Spectroscopic, antioxidant and cytotoxicity studies of vanillic acids

Vanillic acid is a phenolic compound recognized for its use as a flavoring agent in the food industry. It can be found in a variety of products, such as thyme, rice, oranges, cherries, green tea, wine, and beer. Vanillic acid has been substantiated to show various beneficial pharmacological properties including anti-inflammatory, antibacterial, cardioprotective, hepatoprotective, antitumorigenic, free radical scavenging, antioxidant and even antivenomous activity. Since vanillic acid has low bioavailability, and bioavailability of a compound depends (among other factors) on its chemical structure, testing isomers of vanillic acid may yield promising results. Several structural and biological studies were carried out to determine the correlation between the molecular structure and biological activity of vanillic acid and its isomers (isovanillic acid and o-vanillic acid). Studies have shown that changes in the electronic structure of vanillic acids affect their different reactivity, antioxidant activity, and cytotoxicity. O-vanillic acid, characterized by the highest reactivity, is a weak antioxidant and the best cytotoxic compound. No direct correlation was observed between the antioxidant activity of vanillic acids and their toxic effect on model cell lines, probably due to the different mechanisms of action in the phenomena studied.