Carnosine is a dipeptide composed of alanine and histidine; it is a non-protein, nitrogen-containing chemical component found in animal muscle cells and can be extracted from ground muscle (such as poultry meat) using boiling water. It appears as colorless crystals and is water-soluble.

Pharmacological research on carnosine in the context of cosmetics includes: inhibition of carotene oxidation; protection of fibroblasts against hydrogen peroxide and AAPH; protection of DNA against X-ray damage; inhibition of elastase activity; and promotion of collagen production in fibroblast cultures.

The specific function of carnosine in muscle tissue remains unclear; some theories link it to the development of muscle contractile function, while others suggest it promotes oxidative phosphorylation, thereby increasing muscle stores of ATP and creatine phosphate (CP) to facilitate contraction. Fibroblasts show significantly prolonged survival in dilute aqueous solutions of carnosine, indicating that it acts not only as a nutrient but also as an agent that promotes cellular metabolism and delays aging. It is used in medicinal creams to promote wound healing. Carnosine scavenges free radicals-being particularly effective at preventing the oxidation of protein-based ingredients-and offers skin-brightening properties; when used in conjunction with urocanic acid, it helps prevent photosensitive dermatitis. It is also readily absorbed by the skin, hair, and scalp, and enhances the penetration of other ingredients; in hair care products, it softens hair, improves manageability, controls dandruff, and relieves itching.