Browsing by Author "Isgor, Yasemin G."

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Citation - WoS: 3
Citation - Scopus: 3
Cellular Defense Enzyme Profile for Non-Cytotoxic and Phenol Enriched Extracts of heliotropium Europaeum, carlina Oligocephala and echinops Ritro
(Asian Network Scientific information-ansinet, 2018) Isgor, Belgin S.; İşgör, Sultan Belgin; Isgor, Yasemin G.; Geven, Fatmagul; İşgör, Sultan Belgin; Chemical Engineering; Chemical Engineering
Background and Objective:The discovery of traditional plants with some medicinal properties, verifying their biological targets and the bioassay guided standardization of their active components are the particular interest of diverse research groups recently. These efforts may help to revise the therapy modalities with natural product supplements. In this context, the possible biological targets of plants, namely Heliotropium europaeum, Carlina oligocephala and Echinops ritro, with no known medicinal value but recognized for their region specific traditional use, were evaluated. Here, the biological targets were enzymes of the antioxidant and xenobiotic defense mechanisms, with roles on inflammatory response. Materials and Methods: Cytotoxicity analyses were performed by using human promyelocytic (HL60) and chronic myelogenous leukemia (K562) cells for circulating models and breastadenocarcinoma (MCF7) cells for epithelial model to evaluate the non-toxic dose range of extracts by virtue of XTT and trypan blue. The target aimed effectiveness of these plants were determined with dose response profiles and IC50 values against glutathione peroxidase (GPX), glutathione transferase(GST),catalase (CAT) and superoxide dismutase (SOD) targets, as well as their capacity to reduce free radicals (DPPH) and non-radical hydrogen peroxide (H2O2). For standardization purposes, all extract concentrations were brought to 23.81 mg L-1 GAE and dilutions were made from these stocks. The IC50 values were determined by nonlinear regression analysis, with sigmoidal dose-response 4-parameter logistic equation. Results: The results showed that the best DPPH and H2O2 scavenging was observed with E ritro extracts. On the contrary, the best enzyme inhibition profile was observed with H europaeum against CAT, SOD, GPX and GST targets. Among the enzymes evaluated, all plants with different fractions also exerted strong GPX and CAT inhibition. Conclusion: The enzyme profiling of extracts may reveal the medicinal value of herbal remedies, by identifying their effects on cellular targets. In addition to define how reasonable the use of plants in traditional and complementary medicine (TCM) practices,these efforts may help to improve the standardized supplement preparations to benefit therapeutics with reduced efficiency due to inference with cellular defense and drug resistance enzymes, or both.
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.; Chemical Engineering
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.
Citation - WoS: 6
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; Chemical Engineering
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.
Citation - WoS: 4
Citation - Scopus: 7
Evaluation of Perylenediimide Derivatives for Potential Therapeutic Benefits on Cancer Chemotherapy
(Wiley, 2012) Keskin, Taner; Isgor, Belgin S.; Isgor, Yasemin G.; Yukruk, Funda; Chemical Engineering
Perylene derivatives, known to have potential therapeutic benefits on particular cancer types as photosensitizers, may also function as small-molecule inhibitors with promising therapeutic value for diverse diseases. This recently recognized biological activity was attributed to their capacity to modulate the function of various enzymes as biological targets in vitro. Although the inhibitory activity on glutathione transferase and Src tyrosine kinase is important in determining the anticancer potential of compounds for target-specific drug design and development, to date, there are no successful inhibitors of this kind. Moreover, there are only a few studies about the effects of perylene derivatives on glutathione transferase and various kinases. In this study, four novel perylene compounds, N,N'-disubstituted perylenediimides and their 1,7-dibromo derivatives, were synthesized and evaluated for their biological activities. Here, among the compounds analyzed, one of them was identified with strong glutathione transferase inhibition and two with dual activity for both glutathione transferase and c-src inhibition. These results revealed that perylene derivatives may be employed as potential chemosensitizers to prevent chemotherapy-dependent drug resistance and identified as prospective anticancer agents with dual activity on both glutathione transferase and c-src enzymes.
Citation - WoS: 61
Citation - Scopus: 83
The Potential Medicinal Value of Plants From Asteraceae Family With Antioxidant Defense Enzymes as Biological Targets
(Taylor & Francis Ltd, 2015) Koc, Suheda; Isgor, Belgin S.; Isgor, Yasemin G.; Moghaddam, Naznoosh Shomali; Yildirim, Ozlem; Chemical Engineering
Context: Plants and most of the plant-derived compounds have long been known for their potential pharmaceutical effects. They are well known to play an important role in 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. Objective: The aim of this study was to evaluate the free radical scavenging activity and total phenolic and flavonoid contents of methanol, ethanol, and acetone extracts from flowers and leaves of Onopordum acanthium L., Carduus acanthoides L., Cirsium arvense (L.) Scop., and Centaurea solstitialis L., all from the Asteraceae family, for investigating their potential medicinal values of biological targets that are participating in the antioxidant defense system such as catalase (CAT), glutathione S-transferase (GST), and glutathione peroxidase (GPx). Materials and methods: In this study, free radical scavenging activity and total phenolic and flavonoid contents of the plant samples were assayed by DPPH, Folin-Ciocalteu, and aluminum chloride colorimetric methods. Also, the effects of extracts on CAT, GST, and GPx enzyme activities were investigated. Results and discussion: The highest phenolic and flavonoid contents were detected in the acetone extract of C. acanthoides flowers, with 90.305 mg GAE/L and 185.43 mg Q/L values, respectively. The highest DPPH radical scavenging was observed with the methanol leaf extracts of C. arvense with an IC50 value of 366 ng/mL. The maximum GPx and GST enzyme inhibition activities were observed with acetone extracts from the flower of C. solstitialis with IC50 values of 79 and 232 ng/mL, respectively.