Ferulic acid ([E]-3-[4-hydroxy-3-methoxy-phenyl] prop-2-enoic acid) (Fig. 1) belongs to the phenolic acid group commonly found in plant tissues. Phenolic acids are secondary metabolites of varying chemical structures and biological properties. The plants are mainly found in bound form as ester or glycosides, lignin components, and hydrolysis tannins. In terms of chemical structure, they can be divided into derivatives of cinnamic and benzoic acid, varying in number and substitution of hydroxyl and methoxy groups, and phenolic acids of unusual character. An additional group is the depside, which is a combination of two or more phenolic acids. Ferulic acid, like caffeic, p-coumaric, synapine, syryte, and vanillin acids, is the most common cinnamic acid derivative.
Ferulic acid is most commonly found in whole grains, spinach, parsley, grapes, rhubarb, and cereal seeds, mainly wheat, oats, rye, and barley (Table 1). One of the most important role of phenolic acids, especially cinnamic acid derivatives, is their antioxidant activity, which depends primarily on the number of hydroxyl and methoxy groups attached to the phenyl ring]. Ferulic acid is more easily absorbed into the body and stays in the blood longer than any other phenolic acids. Ferulic acid is considered to be a superior antioxidant. Ferulic acid has low toxicity and possesses many physiological functions, including anti-inflammatory, antimicrobial, anticancer (for instance lung, breast, colon and skin cancer), anti-arrhythmic, and antithrombotic activity, and it also demonstrated antidiabetic effects and immunostimulant properties, and it reduces nerve cell damage and may help to repair damaged cells. Furthermore, it is a sports supplement because it can neutralize free radicals in muscle tissue (alleviate muscle fatigue). It has been widely used in pharmaceutics and food. Moreover, it is widely applied in skin care formulations as a photoprotective agent (sunscreens), delayer of skin photoaging processes, and brightening component. Nonetheless, its use is limited by its tendency to be rapidly oxidized.