and modulate innate immune signaling including Toll-like receptor pathways.

Mitochondria-targeted tetrapeptide

SS-31 (Elamipretide) — SS-31/elamipretide selectively concentrates in the inner mitochondrial membrane, where it is reported to bind the phospholipid cardiolipin.

Mitochondrial-derived peptide

Humanin — Humanin is reported to have cytoprotective and anti-apoptotic effects.

Senolytic peptide

FOXO4-DRI — FOXO4-DRI is designed to competitively interfere with the interaction between FOXO4 and the tumor suppressor p53 in senescent cells.

Synthetic tetrapeptide

Epitalon — Epitalon is proposed to act as a peptide bioregulator influencing gene expression and pineal function.

Thymic peptide fraction

Thymalin — Thymalin is described as a thymic peptide preparation reported to modulate immune function, particularly influencing T-lymphocyte differentiation and the balance of immune cell populations.

Each line is the opening sentence of that entry's own mechanism record, reproduced verbatim. The full mechanism, the research areas behind it and the evidence level sit on the entry's page.

How the compounds in this category differ

Sharing a category does not make two compounds substitutes. Each note below is the differentiator recorded on that entry — the property that separates it from the others in the table.

NAD+

A coenzyme studied extensively in cellular-energy and longevity research.

Unlike the peptides in this category, NAD+ is a small-molecule coenzyme central to redox metabolism rather than a signaling peptide, and it is studied primarily via precursor supplementation.

Epitalon

A synthetic tetrapeptide studied for its role in telomerase and aging research.

Epitalon is a defined 4-amino-acid pineal bioregulator peptide, distinct from thymic peptides (immune focus) and mitochondrial peptides, with a research emphasis on telomere/telomerase biology.

Thymalin

A thymic-derived peptide studied in immunomodulatory research.

Unlike Thymosin alpha-1 (a single, defined 28-residue peptide), Thymalin is a multi-peptide thymic tissue fraction, so it has no single sequence or molecular weight.

Thymosin Alpha-1

A 28-amino-acid peptide studied in immune-modulation research.

Thymosin alpha-1 is a single, well-characterized synthetic peptide with genuine clinical trial data and approvals in some countries, unlike the research-only thymic fraction Thymalin.

FOXO4-DRI

A synthetic peptide studied in senolytic and cellular-aging research.

FOXO4-DRI is the only senolytic in this set, working by clearing senescent cells via FOXO4-p53 disruption, rather than acting on immune, mitochondrial, or pineal pathways.

SS-31 (Elamipretide)

A mitochondria-targeting tetrapeptide studied in cellular-energy and longevity research.

SS-31 is a synthetic mitochondria-targeting tetrapeptide that physically localizes to the inner membrane and binds cardiolipin, and unlike most peptides here it has advanced into human clinical trials as elamipretide.

Humanin

A 24-amino-acid mitochondrial-derived peptide studied in cytoprotection and cellular-aging research.

Humanin is a naturally encoded mitochondrial-derived signaling peptide focused on cytoprotection and metabolism, distinct from the synthetic mitochondria-targeting SS-31 and from immune or pineal peptides.

Commonly co-studied pairs

Pairings documented on the entries themselves, with the reason each is co-referenced. Cross-referencing research context is not a combination recommendation, and PeptiDex gives no protocol, ratio or dosing guidance.

Within Longevity & Cellular

NAD+ + Epitalon — Commonly co-studied in longevity and anti-aging research contexts as complementary mechanisms.
NAD+ + SS-31 (Elamipretide) — Both target mitochondrial bioenergetics, so they are discussed together in mitochondrial-aging research.
Epitalon + Thymalin — Both are Khavinson-lineage bioregulators (pineal and thymus) frequently co-studied for combined geroprotective effects.
Epitalon + Thymosin Alpha-1 — Paired in aging-immunity research to combine pineal and thymic axis effects.
Thymalin + Thymosin Alpha-1 — Both are thymic immunomodulators, contrasted and sometimes co-studied in immune-restoration research.
FOXO4-DRI + Epitalon — Both are studied in cellular-aging research, pairing senescent-cell clearance with telomere-focused mechanisms.
FOXO4-DRI + NAD+ — Co-discussed in longevity research as complementary approaches to senescence and mitochondrial/metabolic aging.
SS-31 (Elamipretide) + Humanin — Both relate to mitochondrial protection and are co-studied in mitochondrial-derived and mito-targeted peptide research.

Reaching into other categories

NAD+ + MOTS-c — Both are studied in mitochondrial-function and metabolic-aging models, where NAD+ metabolism and mitochondrial signaling intersect.
Thymosin Alpha-1 + LL-37 — Both are studied in immune-modulation and host-defense contexts, so they are discussed together in immunity research.
SS-31 (Elamipretide) + MOTS-c — Both are mitochondria-focused compounds studied together in mitochondrial-function and metabolic-aging research.
Humanin + MOTS-c — Both are mitochondrial-derived peptides (MDPs), naturally grouped and co-studied in MDP and metabolic-aging research.

1 further pairing is documented on the individual entries. Each note is reproduced from the entry that records the pairing.

What this category is studied for

Research areas drawn from the 7 compounds in this category, deduplicated and ordered by how many entries list them. A further 17 research areas are listed across the individual entries.

Listing a research area records where a compound has been studied. It is not a claim of efficacy, an indication, or a suggestion of human use.

Category questions

How many compounds does PeptiDex list under Longevity & Cellular?

7: NAD+, Epitalon, Thymalin, Thymosin Alpha-1, FOXO4-DRI, SS-31 (Elamipretide) and Humanin. Each has its own research overview covering compound class, mechanism, studied research areas, specifications and entry-specific questions.

Why do some entries show "Not listed" instead of a molecular weight or half-life?

Because PeptiDex records a specification only where a source documents it. In this category 5 of 7 entries have a published molecular weight and 1 has a reported half-life. Some entries here are blends or multi-component preparations, which have no single molecular weight to report; for the rest, the value has simply not been established in the published literature. An estimate there would look like data and function as a guess, so the gap is shown instead.

What compound classes are represented in this category?

7 distinct classes across the 7 compounds: Cellular coenzyme, Synthetic tetrapeptide, Thymic peptide fraction, Immunomodulatory peptide, Senolytic peptide, Mitochondria-targeted tetrapeptide and Mitochondrial-derived peptide. Entries sharing a class are grouped together in the mechanisms section; the comparison table lists each entry's full class verbatim, qualifiers included.

Which entries in this category are studied together?

NAD+ and Epitalon are cross-referenced on each other's entries: Commonly co-studied in longevity and anti-aging research contexts as complementary mechanisms. The co-studied pairs section lists the rest. Co-reference describes how the literature groups compounds; it is not a combination recommendation and no ratios or protocols are given.

Are the compounds in this category approved for human use?

PeptiDex documents all 7 entries strictly for research and educational purposes and provides no dosing, protocol or human-use guidance. Regulatory status differs from entry to entry and is stated in the regulatory note on each entry's own page. Nothing here is medical advice or a therapeutic claim.

Where should I start in this category?

The comparison table gives the fastest orientation, then the differentiator notes explain why two entries with similar research contexts are not interchangeable. NAD+ is the entry PeptiDex features here. The glossary defines the vocabulary the entries are written in.

Answers summarise what the catalog records for this category. They are educational context, not medical advice. See the Research Library, the Glossary and each entry's own page for detail.