Antioxidant and metal binding

Scavenging reactive species

Kohen and colleagues reported in 1988 that carnosine, homocarnosine and anserine act as antioxidants in laboratory systems (Kohen 1988). Proposed actions include electron donation, singlet oxygen quenching and binding of lipid peroxidation products (Open Heart review 2014). In one set of assays, carnosine inhibited hypochlorous acid damage to protein more than anserine or histidine, but had little effect against hydroxyl radical or peroxynitrite.

Aldini and colleagues separate a direct antioxidant action from an indirect one: activation of the Nrf2 transcription factor, which switches on the cell’s own antioxidant genes (Free Radical Research 2021). A 2019 laboratory study in macrophages is listed at Caruso 2019.

Metal binding

Carnosine binds transition metal ions, including copper and zinc (Nutrients 2023 review). Zinc binding is the basis of zinc-L-carnosine, a defined complex used as a medicine in Japan. Copper and zinc binding has also been proposed as a mechanism in the brain (Kawahara 2018, cited in AIMS Neuroscience 2025).

What this evidence shows

These are chemical properties shown in test tubes and cells. Carnosine in human blood is broken down within minutes, so the concentrations used in these experiments are not reached in human plasma after a dose by mouth. See Carnosinase and absorption and Laboratory studies.