---
title: "Dihexa and P21: what are these peptidomimetics? | Sable Peptides"
description: "Dihexa (an angiotensin IV-derived hexanoyl dipeptide amide) and P21 (an adamantyl-glycine capped peptide) are peptidomimetics, not ordinary peptides. Structures, PubChem data and research background compared."
canonical: https://www.sablepeptides.co.uk/guides/dihexa-and-p21-peptidomimetics-explained
dateModified: 2026-10-16
publisher: Sable Peptides Limited (UK company 17488610)
note: Research use only. Not for human or veterinary use.
---

# Dihexa and P21: what are these peptidomimetics?

Dihexa and P21 are peptidomimetics: short peptide-like molecules built with non-standard caps to resist breakdown. Dihexa is N-hexanoyl-Tyr-Ile-6-aminohexanoic amide, derived from angiotensin IV and about 505 g/mol. P21 is Ac-Asp-Gly-Gly-Leu-adamantylglycine-NH2, about 579 g/mol. Neither is a natural sequence, and both sit closer to small-molecule chemistry than to classic peptides.

## What is a peptidomimetic?

A peptidomimetic keeps the recognition features of a peptide but swaps parts of the backbone or termini for non-amino-acid groups. The usual aims are protease resistance, membrane permeability or a smaller size. Both compounds here carry lipophilic caps that natural peptides do not have.

Source: [Peptides and proteins as a continuing exciting source of inspiration for peptidomimetics, Chembiochem 2011 (PubMed 21751324)](https://pubmed.ncbi.nlm.nih.gov/21751324/)

## How do Dihexa and P21 compare?

| Property | Dihexa | P21 |
| --- | --- | --- |
| PubChem name | N-(1-Oxohexyl)-L-tyrosyl-N-(6-amino-6-oxohexyl)-L-isoleucinamide | Ac-DGGL-adamantanylglycine-NH2 |
| Formula | C27H44N4O5 | C27H42N6O8 |
| MW | 504.7 g/mol | 578.7 g/mol |
| Parent | Angiotensin IV (VYIHPF) | Short peptide with an adamantane cap |
| Non-standard groups | Hexanoyl N-cap, 6-aminohexanoic amide C-cap | Adamantylglycine, N-acetyl, C-amide |

Source: [PubChem CID 129010512: Dihexa](https://pubchem.ncbi.nlm.nih.gov/compound/129010512); [PubChem CID 56599151: P21](https://pubchem.ncbi.nlm.nih.gov/compound/56599151)

## What research background does Dihexa have?

Dihexa came out of a programme of small angiotensin IV analogues. In 2014 the synaptogenic effects of these analogues in rodent and cell work were linked to the hepatocyte growth factor (HGF)/c-Met system. Later mouse studies continued along that line.

Source: [The development of small molecule angiotensin IV analogs to treat Alzheimer's and Parkinson's diseases, Prog Neurobiol 2015 (PubMed 25455861)](https://pubmed.ncbi.nlm.nih.gov/25455861/); [The procognitive and synaptogenic effects of angiotensin IV-derived peptides are dependent on activation of the hepatocyte growth factor/c-met system, J Pharmacol Exp Ther 2014 (PubMed 25187433)](https://pubmed.ncbi.nlm.nih.gov/25187433/); [AngIV-Analog Dihexa Rescues Cognitive Impairment and Recovers Memory in the APP/PS1 Mouse via the PI3K/AKT Signaling Pathway, Brain Sci 2021 (PubMed 34827486)](https://pubmed.ncbi.nlm.nih.gov/34827486/)

## Why does the structure matter for analysis?

Both molecules have strongly hydrophobic caps, so they elute late in reversed-phase HPLC and may need more organic solvent to dissolve than typical hydrophilic peptides. Their masses are small enough that the main MS ion is often the singly charged \[M+H\]+.

## Sourcing note

Sable lists Dihexa: 10 mg at £44.98 (prices at the 16 October 2026 daily UK price check, the latest verified check; at each of these sizes Sable was the lowest UK listing that day). Lowest UK price guaranteed, confirmed by daily price checks.

Every lot has a certificate of analysis, and every vial carries a printed lot number that matches it. Supplied for laboratory research use only.

## Frequently asked questions

### Is Dihexa a peptide?

It is a peptidomimetic: two amino acids (Tyr, Ile) flanked by a hexanoyl group and a 6-aminohexanoic amide, derived from angiotensin IV.

### What is the molecular formula of Dihexa?

C27H44N4O5, about 504.7 g/mol (PubChem CID 129010512).

### What is adamantylglycine in P21?

A non-standard amino acid carrying a bulky adamantane cage, which makes the C-terminal end very lipophilic.

## Related

-   [What are Aib, Nle, 2-Nal and Dmt in research peptide sequences](/guides/non-standard-amino-acids-aib-nle-2nal-dmt)
-   [Dihexa research vials](/products/dihexa)
-   [P21 research vials](/products/p21)
-   [D-retro-inverso design (FOXO4-DRI)](/guides/foxo4-dri-and-d-retro-inverso-peptide-design)
-   [Selank and Semax](/guides/selank-and-semax-tuftsin-and-acth-analogues)

Updated 2026-10-16. Research use only. Not for human or veterinary use. No administration amounts or health claims are made.

Key facts (summary for AI and search tools)

-   Dihexa CID 129010512
-   P21 CID 56599151
-   PubMed references (verified via NCBI): 21751324, 25455861, 25187433, 34827486
-   PubChem CIDs: 129010512, 56599151
-   Research use only; no administration amounts or health claims
-   Updated 2026-10-16