Phenolic antioxidants are used in the industry to delay the oxidation of fats being the most used butyl hydroxy anisole (BHA) and butyl hydroxy toluene (BHT). However, the consumer concern respects their safety has motived to study natural alternatives. In this sense, the aim of this work was to evaluate the behavior of 3,3'- dimethoxy-5,5'-di-2-propenyl-1,1'-biphenyl-2,2'-diol and 6,6'- dihidroxi-5,5’-dimethoxy-(1,1'-biphenyl)-3,3'-dicarbaldehyde free and supported on mesoporous alumina. Biphenolic compounds were synthesized by radical coupling and then anchored on alumina by microwave-assisted process. The antioxidant activity of these compounds was investigated by phosphomolybdenum method. The results showed that phenolic compounds anchored on mesoporous alumina have a marked antioxidant activity better than free antioxidants. Biphenolic compounds supported on alumina display antioxidant properties and hence have the potential for use as a food preservative, beverage, cosmetics, and pharmaceutical industries.