Life Science Journal 2014;11(2) http://www.lifesciencesite.com 385 Protective role of aqueous medicinal herbal extracts against oxidative stress on Glucose-6-phosphate dehydrogenase activity and red blood cells fragility Wajdy Al-Awaida 1 *, Muhanad Akash 1,2 , Baker Jawabrah Al-Hourani 3 1 Department of Biology and Biotechnology, American University of Madaba, Madaba, Jordan; 2 On Sabbatical leave from Faculty of Agriculture, The University of Jordan, Amman, Jordan; 3 Department of Basic Sciences and Humanities, American University of Madaba, Madaba, Jordan w.alawaida@aum.edu.jo Abstract: We investigated the protective effect of the aqueous extracts of Salvia oficinalls, Thymus vulgaris and trigonella Foem–graecum against oxidative stress on Glucose-6-phosphate dehydrogenase (G6PD) activity and red blood cells (RBC) hemolysis. The NO donor compounds nitrosocysteine and nitrosoarginine caused strong inhibition on G6PD activities. Those oxidative compounds promoted RBC hemolysis in parallel to their inhibition extents on G6PD activities. The complete protection of both G6PD activity and red blood cells hemolysis against oxidative stress induced by NO donor compounds was achieved by preincubation with the above mentioned aqueous extracts. Those extracts were able to protect hemolysis in parallel to their activation extents on G6PD activities. Compared to nitrosoarginine, nitrosocysteine showed more effect on both G6PD activity and RBC hemolysis. Thus, more aqueous extracts concentration is needed for protection against nitrosocysteine. [Wajdy Al-Awaida, Muhanad Akash. Protective role of aqueous medicinal herbal extracts against oxidative stress on Glucose-6-phosphate dehydrogenase activity and erythrocyte hemolysis. Life Sci J 2014;11(2):385- 391]. (ISSN:1097-8135). http://www.lifesciencesite.com. 53 Keyword: Salvia oficinalls; Thymus vulgaris; trigonella Foem–graecum extracts; Glucose-6-phosphate dehydrogenase; Nitrosocysteine; Nitrosoarginine; aqueous extract. 1. Introduction: Glucose-6-phosphate dehydrogenase is the first enzyme in the pentose phosphate pathway, with main physiological function to produce NADPH and pentose sugars (Sodeinde, 1992; Mehta, 1994; Prchal and Gregg, 2005). G6PD is not the sole NADPH producing enzyme in nucleated cell, but in red blood cell only G6PD enzyme can generate NADPH (Scriver, 1995). The NADPH plays important role in erythrocytes, by preserving the integrity of red blood cell membrane sulfhydryl groups and detoxifies harmful hydrogen peroxide and oxygen radicals. Also it is used in the regeneration of reduced glutathione which prevents hemoglobin denaturation (Ciftci et al., 2004; Abboud and Awaida, 2010). Hemolysis is the destruction or removal of red blood cells from the circulation before the completion of their 120 days normal life span (Beutler, 1959; Bowman et al., 2004). Decrease in G6PD enzyme activity leads to decrease in NADPH and reduced Glutathione. It is believed that a lack of reduced glu- tathione availability causes early hemolysis in the spleen (Tian et al., 1999). G6PD deficient erythrocytes are sensitive to oxidative stress (Gerli et al., 1982). A deficiency in G6PD activity was connected with increases accumulation of cellular reactive oxygen species (ROS) while an overexpression of G6PD activity decreases the accumulation of these species in response to oxidative stress (Leopold et al., 2003; Fico et al., 2004). Sodium nitroprusside, spermidine and nitroso derivatives are nitro compounds that act as oxidants (Kuhn and Arthur., 1997; Gobble et al., 1997; Xian et al., 2000; Abboud and Awaida, 2010). Nitric oxide (NO) and its derivatives directly inactivate Glutathione peroxidase enzyme, resulting in an increase of intra- cellular peroxides that are responsible for cellular damage (Asahi et al., 1997). Herbs and spices have been widely used as food flavors for natural antioxidants. Spices and aromatic herbs are considered to be essential in diets or medical cures for delaying aging and biological tissue deterioration (Frankel, 1996). Salvia oficinalls is an old medicinal plant, which is rich source of different chemical constituents including terpenoids, polyphenol as well as essential oils (Wang et al., 2000; Bozin et al., 2007). Salvia officinalis extract is used to stabilize fat and fat-containing food against oxidation (Schwarz and Ternes., 1992). The main antioxidant compounds in the sage are carnosic acid and carnosol rosmarinic acid (Cuvelier et al., 1996). Thymol and carvacrol were found to be the major components of Thymus vulgaris essential oil. However, the thymol showed more effectiveness than carvacrol in preventing oxidation during the autoxidaion of lipids (Yanishlieva, 1999; El-