Evaluation of Antioxidant Activity of Cinnamic Acid and Some of its Derivatives

Abstract

Cinnamic acid, chemically known as 3-phenyl-2-propenoic acid is a white-colored crystalline substance which has a broad spectrum of pharmacological actions including antioxidant activity. It is used principally in the flavoring and perfumery industries. The identity, purity, integrity and suitability of the acid were ascertained and established prior to the derivatization reactions. Furthermore, a simple titrimetric method for its assay was designed. The esterification and selective reduction of the acid led to two derivatives coded A2 and S2 whose identities have been established to be ethyl cinnamate and cinnamyl alcohol respectively using the IR spectroscopic technique. Cinnamic acid coded S1 demonstrated a poor antioxidant activity (IC 50 ) of 1.2 µg/mL while A2 and S2 elicited activities of 0.64 µg/mL (moderate) and 0.84 µg/mL (marginal) respectively. The obtained results indicate that esterification enhances the antioxidant activity of cinnamic acid.