CRITICAL REVIEW IN PHARMACEUTICAL SCIENCES eISSN 2319-1082 14 Volume 4, Issue 4, 2015 www.earthjournals.org Review Article A review on Ellagic acid as a natural antioxidant Chaganbhai Patel a , Shailesh Shah b , Dinesh Shah b , Gajanan Kalyankar* b and Sandesh Lodha b a Shri Sarvajanik Pharmacy College, Mehsana, PIN-384 001 b Maliba Pharmacy College, Tarsadi, PIN-394 350 Corresponding author: Gajanan Kalyankar, Assistant Professor, Maliba Pharmacy College, Gopal Vidhyanagar, Tarsadi, PIN- 394350, Ph. No. +919574212301 ABSTRACT Ellagic acid(EA) is a naturally occurring polyphenolic compound. Recently there is growing interest in understanding the role and mechanism of the phytochemicals; such as polyphenolics, flavonoids and phenylpropanoids as inhibitors of oxidative stress. EA has wide array of biological properties, such as radical scavenging, chemopreventive, antiviral and antibacterial properties. EA is a naturally occurring dietary antimutagen and anticarcinogen with strong antioxidant and anti-inflammatory activities. EA is abundant in berries, walnuts pecans, pomegranate, cranberries and other plant foods in the form of hydrolysable tannins called ellagitannins. Ellagitannins are mostly found in the plants belonging to families Myrtaceae, Punicaceae and Combrataceae. While focusing on the multifunctional activities of such compounds, this review briefly points out increasing interest in polyphenolic derivatives as an antioxidant, which holds future promises. Keywords: Ellagic acid, polyphenolic, natural, antioxidant INTRODUCTION The term tannin was first applied by Seguin in 1796 to denote substances present in plant extract, which are able to combine with protein of animal hides to prevent their putrefaction and convert them into leather. The tannin-protein co-precipitation is important not only in the leather industry but also in relation to the physiological activity of herbal medicines, taste of foodstuffs and value of feed for herbivores. Two main groups of tannins are usually recognized; these are the hydrolysable tannins and the condensed tannins. Acids or enzymes such as tannase may hydrolyze the hydrolysable tannins. They are formed from several molecules of phenolic acids, which are united by ester linkage to a central glucose molecule. Two principal types of hydrolysable tannins are gallitannins and ellagitannin, which are units composed of gallic acid and hexahydroxydiphenic acid respectively. Ellagitannins are mostly found in the plants belonging to families Myrtaceae, Punicaceae and Combrataceae 1 . Ellagitannins are a major class of phenolics largely responsible for the astringent and antioxidant properties of raspberries and blackberries. The Rubus ellagitannins constitute a complex mixture of monomeric and oligomeric tannins. Rubus oligomeric ellagitannins contain besides the well-known ellagic acid (EA) and gallic acid moieties, the sanguisorboyl linking ester group. When exposed to acids or bases, ester bonds are hydrolyzed and the hexahydroxydiphenic acid spontaneously cyclizes into EA 2 . On hydrolysis ellagitannins spontaneously rearrange to the dilactone EA 3 . Recently there is growing interest in understanding the role and mechanism of the phytochemicals; such as polyphenolics, flavonoids and phenylpropanoids as inhibitors of oxidative stress 4 . Among all phytochemicals, EA has been receiving the most attention because of its wide array of biological properties, such as radical scavenging,