Developed in the early 2000s, hydroxypinacolone retinoate, also known as HPR, is a synthetic ester of all-trans retinoic acid (vitamin A), with the chemical formula C₂₆H₃₈O₃ and a molecular weight of 398.58 g/mol. This innovative molecule was developed in the cosmetic field to provide benefits similar to retinoic acid, a retinoid used exclusively in the medical sphere and available by prescription only.
Chemically, hydroxypinacolone retinoate is more stable than retinol, a well-known derivative of vitamin A, due to the presence of the ester group in its structure. This group acts as a protective barrier around the retinoid core, limiting oxidation reactions that often affect retinol. Hydroxypinacolone retinoate is thus less sensitive to air, light, and heat. Moreover, unlike retinol, which must undergo a double enzymatic conversion (into retinal, then into retinoic acid), HPR is active upon application.
Its direct affinity for RAR (Retinoic Acid Receptors) enables the activation of signalling pathways involved in cell renewal, collagen synthesis, and pigmentation regulation, while avoiding the inflammatory cascade that often accompanies free retinoic acid. Moreover, its esterified structure slightly slows its skin penetration, contributing to a gradual release and reducing the risk of irritation. This gentle action makes it a particularly interesting choice for sensitive, reactive or beginner retinoid users.