Is Procyanidin C1 legal in the United Kingdom?

A grape seed polyphenol reported in 2021 to kill senescent cells and extend lifespan in old mice. That paper has carried an Editorial Expression of Concern since March 2026, and there is no human evidence for the isolated compound.

Procyanidin C1 is a trimeric proanthocyanidin found in grape seed extract. The 2021 Nature Metabolism paper that put it on the map reported a concentration-dependent double action: at low concentrations it suppressed the senescence-associated secretory phenotype, and at higher concentrations it selectively killed senescent cells.

Mechanism: Reported in cultured cells and mice: at low concentrations procyanidin C1 suppresses senescence-associated secretory factors, acting as a senomorphic; at higher concentrations it induces apoptosis in senescent cells, acting as a senolytic. The concentration dependence is the central claim and it comes from the paper now under Editorial Expression of Concern.

Regulatory history: Not approved for any indication. Not in clinical development. Present as one constituent of grape seed extracts sold as supplements; the isolated compound is a research chemical.

Licenses medicines for the UK market. A compound without a marketing authorisation is an unlicensed medicine, which can only lawfully be supplied for human use through a prescriber under the specials scheme, not sold as a research product.

The classification above is the The Longevity Archive reading of Medicines and Healthcare products Regulatory Agency listings for Procyanidin C1 at the reviewed date, not a legal opinion. Rules change, and importing, prescribing and possessing a compound can each be treated differently. Check the regulator directly before acting on anything here.