ROS/RNS can arise from accidental generation; this encompasses such mechanisms as ‘leakage’ of electrons onto O2 from mitochondrial electron transport chains; nuclear membrane, endoplasmic reticulum (xenobiotic metabolism, prostaglandin synthesis) and hepatocytes (detoxification) contain electron transport systems, cytochrome P-450 and b5, which produce free radicals .Accidental generation also includes the direct reaction of autoxidisable molecules with molecular O2, generating superoxide free radical. generation is the electron transport associated with mitochondrial membrane; ubiquinone-cytochrome b is the most important site of O2- production.Dietary nutraceuticals such as vitamins C, E and polyphenolics and reduction of cardiovascular disease incidence are a notable example.This paper reviews the biology of ROS/RNS, their pathways through which they relate to the pathology of cardiovascular disease and discusses the putative roles that antioxidants, including phenolics, may play in controlling oxidative stress and reduce the incidence of cardiovascular disease.Oxidative stress is the term referring to the imbalance between generation of reactive oxygen species and the activity of the antioxidant defences.Humans and other aerobes are able to tolerate oxygen (O2) because, at the same time that organisms were evolving electron-transport chains and other enzyme systems to utilize this molecule, antioxidant defenses to protect against the toxic effects of O2 were evolving in parallel.ABSTRACT Current hypotheses favour the concept that lowering oxidative stress can have a health benefit.
This leads to the formation of two stable molecules, with the atom abstracted being b to the radical center: Free radicals and reactive oxygen/nitrogen species of importance in living organisms include hydroxyl (OH.), superoxide (O2.-), nitric oxide (NO.), nitrogen dioxide (NO2.) and peroxyl (ROO.).KEY WORDS: INTRODUCTION Cardiovascular disease (CVD) is the leading cause of death in the United States, Europe and Japan  and is poised to become the most significant health problem worldwide.According to the World Health Organisation (WHO), an estimated 17 million people die of CVDs, particularly heart attack, stroke and heart failure, every year.In Mauritius deaths due to cardiovascular dysfunctions have kept on increasing for the last 10 years attaining the 51% mark in 2004 .Cardiovascular disease is of multifactorial etiology associated generally to a variety of risk factors for its development including hypercholesterolaemia, hypertension, smoking, diabetes, poor diet, stress and physical inactivity amongst others.
It has been estimated that about 1-3% of O2 respired is converted to O2-., a rate that increases during periods of increased energy metabolism.