Medicinal Chemistry, 2011, 7, 639-644 639 1573-4064/11 $58.00+.00 © 2011 Bentham Science Publishers Free Radical Scanvenging and Antioxidant Effects of Some Anthraquinone Derivatives Abderrahmane Baghiani 1 , Noureddine Charef 1 , Meriem Djarmouni 1 , Haythem A. Saadeh 2 , Lekhmici Arrar 1,* and Mohammad S. Mubarak 2, * 1 Laboratory of Applied Biochemistry, Department of Biochemistry, Faculty of Nature and Life Sciences, University Ferhat Abbas, Setif 19000, Algeria 2 Department of Chemistry, Faculty of Science, The University of Jordan, Amman 11942, Jordan Abstract: In this study, the screening of five anthraquinones (purpurin, xanthopurpurin, rubiadin, kermisic acid and fla- vokermisic acid), for their free radical scavenging and antioxidant effects was carried out, using three complementary methods. DPPH (2,2 ´ -diphenyl-1-picrylhydrazyl) revealed that purpurin has a scavenging effect with IC 50 = 3.491 ± 0.014 g/ml. Results of -carotene / linoleic acid assay showed that kermisic and flavokermisic acids have significant inhibition of lipid peroxidation with I % = 76.1 ± 1.5 % and 68.6 ± 2.5 %, respectively. In addition, the ferrous ion chelating test showed that only purpurin, with small concentrations, interferes in a dose dependant manner with the formation of Fe 2+ - ferrozine complex. These results are promising for further studies of the biological and pathological effects of these natu- ral products. Keywords: Anthraquinones, antioxidant, free radical, scavenger, lipid peroxidation, ion chelating. 1. INTRODUCTION Oxidative stress is defined in general as excess formation and/or incomplete removal of highly reactive molecules such as reactive oxygen species (ROS). In vivo, some of these ROS play a positive role such as energy production, phago- cytosis, regulation of cell growth and intracellular signaling [1]. However, ROS are known to be the major cause of vari- ous chronic and degenerative diseases, including aging, coronary heart disease, inflammation, diabetes mellitus and cancer [2], and can cause cellular injuries and initiate per- oxidation of fatty acids in biological membranes. The tissue injury caused by ROS may include DNA [3] and protein [4], and oxidation of important enzymes [5]. Epidemiological studies have shown that many of these antioxidant com- pounds possess anti-inflammatory, antiatherosclerotic, anti- tumor, antimutagenic, anticarcinogenic, antibacterial, or an- tiviral activities to a greater or lesser extent [6], and it was found that their antioxidant activity surpasses the effect of known antioxidants, such as that of vitamins A and E [7]. Many edible plant species such as tea, fruits, juices, spices, and vegetables throughout the history of mankind have been attractive to scientists as natural sources of com- pounds that are safer than the synthetic ones. Many other plants have also been screened for their antioxidant capaci- ties, and attempts led to the introduction of natural antioxi- dants. *Address correspondence to these authors at the Prof Lekhmici Arrar, Labo- ratory of Applied Biochemistry, Department of Biochemistry, Faculty of Nature and Life Sciences, University Ferhat Abbas-Setif 19000, Algeria; Email: lekharrar@hotmail.com; Prof Mohammad S. Mubarak, Department of Chemistry, Faculty of Science, The University of Jordan, Amman 11942, Jordan; E-mail: mmubarak@ju.edu.jo Anthraquinone compounds are found widely in plants, and some of these are used as herbal medicines or food pig- ments. Investigations have demonstrated the preventive ef- fect of anthraquinones against genotoxicity or cytotoxicity [8], the modulation of metabolic enzyme activities in re- sponse to xenobiotics [9] and the anti-viral activity [10]. Ta- kahashi and colleagues [11,12] discovered that purpurin and alizarin inhibit the activity of human recombinant cyto- chrome P450 (CYP) isozymes CYP 1A1, CYP 1A2 and CYP 1B1, resulting in the anti-mutagenic effect observed in recombinant Salmonella possessing. Cell culture preparation, treated with plant extracts con- taining purpurin as a predominant compound, exhibits anti- inflammatory activity, which is manifested by an antioxida- tive effect and anti-proliferative action during the rapid de- velopment of a model oedema. A decrease in the antioxidant state without significant suppression of enzymatic activity is demonstrated by the work of Mishchenko and coworkers [13]. This anti-inflammatory effect is also shown by Tailor et al. [14]. Anthraquinones isolated from Heterophyllaea pus- tulata Hook f. (Rubiaceae), namely soranjidiol, rubiadin, damnacanthal and 5,5'-bisoranjidiol, showed antibacterial activity (bacteriostatic/ bactericide) on Staphylococcus aureus. The mechanism of action seems to involve an in- crease in the levels of superoxide anion (O 2 - ) and/or singlet molecular oxygen ( 1 O 2 ) [15]. In addition, Rao et al. [16] (2006) have demonstrated that rubiadin has a potent hepato- protective action against carbon tetrachloride induced he- patic damage in rats. The studies of bioactivities of two an- thraquinones bound to ubiprofen demonstrated that both prodrugs showed significant binding capability to hydroxya- patite, the major component of bone, and were hydrolytically activated under physiological conditions in vitro and better