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Author: Isgor, Yasemin G.COAR Access Rights: metadata only access

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    Article
    Citation - WoS: 8
    Citation - Scopus: 9
    Effect of Alpha-1-Adrenoceptor Blocker on Cytosolic Enzyme Targets for Potential use in Cancer Chemotherapy
    (Asian Network Scientific information-ansinet, 2012) Isgor, Belgin S.; Isgor, Yasemin G.
    Doxazosin is one of the quinazoline-based alpha 1-adrenergic receptor antagonists in clinical use for the treatment of hypertension and benign prostate hyperplasia. Doxazosin-induced cytotoxicity studies, resulted in growth inhibition and apoptosis, show its potential therapeutic benefits for several forms of cancers. These effects on cells occur as adrenoceptor-independent mechanisms, as observed with other quinazoline family of alpha-1 blockers. Moreover, Doxazosin induced apoptosis is associated with pathways, including EGFR, NF-kappa beta and TGF-beta signaling which typically engage Src as a central signaling component. Recent evidences show that glutathione transferases, may also contribute to these signaling events, through the kinases that share signaling pathways with Src, responsible for the regulation of transferase activity. In addition, the overactive glutathione transferases are related with anticancer drug resistance, as well as cancer development. Therefore, in the present study, the anticancer potential of Doxazosin was investigated by in vitro enzyme assays that were used to develop full dose-response profiles of drug at varying doses. The drug dose that exerts 50% inhibition of enzyme activity is defined as IC50 value and determined through the nonlinear regression analysis of dose-response data. The IC50 values determined for Src kinase, total protein tyrosine kinase, cytosolic total Src family kinase and total glutathione transferase enzymes were within nanomolar to low micromolar range. These results suggest that Doxazosin may be used to improve multifunctional therapeutic formulations to provide reduced drug resistance and enhanced cytotoxicity at target tissues.
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    Article
    Citation - WoS: 7
    THE EVALUATION OF INHIBITORY EFFECTS OF SELECTED PLANT EXTRACTS ON ANTIOXIDANT ENZYMES
    (Parlar Scientific Publications (p S P), 2015) Moghaddam, Naznoosh Shomali; Isgor, Belgin S.; Isgor, Yasemin G.; Geven, Fatmagul; Yildirim, Ozlem
    Plants and most of the plant derived compounds have been known because of their potential pharmaceutical effects for a long time. They are playing an important role on the treatment of several diseases from diabetes to various types of cancers. Today most of the clinically effective pharmaceuticals are developed from plant derived ancestors in the history of medicine. In this study different parts of the plants, namely Centaurea virgata (Lam.), Cichorium intybus (L.), Euporbia macroclada (Boiss.), Melilotus of ficinalis (L.) Pall. and Zygophyllum fabago (L.) were evaluated for their potential medicinal value in terms of biological targets which are participating in antioxidant defense such as catalase (CAT), glutathione-S-transferase (GST), superoxide dismutase (SOD) and glutathione peroxidase (GPx). The results indicate that the highest total phenolic contents of leaf and flower extracts were for E. macroclada. The highest flavonoid contents are detected for the leaves of E. macroclada and Z. fabago. The evaluation of extracts against biological targets reveals that the fruit extract of Z. fabago and the flowers of C. intybus show the inhibition against GST. For CAT, the highest inhibition is observed with E. macroclada leaf extract. Among the extracts analyzed, the only but slight SOD inhibition is determined with flower part of E. macroclada.