Intercalation of the radical scavenger ferulic acid in hydrotalcite-like anionic clays.

Hydrotalcite is a biocompatible lamellar anionic clay formed by double hydroxide layers with a metal cation coordinating four OH groups. The different layers are held together by anionic hosts that can be replaced by a simple ion-exchange process. The synthetic Mg-Al-hydrotalcite was used to intercalate ferulic acid, a compound that shows antioxidant properties due to its free radical scavenger capacity. Analysis of the intercalated compound showed a good intercalation percentage (35.53%) accompanied by an increase of the interlayer space from 7.8A (chloride form) to 17.1A due to the presence of the ferulate. The intercalation product was stable in water, did not show any significant degradation after UV-irradiation, had a higher capacity of UV absorption in comparison to both the pure ferulic acid and ferulic acid-hydrotalcite chloride physical mixture. The intercalated compound was formulated in a siliconic cream and the ferulate in vitro release profiles determined.