Antioxidants are molecules that work to prevent damage that occurs in cells and body tissues.

Ajoene has an antioxidative effect.

In 2010, two groups of researchers in Asia studied the antioxidant effect of ajoene and both studies reported promising results. In Korea, Kay and colleagues investigated the in vitro antioxidative properties of ajoene by treatment on the human hepatocyte derived cell, and demonstrated that ajoene-treated oxidative stress induced-cells showed a consistent level of glutathione (GSH), a major antioxidant in the body, compared to untreated cells. GSH is an effective scavenger of free radicals. Low levels of antioxidants will impose a state known as oxidative stress due to the building up of excessive amounts of free radicals. Oxidative stress results in the damage of biological macromolecules such as DNA, carbohydrates and proteins.

On the other hand, Naznin et al in Japan evaluated the antioxidative activities of ajoene by using various radical scavenging effects. Results show that ajoene has the highest hydroxyl radicals scavenging activity, where Z-ajoene has better results compared to E-ajoene.