*Corresponding author: E-mail: msiddharthasankar@gmail.com; Mb.: +919681039710. www.sospublication.co.in Journal of Advanced Laboratory Research in Biology We- together to save yourself society e-ISSN 0976-7614 The Role of Antioxidants on Cellular Aging Siddhartha Sankar Mandal*, Biplab Mandal and Jayanta Kumar Kundu Molecular Biology Research Unit, Department of Zoology, Vidyasagar University, Midnapore- 721102, West Bengal, India. Abstract: Aging is the multidimensional process of changes in physical, physiological and behavioral condition of a cell over time. It is characterized by decline of multiple physiological functions that increase the probability of homeostatic imbalance and cellular death. Various free radicals are produced due to endogenous oxidative reactions. These highly reactive atoms cause oxidative damage and shorten lifespan of a cell. The antioxidants are the molecules, which neutralize free radicals and delay the cellular aging. Keywords: Cellular aging, Free radical, Antioxidant. 1. Introduction Cellular aging is the declining of physical, physiological and behavioral state of a cell in respect of time. The process by which cellular aging occurs is called cellular senescence (Hayflick, 1961). It is an avoidable property of a cell, that it is the result of genetic programming. The shortening of telomere, DNA damage and any lethal mutation induce aging. Besides these, the endogenous oxidative reactions, which are occurred mostly in mitochondria, produce free radicals, which alter biological structures and thus enhance the cellular aging. Antioxidants such as vitamin A, vitamin C, vitamin E, selenium, superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) act over and neutralize the free radicals such as reactive oxygen species (ROS), which alters or deletes a functional genomic sequence. Thus, antioxidants play antagonistic effects on free radicals. Hence, cellular aging is delayed. 2. Overview of the role of free radicals in cellular aging The free radical theory of aging (FRTA) states that organisms age because cells accumulate free radical damage over time. A free radical is any atom or molecule that has a single unpaired electron in an outer shell. It has a short lifespan and highly reactive (Denham Harman, 1950). After producing from endogenous oxidative reactions, it causes oxidative damage. Damage occurs when the free radical encounters another molecule and seeks to find another electron to pair its unpaired electron. The free radical often pulls an electron off a neighboring molecule, causing the affected molecule to become a free radical itself. The new free radical can then pull an electron off the next molecule and a chemical chain reaction of radical production occurs. There are five main types of free radicals, all with varying degrees of toxicity. They are- Nitric oxide, Peroxynitrite, Hydrogen peroxide, Superoxide anion, Hydroxyl radical. a. In humans and other animals, cellular aging has been attributed to the shortening of telomeres with each cell cycle; when telomeres become too short, the cells die. Thus, the telomeres are called "molecular clock" (Clark, 1998). b. There is a consistent shortening of telomeres during cellular aging. Human telomeres shorten by about 100 bp per cell division. When several KB of telomeric DNA is lost, this triggers the cell to undergo senescence. The free radicals act over Volume 4, Issue 3, July 2013 Review Article