Pyrrolidone carboxylic acid (PCA) is the primary constituent of the natural moisturizing factor (NMF)
Creams and lotions containing the sodium salt of PCA are widely reported to aid in hydrating the skin and ameliorating dry flaky skin conditions. In addition, the zinc salt of L-pyrrolidone carboxylate (Zinc PCA) is a longtime cosmetic ingredient due to antimicrobial and astringent qualities.