Ken to characterize its ability to scavenge free radicals such as superoxide, hydroxyl and hydrogen peroxide and to protect bio-molecules within a cell against oxidative insult. Methods: Anti-oxidant activity of Pterostilbene was evaluated extensively by employing several in vitro radical scavenging/inhibiting assays and pulse radiolysis study. In addition, its ability to protect rat liver mitochondria against PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/27484364 tertiary-butyl hydroperoxide (TBHP) and hydroxyl radical generated oxidative damage was determined by measuring the damage markers such as protein carbonyls, protein sulphydryls, lipid hydroperoxides, lipid peroxides and 8-hydroxy-2′-deoxyguanosine. Pterostilbene was also evaluated for its ability to inhibit H radical induced single strand breaks in pBR322 DNA. Result: Pterostilbene exhibited strong anti-oxidant activity against various free radicals such as DPPH, ABTS, hydroxyl, superoxide and hydrogen peroxide in a concentration dependent manner. Pterostilbene conferred protection to proteins, lipids and DNA in isolated mitochondrial fractions against TBHP and hydroxyl radical induced oxidative damage. It also protected pBR322 DNA against oxidative assault. Conclusions: Thus, present study provides an evidence for the strong anti-oxidant property of Pterostilbene, methoxylated analog of Resveratrol, thereby potentiating its role as an anti-oxidant. Keywords: Anti-oxidant activity, Free radicals, Oxidative Alvocidib clinical trials stress, PterostilbeneBackground Several polyphenols are well-known in inducing an array of biological responses in animal cells such as modulation of intercellular signaling, altered gene expression, protection against oxidation and enzyme inhibition. Among different classes of polyphenols, Stilbenoids, low molecular weight phenolics, are present in a very small proportion, and have not been studied to a great extent until recently. Resveratrol was first such stilbene to be found and isolated, and has been studied extensively since then for various activities such as anti-cancer, antioxidant, anti-inflammatory and several other beneficial activity [1]. Pterostilbene (trans-3,5-dimethoxy-4′-hydroxystilbene) is another such stilbene which is a naturally occurring methoxylated analog of Resveratrol and owing to its* Correspondence: [email protected] Department of Zoology, University of Pune, 411 007 Pune, Indiaclose structural similarity with Resveratrol, has gained importance [2]. Replacement of two hydroxyl groups with methoxy groups increases its oral bio-availability, and biological activity and slows its metabolism thereby prolonging its activity. It has been reported to be identified from various plant sources like the heartwood of Pterocarpus santalinus [3], Pterocarpus marsupium [4], leaves of Vitis Vinifera [5] and in healthy and immature berries of Pinot Noir and Gamay [6]. Pterocarpus marsupium Roxb is commonly known as the Indian kino tree (known in the vernacular as “Vijaysar” of “Bijasar”) and commonly grows in the central, western, and southern parts of India and in Sri Lanka. Its bark is used as an astringent, anti-diarrheal, and antacid [7] and is also effective in -cell regeneration [8]. P. marsupium wood water has been reported to have hypoglycaemic activity in diabetic patients [9] and extract of its heartwood was found to be effective in reducing plasma glucose levels?2013 Acharya and Ghaskadbi; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Att.