Yazar "Akkemik, Ebru" seçeneğine göre listele

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    Activation and inhibition effects of some natural products on human cytosolic CAI and CAII
    (Springer Birkhauser, 2019) Adem, Sevki; Akkemik, Ebru; Aksit, Huseyin; Guller, Pinar; Tufekci, Ali Riza; Demirtas, Ibrahim; Ciftci, Mehmet
    Carbonic anhydrases (CAs) play a significant function in diverse pathological and physiological processes. Their inhibitors and activators are suitable molecules to use as a drug in the treatment of different disease. In the present study, seven natural compounds, namely didymin, retusin isoquercitrin, silymarin, verbascoside, teucroside, and 3'-O-methylhypolaetin 7-O-[6'-O-acetyl-beta-D-allopyranosyl-(1 -> 2)]-6 ''-O-acetyl-beta-D-glucopyranoside were isolated from Mentha spicata, Sideritis libanotica linearis, Platanus orientalis, Teucrium chamaedrys subsp. chamaedrys, and Silybum marianum. The influences of compounds on the carbonic anhydrase I(hCAI) and II(hCAII) purified from human erythrocytes were tested. Five phenolic compounds acted as an inhibitor on the activity of hCAI, and IC50 values were computed between 18.16 and 172.5 mu M. Isozyme hCAII is only inhibited by silymarin with an IC50 value of 43.12 mu M. This isoenzyme was effectively activated by five natural compounds with AC(50) values in the range of 2.98-18.53 mu M. To understand the binding patterns of molecules that show activation effect against hCAII, molecular docking was done using Leadit 2.3.2 software, and calculated between -19.05 and -14.42 (kJ/mol) binding energies. Both in vitro and in silico results demonstrated that the best activators against hCAII were teucroside and isoquercitrin, with AC(50) values of 2.98 and 3.17 mu M, and binding energies -19.05 and -18.01 (kJ/mol), respectively. According to the ADME results, retusin demonstrated physicochemical and pharmacokinetic properties specific to the drug candidates.
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    Bitkisel Ekstraktlarının Yenilebilir Film ve Kaplamalarda Kullanımı
    (2024) Pekdoğan, Esra; Akkemik, Ebru; Hallaç, Bülent
    Geri dönüşümün vazgeçilmezi olan, biyoyararlı olarak sınıflandırılan yenilebilir film ve kaplamalar (YFK) biyopolimer materyallerdir. Bugüne kadar çevre dostu olan YFK ile ilgili sayısız çalışma yapılmıştır. Bu çalışmaların birçoğu bitki ekstrelerinin YFK’da kullanılması ile ilgilidir. Söz konusu YFK’a bitki ekstresi ilave edilmesi antioksidan, antimikrobiyal, karekterizasyon (kalınlık, su buharı geçirgenliği, kopma anındaki uzama katsayısı (%E), çekme dayanımı (TS), renk, biyobozunurluk, suda çözünürlük, absorbans-transmittans analizleri, termal gravimetrik analiz (TGA) (kalınlık, su buharı geçirgenliği, kopma anındaki uzama katsayısı (%E), çekme dayanımı (TS), renk, biyobozunurluk, suda çözünürlük, absorbans-transmittans analizleri, termal gravimetrik analiz (TGA) ve diferansiyel taramalı kalorimetre (DSC), yenilebilir filmlerde fourier dönüşümlü kızılötesi spektroskopisi (FT-IR), taramalı elektron mikroskobu (SEM)) (SEM) (yenilebilir filmlerde fourier dönüşümlü kızılötesi spektroskopisi (FT-IR), taramalı elektron mikroskobu (SEM)) özelliklerinin iyileştirilmesi için yapılmaktadır. Ne yazık ki ilave edilen bitki ekstreleri her zaman beklenen etkiyi göstermemektedir. Bu çalışmada Yüksek Öğretim Tez Merkezi, Google Akademik, Web of Science veri tabanları incelenerek bitki ekstresi, yenilebilir film, karakterizasyon, kaplama anahtar kelimeleri kullanılarak, toplamda 78 çalışma analiz edilmiştir. Yapılan çalışmalar incelendiğinde bitki ekstresinin kimyasal yapısı ve filme eklenen dozajının antioksidan aktiviteyi artırıcı yönde etki gösterdiği gözlemlenmiştir. Antimikrobiyal aktivitenin belirlenmesinde ise analiz yönteminin sonucu etkilediği belirtilmiştir. Diğer özelliklerin ise bitki ekstresinin lipofilik ve hidrofilik olmasına bağlı olarak değişkenlik gösterdiği ifade edilmektedir. Sonuç olarak yaptığımız bu çalışma araştırmacılara farklı araştırma konuları geliştirmeleri için katkı sunmaktadır. Dahası genç araştırmacılara YFK’ın karekterizasyon parametreleri kapsamında temel bir kaynak oluşturmaktadır.
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    Comparison of traditional Zivzik pomegranate vinegar against commercial pomegranate vinegar: antioxidant activity and chemical composition
    (2022) Aybek, Abdulkerim; Akkemik, Ebru
    The vinegar, which is known to be very beneficial for health, also changes its usage potential and chemical properties according to the raw material it is obtained from. In this study, Zivzik pomegranate Vinegar produced with the traditional methods from Zivzik pomegranate varieties was compared with commercial pomegranate vinegar in terms of physicochemical properties, total phenolic, total flavonoid, and total anthocyanin content, organic acid, sugar, and phenolic acid composition by HPLC, elemental analysis by ICP-OES and antioxidant properties. As a result of the study, Zivzik pomegranate vinegar was found to be more antioxidant than commercial vinegar. In both vinegar samples, K is the dominant element. Similarly, acetic acid is the dominant organic acid detected in both types of vinegar. While chlorogenic acid was the dominant phenolic compound in commercial pomegranate vinegar, it was determined that gallic acid was dominant in Zivzik pomegranate vinegar. As a result, while it was determined that the origin and variety of the raw material had a direct effect on the product quality obtained, it was concluded that the vinegar obtained by traditional methods was more beneficial in terms of health than commercial vinegar.
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    Çuha Çiçeği (Oenothera biennis) ve Tatlı Badem (Prunus dulcis Mill) Yağlarının Anti-enzim Aktivitelerinin Araştırılması
    (2020) Akkemik, Ebru
    Çalışmamızda iki farklı enzim aktivitesi üzerine Çuha çiçeği (Oenothera biennis) ile tatlı badem (Prunus dulcis Mill.) yağlarının etkilerine olabilecek sorusu cevaplanmak istendi. Kullandığımız ilk enzim canlılarda $CO_2$’in hidratasyonu ve $HCO_3$-‘ın dehidratasyonunudönüşümlü olarak katalizleyerek, hücre içi bikarbonat tampon sistemini oluşturarak, birçok fizyolojik olayda oldukça önemli rol alankarbonik anhidraz I-II izoenzimleridir. İkinci enzim ise asetilkolin molekülünün ayrışmasını katalizleyen, kas hücresi ve sinir arasındakisinapsta yer alan asetilkolinesteraz enzimidir. Her iki enzimin inhibitörleri, ilaç olma potansiyeli taşımaktadır. Bu nedenle belirtilenyağların inhibisyon etkisi araştırıldı. Bu amaçla ilk olarak karbonik anhidraz I-II izoenzimi sefaroz-4B-L-tirosin-sülfanilamid afinitekolonu ile saflaştırıldı. Ardından en az beş farklı inhibitör konsantrasyonunda enzim aktivitesi bakılarak Çuha çiçeği (Oenotherabiennis) ve tatlı badem (Prunus dulcis Mill.) yağlarının enzim aktiviteleri üzerindeki etkileri araştırıldı. Son olarak %aktivite-[I] grafiğiçizilerek Çuha çiçeği (Oenothera biennis) ve tatlı badem (Prunus dulcis Mill.) yağlarının IC50 değerleri tespit edildi. İnsaneritrositlerinden karbonik anhidraz I izoenzimi %20,12 verimle 119 kat saflaştırılırken, karbonik anhidraz II izoenzimi %83,05 verimle535,72 kat saflaştırıldı. Çuha çiçeği (Oenothera biennis) yağının karbonik anhidraz I-II ve asetilkolinesteraz enzim aktivitesi üzerindeki$IC_{50}$ değerleri sırasıyla 0,1950, 0,1406 ve 0,1097 mg/mL olarak, tatlı badem (Prunus dulcis Mill.) yağının karbonik anhidraz I-II veasetilkolin esteraz enzim aktivitesi üzerindeki $IC_{50}$ değerleri ise sırasıyla 0,0345, 0,0266 ve 0,0394 mg/mL olarak tespit edildi.Çalışmada kullanılan her iki yağ karşılaştırıldığında, tatlı badem (Prunus dulcis Mill.) yağının her iki enzim aktivitesi üzerinde dahaetkili olduğunu görülmektedir. Bu nedenle sentetik ilaçlar yerine tatlı badem (Prunus dulcis Mill.) yağının söz konusu enzimlerin sebepolduğu hastalıkların tedavisinde takviye ilaç olarak kullanılabileceği düşünülmektedir.
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    Depletion of Tip60/Kat5 affects the hepatic antioxidant system in mice
    (Wiley, 2023) Kocpinar, Enver Fehim; Baltaci, Nurdan Gonul; Akkemik, Ebru; Budak, Harun
    Tat-interactive protein 60 kDa (TIP60, also known as lysine acetyltransferase 5 [KAT5]) is a member of the MYST protein family with histone acetyltransferase activity. Recent studies have reported that TIP60 has multiple functions in many signal transduction mechanisms, especially p53-mediated apoptosis. Although the activation of apoptosis signaling pathways requires the presence of cellular reactive oxygen species (ROS) at a certain level, an imbalance between the production and consumption of ROS in cells results in oxidative stress (OS). In this study, we investigated for the first time how the absence of the Tip60 gene in the liver affects gene expression, enzyme activity, and protein expression of the hepatic antioxidant members localized in the cytoplasm, including superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), and glutathione S-transferase (GST). First, we successfully generated liver-specific Tip60 knockout mice (mutants) using Cre/LoxP recombination. The reduced glutathione level and nicotinamide adenine dinucleotide phosphate oxidase 4 (Nox4) expression, a marker of OS, increased significantly in the Tip60 mutant liver. Gene expression, activity, and protein expression of the enzymatic antioxidant system, including SOD, CAT, GR, GPx, and GST were investigated in mutants and control groups. Despite a significant correlation between the gene, enzyme activity, and protein content for CAT and GR, this was not true for SOD and GPx. The overall results suggest that TIP60 acts on the hepatic antioxidant system both at the gene and protein levels, but the actual effect of the deletion of Tip60 is observed at the protein level, especially for SOD and GPx.
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    Hindi Karaciğerinden NADPH-Sitokrom P450 Redüktaz’ın Saflaştırılması, Karakterizasyonu ve Bazı Metal İyonlarının Enzim Aktivitesi Üzerindeki Etkileri
    (2018) Akkemik, Ebru; Çiftçi, Mehmet
    NADPH-Sitokrom P450 redüktaz (CPR) enzimi, detoksifikasyon metabolizmasında elektron transferinikatalizleyen anahtar bir enzimdir. Bu çalışmada, hindi karaciğer mikrozomlarından CPR enziminin saflaştırılmasıiçin iki yöntem kullanılmıştır. Birinci yöntemde, CPR enzimi ~114 saflaştırma katsayısıyla ve ~%23 verimle2’, 5’-ADP Sefaroz 4B afinite kolonu kullanılarak saflaştırılmıştır. İkinci yöntemde, CPR, DE-52 selüloz anyondeğişim kolonu ve 2’, 5’-ADP Sefaroz 4B afinite kolonu kullanılarak, ~124’lük saflaştırma katsayısı ve %8verimle saflaştırılmıştır. Enzim saflığı her iki yöntemde de SDS-PAGE ile kontrol edilmiştir. Saflaştırılmış enziminkarakteristik kinetik özellikleri belirlenmiştir. Bazı metal iyonlarının saflaştırılmış CPR enzim aktivitesi üzerindekietkileri in vitro şartlarda araştırılmıştır. Ag+, Hg2+ ve Cu2+ metal iyonlarının CPR enzim aktivitesi üzerinde inhibisyonetkisi gösterdiği tespit edilmiştir.
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    ICP-OES AND LC-ESI-MS/MS ANALYSES, ENZYME INHIBITION AND DNA PROTECTION POTENTIAL OF PELARGONIUM QUERCETORUM AGNEW
    (Univ Babes-Bolyai, 2022) Akkemik, Ebru; Fidan, Mehmet; Balaban, Merve; Inal, Behcet
    Pelargonium quercetorum Agnew extract affects activities of acetylcholinesterase (AChE) and carbonic anhydrase I-II enzymes (hCA I-II) was investigated under in vitro conditions. IC50 values of P. quercetorum Agnew on hCA I-II and AChE activity were determined as 0.144 +/- 0.0720, 0.209 +/- 0.0593, and 0.062 +/- 0.0097 mg/mL, respectively. Rutin and shikimic acid was found to be the main phenolic component in P. quercetorum Agnew flower extract from the results of LC-ESI-MS/MS analysis. Rutin was found to be the main phenolic component in P. quercetorum Agnew leaf extract from the results of LC-ESIMS/MS analysis. ICP-OES analysis showed that the leaves of P. quercetorum Agnew were rich in potassium. The DNA protective effect on plasmid DNA was demonstrated by using extracts obtained from leaf and flower tissues. Consequently, based on the findings of the current study, it could be anticipated that clinical trials related to P. quercetorum Agnew could be completed and the plant could be used pharmacologically.
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    İn vitro ve İn vivo Şartlarda Tiyoredoksin Redüktaz (TrxR) ve Piruvat Kinaz M2 (PKM2) Enzim Aktiviteleri Üzerine Bazı Yeni İmin Bileşiklerinin Etkisinin İncelenmesi
    (2017) Akkemik, Ebru; Çiftçi, Mehmet; Güneş, Yakup
    Bu çalışmada temel amaç kanserle doğrudan ilişkili olduğu düşünülen Tiyoredoksin Redüktaz (TrxR) ve Piruvat Kinaz M2 (PKM2) enzimlerinin potansiyel inhibitör/aktivatörlerini sentezlemektir. Günümüzün vebası haline gelen kanser, gün geçtikçe daha çok insanı etkisi altına almaktadır. Bu nedenle birçok araştırmacı çalışmalarını antikanser ajanlar ve kanser tedavisiyle ilgili alanlara yönlendirmektedir. Yapılan her çalışma, kanser oluşumu ve sürecinin ne kadar karmaşık olduğunu göstermektedir. Kanser etmenlerinden biri olarak kabul edilen TrxR?nin ise tümörlü hücrelerde aşırı bir şekilde eksprese olarak, tümör hücrelerinin gelişimine yol açtığı ayrıca söz konusu enzimin apoptosisle de bağlantılı olduğu tespit edilmiştir. PKM2 enziminin de kanserli hücrelerde aşırı derecede eksprese olduğu ve bu şekilde kanserli hücrelerin enerji ihtiyacını karşıladığı bilinmektedir. Son yapılan çalışmalarda PKM2 enziminin aktivatörlerinin de antiproliferatif ajan olarak kullanılabileceği belirtilmiştir. Metabolizma üzerinde belirtilen fizyolojik önemleri sebebiyle TrxR ve PKM2 enzimleri, bu araştırmanın odak noktasını oluşturmaktadır. Kiral imin bileşikleri, dialdehitler ile kiral aminler arasındaki reaksiyondan sentezlendi. Elde edilen 10 farklı imin bileşiği 1H-,13C-NMR, FTIR, Q-TOF LC/MS ve termal analiz metotları ile karakterize edildi. Sentezlenen bileşiklerin sekiz farklı yöntemle antioksidan özellikleri spektrofotometrik olarak belirlendi. Bunun sonucunda 10 bileşiğinde en az bir yöntemde antioksidan özellik gösterdiği tespit edildi. Ayrıca bu bileşiklerin in vitro şartlarda PKM-2 ve TrxR için inhibisyon etkisi araştırıldı. İn vitro şartlarda TrxR enzim aktivitesi üzerinde en yüksek inhibisyonu AS6 (IC50 15,85 ?M) bileşiğinin sağladığı, PKM-2 enzim aktivitesi üzerinde en yüksek inhibisyonu ise CS8 (IC50 4,34 ?M) bileşiğinin sağladığı tespit edildi. Son olarak CS3 (AC50 26,18 ?M) bileşiğinin PKM-2 enzim aktivitesi üzerinde aktivasyon etkisi gösterdiği belirlendi. CS3, AS6 ve CS8 için MCF7, ATCC HTB-22 hücrelerinde MTT Yöntemi ile antikanser çalışması yapıldı. İn vitro çalışmalar sonucu elde edilen veriler ışığında CS3, AS6 ve CS8?in Wistar Albino Rat?lar üzerinde in vivo çalışmaları gerçekleştirildi. Sıçanların karaciğer, böbrek, beyin, kas ve akciğerlerinde piruvat kinaz ve tiyoredoksin redüktaz enzim aktiviteleri incelendi. Her bir dokuda kontrol aktivitesi 100 kabul edilerek, AS6 uygulanmış sıçanların beyin, kas, böbrek, karaciğer ve akciğer dokularında TrxR aktiviteleri kıyasladığında sırasıyla aktvitenin %86.56, %108.83, %84.41, %80.78 ve %41.38 olarak değiştiği tespit edildi. CS3 uygulanmış sıçanlarn beyin, kas, böbrek, karaciğer ve akciğer dokularında Piruvat Kinaz enzim aktiviteleri kıyaslandığında enzim aktivitesinin sırasıyla %37.84, %6.19, %62.46, %304, %160 olarak değiştiği tespit edildi. CS8 uygulanmış sıçanların beyin, kas, böbrek, karaciğer ve akciğer dokularında Piruvat Kinaz enzim aktiviteleri kıyasladığında enzim aktivitesinin sırasıyla %25.23, %12.46, %19.37, %87.38, %62.86 şeklinde değiştiği tespit edildi.
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    Inhibition Effects of Some Non-Proteinogenic Amino Acid Derivatives on Carbonic Anhydrase Isoenzymes and Acetylcholinesterase: An In Vitro Inhibition and Molecular Modeling Studies
    (Wiley-V C H Verlag Gmbh, 2024) Alim, Zuhal; Rawat, Ravi; Adem, Sevki; Eyuepoglu, Volkan; Akkemik, Ebru
    Amino acid derivatives are molecules of interest for medicinal chemistry and drug design studies due to their important chemical properties. In this study, the inhibition effects of some non-proteinogenic amino acid derivatives (hippuric acid (A), N-(9-Fluorenylmethoxycarbonyl)-D-valine (B), N-Z-(1-Benzotriazolylcarbonyl) methylamine (C), (S)-N-Z-1-Benzotriazolylcarbonyl-2-phenylethylamine (D)) on carbonic anhydrase I (hCA-I), II (hCA-II) isoenzymes and acetylcholinesterase (AChE) activity, whose inhibitors are of vital pharmacological importance, were examined. While carbonic anhydrase (CA) inhibitors are effective molecule candidates for the treatment of many diseases from glaucoma to cancer, acetylcholinesterase inhibitors are target molecules for the treatment of Alzheimer ' s disease. According to the results of this study, compound D had a strong inhibitory effect on hCA-I (IC50: 0.836 mu M) and hCA-II (IC50: 0.661 mu M), while compound B (IC50: 100 mu M) showed a strong inhibitory effect on AChE activity. In addition, inhibition results were supported by molecular modeling studies. We hope that the obtained results will contribute to the synthesis of new and effective amino acid derivative inhibitors for CA and AChE.
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    Inhibitory properties of some heavy metals on carbonic anhydrase I and II isozymes activities purified from Van Lake fish (Chalcalburnus Tarichi) gill
    (Springer, 2018) Kuzu, Muslum; Comakli, Veysel; Akkemik, Ebru; Ciftci, Mehmet; Kufrevioglu, Omer Irfan
    In this study, CA I and II isoenzymes were purified from Van Lake fish gills by using Sepharose-4B-L-tyrosine-sulfanilamide affinity chromatography and to determine the effects of some metals on the enzyme activities. For purified CA I isoenzyme, yield, specific activity, and purification fold were obtained as 42.07%, 4948.12 EU/mg protein, and 116.61 and for CA II isoenzyme, 7%, 1798.56 EU/mg protein, and 42.38 respectively. Activity of CA was determined by measuring CO2-hydratase activity. Purity control was checked by SDS-PAGE. In vitro inhibitory effect of Cu2+, Ag+, Cd2+, Ni2+ metal ions, and arsenic (V) oxide were also examined for both isozymes activities. Whereas Cu2+, Ag+, Cd2+, and Ni2+ ions showed inhibitory effects on both isozymes, arsenic (V) oxide showed activation effect. IC50 values were calculated by drawing activity %-[I] graphs for metal ions exhibiting inhibitory effects. IC50 values were determined as 3.39, 6.38, 13.52, and 206 mu M for CA I isozyme and 6.16, 20.29, 46, and 223 mu M for CA II isozyme respectively.
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    İnsan karbonik anhidraz I,II izoenzim aktiviteleri üzerine bazı tiyocrown eterlerin etkisi
    (2017) Akkemik, Ebru; Çalışır, Ümit; Çiçek, Baki
    Metalo enzim sınıfının bir üyesi olan karbonik anhidrazlar karbondioksitin bikarbonata ve protona dönüşümünü katalizlerler. Bir çok izoenzime sahip olan karbonik anhidrazların inhibisyonu veya aktivasyonu fizyolojik açıdan oldukça önemlidir. Bu yüzden bizde çalışmamızda insan eritrositlerinden karbonik anhidraz I ve II izoenzimini saflaştırdık. Saflaştırdığımız enzim aktiviteleri üzerinde bazı tiyoeter türevlerinin (1,10ditiyo-18-crown-6 (B1), 1,7-ditiyo-15-crown-5 (B2), 1,7- ditiyo -12-crown-4 (B3), 1,7ditiyo-18-crown-6 (B4), 1,10-ditiyo-21-crown-7 (B5) ve 1,4-ditiyo-12-crown-4 (B6)) etkilerini in vitro şartlarda araştırdık. B1 ve B5 her iki izoenzim aktivitesi üzerinde düzenli bir etki göstermezken, en iyi aktivasyon etkisini her iki izoenzim için B2 bileşiği (hCA I için AC50 = 25.27µM ve hCA II için AC50 = 32.74 µM) göstermiştir
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    Investigation of in vitro and in silico effects of some novel carbazole Schiff bases on human carbonic anhydrase isoforms I and II
    (Taylor & Francis Inc, 2022) Camadan, Yasemin; Cicek, Baki; Adem, Sevki; Calisir, Umit; Akkemik, Ebru
    Carbonic anhydrases (CAs, EC4.2.1.1) are metalloenzymes that catalyse reversible hydration reaction of carbon dioxide to bicarbonate and protons. In recent years, there has been a great interest in inhibitors/activators of carbonic anhydrase isoenzymes. Therefore, we investigated the effects of four different carbazole Schiff base derivatives, which are believed to have a potential to be used as a drug, on human carbonic anhydrase (hCA) isoenzymes I and II under in vitro conditions. The IC50 values of carbazole Schiff base derivatives were found to be in the range of 32.09-151.2 mu M for hCA isoenzyme I and 21.82-40.54 mu M for hCA isoenzyme II. Among all compounds, (E)-3-(((9-Octyl-9H-carbazole-3-yl)imino)methyl)benzene-1,2-diol (C3) had the strongest inhibitory effect on hCA isoenzyme II. It was determined that 2,3,4-trimethoxy and 4-hydroxy phenyl containing carbazole compounds have selective inhibition against hCA II isoenzyme. Docking studies were performed against hCA I and II receptors using induced-fit docking method. The compounds had affinity scores varying from -7.74 +/- 0.27 to -6.27 +/- 0.07 kcal/mol for hCA I and from -8.04 +/- 0.17 to -7.27 +/- 0.18 kcal/mol for hCA II. Communicated by Ramaswamy H. Sarma
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    Investigation of Inhibition Effects of Honey, Pollen, Propolis and Royal Jelly Extracts on Thioredoxin Reductase Enzyme Activity
    (2018) Akbulut, Gamze; Akkemik, Ebru
    The thioredoxin reductase enzyme is an enzyme that prevents the mechanism of apoptosis from workingand thus triggers the formation of cancer. Therefore, the inhibition of the thioredoxin reductase enzyme isthought to prevent or inhibit cancer. In this study, the effects of extracts of plateau honey, pine honey,chestnut honey, mad or wild honey, pollen, propolis and royal jelly on thioredoxin reductase enzymeactivity were investigated. Enzyme activities were measured at constant substrate and different inhibitorconcentrations to calculate IC50 values. Total antioxidant activity were investigated in order to compare theextracts used in the inhibition study. The strongest inhibitory effect was seen in the pollen methanol extract(IC50 = 2.44?g /mL)
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    Investigation of Some Pesticides’ Effects on Activities of Glutathione Reductase and Glutathione S-Transferase Purified from Turkey Liver under in Vitro Conditions
    (2018) Güller, Pınar; Akkemik, Ebru; Kör, Sevil; Çiftçi, Mehmet
    Whereas a very small amount of pesticides which are used for elimination of undesirable speciesand for a more fertile agriculture reach the target organism, majority of pesticides reach to nontarget organisms. It isforeseen by our team that the pesticides used for various purposes may negatively affect the glutathione mechanismof the organisms. However, determination of effective dosage range is the objective of our study subjects. For thisreason, the in vitro effects of widely used pesticides (lambda-cyhalothrin, cypermethrin, chlorpyrifos, dichlorvos,glyphosate isopropylamine) on the activities of glutathione reductase (GR) and glutathione S-transferase(GST) which are two important enzymes of the glutathione system have been investigated in this study. It hasbeen determined that when lambda-cyhalothrin does not affect the GR enzyme purified from the turkey liver,chlorpyrifos, glyphosate isopropylamine, dichlorvos and cypermethrin cause inhibition. When the effects ofpesticides on GST enzyme purified from turkey liver were investigated in in vitro conditions, it was determinedthat all examined pesticides had inhibitory effects. In this context, the potential doses which can create a risk forlive life, of pesticides that are commonly used, have been identified.
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    Investigation of the Effect of Some Optically Active Imine Compounds on the Enzyme Activities of hCA-I and hCA-II under In Vitro Conditions: An Experimental and Theoretical Study
    (Wiley, 2016) Tektas, Osman; Akkemik, Ebru; Baykara, Haci
    Inhibitors of carbonic anhydrase (hCA; EC 4.2.1.1) are used as medicines for many diseases. Therefore, they are very important. In this study, a known series of Schiff bases were synthesized and their effects on the activities of hCA-I and hCA-II, which are cytosolic isoenzymes of carbonic anhydrase, were investigated under in vitro conditions. The synthesized compounds (H1, H2, H3, and H4) were found to cause inhibition on enzyme activities of hCA-1 and hCA-II. IC50 values of H1, H2, H3, and H4 compounds were 140, 88, 201, and 271 M for hCA-I enzyme activity and 134, 251, 79, and 604 M for hCA-II enzyme activity, respectively. The synthesized Schiff bases were characterized by several methods, including H-1 NMR, FT-IR, elemental analysis, and polarimetric measurements. Correlation coefficient square values (R-2) of comparison of the theoretical and experimental H-1 NMR shifts for H1, H2, H3, and H4 compounds were found as 0.9781, 0.9814, 0.9758, and 0.8635, respectively.
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    Investigation of the Effects of 1,2,4-Triazole and Thiazole Ring-Containing Hybrid Molecules on Carbonic Anhydrase I and II
    (Wiley-V C H Verlag Gmbh, 2024) Camadan, Yasemin; Akkemik, Ebru; Guller, Pinar; Ceylan, Sule; Ozdemir, Hasan
    Carbonic anhydrase (CA, EC 4.2.1.1) is an enzyme that catalyzes the reversible reaction of carbon dioxide to bicarbonate and a proton under physiological conditions. Pharmaceutical research has gained importance since the design of novel compounds that inhibit CA I-II isoenzymes has a promising approach for pharmacological intervention in many diseases. Triazole derivatives have attracted attention due to their chemotherapeutic, antifungal, antiviral, antibiotic, analgesic, and antifungal activities. Therefore, in this study, the effect of 1,2,4-triazole and thiazole ring-containing compounds on human carbonic anhydrase I (hCA I) and II (hCA II) isoenzymes were investigated in vitro. For this purpose, hCA I and hCA II isoenzymes were purified by Sepharose-4B affinity column chromatography. Estimation of inhibition mechanism and drug-likeness characteristics of compounds were also determined using molecular docking simulation. The inhibitory effects of ten compounds were investigated. Activity vs. concentration graphs were prepared for each compound and IC50 values or AC50 were calculated from these graphs. It was revealed that some of the compounds exhibited selective inhibition on carbonic anhydrase isoenzymes. The studied compounds are considered to be drug candidates. 1,2,4-triazole and thiazole ring-containing hybrid molecules inhibited hCA-I isoenzyme with IC50 values between 0.135 and 0.523 mM and hCA II with IC50 values between 0.108 and 0.523 mM. Molecule 8 showed the highest inhibition potency against hCA-I while molecule 3 showed the highest inhibitory effect against hCA-II. Estimated binding energies for molecule 10 into hCA I is -9.31 kcal/mol and for molecule 2 on hCA II is -8.21 kcal/mol. image
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    Searching for New Natural Inhibitors of Acetylcholinesterase Enzyme
    (2022) Camadan, Yasemin; Akkemik, Ebru
    Acetylcholinesterase enzyme (AChE) is the enzyme that catalyzes the hydrolysis of the neurotransmitter acetylcholine to choline. Inhibitors of this enzyme (AChE-i) are used to treat Alzheimer's, a neurodegenerative disease. Due to the side effects of the drugs used, there has been an increased interest in investigating the inhibitory potentials of natural products which are presumed to have fewer side effects. For this purpose, the inhibitory effects of highland honey, chestnut honey, royal jelly and the seeds of peach, cherry, plum and apricot on human erythrocyte AChE enzyme was investigated in vitro in the present study. Extracts of the seeds and bee products were prepared in ethanol solvent. In order to determine the inhibitory effect of the extracts, the inhibition concentration (IC50) and Ki values which cause 50% inhibition of the enzyme were calculated using the Ellman method. It was found that among the natural product extracts studied, peach seed had the highest inhibition level (IC50 value 0.05708 mg/ml). IC50 values of highland honey, royal jelly, plum seed and apricot seed were determined as 0.2555 (mg/mL), 0.300 (mg/mL), 0.7049 (mg/mL) and 0.4544 (mg/mL) respectively.
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    Synthesis, characterizations of aryl-substituted dithiodibenzothioate derivatives, and investigating their anti-Alzheimer's properties
    (Taylor & Francis Inc, 2023) Calisir, Umit; Camadan, Yasemin; Cicek, Baki; Akkemik, Ebru; Eyupoglu, Volkan; Adem, Sevki
    The main objective of the present study was to synthesize potential inhibitor/activators of AChE and hCA I-II enzymes, which are thought to be directly related to Alzheimer's disease. Dithiodibenzothioate compounds were synthesized by thioesterification. Six different thiolate compounds produced were characterized by H-1-, C-13-NMR, FT-IR, LC-MS/MS methods. HOMO-LUMO calculations and electronic properties of all synthesized compounds were comprehensively illuminated with a semi-empirical molecular orbital (SEMO) package for organic and inorganic systems using Austin Model 1 (AM1)-Hamiltonian as implemented in the VAMP module of Materials Studio. In addition, the inhibition effects of these compounds for AChE and hCA I-II in vitro conditions were investigated. It was revealed that TE-1, TE-2, TE-3, TE-4, TE-5, and TE-6 compounds inhibited the AChE under in vitro conditions. TE-1 compound activated the enzyme hCA I while TE-2, TE-3 TE-4 compounds inhibited it. TE-5 and TE-6, on the other hand, did not exhibit a regular inhibition profile. Similarly, TE-1 activated the hCA II enzyme whereas TE-2, TE-3, TE-4, and TE-5 compounds inhibited it. TE-6 compound did not have a consistent inhibition profile for hCA II. Docking studies were performed with the compounds against AChE and hCA I-II receptors using induced-fit docking method. Molecular Dynamics (MD) simulations for best effective three protein-ligand couple were conducted to explore the binding affinity of the considered compounds in semi-real in-silico conditions. Along with the MD results, TE-1-based protein complexes were found more stable than TE-5. Based on these studies, TE-1 compound could be considered as a potential drug candidate for AD. Communicated by Ramaswamy H. Sarma
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    The determination of the carbonic anhydrases activators in vitro effect of mixed donor crown ethers
    (Wiley, 2018) Akkemik, Ebru; Cicek, Baki; Camadan, Yasemin; Calisir, Umit; Onbasioglu, Zekai
    Carbonic anhydrases (CAs) play an important function in various physiological and pathological processes. Therefore, many researchers work in this field in order to design and synthesize new drugs. Both inhibitors and activators of CAs, which are associated with the diagnosis and treatment of many diseases, are very important. The emergence of the use of CA activators in the treatment of Alzheimer has led many scholars to work on this issue. In this study, CA activators and inhibitors are determined. The crown ethers compounds (1, 2, 3, 6, 7, 8, and 9) were found to cause activation on enzyme activities of hCA I and II. The AC(50) values on hCA I and II of the compounds are in the range of 4.6565-374.979M. The 4 (IC50; 1.301 and 3.215M for hCA I and II) and 5 (IC50; 73.96 and 378.5M for hCA I and II) compounds were found to cause inhibition on enzyme activities of hCA I and II.
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    The role of Bax/Bcl-2 and Nrf2-Keap-1 signaling pathways in mediating the protective effect of boric acid on acrylamide-induced acute liver injury in rats
    (Pergamon-Elsevier Science Ltd, 2022) Cengiz, Mustafa; Ayhanci, Adnan; Akkemik, Ebru; Sahin, Ilknur Kulcanay; Gur, Fatma; Bayrakdar, Alpaslan; Cengiz, Betul Peker
    Introduction: This study aims to investigate whether boric acid (BA) can protect rats from acrylamide (AA)induced acute liver injury. Materials and methods: AA was used to induce acute liver injury. Thirty rats were divided into five group including Group 1 (saline), Group 2 (AA), Group 3 (20 mg/kg BA), Group 4 (10 mg/kg BA+AA) and Group 5 (20 mg/kg BA+AA). Their blood and liver were harvested to be kept for analysis. Liver function enzyme activities were performed by spectrophotometric method. Catalase (CAT), superoxide dismutase (SOD) activity, and malondialdehyde levels were determined by colorimetric method. The in-silico studies were performed using the blind docking method. Results: Administration AA to rats, biochemical parameters, liver histology, and expression levels of apoptotic markers were negatively affected. However, after the administration of BA, the altered biochemical parameters, liver histology, and expression levels of apoptotic markers were reversed. Moreover, the mechanisms of AA-induced deterioration in the levels of SOD, CAT, and Nrf2-Keap-1 and the mechanisms of the protective effect of BA against these deteriorations were explained by in silico studies. Conclusion: Thus, the present study could explain the interactions between AA and thiol-containing amino acid residues of Keap-1, the effect of BA on these interactions, and the biochemical toxicity caused by the AA. In this sense, this work is the first of its kind in the literature. Based on the biochemical, histopathological, and in silico results, it can be suggested that BA has the potential to be used as a protective agent against AA-induced liver injury.