Antioxidants: Structure-activity of plant polyphenolics.

The excessive accumulation of reactive oxygen species (ROS)/free radicals can lead to abnormal oxidation of biomolecules such as proteins, lipids, fats, carbohydrates and nucleic acids in human organisms. Accordingly, endogenous oxidative stress induces the progressive development of various chronic diseases like rheumatoid arthritis, cancers, cardiovascular risks, diabetes, digestive ulcers, hypertension, obesity, neurological disorders, and age-related complications. Therefore, anti-oxidant defense mechanisms are needed to control/prevent the unbalanced molecular oxidative damage. Indeed, the oxidative stress arises from both endogenous and exogenous factors such as smoking, alcohol, medications, air pollution, sunlight, lifestyle disorders, and metabolic processes. Therefore, consumption of fruits, vegetables, grains, beverages, and leafy vegetables rich in antioxidants may inhibit or treat oxidative damage accompanying diseases. From this aspect, dietary foods are rich in various antioxidant metabolites such as flavonoids, vitamin A, C, E, phenolic acids, curcumin, stilbenes, anthocyanins, etc., which promote healthy life and nutritional benefits. Additionally, various studies have also proven that foods rich in antioxidants interact with reactive species to prevent cell damage(s) or therapeutic pathways for diseases. Although, there are various myths about the antioxidant mechanism(s), the optimal dosage of antioxidants can show beneficial pharmacological activities against various molecular oxidation paths.