PCA (Pyrrolidone Carboxylic Acid)

2-pyrrolidone-5-carboxylic acid

PCA or Pyrrolidone Carboxylic Acid, naturally occurring in the skin, is an amino acid, a metabolite of Filaggrin (one of the pivotal proteins that play a key role in skin barrier function). Pyrrolidone Carboxylic Acid is one of the most important NMFs (natural moisturizing factors) of the skin.

It's the most hygroscopic amino acid in the epidermis, which means it has the strongest water-binding ability and naturally provides hydration, elasticity, and volume. As a result, PCA and its sodium salt (know as sodium pyroglutamate, NaPCA, sodium PCA, or sodium pidolate) is a common humectant in skincare formulas thanks to its physiological hydrating action.

Cold weather negatively affects the natural degradation process of Filaggrin, so people living in northern latitudes or frequently being under A/C cold airflow should consider using skincare products with PCA. It is also essential for dry skin or atopic conditions.