Every Peptide

Peptide field guide

Ac2-26

An Annexin A1 (AnxA1)-derived N-terminal peptide used in inflammation-resolution research, with recent preclinical work in osteoarthritis models.

Evidence: emerging Safety: unknown Status: research Updated: March 21, 2026 InflammationOsteoarthritis

What it is

Ac2-26 is a peptide corresponding to the N-terminal region of Annexin A1 (AnxA1).

In the literature, Annexin A1 is often discussed as a pro-resolving mediator. Ac2-26 is used as an “active fragment” in research to probe or amplify those resolution-of-inflammation pathways.

Why people care

Many inflammatory conditions have two overlapping problems:

  • inflammation starts and becomes chronic
  • the body’s “resolution” programs fail to shut it down cleanly

If a peptide like Ac2-26 can strengthen resolution biology locally (for example, inside a joint), it could potentially reduce pain and tissue damage without needing broad systemic immunosuppression.

That said, this is a research-stage idea.

Evidence landscape

As of March 2026, evidence we’ve indexed is preclinical, including mouse model work in osteoarthritis.

Key upgrades in confidence would include:

  • replication across OA models (and across labs)
  • dose-response and durability studies
  • stronger mechanistic mapping (receptor targets, downstream pathways)
  • safety and tolerability packages that translate to humans

Latest updates

  • 2026-03-22: A mouse collagenase-induced OA study reports that weekly intra-articular Ac2-26 reduced mechanical nociception, lowered joint MMP-3 expression, and improved several inflammatory and synovial-cell readouts.

Safety reality

There is no mature human safety database for Ac2-26 as a therapeutic. Safety depends heavily on context (route of administration, dosing, formulation) and on whether immune effects show up with repeated exposure.

References

  • Bosi PL, et al. Pro-resolving Annexin A1-derived peptide Ac2-26 reduces nociception and mitigates joint damage in experimental osteoarthritis. Inflamm Res. (2026).