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- ArticleAçık Erişim2023Ferruginoside D: A Novel Phenylethanoid from Verbascum leiocarpum
Şimşek, Samed; Akşit, Hüseyin; Aydın, Ali; Köksal, Ekrem
A novel phenylethanoid, ferruginoside D, together with fourteen known compounds were isolated from the Verbascum leiocarpum for the first time. Chemical structures of isolated compounds were determined by spectroscopic analysis including HR-ESI-MS and NMR spectra. The antioxidant, α-glucosidase inhibitory properties, and antiproliferative activities against multiple cell lines (A172, C6, HeLa, A2780, SW620, HT29, Beas2B, RPE, and HSF) of the isolated compounds were evaluated in vitro. According to the results, iridoids, flavonoids (luteolin and apigenin), and phenylethanoids (poliumoside and isoverbascoside) with strong antiproliferative potential were also found to have cytostatic effects. Furthermore, the investigation revealed that compounds luteolin, poliumoside, verbascoside, isoverbascoside, ferruginoside C, ferruginoside D, and ursolic acid show potent alpha-glucosidase inhibitory activity, while compounds luteolin, verbascoside, and isoverbascoside exhibit substantial antioxidant activity. The new compound (ferruginoside D) was found moderately active against cancer cell lines, with strong alpha-glucosidase inhibitory activity, and moderate antioxidant properties.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2022Inhibitory Effect of Methotrexate (MTX) Used in Human Cancer Treatment on Paraoxonase-1 (PON1)
Söyüt, Hakan; Ulutas, Yakup; Köksal, Ekrem
Background and Objective: Paraoxonase-1 (PON1) is a lactonase that plays a role in the destruction of carcinogenic free radicals and in reducing oxidative stress. In this article, it was aimed to investigate the inhibitory effect of methotrexate (MTX) on PON1. Materials and Methods: In this study, the inhibition between methotrexate used in cancer chemotherapy and PON1 was studied. Results: Methotrexate showed very strong inhibitory properties for human serum PON1, with an IC(50)value of 38.50 mu M and a mean K-i value of 42.36 mu M. Hence methotrexate showed competitive inhibition. Conclusion: The widespread use of methotrexate, a dihydrofolate reductase (DHFR) inhibitor, in the treatment of human cancers can be very harmful.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2022Phytochemical Analysis and Biological Evaluation of Hypericum linarioides Bosse: in Vitro and in Silico Studies
Altay, Ahmet; Yeniçeri, Esma Kübra Kağan; Taslimi, Parham; Taskin-Tok, Tugba; Yılmaz, Mustafa Abdullah; Köksal, Ekrem
The aim of this study is to determine the phenolic composition of Hypericum linarioides Bosse, to assess its various biological properties, and finally to confirm the experimental data of enzyme inhibitions via docking studies. LC-MS/MS analysis performed over methanol extract (ME) revealed the presence of 27 phytochemicals. Antioxidant activity results indicated that ME had the strongest DPPH radical scavenging and ferric ion reducing capacity than water and hexane extracts. XTT assays revealed the strongest anti-proliferative activity of ME against MCF-7 and HT-29 cancer cells. Flow cytometry results also confirmed the notable apoptotic effect of ME on MCF-7 cells through mitochondria-dependent pathway. Enzyme activity results exhibited the most promising acetylcholinesterase and α-glycosidase inhibitory activities of the ME. Molecular docking calculations of α-glycosidase with the major compounds (1, 15, 17 and 19) indicated that 17 (isoquercitrin) had the best docking binding energy (−10.92 kcal/mol) with appropriate binding interactions.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2021Lallemantia canescens (L) Fisch & Mey. Bitkisinin Antimikrobiyal Aktivitesinin Araştırılması
Akyüz, Sümeyye; Köksal, Ekrem; Altay, Ahmet; Alp, Cemalettin; Altin, Sevgi; Yeniçeri, Esma Kübra Kağan
Bitkilerin zararlı mikroorganizmaları öldürücü etkileri ile ilgili yapılan çalışmalar onların sağlık açısından önemli ve değerli bir kaynak haline gelmelerini sağlamıştır. Türkiye üç fitocoğrafik bölgenin birleşim merkezi olmasından dolayı zengin florasıyla sayısız tıbbi ve aromatik bitkiye ev sahipliği yapmaktadır. Bu çalışmada Türkiye’de “Topajdarbaşı” olarak bilinen L. canescens bitkisinin toprak üstü kısımlarının hekzan, etilasetat, metanol ve su ekstrelerinin antimikrobiyal aktivitesi araştırılmıştır. Bitki örnekleri Erzincan İli Pöske Dağı bölgesinden toplanmıştır. Ekstraktların antimikrobiyal aktiviteleri; standart Gram negatif bakterilere (Pseudomonas aeruginosa, Klebsiella pneumoniae, kolistin dirençli Escherichia coli, Escherichia coli) ve standart Gram pozitif bakterilere (Enterococcus faecalis, Staphylococcus aureus, Streptococcus pneumoniae) karşı Kirby-Bauer disk difüzyon yöntemi ile belirlenmiştir. L. Canescens’in hekzan, etilasetat ve metanol ekstreleri S. aureus, E. faecalis, S. pneumoniae suşlarına karşı antimikrobiyal aktivite göstermiştir.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2021In vitro Antioxidant and Cytotoxic Activities of Extracts of Endemic Tanacetum erzincanense Together with Phenolic Content by LC-ESI-QTOF-MS
Yapıcı, İsmail; Altay, Ahmet; Öztürk Sarıkaya, Beyza; Korkmaz, Mustafa; Atila, Alptuğ; Gülçin, İlhami; Köksal, Ekrem
In this study, phenolic composition, and in vitro biological activities of ethyl acetate (EAE) and methanol (ME) extracts obtained from the aerial parts of endemic Tanacetum erzincanense were investigated. Total phenolic and flavonoid content of the extracts were determined by Folin-Ciocalteu and aluminum chloride colorimetric methods, respectively. Antioxidant capacity of the extracts was evaluated over radical scavenging (DPPH and ABTS) and metal ion reducing power (FRAP and CUPRAC) tests. Individual phenolic compounds in ME was analyzed by high-performance liquid chromatography coupled to electrospray ionization quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF/MS). Cell inhibitory potential of the extracts was tested against colorectal adenocarcinoma (HT-29), breast adenocarcinoma (MCF-7), and hepatocarcinoma (HepG2) cells by 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) assay. The results showed that ME contains higher TPC (64.4 mg GAE/g) and TFC (62.2 mg QE/g) than those of EAE (41.5 mg GAE/g and 40.0 mg QE/g). LC-ESI-QTOF/MS analysis revealed that ME is rich in phenolic compounds, namely, chlorogenic acid, apigenin, quercetin, luteolin, and diosmetin. Antioxidant assay results indicated that ME possess stronger activity than EAE and a power that competes with synthetic antioxidants. XTT assay results demonstrated that although both extracts displayed a considerable cytotoxicity against the tested cancer cell lines in a time and dose-dependent manner, ME expressed its selective inhibitory action towards MCF-7 cells with an IC50 value of 20.4 μg/mL for 72 h. These results may serve as a basis for further in vivo studies to examine the potential applications of T. erzincanense in food and pharmaceutical industries.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2021Isolation, characterization and antiproliferative activity of secondary metabolites from tanacetum alyssifolium (Bornm.) grierson
Köksal, Ekrem; Ulutaş, Yakup; Şimşek, Samed; Bayraktar, Taha; Altay, Ahmet; Çatır, Mustafa; Demirtaş, İbrahim; Tüfekçi, Ali Rıza; Kandemir, Ali; Alp, Cemalettin
Secondary metabolites of Tanacetum alyssifolium (Bornm.) Grierson (Asteraceae) were investigated for the first time. Thirteen compounds including axillarin (1), Luteolin-7-O-β-glucoside (8) and rutin (13) as flavonoids, fraxetin (7), isofraxidin (9), isofraxidin-7-O-glucoside (11) and fraxidin (12) as coumarins, tatridin A (2), altissin (3), tamirin (4) and tanachin (5) as sesquiterpene lactones and 2,4-dihydroxy-6-methoxy acetophenone (6) and picein (10) as acetophenone derivatives were isolated from the methanol extract of the species. The structures of all isolated compounds were elucidated by 1D and 2D-NMR techniques and by comparing with the literature data. In addition, in vitro cytotoxic activity of all isolated compounds was evaluated against breast cancer MCF-7 cell line by XTT assay. Sesquiterpene lactones; tatridin A (2), tamirin (4) and tanachin (5) were found to be the most cytotoxic molecules against MCF-7 cell line.
RDL Kalıcı Kaydıİncele - ArticleYayıncıda açık erişim2021Phytochemicals Analysis and Some Bioactive Properties of Erica manipuliflora Salisb. (EMS); Antibacterial, Antiradical and Anti-lipid Peroxidation
Yüksel, Arzu Kavaz; Dikici, Emrah; Yüksel, Mehmet; Işik, Mesut; Tozoğlu, Fatih; Köksal, Ekrem
In the present study, the phenolic content by using LC MS/MS method, anticholinergic, antioxidant (metal reduction, radical and removal of lipid peroxidation), and antibacterial activities of Erica manipuliflora Salisb. (EMS) extract were determined. The amount of vanillic acid, fumaric acid, catechin hydrate, quercetin, and phloridzin dihydrate were found higher than other compounds. The ethanol extract of the EMS showed an inhibition effect on the Acetylcholinesterase (AChE) enzyme with IC50 value of 0.124 ± 0.008 mg mL-1. Also, this extract of the EMS indicated radical (DPPH and ABTS) scavenging activity (about 20%) and the reducing capacity for Cu(II) and Fe(III) close to trolox, and inhibited the oxidation of linoleic acid with 40.5% at 20 μg mL-1. Antibacterial activity of the extracts was investigated against Staphylococcus aureus, Escherichia coli, and Salmonella Typhimurium using agar disc diffusion and minimum inhibitory concentration (MIC) methods. The EMS extract was found to be effective when used at least 312 mg mL-1 concentration on the pathogenic microorganisms. Consequently, it has an important non-synthetic natural content that can be used in the treatment of many diseases due to its many bioactivities such as anticholinergic, antioxidant (radical removal, lipid peroxidation prevention, etc.) and antibacterial.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2021Phytochemical, phenolic profile, antioxidant, anticholinergic and antibacterial properties of Epilobium angustifolium (Onagraceae)
Kavaz Yüksel, Arzu; Dikici, Emrah; Yüksel, Mehmet; Işık, Mesut; Tozoğlu, Fatih; Köksal, Ekrem
Epilobium angustifolium is widely used in medicine for disease treatments, as well as in the cosmetic and food industries. The aim of this research was to investigate the antioxidant, and anticholinergic properties, phenolics profile and antibacterial activities of the E. angustifolium ethanol extract. The analysis of phenolic compounds was performed with LC–MS/MS. The antioxidant capacity (radical scavenging, metal-reducing power and total antioxidant activity) was assessed by DPPH, ABTS, Cu2+–Cu+ reducing (CUPRAC), Fe3+–Fe2+ reducing and ferric thiocyanate methods. The antibacterial activity was determined by disc diffusion and MIC (Minimum inhibitory concentration) methods and the anticholinergic property was predicted by inhibition of acetylcholinesterase (AChE). The major phenolic compounds, founding in the plant extract were luteolin, fumaric acid, vanillic acid, and caffeic acid. The ethanol extract of the plant showed DPPH free radical scavenging value of 11.3%, while the ABTS radical scavenging activity was 19.4% and showed moderately metal-reducing power. Also, the extract had 39.3% inhibition on lipid peroxidation of linoleic acid emulsion and showed an inhibition effect on the AChE with IC50 values (0.14 mg mL−1). The ethanol extract of the plant showed antibacterial effect on Staphylococcus aureus, Escherichia coli, and Salmonella Typhimurium at different levels. These results suggested that E. angustifolium extract might be a suitable natural antioxidant in the preservation of foods by preventing the oxidation of polyunsaturated fatty acids, and might play a role in the treatment of some diseases with its antioxidant, anticholinergic, and antibacterial activity.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2020Anti-Alzheimer, antidiabetic and antioxidant potential of Satureja cuneifolia and analysis of its phenolic contents by LC-MS/MS
Taslimi, Parham; Köksal, Ekrem; Gören, Ahmet C.; Bursal, Ercan; Aras, Abdülmelik; Kılıç, Ömer; Alwasel, Saleh; Gülçin, İlhami
Many chronic diseases such as diabetes and Alzheimer's disease are related to the type and quality of foods, which are consumed. Particularly, various plant origin products are stated as beneficial against such kind of chronic diseases with secondary metabolites such as their phenolic structures. Satureja cuneifolia is a plant, which is consumed as an herbal tea in some regions of Turkey and that's why investigate of its biological activity is important. In our study, the anti-diabetic and anti-Alzheimer potentials of the methanol and water extracts of S. cuneifolia plant were measured via some enzymes inhibition experiments as in vitro. The antioxidant ability of the same extracts was measured via radical scavenging and reducing power methods. Also, the total phenolics and flavonoids of the plant were identified. Finally, the extracts were analyzed by the LC-MS/MS analysis and the phenolic content of S. cuneifolia was clarified.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2019Arbutin’in yeni kaynakları: Onobrychis nitida and Onobrychis galegifolia
Özdokur, Kemal Volkan; Akşit, Hüseyin; Köksal, Ekrem; Şimşek, Samed
Arbutin (4-Hidroksifenil-β-D-glukopiranozit), hidrokinonun mono glikozidik formudur ve cilt beyazlatma ve çil giderme özellikleri nedeniyle kozmetiklerde uzun süredir yaygın olarak kullanılmaktadır. Bu çalışmada; arbutin flash kromatografi kullanılarak Onobrychis galegifolia'nın metanol ekstraktından izole edilmiştir. Arbutin yapısı, 1 H ve 13C -NMR spektroskopisi ve ayrıca 2D NMR teknikleri ile aydınlatıldı. Ek olarak, O. galegifolia ve O. nitida türlerinde bulunan arbutinin kantitatif analizi HPLC-DAD kullanılarak yapıldı. Sonuçlara göre, O. galegifolia ve O. nitida'nın metanol ekstraktlarının arbutin içeriği sırasıyla 212.02 ve 196.46 mg/g ekstrakt olarak bulundu. Ayrıca, O. galegifolia ve O. nitida'nın soğuk su ekstraktlarının arbutin içeriği 128.2 ve 99.40 mg/g ekstrakt olarak bulundu. Kuru ağırlıklardaki arbutin miktarı, yaklaşık% 5.66 ila% 6.86 arasında hesaplandı.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2019Phytochemical Content, Antidiabetic, Anticholinergic, and Antioxidant Activities of Endemic Lecokia cretica Extracts
Aras, Abdülmelik; Bursal, Ercan; Türkan, Fikret; Tohma, Hatice; Kılıç, Ömer; Gülçin, İlhami; Köksal, Ekrem
The aim of this work was to investigate the enzyme inhibition, antioxidant activity, and phenolic compounds of Lecokia cretica (Lam.) DC. Acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and α-glycosidase enzymes were strongly inhibited by the L. cretica extracts. IC50 values for the three enzymes were found as 3.21 mg/mL, 2.1 mg/mL, and 2.07 mg/mL, respectively. Antioxidant activities were examined in both aqueous and ethanol (EtOH) extracts using CUPRAC, FRAP, and DPPH method. Also, the phenolic compounds of the endemic plant were identified and quantified by using HPLC/MS/MS. According to the results, the extracts have remarkable antioxidant activities. The most abundant phenolic acids of L. cretica in EtOH extract were determined as quinic acid (12.76 mg/kg of crude extract), chlorogenic acid (3.39 mg/kg), and malic acid (2.38 mg/kg).
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2019Measurement of anticancer, antidiabetic and anticholinergic properties of sumac (Rhus coriaria): analysis of its phenolic compounds by LC–MS/MS
Tohma, Hatice; Altay, Ahmet; Köksal, Ekrem; Gören, Ahmet Ceyhan; Gülçin, İlhami
The present study aimed to investigate Sumac (Rhus coriaria) for anticancer, antidiabetic, anticholinergic activities and total phenolic and flavonoid contents. Two solvents, water and ethanol, were used for extraction. For anticancer activity, the extracts were tested against human cancer cell lines including HT-29 and MCF-7. The cell growth inhibition rate was measured via XTT assay. The antidiabetic activity of the sumac extracts was measured by the inhibition of α-glycosidase and α-amylase enzymes, whereas the anticholinergic activity was measured via the inhibition of acetylcholinesterase and butyrylcholinesterase enzymes. The total phenolic and flavonoid contents were determined using the Folin–Ciocalteau and the aluminum chloride colorimetric methods, respectively. Liquid chromatography–mass spectrometry/mass spectrometry (LC–MS/MS) method was used for the separation, identification and quantification of phenolic compounds in the samples. The ethanolic extract had higher phenolic and phenolic contents than aqueous extract. It exhibited substantial antiproliferative, antidiabetic and anticholinergic activities. The aqueous extract of sumac showed moderate therapeutic efficiency in all the preformed assays. LC–MS/MS study revealed fumaric acid as a main compound in both the ethanolic (452.78 mg/kg) and aqueous (180.72 mg/kg) extracts. These results suggest that sumac may have health-enhancing effects and act as inhibitors of certain enzymes or interfering with some cellular pathways.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2018Purification and selected biochemical properties of peroxidase from cress (Lepidium sativum sub sp. sativum)
Altay, Ahmet; Koktepe, Tubanur; Durmaz, Lokman; Topal, Fevzi; Gülçin, İlhami; Köksal, Ekrem
Cress (Lepidium sativum) is an annual herb from Brassicaceae family, and in some regions. It is known as peppergrass, garden cress, garden pepper-cress, pepperwort, or poor man’s pepper. Cress is an important medicinal plant in some countries including Turkey. This plant has major scientific and therapeutic significance. Peroxidase (POD, E.C.1.11.1.7) is an oxidor-eductase enzyme produced by a number of organisms. In this study, POD enzyme was purified from cress by ammonium sulphate precipitation, gel filtration, and CM-Sephadex ion-exchange chromatographies. K m and V max values were calculated from the Lineweaver-Burk graph for H 2 O 2 and guaiacol substrates and the substrate specificity of POD was investigated. The results showed that substrate specificity of H 2 O 2 is better than substrate specificity of guaiacol for this enzyme. The inhibition effects of three cations (Al 3+ , Cu 2+ , and Cr 3+ ) and one organic compound of cetyl trimethylammonium bromide were performed and their inhibition types were determined. Finally, optimum pH, optimum temperature, optimum ionic strength, and stable pH were determined.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2017Antioxidant Activity and Total Phenolic/Flavonoid Contents of Phlomis pungens L.
Tohma, Hatice; Işık, Mesut; Köksal, Ekrem; Dikici, Emrah
Plants generate secondary metabolites, which could be used as novel therapeutic compounds. These compounds are well known for their beneficial effects on human health. Thus, it is important to evaluate total phenolic and flavonoid contents as well as antioxidant activities of different plants. The present study was conducted to determine the total phenolic/flavonoid content and antioxidant activity of ethanol extract prepared from leaves of Phlomis pungens L. The total phenolic content of the ethanol extract of the sample were determined using the Folin-Ciocalteu reagent. Antioxidant activity of Phlomis pungens L. was determined using different in vitro experimental models, which include DPPH, FRAP, CUPRAC and potassium thiocyanate method. Total phenolic and flavonoid contents of Phlomis pungens L. were found to be 68.4 mg GAE/g and 4.9 mg QE/g, respectively. Antioxidant activity of the sample was comparable to commercial antioxidant standards (BHT, - tocopherol and trolox). The results showed that Phlomis pungens L has moderate free radical scavenging and reducing capacity. Overall, this study discovers total phenolic and flavonoid content as well as antioxidant properties of Phlomis pungens L
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2017Assessment of antimicrobial and antioxidant activities of nepeta trachonitica: Analysis of its phenolic compounds using HPLC-MS/MS
Köksal, Ekrem; Tohma, Hatice; Kılıç, Ömer; Alan, Yusuf; Aras, Abdülmelik; Gülçin, Ilhami; Bursal, Ercan
Continuing our work on the sources of natural bioactive compounds, we evaluated the antimicrobial and antioxidant activities of Nepeta trachonitica as well as its major phenolic content using the high-performance liquid chromatography-mass spectrometry/mass spectrometry (HPLC-MS/MS) technique. For antioxidant activity, ferric reducing antioxidant power (FRAP) and cupric ion reducing antioxidant capacity (CUPRAC) methods were performed to measure the reducing power and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay was employed to evaluate the radical scavenging activity of the sample. For antimicrobial activity, three Gram-positive and four Gram-negative microbial species as well as three fungi species were tested. N. trachonitica appeared to have reasonable antioxidant activity and decent antimicrobial activity as indicated by the inhibition of the organisms’ growth. The most susceptible species were Bacillus subtilis ATCC 6633 and Escherichia coli ATCC 11229 among the organisms tested. Ethanol extract of the plant has the highest effect on Saccharomyces cerevisiae but no effect on Yarrowia lipolytica. The HPLC-MS/MS analysis showed that at least 11 major phenolic compounds of N. trachonitica exist, the major ones being rosmarinic acid, chlorogenic acid and quinic acid. The obtained results suggest that N. trachonitica could be a promising source for food and nutraceutical industries because of its antimicrobial and antioxidant properties and phenolic compounds.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2017Antioxidant activity and polyphenol content of Turkish thyme (Thymus vulgaris) monitored by liquid chromatography and tandem mass spectrometry
Köksal, Ekrem; Bursal, Ercan; Gülçin, İlhami; Korkmaz, Mustafa; Çağlayan, Cüneyit; Gören, Ahmet C.; Alwasel, Saleh H.
Like tea, the leaves of Turkish thyme (Thymus vulgaris) can be boiled in water to produce an extract. This is widely used as syrup for the treatment of coughs and bronchitis at alternative medicine clinics in many parts of the world. In the current study, we assessed the phenolic content and antioxidant activity of thyme. The antioxidant activities of both ethanol and aqueous extracts of thyme were determined using various in vitro methods. The total phenolic and total flavonoid contents were determined to be a gallic acid equivalent and a quercetin equivalent, respectively. Finally, the quantities of the phenolic compounds were detected using high-performance liquid chromatography and tandem mass spectrometry. The total phenolic compounds in the aqueous extract and ethanol extracts of Turkish thyme were 256.0 μg gallic acid equivalent/mg dried extract and 158.0 μg gallic acid equivalent/mg dried extract, respectively. Conversely, the total flavonoid compounds in both extracts were 44.2 μg and 36.6 μg quercetin equivalent/mg dried extract, respectively. For the first time, we determined phenolic contents and investigated the antioxidant potential of thyme. The results indicate that Turkish thyme is a good dietary source with phenolic properties.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2017Purification, characterization, and inhibition sensitivity of peroxidase from wheat (Triticum aestivum ssp. vulgare)
Altın, Sevgi; Tohma, Hatice; Gülçin, İlhami; Köksal, Ekrem
The purification and characterization of peroxidase is currently growing interests since peroxidases have implications in various industrial and biochemical applications. In this study, wheat peroxidase was purified using (NH4)2SO4 precipitation, CM-Sephadex cation exchange, and gel filtration chromatographies. Enzyme purity and molecular mass were checked by sodium dodecyl sulphate polyacrylamide gel electrophoresis. Enzyme kinetics was studied using two substrates: guaiacol and hydrogen peroxide (H2O2). Km and Vmax values were calculated from Lineweaver-Burk graph for each substrate. Wheat peroxidase activity has been enhanced 284-fold. Wheat peroxidase had molecular mass of 38.8 kDa. Km values for guaiacol and H2O2 were found as 2.467 mM and 7.307 mM, respectively. The pH and temperature optima were 5.5 and 40.0°C, respectively. Also, the enzyme was highly inhibited by citric acid and Cetyltrimethylammonium bromide.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2017Antioxidant activity and phenolic compounds of ginger (Zingiber officinale Rosc.) determined by HPLC-MS/MS
Tohma, Hatice; Gülçin, İlhami.; Bursal, Ercan; Gören, Ahmet C.; Alwasel, Saleh H.; Köksal, Ekrem
Oxidative stress related diseases often arise from over production of free radicals and reactive oxygen/nitrogen species. The prevention of these diseases could be possible with the use of natural antioxidant plants that could be promising as therapeutic candidates. Since antioxidant properties of a species could be stem from phenolic compounds, it is, therefore, important to evaluate antioxidant and total/individual phenolic and flavonoid content. For this purpose, we evaluated antioxidant properties of ginger (Zingiber officinale Rosc.) based on three parameters: the antioxidant capacity, total phenolic and flavonoid content as well as identification of phenolic acids of water extract (WEG) and ethanol extract (EEG) of ginger. For antioxidant capacity, we performed FRAP, CUPRAC assay, Fe2+ chelating ability, DPPH and DMPD radical scavenging activities. Also, total phenolic and flavonoid contents in both extracts were also measured via Folin Ciocalteu’s method. For identification of phenolic acids, HPLC-MS/MS method was performed. The results showed that EEG had generally better antioxidant activity than WEG in all assays. HPLC-MS/MS analysis showed that there are at least eight different phenolic acids found in ginger, among which pyrogallol p-hydroxybenzoic acid, ferulic acid and p-coumaric acid were more abundant in both extracts. This study clearly showed that ginger extracts demonstrated effective antioxidant properties and their consumption may reduce or delay the progression of diseases that oxidative stress take place due to lack of antioxidant supplementation.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2017Purification, characterization and selected inhibition properties of peroxidase from haricot bean (Phaseolus vulgaris L.)
Köktepe, Tubanur; Altın, Sevgi; Tohma, Hatice; Gülçin, İlhami; Köksal, Ekrem
In this study, a cationic soluble peroxidase (POD) was homogeneously purified and biochemically characterized. The enzyme purification involved the combination of (NH4)2SO4 precipitation, CM-Sephadex cation exchange, and gel filtration chromatography. The purity of the enzyme was examined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis, and one single prominent band was obtained with a molecular weight of approximately 45 kDa. The thermal and pH stability showed that the enzyme was stable at pH 5.0 and at 40°C, respectively. The activity remained stable at pH 4.0 at least for 10 days. Km and Vmax values were calculated from Lineweaver–Burk graph for each substrate. POD exhibited Km values of 0.0154 and 0.065 mM for guaiacol and H2O2, respectively. The enzyme was highly inhibited by sodium azide. This study could enrich the literature regarding the properties of POD from haricot bean that could be applicable to biomedical analysis.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2016RP-HPLC/MS/MS analysis of the phenolic compounds, antioxidant and antimicrobial activities of salvia L. Species
Tohma, Hatice; Köksal, Ekrem; Kılıç, Ömer; Alan, Yusuf; Abdullah Yılmaz, Mustafa; Gülçin, İlhami; Bursal, Ercan; Alwasel, Saleh H.
The identification and quantification of the phenolic contents of methanolic extracts of three Salvia L. species namely S. brachyantha (Bordz.) Pobed, S. aethiopis L., and S. microstegia Boiss. and Bal. were evaluated using reverse phase high performance liquid chromatography, UV adsorption, and mass spectrometry (RP-HPLC/MS). In order to determine the antioxidant capacity of these species, cupric ions (Cu2+) reducing assay (CUPRAC) and ferric ions (Fe3+) reducing assay (FRAP) were performed to screen the reducing capacity and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay was employed for evaluation of the radical scavenging activity for both solvents. In further investigation, the antimicrobial activities of Salvia species were tested using the disc diffusion method against three Gram-positive and four Gram-negative microbial species, as well as three fungi species. The results showed that there is a total of 18 detectable phenols, the most abundant of which was kaempferol in S. microstegia and rosmarinic acids in S. brachyantha and S aethiopis. The other major phenols were found to be apigenin, luteolin, p-coumaric acid, and chlorogenic acid. All species tested showed moderate and lower antioxidant activity than standard antioxidants such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and ascorbic acid. The ethanolic extracts of Salvia species revealed a wide range of antimicrobial activity. S. brachyantha and S. microstegia showed the highest antimicrobial activities against B. subtilis, whereas S. aethiopis was more effective on Y. lipolytica. None of the extracts showed anti-fungal activity against S. cerevisiae. Thus these species could be valuable due to their bioactive compounds.
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