Oxidative stress and antioxidants in hypertension-a current review

Free radicals or reactive oxygen species (ROS) are generated by oxygen metabolism which is balanced by the rate of oxidant formation and the rate of oxidant elimination. Oxidative stress is a result of imbalance between the generation of reactive oxygen species (ROS) and the antioxidant defence systems. Hypertension is one of the major risk factors for cardiovascular diseases and is considered as a leading cause of mortality and morbidity. These diseases affect more than 600 million people and it has been estimated that 29% of the world population will be suffering from hypertension by 2025. It has been indicated by experimental evidence that reactive oxygen species (ROS) play an important role in the pathophysiology of hypertension. The vasculature is a rich source of NADPH oxidase which produces most of the reactive oxygen species and plays an important role in renal dysfunction and vascular damage. Recent studies indicate that increased oxidative stress is the important mediator of endothelial injury in the pathology of hypertension associated to increased production of pro oxidants such as superoxideanion hydrogen peroxide, reduced nitric oxide synthesis and decreased bioavailability of antioxidants. Oxidative stress is found to be associated with endothelial dysfunction, inflammation, hypertrophy, apoptosis, cell migration, fibrosis, and angiogenesis in relation to vascular remodelling of hypertension. Results in humans are still less conclusive inspite of data available that involve oxidative stress as a causative factor of essential hypertension. The aim of this review is to present a novel focus on the role of oxidative stress in the pathophysiology of hypertension and recent biomarkers which are found to be associated with reactive oxygen species and the role of antioxidants as therapy of hypertension.