World Applied Sciences Journal 22 (11): 1561-1565, 2013 ISSN 1818-4952 © IDOSI Publications, 2013 DOI: 10.5829/idosi.wasj.2013.22.11.184 Corresponding Author: Syed Majid Bukhari, Institute of Chemistry, NTNU, 7491 Trondheim Norway. 1561 Determination of Antioxidant Activity of Crambe Cordifolia Syed Majid Bukhari, Nebojsa Simic, Hamid Latif Siddiqui and Viqar Uddin Ahmad 1 1 2 3 Institute of Chemistry, NTNU, 7491 Trondheim Norway 1 Institute of Chemistry, University of the Punjab Lahore, 54590, Pakistan 2 HEJ, Research Institute of Chemistry, University of Karachi-75270, Pakistan 3 Abstract: In the present investigation, the antioxidant activity and free radical scavenging activity of Crambe cordifolia plant were spectrophotometrically studied. Free radical scavenging activity was determined by DPPH method and the obtained IC value was 1106.65 µg/mL. For comparison, the IC value of standard ascorbic acid 50 50 was 21.69 µg/mL. Antioxidant activity was determined by phosphomolybdate method and the results showed that the plant had 205.73 µg per gram -tocopherol equivalent antioxidant content. Spectrophotometric determination of phenolic and flavonoid content was also carried out in terms of pyrocatechol equivalent and quercetin equivalent, respectively. Plant contained 10.60 µg pyrocatechol equivalent phenolic content and 1.43 µg quercetin equivalent flavonoid content per gram of plant material. The results indicated that Crambe cordifolia was a potent source of natural antioxidants. Key words: Free radical scavenging activity Anti-oxidant activity Phenolic content Flavonoid content Crambe cordifolia Methanolic extract INTRODUCTION Today there are two types of commercially available Our atmosphere contains around 21% of oxygen. natural sources, mostly from plants. The synthetic It is not only the key element for plants in antioxidants typically have phenolic groups as the main photosynthesis, but is also vital for animals and functionality and their variety is related to the number and humans. Once oxygen is inhaled, it undergoes the nature of substituents. Those which are obtained from process of reduction and results in the formation of natural sources (e.g. plants), show much bigger diversity, several very reactive radicals, among which superoxide with respect to their moieties. They can either be the anion radical, singlet oxygen and hydroxyl radical are nitrogen containing compounds, such as alkaloids, the important ones [1]. These reactive oxygen species chlorophyll derivatives, amines and amino acids, or have the tendency to cause peroxidation of membrane phenolic compounds such as tocopherols, flavonoids lipids and damage proteins, carbohydrates and nucleic and phenolic acids, which can terminate the activity of acids [2]. free radicals by acting as oxygen scavengers [6, 7]. Most living species have the natural defence system Flavonoids, a class of compounds with phenolic moiety, based on antioxidant activity, which protects them are considered to be the potent antioxidants. They can against these reactive oxygen species. The capacity of delay or inhibit the oxidation of lipids or other molecules such protective systems decreases, as the process of by inhibiting the propagation of oxidative chain reactions aging goes on resulting in disturbance of the redox [5, 8]. Ascorbic acid and carotenoids also act as good equilibrium system in the body. This disturbance is the antioxidants in nature. There has been a great interest in cause of some major diseases, such as malaria, acquired finding natural antioxidants from plant materials in the immunity deficiency syndrome, heart disease, stroke, recent years [9]. diabetes and cancer [3-5]. The most effective way to Genus Crambe is the largest genus in the family reduce the unwanted effects of that process is to use Brassiceae. Much work has been done upon different antioxidants as food supplements. species of Crambe in order to evaluate their industrial and antioxidants: synthetic ones and those obtained from