663 Review doi: 10.12980/JCLM.3.2015J5-84 ©2015 by the Journal of Coastal Life Medicine. All rights reserved. Redox protective potential of fruits and vegetables: A review Zainab Tahir, Muhammad Arshad, Sunbal Khalil Chaudhari * Department of Botany, PMAS Arid Agriculture University, Rawalpindi, Pakistan Journal of Coastal Life Medicine 2015; 3(8): 663-668 Journal of Coastal Life Medicine *Corresponding author: Sunbal Khalil Chaudhari, Department of Botany, PMAS Arid Agriculture University, Rawalpindi, Pakistan. E-mail: khalilsunbal@yahoo.com 1. Introduction Free radicals adversely alter lipids, proteins, and DNA and trigger a number of human diseases. This radical formation occurs continuously in the cells as a consequence of both enzymatic and non-enzymatic oxidation reactions[1]. Currently, there is global interest in finding new and safe antioxidants from natural sources, to minimise oxidative injury of living cells through free radicals. Antioxidants may act as chemical traps/sinks that “absorb” energy and electrons, quenching reactive oxygen species (ROS) (carotenoids, anthocyanidins); catalytic systems that neutralize or divert ROS (antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase); binding/inactivation of metal ions to prevent generation of ROS (ferritin, ceruloplasmin, catechins); and chain-breaking antioxidants which scavenge and destroy ROS (ascorbic acid, tocopherols, uric acid, glutathione, flavonoids)[2,3]. Natural antioxidants such as flavonoids, hydrolysable tannins, coumarins, xanthones, phenolics, terpenoids, ascorbic acid, carotenoids and proanthocyanins are found in various plant products, including fruits, leaves, seeds, oils, and juices[4-7]. So regular consumption of fruits and vegetables has been consistently shown to be associated with reduced risk of developing chronic diseases such as cancer and cardiovascular disease[8,9]. This review discusses how fruits and vegetables that we eat are playing a positive role in sustaining our health through supply of natural antioxidants on daily basis. 2. Fruits as natural antioxidants Fruits are the most common ingredient in our food prescribed by nutritionists. Among all fruits, apples are commonly consumed and are the major contributors of phytochemicals in human diets[10]. Epidemiological studies have linked the consumption of apples with reduced risk of some cancers, cardiovascular disease, asthma, and diabetes[11]. In the laboratory, apples have been found to have very strong antioxidant activity. Apples contain a variety of phytochemicals, including quercetin, catechin, phloridzin and chlorogenic acid, all of which are strong antioxidants[12]. Apple peels have high concentration of phenolic content. The antioxidant activities of 4 varieties of apples (Golden Delicious, Rome Beauty, Idared and Cortland) were investigated. The total phenolic and flavonoid contents were higher in the peels then flesh[13]. Further observation showed quercetin glycosides in peels. Unripe apples with apple peels constitute valuable source of polyphenols[14-17]. In a study, indigenous fruits such as wood apple and Jambul were analyzed for total phenolic contents, total flavonoid content and ascorbic acid contents. Their antioxidant potential was in the order: Jambul > wood apple > ambadi > ambat chukka[18]. A variety of antioxidant entities, such as phenolics, anthocyanins and proanthocyanidins are present in grapes. They suppress platelet aggregation, lower cholesterol level in blood and are also anti- carcinogenic in action[19]. Similarly, in guava, antioxidant nutrients include ellagic acid derivatives, myricetin and apigenin[20]. Papaya pulps are rich in antioxidant agents which protect against colon cancer and heart diseases. These antioxidant components ARTICLE INFO ABSTRACT Although oxidation reactions are crucial for life, they can also be damaging to cells and tissues, causing variety of chronic ailments like, aging, cancer, autoimmune problems, cardiovascular and neurodegenerative disorders etc. Redox protective systems are present in body for general immunization against free radicals, which can be supported by antioxidants that we take in our daily diet. Natural antioxidants such as flavonoids, hydrolysable tannins, coumarins, xanthones, phenolics, terpenoids, ascorbic acid, carotenoids and proanthocyanins are found in various plant products, including fruits, leaves, seeds oils, and juices. This review gives a brief account of research reports on fruits and vegetables which provide free radical scavenging compounds to the body. Article history: Received 16 Jun 2015 Received in revised form 4 Jul 2015 Accepted 8 Jul 2015 Available online 14 Jul 2015 Keywords: Autoimmune problems Redox protective systems Fruits and vegetables Free radical scavenging compounds journal homepage: www.jclmm.com