ABSTRACT
Hydroxy acids represent a fascinating group of substances, which belong to the category of cosmeceuticals. In the past two decades they have been widely used into a variety of skin care products for moisturizing, keratolytic and antiaging effects. The family of hydroxy acids include a-hydroxy acids (AHAs), b-hydroxy acids, combination hydroxy acids, and polyhydroxy acids. AHAs are organic carboxylic acids characterized by a hydroxy group in the alpha position. They are hydrophilic because of their aliphatic and linear structure. On the basis of the number of hydroxy group, AHAs can be divided into three subcategories: monocarboxylic acids (glycolic acid), dicarboxylic acids (malic acid), and tricarboxylic acids (citric acid) (1).
