Browsing by Author "Celep, A. G. Sagdicoglu"

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Antioxidant Capacities of Gundelia Tournefortii L. Extracts and Inhibition on Glutathione-S Activity
(Elsevier Sci Ltd, 2007) Coruh, N.; Celep, A. G. Sagdicoglu; Ozgokce, F.; Iscan, M.
Gundelia tournefortii L. is an important food source and a well-known medicinal plant in Eastern Anatolia. Therapeutic effects of medicinal plants are known to be closely related to their antioxidant capacities. Antioxidant activities of G. tournefortii, both for the aerial parts and seeds, were investigated by using both 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and lipid peroxidation inhibition methods. The seeds were found to have higher antioxidant potential than the aerial, with IC50 values of 0.073 mg/mL for DPPH scavenging and 0.146 mg/mL for lipid peroxidation inhibition capacities. In addition, total phenolic contents of the Gundelia tournefortii L. extracts, especially the seed extracts correlates to its high antioxidant activity with 105.1 +/- 8.7 mu g gallic acid equivalents (GAEs) per mg of seed extract. Plant extracts with high phenolics content are known to have important effects on various enzymes, as well as glutathione-S-transferases, which are important detoxification enzymes in phase 11 systems with an important role in developing multi-drug resistance to chemotherapy in tumour cells. Consequently, the effects of G. tournefortii extracts on crude cytosolic glutathione-S-transferase was also studied and the seed extracts have shown effective inhibition of cytosolic GST activity, with an IC50 of 97.51 mu g/mL. (c) 2005 Elsevier Ltd. All rights reserved.
Antioxidant Properties of Prangos Ferulacea (L.) Lindl., Chaerophyllum Macropodum Boiss. and Heracleum Persicum Desf. From Apiaceae Family Used as Food in Eastern Anatolia and Their Inhibitory Effects on Glutathione-S
(Elsevier Sci Ltd, 2007) Coruh, N.; Celep, A. G. Sagdicoglu; Ozgokce, F.
Therapeutic effects of several medicinal plants and vegetables, which are commonly used as food and in folk medicine against many disease, are well known. Antioxidant capacities of Heracleum persicum Desf., Prangos ferulacea (L.) Lindl., Chaerophyllum macropodum Boiss. species from Apiaceae family were evaluated by determining their effects on DPPH radical scavenging, and lipid peroxidation inhibition, as well as their total phenolic contents. Potential natural glutathione-S-transferase inhibitors have gained great importance in the last decade especially because of the role of glutathione-S-transferases in developing resistance to chemotherapy. Selected plants were therefore further investigated for their influence on the activity of glutathione-S-transferase enzyme. In comparing antioxidant capacities, P. ferulacea was found to be a better antioxidant than the other two plants in the family, with 50% inhibitory concentration values as 0.242 and 0.152 mg/ml for DPPH radical scavenging and lipid peroxidation inhibition, respectively. The same plants were also evaluated for their effects on GST activities and among the studied plants, P. ferulacea was the most efficient inhibitor with IC50 value of 79.25 mu g/ml for GST. C macropodum and H. persicum were less effective antioxidants than P. ferulacea with IC50 values of 0.623 and 0.438 mg/ml for DPPH radical scavenging, respectively, however, they could also be considered as potential GST inhibitors. (c) 2005 Elsevier Ltd. All rights reserved.