Bazı kumarin türevlerinin glutatyon s-transferaz enzimi üzerindeki inhibe edici etkilerinin araştırılması

ÖZETBAZI KUMARİN TÜREVLERİNİN GLUTATYON S-TRANSFERAZ ENZİMİ ÜZERİNDEKİ İNHİBE EDİCİ ETKİLERİNİN ARAŞTIRILMASIKanser günümüzde gelişmiş ülkelerde en önde gelen ölüm sebeplerinden biridir. Kanser tedavisi için kullanılan ilaçlar belirli sınırlamalara sahiptir ve kanserin gelecekte bir numaralı ölüm sebebi olacağı öngörülmektedir. Kemoterapi kanser tedavisinde kullanılan en önemli yöntemlerden biridir. Tümör hücrelerinin kemoterapik ajanlara karşı direnç geliştirmeleri çeşitli kanser tiplerinin tedavisinde çok önemli bir sorun oluşturmaktadır. Bu direnci aşabilmek için daha önce kullanılan ilaçların yerini alabilecek yeni antikanser ilaçlarının bulunması veya ilaç direncini geri çevirebilecek kimyasal ajanların keşfedilmesi çok büyük önem taşımaktadır. Kemoterapide yaygın olarak kullanılan, farklı yapıya ve fonksiyona sahip ilaçların sitotoksik etkilerine karşı, tümör hücrelerinin direnç geliştirmesi olarak tanımlanabilen Çoklu İlaç Direnci, kötü huylu tümör hücrelerinin kemoterapi ilaçlarına karşı geliştirdiği direnç mekanizmalarının en önemlisidir. Çoklu ilaç direncini oluşturan mekanizmalardan en önemlisi, Glutatyon S-Transferaz (GST) enzimlerinin ekspresyonunun artmasıdır. Bu artış sonucunda antikanser ilaçları etkisiz hale gelirler. Glutatyon S-Transferaz enzimleri (EC 2.5.1.18) hücreyi sitotoksik ve genotoksik streslerden koruyan çok fonksiyonlu polimorfik bir izoenzim ailesidir. Memeli hayvanlarda GST enzimleri faz II zehirsizleştirme enzimleri olarak görev yaparlar. Farklı insan dokularında farklı GST izoenzimlerinin ekspresyonları baskındır. İnsan plasentasında GST enzimlerinin ana bileşenini, GSTpi izoenzimi oluşturur. GST enzimleri, özellikle GSTpi izoenzimi, kemoterapide kullanılan bileşikleri glutatyona konjuge ederek etkisiz hale getirir. Yükselmiş GSTpi aktivitesinin kemoterapi direncinin bir göstergesi olduğu bilinmektedir. Hidrofobik bileşikler kovalent veya kovalent olmayan bir şekilde GST enzimlerine bağlanarak katalitik aktiviteyi inhibe edebilirler. Bazı doğal olarak bulunan polifenolik bitki bileşiklerinin GST enzimini inhibe ettikleri bilinmektedir. Doğal olarak bulunan ve polifenolik bir yapıya sahip olan kumarinler çok çeşitli ve önemli fizyolojik aktivitelere sahip olan benzo-α-piron türevi bileşiklerdir. Bu çalışmada kemoterapi direncini aşmak için destekleyici olarak kullanılabilecek potansiyel GST inhibitörlerinin belirlenmesi amacıyla ana bileşeni GSTpi izoenzimi olan insan plasenta GST enziminin aktivitesinin, çeşitli hidroksi ve metoksikumarin türevlerince inhibisyonu in vitro olarak incelendi. Kumarin halkasının 6. ve 7. pozisyonlarında hidroksil grubu taşıyan dihidroksikumarin türevlerinin, insan plasenta GST enzimi üzerinde etkili olarak inhibitör özelliği gösterdiği bulundu. En iyi inhibisyon gösteren kumarin türevinin inhibisyon mekanizsması tayin edilerek inhibisyonun geri dönüşümlü yarışmasız inhibisyon olduğu saptandı.ABSTRACTINVESTIGATION OF INHIBITORY EFFECTS OF VARIOUS COUMARIN DERIVATIVES ON GLUTATHIONE S-TRANSFERASE ENZYMECancer is at present one of the most leading causes of death in developed countries. Cancer treatments have clear limitations and unfortunately cancer is projected as the primary cause of death in the future. Chemotherapy is one of the most important methods used to treat cancer. Drug resistance during chemotherapy is the leading cause of treatment failure and decreased survival in cancer patients. To overcome this resistenceit is very important to find replacements for drugs previously used or find suitable chemomodulators to reverse the drug resistance. Multidrug resistance (MDR) is defined as resistance of tumor cells to the cytotoxic action of multiple structurally dissimilar and functionally divergent drugs commonly used in chemotherapy. One of the mechanisms leading to drug resistance is mediated by the increase in the expression of Glutathione S-Transferases (GST) which results in inactivation of anti cancer drugs. Glutathione S-transferases (GST, EC 2.5.1.18) are a polymorphic superfamily of multifunctional enzymes that protects cells from cytotoxic and genotoxic stresses. GST enzymes as as phase II detoxification enzymes in mammals. GST enzymes, especially GSTpi isoenzyme, inactivate chemotherapeutic substances by conjugating them to glutathione. GST isoenzymes are expressed in various tissues. GST-pi is the major molecular form of GST enzymes found in human placenta. Elevated GST activity is regarded as an indicator for the resistance to chemotherapy. Hydrophobic compounds may inhibit catalytic activities of GST enzymes by binding reversibly or irreversibly. Naturally occurring plant polyphenols are potent inhibitors of GST activity. Coumarins are comprised of numerous naturally occurring polyphenolic benzo-α-pyrone compounds with important and diverse physiological activities.In this study, in order to evaluate potential GST inhibitors that can be used as adjuvant to overcome chemotherapy resistance, in vitro inhibition of human placenta GST enzyme, which is mainly composed of GSTpi isoenzyme activity was investigated by various hydroxy and methoxycoumarin derivatives. We have found that dihydroxycoumarin derivatives which is bearing hydroxyl substitution at 6 and 7 position of the coumarin ring is the most potent inhibitors of human placenta GST enzyme. Inhibition mechanism of the most active coumarin compound was also investigated and as a result of kinetic studies it was found that inhibition was reversibly non competetive inhibition

Bazı kumarin türevlerinin glutatyon s-transferaz enzimi üzerindeki inhibe edici etkilerinin araştırılması

BAZI KUMARİN TÜREVLERİNİN GLUTATYON S-TRANSFERAZ ENZİMİ ÜZERİNDEKİ İNHİBE EDİCİ ETKİLERİNİN ARAŞTIRILMASI Kanser günümüzde gelişmiş ülkelerde en önde gelen ölüm sebeplerinden biridir. Kanser tedavisi için kullanılan ilaçlar belirli sınırlamalara sahiptir ve kanserin gelecekte bir numaralı ölüm sebebi olacağı öngörülmektedir. Kemoterapi kanser tedavisinde kullanılan en önemli yöntemlerden biridir. Tümör hücrelerinin kemoterapik ajanlara karşı direnç geliştirmeleri çeşitli kanser tiplerinin tedavisinde çok önemli bir sorun oluşturmaktadır. Bu direnci aşabilmek için daha önce kullanılan ilaçların yerini alabilecek yeni antikanser ilaçlarının bulunması veya ilaç direncini geri çevirebilecek kimyasal ajanların keşfedilmesi çok büyük önem taşımaktadır. Kemoterapide yaygın olarak kullanılan, farklı yapıya ve fonksiyona sahip ilaçların sitotoksik etkilerine karşı, tümör hücrelerinin direnç geliştirmesi olarak tanımlanabilen Çoklu İlaç Direnci, kötü huylu tümör hücrelerinin kemoterapi ilaçlarına karşı geliştirdiği direnç mekanizmalarının en önemlisidir. Çoklu ilaç direncini oluşturan mekanizmalardan en önemlisi, Glutatyon S-Transferaz (GST) enzimlerinin ekspresyonunun artmasıdır. Bu artış sonucunda antikanser ilaçları etkisiz hale gelirler. Glutatyon S-Transferaz enzimleri (EC 2.5.1.18) hücreyi sitotoksik ve genotoksik streslerden koruyan çok fonksiyonlu polimorfik bir izoenzim ailesidir. Memeli hayvanlarda GST enzimleri faz II zehirsizleştirme enzimleri olarak görev yaparlar. Farklı insan dokularında farklı GST izoenzimlerinin ekspresyonları baskındır. İnsan plasentasında GST enzimlerinin ana bileşenini, GSTpi izoenzimi oluşturur. GST enzimleri, özellikle GSTpi izoenzimi, kemoterapide kullanılan bileşikleri glutatyona konjuge ederek etkisiz hale getirir. Yükselmiş GSTpi aktivitesinin kemoterapi direncinin bir göstergesi olduğu bilinmektedir. Hidrofobik bileşikler kovalent veya kovalent olmayan bir şekilde GST enzimlerine bağlanarak katalitik aktiviteyi inhibe edebilirler. Bazı doğal olarak bulunan polifenolik bitki bileşiklerinin GST enzimini inhibe ettikleri bilinmektedir. Doğal olarak bulunan ve polifenolik bir yapıya sahip olan kumarinler çok çeşitli ve önemli fizyolojik aktivitelere sahip olan benzo-α-piron türevi bileşiklerdir. Bu çalışmada kemoterapi direncini aşmak için destekleyici olarak kullanılabilecek potansiyel GST inhibitörlerinin belirlenmesi amacıyla ana bileşeni GSTpi izoenzimi olan insan plasenta GST enziminin aktivitesinin, çeşitli hidroksi ve metoksikumarin türevlerince inhibisyonu in vitro olarak incelendi. Kumarin halkasının 6. ve 7. pozisyonlarında hidroksil grubu taşıyan dihidroksikumarin türevlerinin, insan plasenta GST enzimi üzerinde etkili olarak inhibitör özelliği gösterdiği bulundu. En iyi inhibisyon gösteren kumarin türevinin inhibisyon mekanizsması tayin edilerek inhibisyonun geri dönüşümlü yarışmasız inhibisyon olduğu saptandı. ABSTRACT INVESTIGATION OF INHIBITORY EFFECTS OF VARIOUS COUMARIN DERIVATIVES ON GLUTATHIONE S-TRANSFERASE ENZYME Cancer is at present one of the most leading causes of death in developed countries. Cancer treatments have clear limitations and unfortunately cancer is projected as the primary cause of death in the future. Chemotherapy is one of the most important methods used to treat cancer. Drug resistance during chemotherapy is the leading cause of treatment failure and decreased survival in cancer patients. To overcome this resistenceit is very important to find replacements for drugs previously used or find suitable chemomodulators to reverse the drug resistance. Multidrug resistance (MDR) is defined as resistance of tumor cells to the cytotoxic action of multiple structurally dissimilar and functionally divergent drugs commonly used in chemotherapy. One of the mechanisms leading to drug resistance is mediated by the increase in the expression of Glutathione S-Transferases (GST) which results in inactivation of anti cancer drugs. Glutathione S-transferases (GST, EC 2.5.1.18) are a polymorphic superfamily of multifunctional enzymes that protects cells from cytotoxic and genotoxic stresses. GST enzymes as as phase II detoxification enzymes in mammals. GST enzymes, especially GSTpi isoenzyme, inactivate chemotherapeutic substances by conjugating them to glutathione. GST isoenzymes are expressed in various tissues. GST-pi is the major molecular form of GST enzymes found in human placenta. Elevated GST activity is regarded as an indicator for the resistance to chemotherapy. Hydrophobic compounds may inhibit catalytic activities of GST enzymes by binding reversibly or irreversibly. Naturally occurring plant polyphenols are potent inhibitors of GST activity. Coumarins are comprised of numerous naturally occurring polyphenolic benzo-α-pyrone compounds with important and diverse physiological activities. In this study, in order to evaluate potential GST inhibitors that can be used as adjuvant to overcome chemotherapy resistance, in vitro inhibition of human placenta GST enzyme, which is mainly composed of GSTpi isoenzyme activity was investigated by various hydroxy and methoxycoumarin derivatives. We have found that dihydroxycoumarin derivatives which is bearing hydroxyl substitution at 6 and 7 position of the coumarin ring is the most potent inhibitors of human placenta GST enzyme. Inhibition mechanism of the most active coumarin compound was also investigated and as a result of kinetic studies it was found that inhibition was reversibly non competetive inhibition

Comparison of hemodynamic response for intubation and propofol pain caused by lidocaine administration with infusion and tourniquet

Propofol is one of the most widely used i.v. anesthetic agent. Nevertheless, pain following i.v. administration of propofol is an important problem in anesthesia induction. A wide range of studies have been performed related to lidocaine effects on propofol injection pain and hemodynamic response to intubation. However, effect of both situations are seldomly studied in the literature. In our study we compare lidocaine effects on propofol injection pain and hemodynamic response to intubation which is given by infusion or under tourniquet as i.v. bolus. 70 patients attended to the study are separated randomly into two groups of 35 patients. Prior to induction, lidocaine has been infused with infusion pump as to be completed in 2 minutes with concentration of 2%, total dosed 1mg/kg in infusion group (Group I, n=35). In this group, after half of the total lidocaine dose is infused (1st minute), anesthesia induction has been started by giving 40 mg propofol of 1% in 10 seconds with infusion pump. In tourniquet group (Group T, n=35) prior to induction 1mg/kg lidocaine has been given as bolus by applying tourniquet with 70 mm/Hg pressure to the arm that is established vascular access and tourniquet has been remained for 60 seconds. After opening the tourniquet, induction has been started by giving 40 mg propofol of 1% in 10 seconds with infusion pump. During induction, patient‟s consciousness was evaluated by questioning his/her name and age after administering 1/4 (VRS0), 1/2 (VRS1), and 3/4 (VRS2) of total propofol dose. Confused patients were eliminated and the sense of pain caused by propofol was evaluated in study patients. The results were recorded according to four-point categorical verbal rating scale (VRS). For groups, the pulse rates and mean arterial pressures before lidocaine administration (T0), after lidocaine (T1), immediately after intubation (T2) and 10th minute after intubation (T3) were recorded. No differences detected among the groups with regards to demographic data and side effects. (p>0.05). No significant differences statically detected when comparing the heart rate (HR), mean arterial pressure (MAP) and pain scores of groups for all times (p>0.05). It is concluded that administering lidocaine by infusion technic may be an alternative method for tourniquet method on suppressing hemodynamic response related to tracheal intubation and on preventing injection pain related to propofol. [Med-Science 2017; 6(4.000): 696-699

Relationship between Epigenetics and Circadian Clock

Sirkadiyen saat organizmaların biyokimyalarının, fizyolojilerinin ve davranışlarının günlük ritmlerini kontrol eder. Sirkadiyen ritmin bozulması, kanserler de dahil olmak üzere birçok uzun süreli hastalığı ve vücuttaki biyolojik süreçleri etkilemektedir. Sirkadiyen düzenleyici yollar, sirkadiyen epigenomların oluşumuna ve ritmik epigenetik değişikliklere neden olur. Sirkadiyenin bozulmasından dolayı oluşan hipermetilasyon gibi anormal epigenetik modifikasyonlar, normal hücrelerin kanser hücrelerine dönüşümüne sebep olabilir. Bu derlemede sirkadiyen genler ve düzenleyici proteinler, sirkadiyen saatin bozulması sonucu oluşan epigenetik değişikliklere ilişkin güncel kanıtlar ve sirkadiyen bozulmanın karsinojenik etkileri ve insanlardaki farklı kanserlerdeki potansiyel rolü tartışılacaktırThe circadian clock controls the daily rhythmicity of the biochemistry, physiology, and behavior of the organisms. Disruption of circadian rhythms, affects many biological processes within the body and results in different long-term diseases, such as cancer. Circadian regulatory pathways causes rhythmic epigenetic modifications and the formation of circadian epigenomes. Abnormal epigenetic modifications, such as hypermethylation, may be involved in the transformation of normal cells into cancer cells. In this review, some of the circadian genes and regulatory proteins, the current evidence related to the epigenetic modifications that result in circadian disruption and he carcinogenic effects of circadian disruption and its potential role in different human cancers using an epigenetic viewpoint will be reviewe

Effects of Osteocalcin on Synthesis of Testosterone and INSL3 during Adult Leydig Cell Differentiation

Proliferation and differentiation of adult Leydig cells are mainly completed in puberty. In many studies, apart from normal postnatal development process, it is widely indicated that, through administrating EDS, Leydig cell population is eliminated and regenerated. It is believed that osteocalcin released from osteoblasts, which is responsible for modulating bone metabolism, induces testosterone production in Leydig cells, independent of the HPG axis. In addition, INSL3 produced by Leydig cells, such as testosterone, plays a critical role in bone metabolism and is known to reflect the development process and functional capacities of Leydig cells. This study is aimed at investigating OC-mediated testosterone regulation and INSL3 synthesis during differentiation of adult Leydig cells that are independent of LH. For this purpose, male rats were divided into 2 groups: prepubertal normal rats and adult EDS-injected rats. Each group was divided into 4 subgroups in which GnRH antagonist or OC was applied. After adult Leydig cells completed their development, testicular tissue samples obtained from the sacrificed rats were examined by light-electron microscopic, immunohistochemical, and biochemical methods. Slight upregulation in 3βHSD, INSL3, and GPRC6A expressions along with the increase in serum testosterone levels was observed in groups treated with osteocalcin against GnRH antagonist. In addition, biochemical and microscopic findings in osteocalcin treated groups were similar to those in control groups. While there was no significant difference in the number of Leydig cells reported, the presence of a significant upregulation in INSL3 and GPRC6A expressions and the increase in serum testosterone and ucOC levels were observed. After evaluation of findings altogether, it is put forward that, for the first time in this study, although osteocalcin treatment made no significant difference in the number of Leydig cells, it increased the level of testosterone through improving the function of existing adult Leydig cells during normal postnatal development process and post-EDS regeneration. This positive correlation between osteocalcin-testosterone and osteocalcin-INSL3 is concluded to be independent of LH at in vivo conditions

Synthesis of selected 3-and 4-arylcoumarin derivatives and evaluation as potent antioxidants

WOS: 000376450700066A series of hydroxyl-, methoxy-, and acetoxy-substituted 3- and 4-arylcoumarins were synthesized. All title compounds were screened for their antioxidant capacity, ability to scavenge the 1,1-diphenyl-1-picrylhydrazyl (DPPH) radical, and ability to chelate iron ions. Furthermore, all derivatives were assessed using molecular properties prediction and drug likeness using Molinspiration. It was found that all studied derivatives were potential candidates for further research, as they complied with Lipinski's rule of five for drug likeness. 3- or 4-arylcoumarins that possess two hydroxyl groups in ortho position, such as 4h, 5b, h, and 6a, had remarkable half-maximal effective concentration (EC50) for radical scavenging, with better performance than known antioxidants in DPPH and metal-chelating assays. In addition, the cupric-reducing antioxidant capacity and ferric-reducing antioxidant power of the synthesized compounds were investigated for antioxidant activity. Among them, 5g, h and 6a, b showed significantly better Trolox equivalent antioxidant capacity (TEAC) than standard compounds. The results demonstrate that the compounds with dihydroxyl groups at 6- and 7-positions of the benzopyrone ring of the arylcoumarin structure are the most active of the series as antioxidants. On the basis of these findings, these new coumarin derivatives are potential therapeutic candidates for pathogenesis of many diseases characterized by free-radical overproduction.Marmara University, Commission of Scientific Research ProjectMarmara University [FEN-A-110908-0223]This work was supported by Marmara University, Commission of Scientific Research Project, FEN-A-110908-0223

Therapeutic Potential of Pterostilbene and Resveratrol on Biomechanic, Biochemical, and Histological Parameters in Streptozotocin-Induced Diabetic Rats

Aims. The aim of this study was to investigate the effects of pterostilbene (PTS) (trans-3,5-dimethoxy-4′-hydroxystilbene) and resveratrol (RSV) (trans-3,5,4′ trihydroxystilbene) applied at different doses for the treatment of streptozotocin- (STZ-) induced diabetic rats. Materials and Methods. At the end of the 5-week experimental period, the right gastrocnemius muscles of the rats were examined biomechanically, while the left ones were examined histologically. In addition, blood glucose, serum insulin, and malondialdehyde (MDA) levels were analyzed in blood samples taken from the rats. Results. The skeletal muscle isometric contraction forces, which showed a decrease with diabetes, were observed to increase with antioxidant applications. Blood glucose, serum insulin, and MDA levels in diabetic rats approached normal levels after applying PTS. When the electron microscopic images of the rat skeletal muscle were examined, those in the combination treatment group were observed to show a better enhancement in the skeletal muscle morphological structure compared to the other diabetic and treatment groups. Conclusion. According to the findings, we suggest that these antioxidant treatments might have good therapeutic nutraceutical potential for some muscle diseases that coexist with diabetes. These treatments should be comprehensively investigated in the future

Arylcoumarin and novel biscoumarin derivatives as potent inhibitors of human glutathione S-transferase

A series of arylcoumarin derivatives and two novel biscoumarin derivatives were investigated for their human recombinant glutathione S-transferase P1-1 (GSTP1-1) enzyme inhibitory activities for the first time. 4-(3,4-Dihydroxyphenyl)-6,7-dihydroxycoumarin (compound 24) was observed to be the most active coumarin derivative (IC50: 0.14 µM). The inhibition was found to be time-dependent and irreversible. Hypothetical binding modes of the ten most active compounds were calculated by molecular docking. Ligand efficiency indices (LEI) were estimated to better understand the binding performance of the coumarin derivatives. Extensive structure-activity relationship studies showed that hydroxy substitution on both the coumarin and the aryl ring enhanced the biological activity and the position of hydroxy group on the coumarin ring is critical for the binding pose and the activity. Top three ligands were subjected to molecular dynamics simulations and MM/PBSA for further investigation. Binding mode of compound 24 suggested that its high inhibitory activity might be attributed to its position between Tyr7 and the cofactor, glutathione (GS-DNB). Exhibiting favorable druglikeness profiles and pharmacokinetics based on ADME studies, compound 5 and 24 can be considered as potential drug leads in future studies for further development. Communicated by Ramaswamy H. Sarma</p